# Gaggia Preinfusion Dimmer & Panel mount Guage mod



## majnu

I'm getting the bits ready to do the preinfusion mod using a dimmer switch. Prior to tackling this I wanted to install a front facing panel mounted pressure guage. This will help "see" what pressure I am getting during pre-infusion and during the extraction process. I guess I can finally see if the OPV was set correctly by the previous owner too!









I did want a glycerin filled 40mm pressure guage but these were hard to source especially at this size. Therefore I ended up using the commonly used Vibiemme capillary guage which isn't as effective as glycerin when it comes to damping but it does the job nevertheless.

*Parts:*

- Vibiemme Manometer 0-16 Bar - *£14.32*

- 6mm High Pressure Tubing

- T Fit Push lock connector

- 1/8" to 6mm push lock connector

(These were given to me free from a local hydraulics supplier. JimBean, I have the parts for you also if you ever decide to want to do this mod too







)

- 40mm stainless steel hole cutting saw

- Cool and Cut lubricant

(Builders on site let me borrow theirs for this project)

*Installation:*

There are various ways to do this, either by:

- Tapping into the OPV

- Tapping into the Pump

- Using a Y connector to the Steam valve or by drilling and tapping into the Steam Valve (Note this depends on the Steam valve variant you have)

I have decided to tap into the pump as plumbing will be easier to manage and there is less fluctuation of the needle.

*Pics:*
































































*Next Steps:*

*
*- Cut the front of GC for the guage

- Install and Test Guage

- Find a suitable dimmer

- Decide if I should panel mount the dimmer from the Steam side or have a separate project box

- Get 2 core lamp wiring and necessary connectors

- Explore pressure profiling vs extraction


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## froggystyle

Looking forward to seeing this one Majnu!


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## ZugZwang

Nice, keep us updated about this, I might be tempted to try that mod on my gaggia as well.


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## majnu

In my haste trying to get this done quicker I used the hole cutter provided by some builders, unaware that their 40mm hole cutter was in fact larger (probably 44mm) so I have to salvage this the best way I can. I've got some shims ordered which should hopefully enable to guage to click into place.

Some lessons I've learned from this are:

- Make sure that the guage depth and the exit connection clear the boiler. It will very likely catch if it is placed too low. The Allen bolt retainer at the bottom of the boiler will definitely cause problems if you judge this wrong.

- Use a smaller hole cutter (38mm) this is because you can then use a stone attachment on a Dremmel to clean any burrs around the edge of the hole to make it cleaner and to slowly remove any material. There are probably hole cutters out there that make a clean cut so this needs looking into.

- The copper pipe on the guage can be tricky to shape into place.

But for now I can read Dynamic pressure. It is showing just over 10 Bars using my back flushing basket locked into the portafilter. Next Update will be when I get my dimmer and fix the guage into place.


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## MrShades

Which dimmer have you gone for?


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## El carajillo

majnu said:


> In my haste trying to get this done quicker I used the hole cutter provided by some builders, unaware that their 40mm hole cutter was in fact larger (probably 44mm) so I have to salvage this the best way I can. I've got some shims ordered which should hopefully enable to guage to click into place.
> 
> Some lessons I've learned from this are:
> 
> - Make sure that the guage depth and the exit connection clear the boiler. It will very likely catch if it is placed too low. The Allen bolt retainer at the bottom of the boiler will definitely cause problems if you judge this wrong.
> 
> - Use a smaller hole cutter (38mm) this is because you can then use a stone attachment on a Dremmel to clean any burrs around the edge of the hole to make it cleaner and to slowly remove any material. There are probably hole cutters out there that make a clean cut so this needs looking into.
> 
> - The copper pipe on the guage can be tricky to shape into place.
> 
> But for now I can read Dynamic pressure. It is showing just over 10 Bars using my back flushing basket locked into the portafilter. Next Update will be when I get my dimmer and fix the guage into place.


L S STARRRETT make /supply 40 mm holesaw's they should be used with "cutting oil" as manju said and the speed for a 40 mm saw on stainless steel is 110 r p m =very slow.


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## grumpydaddy

If you are buying a holesaw for precise work, get a new pilot drill too, a straight one







they are quite prone to bending in the hands of a "builder"


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## Jim bean

Hi majnu good effort good idea for taping in to the pump if the bigger hole bothers you try fixing a small piece of aluminium plate or similar With the correct size hole fix in place inside the casing with JB weld if you have some already

then file the retaining clips down on the gauge to fit

thanks for the offer I might take you up on that if I go for it

cheers James


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## El carajillo

grumpydaddy said:


> If you are buying a holesaw for precise work, get a new pilot drill too, a straight one
> 
> 
> 
> 
> 
> 
> 
> they are quite prone to bending in the hands of a "builder"


Starrett drills do not bend they are high speed steel, if they go they snap. If the cutter has a soft drill it is a D I Y job and will not be up to stainless steel, neither will the holesaw.


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## majnu

MrShades said:


> Which dimmer have you gone for?


Not chosen one yet. I've seen some varilight vpro control modules that are rated for 10watt min load, I might go for that but do I get one that has a higher rating for 100W, 400W, 600W etc bulbs? Additionally shall I get one that clicks on/off or one which you have to turn on/off?



grumpydaddy said:


> If you are buying a holesaw for precise work, get a new pilot drill too, a straight one
> 
> 
> 
> 
> 
> 
> 
> they are quite prone to bending in the hands of a "builder"


I was going to buy either of these before I guess they would have been much better:

http://www.amazon.co.uk/gp/product/B00EZAQTU6?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_

http://www.amazon.co.uk/Cutting-Metal-Working-Drilling-Cutter/dp/B00AUBBJ0O/ref=pd_sim_sbs_diy_2?ie=UTF8&refRID=1HPSJ88REJPRNMV3ETM9


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## majnu

Jim bean said:


> Hi majnu good effort good idea for taping in to the pump if the bigger hole bothers you try fixing a small piece of aluminium plate or similar With the correct size hole fix in place inside the casing with JB weld if you have some already
> 
> then file the retaining clips down on the gauge to fit
> 
> thanks for the offer I might take you up on that if I go for it
> 
> cheers James


That's what I plan on doing bar filing down the retaining clips. I couldn't find a washer with a 40mm id but found some tractor firm selling shims which are the correct measurements. All will be revealed if they arrive by next week hopefully.

I'm OCD so if it's not perfect/oem looking it will bug me for the rest of my life


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## majnu

El carajillo said:


> L S STARRRETT make /supply 40 mm holesaw's they should be used with "cutting oil" as manju said and the speed for a 40 mm saw on stainless steel is 110 r p m =very slow.


I set the cordless drill on the slowest speed but high torque setting, I used the lubricant when it got too hot or snagged but it did the job except it didn't give a clean cut and was obviously the wrong size. Care had to be taken securing the Gaggia so that it didn't wobble whilst drilling. I'll look into that make cheers.


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## majnu

Tried a 40Watt min 250Watt max dimmer I had lying around and it doesn't bring the pressure down low enough, it went as far down as half a bar.

I will experiment with a lower load or a greater load dimmer and see what the results are.


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## MrShades

You mean it dropped BY half a bar or it dropped TO half a bar?


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## majnu

MrShades said:


> You mean it dropped BY half a bar or it dropped TO half a bar?


Sorry bad engrish, it dropped by half a bar if it dropped to half a bar I'd be happy as larry right now.









I can hear the pump changing in tone and the flow slowing down slightly but the pressure guage shows 9.5 bar static with the portafilter and blanking disc in place.

Edit found some old beans and pulled a shot the pressure went down to 6.5 bar at lowest setting and 10 bar was maximum. Is the opv adjusted correctly then as I expected it to go to 9? Why doesn't it show 6.5bar when the blanking plate is used?


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## El carajillo

The old beans are allowing the water to flow away too quickly, try it with some fresh beans and "possibly" grind finer.

It could also be that the pump cannot maintain sufficient flow/ volume and pressure.


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## hotmetal

Wow this level of modding is far beyond my comfort zone or abilities but I love reading the threads! It's like watching a streetfighter build on the motorbike forums. Thanks for sharing.


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## majnu

El carajillo said:


> The old beans are allowing the water to flow away too quickly, try it with some fresh beans and "possibly" grind finer.
> 
> It could also be that the pump cannot maintain sufficient flow/ volume and pressure.


How does that affect the pump pressure (I'm guessing coarser grinds diverts too much pressure)?

I want to have consistent readings using the blanking plate in place so that I'm reading static pressure when I adjust the dimmer.

My pump is new, only fitted it last month iirc so it can't be knackered.


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## Bigpikle

this is really interesting - thanks.

I'm very tempted by the idea of an Auber PID with the pre-infusion, as my tech skills arent up to building my own. Challenge is whether I can actually fit the damn thing or not?

Looking forward to seeing pics of the final build.


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## majnu

40/600Watt dimmer ordered, I'm hoping that this will do the trick as reading on HB and CG they used 600Watt module (This), However it doesn't specify the minimum wattage. It's a shame that I couldn't find a cheaper module like the options they have in the States but we are where we are.


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## MrShades

I've got one of those US dimmers (in a 220V version) and it works about the same as every other dimmer I've tried. It's not as magical as the yanks make out - and certainly can't get down to 1bar (with a 48W Ulka pump - I need to try with the 65W Invensys pump as well, I've got one somewhere).

Currently I use a 40/300W slide dimmer, like this: http://www.savemylight.co.uk/kfd527g3.html#.VIW8pHtMD30

You can't control the actual pressure very easily with any of them (especially with the heating elements going on/off courtesy of a PID - as you'll discover!)... but you can use it to blip the pump for preinfusion, and then leave the pump off for a while, and then pump on again (all without activating the solenoid valve).

I have thought of having either the elements ON all the time that the pump is on, or OFF all the time, to help the stability of the pressure 'profiling' - but I don't think either option is a good one. I may install a momentary push switch that would allow the heating elements to be turned off just for the duration of the preinfuse / pressure profile - and turned on again when you're running the pump 'flat out' (as the heater makes no difference then).

Keep going though - and report back... as it's all good fun!


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## majnu

Good and Bad News:

*Good*

*
*I managed to rescue fitting the guage using the shims



*
Bad*

*
*With the new 40/600 dimmer the needle fluctuates like mad whilst pulling a shot of espresso at the higher range, at the lowest range the guage shows 6.5barI really have no idea what's going on now.


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## MrShades

Watch the video I'm just uploading to my thread about low pressure... and then get on eBay and buy an Invensys pump for £20


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## majnu

MrShades said:


> Watch the video I'm just uploading to my thread about low pressure... and then get on eBay and buy an Invensys pump for £20


Done. Frustrates me though that in the preinfusion threads over the internet that nobody mentioned that the Ulka doesn't work. It's possible that I could be wrong but I've wasted money on a few dimmers now and the pressure doesn't drop where we want it to go using a pressure guage to quantify the result.

Oh LF seem to stock them too but I'm not sure if it's the right model as it's not specified.

But looking at your video it appears Invensys is the pump that will only work.


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## MrShades

1122741 is what you want... but cheaper on eBay (Invensys CP3A) when you factor in shipping.


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## majnu

Shims had time to set overnight and guage now installed.


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## majnu

Invenysys pump is now installed and looks like it handles voltages much better. Until I get the bits for my thermofilter build I used a crude method for restricting the brew to read and mark of pressure profiles at 3,6,9 bars. It appears that the lowest it goes to is 2 bars. I can use the full range of the dimmer switch's dial therefore it gives plenty of turning space between each profile.

I pulled a shot and it looks similar to MrShade's whereby their is more striping in the crema. I ground finer and the first drops of coffee appeared after 10-15 seconds. At around 35 seconds (when I stopped the extraction) the pour still hadn't blonded, so it looks like you can stretch this phase out. What does concern me however is what is happening to the water temperature during the shot, so until I build a thermofilter I assume (judging from the PID) that it's dropping below 90 degrees.

Taste wise, until I experiment more (next week) my first impressions were that there was plenty of mouth feel and more of a caramel taste with Rave's Mocha Java blend.

*Pics*


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## Dylan

Loving this thread, a very cool mod. It's great to see quite what you can do with the most basic of machines!

Shame the dimmer switch is ugly as sin, the rest look great


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## grumpydaddy

I'm looking at this and thinking that it is so small you could get another, modify it some so that it attaches to the back and voilà: gaggia dual boiler classic.

Good read this.


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## MrShades

What's that little rotary knob MrShades..,

Ah, that's a very good question ;-)


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## majnu

Dylan said:


> Shame the dimmer switch is ugly as sin, the rest look great


I have an evil plan, just wanted to know it worked first before hacking into the machine.


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## MrShades

majnu said:


> 40/600Watt dimmer ordered, I'm hoping that this will do the trick as reading on HB and CG they used 600Watt module (This), However it doesn't specify the minimum wattage. It's a shame that I couldn't find a cheaper module like the options they have in the States but we are where we are.


Just FYI, I managed to source a 220V version of the Leviton dimmer that the yanks use... and even with the Invensys pump, it's rubbish... you 'click' it on and it immediately ramps up to about 7 bar...


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## majnu

I've borrowed JimBean's thermofilter so that I can dial in pressure profiles but need your help.

(1)Why is it when I set the thermofilter to output 2oz of water (double shot) within 25-30 seconds (so that it simulates extraction) that the pressure gauge only shows 9-10bar no matter what dial setting (lowest or highest) I use on the dimmer?

(2)When I increase the flow rate on the thermofilter's orifice so that water is coming out at a much faster rate only then does the pressure gauge visually show an increase or decrease in pressure when I turn the dimmer's dial.

In both cases when I turn the dimmer to the lowest setting I can visually see a decrease in flow rate (but not pressure in the first case (1)), but then how do I accurately mark pressure profiles on the dimmer knowing the above?


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## MrShades

I've now managed to mount my gauge in the Classic - but had to get a friend with a CNC milling machine to cut the damn stainless for me... I was breaking drill bits and going nowhere!

Anyway, I found the ideal T to fit it and it all works well with no hint of any leaks anywhere. Very pleased with the end result.

A quick snap of internal plumbing and final result:



















Thanks for the idea Majnu


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## MartinB

Lovely job, I started a thread about this a couple of years back and this answers the questions I have!

Do either of you have videos of this in action? I was thinking of tapping into the steam valve but this seems a hell of a lot easier.


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## froggystyle

Whats the box on top for?


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## MrShades

froggystyle said:


> Whats the box on top for?


Read and enjoy: http://coffeeforums.co.uk/showthread.php?21171-Automatic-shot-timer-project


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## MrShades

MartinB said:


> Lovely job, I started a thread about this a couple of years back and this answers the questions I have!
> 
> Do either of you have videos of this in action? I was thinking of tapping into the steam valve but this seems a hell of a lot easier.


You can see it working in the shot-timer post (inc video) that I've linked to above.


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## majnu

Looks great. Is that a different gauge?

Also apologies that I haven't been on recently. A good friend of mine passed away from Bowel Cancer and it hit me pretty hard watching him deteriorate and then eventually die a few days later. He was only 31 and left behind a loving wife, mother and 2 kids. He was diagnosed with Cancer at 27 and left us all at no age at all. When I'm feeling up to it I'll be active and posting again but in the meanwhile will just be lurking and catching up on threads. I did plan to do another Group Buy for Brass Plates in the New Year but that's on hold for now.


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## MrShades

Well, it's not the same gauge that you bought no - it's still a 0-16 bar gauge suitable for a Vibiemme, but sourced from LF.

It's this fella: http://www.espressoxxl.de/shop/artikel/IS0318/nonJava/detail.html

Quite nice as it has bar and psi on it.

40mm wide etc - and a tight fit but easily doable:














































[


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## mremanxx

Hi, just ordered a gauge to do this, did you have any problems cutting the hole MrShades?

Also what was the dimmer switch for.

Thanks


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## MrShades

Cutting the hole - bloody nightmare. I have much more respect for shiney stainless steel now than I did a week or two ago. Nothing I had would touch it...

In the end I had a friend CNC mill the hole for me.

Good luck!

(dimmer switch is for pressure profiling - or controlling the pump so that you can vary pump pressure - look at some of my other posts on here about it)


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## gingerneil

majnu said:


> Looks great. Is that a different gauge?
> 
> Also apologies that I haven't been on recently. A good friend of mine passed away from Bowel Cancer and it hit me pretty hard watching him deteriorate and then eventually die a few days later. He was only 31 and left behind a loving wife, mother and 2 kids. He was diagnosed with Cancer at 27 and left us all at no age at all. When I'm feeling up to it I'll be active and posting again but in the meanwhile will just be lurking and catching up on threads. I did plan to do another Group Buy for Brass Plates in the New Year but that's on hold for now.


Sorry to hear that. I'm 36, with an amazing wife and two fantastic kids. I cant imagine something like that hitting the family. Certainly makes you stop, think, and puts my shite attempt at a flat white this morning into perspective!

(ps - on the brass plate buy - I'll keep an eye out - hopefully I wont miss this one!!)


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## Finley

majnu said:


> Looks great. Is that a different gauge?
> 
> Also apologies that I haven't been on recently. A good friend of mine passed away from Bowel Cancer and it hit me pretty hard watching him deteriorate and then eventually die a few days later. He was only 31 and left behind a loving wife, mother and 2 kids. He was diagnosed with Cancer at 27 and left us all at no age at all. When I'm feeling up to it I'll be active and posting again but in the meanwhile will just be lurking and catching up on threads. I did plan to do another Group Buy for Brass Plates in the New Year but that's on hold for now.


Just echoing what gingerneil said, sorry to hear that majnu


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## mremanxx

Thanks MrShades, I did read earlier posts but still wasn't sure what the dimmers function was for. I take it that it isn't really necessary? I only fancy fitting a gauge to help with tamp/dose regulation.

Did you try and cut the hole using a normal hole cutter that was hopeless?


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## matthew2456

Where's the best place to get a gauge?


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## Mrboots2u

matthew2456 said:


> Where's the best place to get a gauge?


Read post 21


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## mremanxx

Got mine from Shock wave on ebay


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## Liam_Smart

Hi all,

Still new to the forum and reading many (many) posts before I feel confident enough to ask questions. This pressure gauge/manometer mod is something I'm going to do. Been doing a lot of reading so thought I'd try and contribute.

Someone had cut their hole too big (possible OP). Depending on how much too big, a solution could be buying another 50mm version or buying a cheap 3-hole mounting plate to go round their 40mm gauge:

http://www.buyagauge.co.uk/epages/211912.sf/en_GB/?ObjectPath=/Shops/211912/Products/3HOLEFIX/SubProducts/3holefix-0001

Glycerin 40mm gauges can be bought here. This is where I'll probably get mines from (although I would like a matching temperature gauge - I can see me attempting to measure water temp in the boiler as I've seen a pic of someone doing this):

http://www.buyagauge.co.uk/epages/211912.sf/en_GB/?ObjectPath=/Shops/211912/Products/%2240MM%20STSTCASE%20GAUGES%22/SubProducts/%2240mm%20ststcase%20gauges-0029%22

However, if I could find a replacement valve to on top of my boiler that had 2 outlet valves, I wonder if a thermo-manometer (thermomanometer depending on how you Google it) could be attached here that measures both pressure and temperature. I can only find one that goes upto 10-bar in the UK though (note: I found a German one that went to 16-bar...):

http://modusgauges.com/Combined-Pressure-Temperature-Gauges-Indicators/Combined-Pressure-Temperature-Gauges/80mm-Dry-Back-Connection-Accuracy-2-5-/prod_22.html

MrShades, where did you get your t-connector from. What spec is it and has it worked without leaks for you?

Majnu, why did you not connect the capillary straight onto the T-Connector you put between the pump and boiler inlet? Did it not reach?

Also I noticed from whoever posted the pics (I'd go back but I'm scared I'll lose this text if I do as I'm of an annoying iPad - Majnu I would have thought) that the capillary/tube from back of the gauge us coiled up as it's long. Would a 25cm one be a better option?

***Update***

The Gaggia Coffee model has the dual steam valve ontop of the boiler. So I search for the following part. Could I just replace my single outlet one with this one, and attch the pressure gauge straight onto the first outlet and re-attach the steam pipe back onto the 2nd one? This would be minimal 'customisation' to the internal working IMO. Plus measuring the pressure as late in the system as possible should be a truer reading AND if I ever foubd a suitable thermomanometer I could do a quick swap around so I am measuring water temp and pressure at the same time. I am tempted to do the PID mod but essentially you are monitoring and controlling the temperature of the boiler, indirectly attempting to control water temp. I could live with just knowing what temperature the water coming out of the boiler is at the time of pulling my shot of espresso.

http://www.gaggia-parts.co.uk/epages/es147467.sf/en_GB/?ObjectPath=/Shops/es147467/Products/EF0097A&ViewAction=ViewProduct

I don't want to puchase anything without discussing with someone incase I've totally misunderstood how the Classic works.

Thanks,

Liam


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## majnu

Liam

I just followed the advice from those who did the mod before on GUG they recommend I placed the connection in it's current position to reduce fluctuations.

As for using a larger guage size I guess if it doesn't look out of place and looks proportional to the size of the machine it will fit. But make sure that it clears the boiler at the bottom of the machine.

25cm length coil/copper pipe? I have no idea on the size sorry as it's soldered into the back of the guage and there wasn't an option to customize the length. The coil acts as a damper if you're getting a glycerin filled one then there is no need to have a coil.

The second link is the same as the first so I can't view your gauge but if it has a 1/4 or 1/8 back fitting you can get a push lock connector similar to what I used and then use high pressure plastic tubing into the T piece instead of a copper pipe.

Replacing the steam valve to the one you've selected would have made the mod more than it's worth for me personally hence why I went down the cheaper and most convient route. But essentially what you described is how it fits together as shown in the video in the OP.

hth

Edit

Seems I didn't link the video but it's this one:

Gaggia Classic Bar Pressure Gauge OPV Mod:


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## Liam_Smart

Thanks Majnu,

I have fixed my link above. I think this will be my first mod









The info about not needing a coiled copper pipe has been very useful!

Thanks,

Liam


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## majnu

The high pressure pipes aren't very flexible so bear that in mind, with copper you can create bends to get a cleaner look but then takes some effort to get right. Also you will need the clamp.

http://www.buyagauge.co.uk/epages/211912.sf/en_GB/?ObjectPath=/Shops/211912/Products/PANELCLAMP/SubProducts/panelclamp-0005


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## mremanxx

How did you cut the hole majnu?


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## MrShades

mremanxx said:


> Thanks MrShades, I did read earlier posts but still wasn't sure what the dimmers function was for. I take it that it isn't really necessary? I only fancy fitting a gauge to help with tamp/dose regulation.
> 
> Did you try and cut the hole using a normal hole cutter that was hopeless?


Dimmer not necessary really no - and difficult to find a good one, and you really have to swap the pump for an Invensys one if you have an ULKA. However, not a huge amount of point to a gauge if it simply points to 9bar all the time is there... ;-)

I tried drilling a pilot hole with a standard HSS drill bit and cutting oil (various sizes of bit - getting smaller and smaller, until I gave up when a 2mm one snapped under the pressure that I was exerting on it - and lightly scratched the damn case). At this point I'd gone from a 6mm bit to a 2mm bit and not even started cutting anything like a hole. Then I tried tungsten carbide grinding tools in my dremel - managed to dent it after a while with them but that was it. A proper stainless steel hole cutting saw with a proper / suitable pilot drill bit may do it (majnu managed it this way). Personally, I think the shiney stainless is harder than the brushed stuff...! The CNC milling machine took about 30 mins to cut the hole out.


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## mremanxx

Yeh hardly seems worth it now, I knew stainless was a git. A gauge looks nice though:drink:


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## MrShades

Liam_Smart said:


> Hi all,
> 
> Still new to the forum and reading many (many) posts before I feel confident enough to ask questions. This pressure gauge/manometer mod is something I'm going to do. Been doing a lot of reading so thought I'd try and contribute.
> 
> Someone had cut their hole too big (possible OP). Depending on how much too big, a solution could be buying another 50mm version or buying a cheap 3-hole mounting plate to go round their 40mm gauge:
> 
> http://www.buyagauge.co.uk/epages/211912.sf/en_GB/?ObjectPath=/Shops/211912/Products/3HOLEFIX/SubProducts/3holefix-0001
> 
> Glycerin 40mm gauges can be bought here. This is where I'll probably get mines from (although I would like a matching temperature gauge - I can see me attempting to measure water temp in the boiler as I've seen a pic of someone doing this):
> 
> http://www.buyagauge.co.uk/epages/211912.sf/en_GB/?ObjectPath=/Shops/211912/Products/%2240MM%20STSTCASE%20GAUGES%22/SubProducts/%2240mm%20ststcase%20gauges-0029%22
> 
> However, if I could find a replacement valve to on top of my boiler that had 2 outlet valves, I wonder if a thermo-manometer (thermomanometer depending on how you Google it) could be attached here that measures both pressure and temperature. I can only find one that goes upto 10-bar in the UK though (note: I found a German one that went to 16-bar...):
> 
> http://modusgauges.com/Combined-Pressure-Temperature-Gauges-Indicators/Combined-Pressure-Temperature-Gauges/80mm-Dry-Back-Connection-Accuracy-2-5-/prod_22.html
> 
> MrShades, where did you get your t-connector from. What spec is it and has it worked without leaks for you?
> 
> Majnu, why did you not connect the capillary straight onto the T-Connector you put between the pump and boiler inlet? Did it not reach?
> 
> Also I noticed from whoever posted the pics (I'd go back but I'm scared I'll lose this text if I do as I'm of an annoying iPad - Majnu I would have thought) that the capillary/tube from back of the gauge us coiled up as it's long. Would a 25cm one be a better option?
> 
> ***Update***
> 
> The Gaggia Coffee model has the dual steam valve ontop of the boiler. So I search for the following part. Could I just replace my single outlet one with this one, and attch the pressure gauge straight onto the first outlet and re-attach the steam pipe back onto the 2nd one? This would be minimal 'customisation' to the internal working IMO. Plus measuring the pressure as late in the system as possible should be a truer reading AND if I ever foubd a suitable thermomanometer I could do a quick swap around so I am measuring water temp and pressure at the same time. I am tempted to do the PID mod but essentially you are monitoring and controlling the temperature of the boiler, indirectly attempting to control water temp. I could live with just knowing what temperature the water coming out of the boiler is at the time of pulling my shot of espresso.
> 
> http://www.gaggia-parts.co.uk/epages/es147467.sf/en_GB/?ObjectPath=/Shops/es147467/Products/EF0097A&ViewAction=ViewProduct
> 
> I don't want to puchase anything without discussing with someone incase I've totally misunderstood how the Classic works.
> 
> Thanks,
> 
> Liam


A few points / answers:

My gauge (non glycerin) is rock solid - and doesn't fluctuate at all (due, probably, to the long capillary tube feeding it). I went looking for a 40mm glycerin filled one and couldn't find anything suitable. If I'd previously seen my machine with my gauge fitted then I wouldn't have bothered even looking for a glycerin one - as I dislike the "half filled" air bubble look anyway.

The T piece is a standard pneumatics part - 6mm push fit Tee piece with 8mm BSP male fitting on the T. I found them on eBay, quite cheaply, but couldn't wait for one and went to a local Pneumatics supplier and bought one for about £4. Officially they're rated to 10bar I think - so works well, doesn't leak at all (I was surprised!) and was VERY easy to fit. I'm still amazed that the pushfit works so well without leaking...

They come with the capillary tube coiled - and it helps the stability of the needle to have a long capillary tube. Not an issue at all, gives you flexibility in tube routing, etc. - and if anything a shorter capillary may introduce needle wobble. Very happy with it entirely.

£3 : http://www.ebay.co.uk/itm/Plastic-Push-In-Fitting-Swivel-Branch-Tee-BSPT-Male-/131401829708?pt=LH_DefaultDomain_3&var=&hash=item1e9828cd4c

Regarding where you measure the pressure: I think you'll find that it makes no difference where in the pipework / process you measure the pressure. It'll be the same pressure all the way through - and my pressure reading (from an inch after the pump) should be the same as one just before the OPV, or inside the boiler, or on top of the puck... (I think!)


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## MrShades

mremanxx said:


> How did you cut the hole majnu?


One of these, with a suitable pilot/thingywhatsit, would probably do it: http://www.wickes.co.uk/Bosch-Progressor-Hole-Saw-40mm/p/216044

However, paying a similar price for the hole saw (that I'd probably never use again) as I paid for the gauge seemed bonkers.... so "phoned a friend".


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## mremanxx

I have that exact on MrShades.

Actually have the 38mm one as normally the hole should be slightly smaller for the retaining tangs. Just wary starting it if drilling is going to be a sod.


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## majnu

mremanxx said:


> How did you cut the hole majnu?





MrShades said:


> One of these, with a suitable pilot/thingywhatsit, would probably do it: http://www.wickes.co.uk/Bosch-Progressor-Hole-Saw-40mm/p/216044
> 
> However, paying a similar price for the hole saw (that I'd probably never use again) as I paid for the gauge seemed bonkers.... so "phoned a friend".


Yup that's the one that the builders lent to me, it has cobalt alloy so is quite strong.

I measured where to drill the pilot hole, I prepunched it, masked the area and then used a hss drillbit to guide the holecutter. During cutting I applied some of that cutting lube to help cool the cutter. I used low speed and high torque setting on the cordless drill and applied enough pressure to manage the cut without jamming it. I took around 20-30 mins to cut the hole as I took some breaks inbetween to also help cool the ss and cutting tool. It's a slow process but I easily managed it.

You will need to keep the gaggia stable whilst cutting though which can be tricky, If you're not confident enough to do it and don't have the tools already then a local machinist shop should be able to cut it for you.


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## mremanxx

Thanks majnu, just measured the gauge and do need a 40mm cutter..bummer, need to get one this size instead first.


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## MrShades

And don't underestimate the power of the stainless - "just shaving a mill off" with any mortal instrument will not be quick or easy!

Good luck...


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## majnu

MrShades said:


> And don't underestimate the power of the stainless - "just shaving a mill off" with any mortal instrument will not be quick or easy!
> 
> Good luck...


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## MrShades

Here's a quick shot of mine from when it was on the operating table :


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## Ian S

I can't see it in any of the photos, did you chaps put the dimmer in series with just the pump, or with the entire coffee machine?



MrShades said:


> My gauge (non glycerin) is rock solid - and doesn't fluctuate at all


Did you flush the air out of the capillary with water? Or leave it filled with air. My Wika gauge does fluctuate. It's oil filled and does have water right up to the gauge. pidsilvia pressure gauge cut out: http://www.pidsilvia.com/cutout.htm


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## MrShades

Dimmer is just on the pump, yes.

Didn't bother explicitly filling capillary with water - just hooked it up and away it went, rock solid.


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## Ian S

Maybe I'll try and remove the water in the capillary. So, here in the UK you've tried the same pump and dimmer on the same machine that AndyPanda on coffeegeek used, and it didn't work? Maybe it's the UK's 240 voltage somehow? The motors current might be the same though, motor's magnets the same. Maybe the zero switching dimmers are different? Was the one from the USA, same as AndyPanda used, rated at 240V? Maybe we need to get a 240 to 110V transformer and USA spec pump and dimmer?


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## Ian S

http://www.coffeegeek.com/forums/espresso/0/581176#581176 He says the Gaggia with a check valve will give 7 Bar minimum, for pressure required to push open the valve. Do you have a check valve or a three way valves on your machines?


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## Ian S

Success







30 year old zero switching lamp dimmer from my hall ceiling light. Says on it "250 Watts maximum, 40 Watts minimum". Can control from 0 Bar to full pressure using the full rotation of the dimmer. Ulka pump on Rancilio Silvia. Needs careful constant adjustment to keep the pressure down. Flow dependant in that pressure will creep up and up if left at a given setting. I've been doing extractions between 3 and 5 Bar. It can quickly pop up to 10 Bar so some manual predictive lowering is needed to keep it adjusted down. I've used 4 different grind settings for the same weight of coffee, 6 grams, in the 7 gram VST basket, and been able to keep the pressure down for all of them. A lot more testing is required, but not today, I'm already a bit too high on caffeine even though I didn't swallow most of them this morning!


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## Ian S

So, I did three shots this morning with unclear results............................. All were 6grams of Coffee Compass Sweet Bourbon blend into the 7gram VST basket. Two clicks up from bottom with the Preciso. Brew weight 9 grams.................... First: whole draw on only 2 Bar. Very little crema. Forgot to count the number of seconds. Started to drip through then picked up speed whereas normally, with 11Bar, it starts to come through then stops for a few seconds, then comes through again, picking up speed and crema...................... Second: Wasn't sure that first one tasted better so did normal one at 11Bar. This I preferred both mouth feel and taste as it was more syrupy and had plenty of crema and perhaps a bit sweeter. Took 20 seconds..................... Third: I did another at low pressure, but this time let it start extra slow, 1Bar until a few seconds after it began to drip, then turn up to about 3Bar, but it slowly vacillated between 3and 5Bar. Also took 20 seconds. Again just continued to come out with no pause. Seemed to blonde sooner than the 11Bar one. It did have stronger taste in some ways, but not sweet particularly, not bitter either. Little, if any, crema.................... When looking at the used pucks the 11Bar is firm with sharp edges and has risen a bit in an even way. The low pressure ones are slurry in the basket. This perhaps explains why the draw time is the same for high and low pressure, the low is turning the pick into more of a paste so there is less resistance to the water flow..............Sorry about the lack of paragraphs, replaced with......This website, uniquely, ignores them all from this computer.


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## Mrboots2u

Try a flat 8 bar extraction


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## Ian S

Four shots this morning. Again with Coffee Compass Sweet Bourbon Blend, 6 grams in the VST 7 gram basket. 2 clicks up from bottom on the Preciso............. First: Normal 11 Bar to establish a familiar base line. 20 seconds draw time, 6g in, 9g out. Some oil droplets, crema............ Second: Tried to keep it at 8 Bar all the way. It didn't hold stable all that well and was mainly at 7 Bar with occasional peaks up to 10 Bar, needed continuous adjustment of the dimmer to try and keep it stable. The pump would suddenly stringly energise and ramp up. It's not impossible that it caused by the mains supply voltage fluctuating a bit at this time in the morning, I'd have to measure that during a shot. Anyway, also 20 seconds draw time to 9 grams. Similar oil, crema, but more flavour and better than with 11 Bar............. Third: As the 'Slayer' style (low initial pressure, then briefly full Bar, letting it drop off to low again) had not done much for me yesterday, I'd try the style as in the video by ''another Jim' Bezzera / Esmeralda Geisha' which is with full pressure to start, then holding off for the duration until blonding starts. So I gave it the full 11 Bar until just after the initial drips and it's pausing, then I dialled it down and watched the pressure drop off over maybe 10 to 15 seconds, then I held it at about 2 Bar. Draw time 50 seconds to 9 grams. This was the best so far with 'multiple' flavours, some oil, some crema. Both the extremes of draw method seemed to be in there. The used puck was similar to the 11 Bar with even expansion with sharp edges and no slurry.............. Fourth: for agreeing results I repeated the third draw but this time dialled it down to minimum on the dimmer, it sat at about 1 Bar dripping slowly. 60 seconds. Didn't appear to show blonding at that point but was 9 grams so I shut it off. Similar oil and crema but a little more flavour, the best yet, and evoked a small grin. Residue in the mouth didn't seem to go dry or bitter over the next 1/4 hour either................ Another Jim had a steady flow whereas I had steady drips, but he had 17 grams to my 6 grams. He had a 42 second draw time from start of dripping and I presume about 20 to 30 grams brew weight............... He was also able to drop the pressure very fast by lifting the lever, rather that my gradual drop. That Bezzera probably has a more gradual initial ramp up to 9 Bar due to the time is takes takes to fill the large chamber volume, rather than just the small area above the puck, but I can get near to that using the dimmer to gradually turn up the pressure................ 'another Jim (Schulman)' Bezzera / Esmeralda Geisha': http://www.home-barista.com/reviews/bezzera-strega-second-look-t18933.html................. Having now tried a lamp dimmer I comprehend the advantage of this Bezzera Strega to facilitate instant removal and application of a chosen pressure. It could do with a gauge so one knows how much pressure.................... On the Silvia, using a knob adjustable OPV might be the best way. Leaving the pump running and manually adjusting the bypass. The pressure would depend of the sensitivity and range of the bypass before it went into uncontrollable non-linearity................


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## Ian S

Coffee Compass Mediterranian Mocha Espresso Blend: Water would run past this very easily and I'd had to overdose to 12 grams in the 7 gram VST, with a coarser grind of 8 clicks up, to get draw time and flavour. Now with pressure profiling: 6g in 13g out. Caught the 14th gram in a sppon and it tasted rather bitter but worked well in the whole. Again best yet from that blend. Developed inthe mouth over the following minutes. Didn't go dry................................. Coffee Compass Java Jampit hit. 1 click up. 6g beans, 7.5 grams brew weight. I shut it off at 100 seconds! 11 Bar initially, took 15 seconds or so to start dripping through, then I dropped the pressure but it leveled off at about 3 Bar, eventually did drop further but dripping all but stopped, so I increased it a bit to maybe 3 Bar. Awash with oil droplets floating on the top, some crema, plenty of flavour, best I've extracted from that one. And lasted in the mouth quite a while.


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## MrShades

Mrboots2u said:


> Try a flat 8 bar extraction


Slow preinfuse ramp (over about 15s) to 6 bar (for around 20s) is where it's at... 

With the Invensys pump and my dimmer I can just set the dimmer to the "6 bar" setting and this all just happens. No need to adjust anything mid pour.


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## MrShades

Ian S said:


> Maybe I'll try and remove the water in the capillary. So, here in the UK you've tried the same pump and dimmer on the same machine that AndyPanda on coffeegeek used, and it didn't work? Maybe it's the UK's 240 voltage somehow? The motors current might be the same though, motor's magnets the same. Maybe the zero switching dimmers are different? Was the one from the USA, same as AndyPanda used, rated at 240V? Maybe we need to get a 240 to 110V transformer and USA spec pump and dimmer?


As I've just revisited this thread - and you've posed some questions Ian, I'll give you some quick answers:

- Yes, same as AndyPanda used (I've even tried PMing him to see if he had any success with an Ulka) - Invensys pump and the same dimmer, but a 220V variant - shipped by Leviton especially from the US (and don't ask how much it cost to buy and get the damn thing here!). It's a Leviton 6602-220 if anyone's interested.

As I said above, it's rated at 220V and not 240V - but I don't see that making a huge difference. There is no 240V variant.

The Yanks have an Invensys CP3A.384 - which is 110/120V 60Hz, whereas we have the Invensys CP3A.381 - 230V 50Hz.


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## Ian S

Thanks for all those details







For my equipment and the coffees I've tried so far, that 'slayer' method of low pressure start, etc, has not produced the best body and taste in the cup, and the puck does not form but turns into just some sludge. The 'another Jim' method has worked better for me and seems good with whatever grind and beans I use. I don't imbibe a lot of coffee, especially at the moment as I'm having to have some time off of it again, so I'm not saying that the slayer method is no good at all, it just doesn't seem to be with my particular set of equipment and that I only do 6 to 8 grams in the VST 8g basket and not 19 grams in the 18g VST that most people seem to report.









I did a Coffee Compass Java Jampit Hit. 6 grams beans, 2 clicks up from bottom. 105 seconds to 10 grams brew weight. 11 Bar for about 10 seconds as it was slow to show and very syrupy. Then I turned down the voltage to minimum and the pressure slowly dropped to about 2 Bar. I had to turn it up a bit as dripping all but stopped. It carried on at about 3 to 4 Bar. Was a little bitter really at the end of the draw.

The taste was the best I've had from this Jampit Hit. Initially impressively flavourful, then became a bit lacking in what I like about some coffee; a lasting sort of sweetness, but it didn't seem to dry in the mouth.

I seem to recall that I found previously this was better with a coarser grind and larger dose. That biased it away from an embedded harshness, perhaps the taste of of the dark roast, but I'm only guessing really. If I had more coffee I could have done a few more to try and 'dial this in' as best I can. And as you can tell, I don't notice the many specific flavours a lot of people talk about.

I want coffee that puts a grin on my face each time I have it, that so far in the last six months, seems mostly to have been done a Sumatra decaf from Coffee Compass, or perhaps the Sumatra caffeinated from Coffee Bean Shop in Kent.


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## Pooper

Impressive. I love your mods


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## Cptnemo14

Hiya

Great mods on your classic, I have tried to add a gauge with the same fittings and gauge as you but when I start brewing the needle buzzing like crazy +-1.5 bar would you have any idea on how to dampen? Thank you in advance


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## mcrmfc

Cptnemo14 said:


> Hiya
> 
> Great mods on your classic, I have tried to add a gauge with the same fittings and gauge as you but when I start brewing the needle buzzing like crazy +-1.5 bar would you have any idea on how to dampen? Thank you in advance


With a vibe pump you will see this with most cheaper guages even if they have the coil tube. You can get glycerin filled guages which would certainly help. I have a pre heat chamber and from memory my guage is sited after this so that effectively buffers the vibe pumps fluctuations, so anything similar to act as a dampner would probably work.


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## joey24dirt

Cptnemo14 said:


> Hiya
> 
> Great mods on your classic, I have tried to add a gauge with the same fittings and gauge as you but when I start brewing the needle buzzing like crazy +-1.5 bar would you have any idea on how to dampen? Thank you in advance


You can get a thing called a snubber. Basically fits inline and is like a load of beads stuck together. Definitely helped to smooth my gauge out, but they can be expensive.


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## Cptnemo14

joey24dirt said:


> You can get a thing called a snubber. Basically fits inline and is like a load of beads stuck together. Definitely helped to smooth my gauge out, but they can be expensive.


I heard somewhere else a snubber would help but there a bit pricey, could be cheaper getting a new gauge.

Do you know if a glycerine would be better than an bourdon gauge?

thanks


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## Cptnemo14

Hmmm thanks for the input, I'd rather get this gauge working somehow over getting another gauge. Maybe I'll try find a way to increase the water pipe to help, the 6mm tube isn't very flexible tho....


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## joey24dirt

Cptnemo14 said:


> I heard somewhere else a snubber would help but there a bit pricey, could be cheaper getting a new gauge.
> 
> Do you know if a glycerine would be better than an bourdon gauge?
> 
> thanks


I swapped the gauge for my DTP from air to glycerine and it did smooth it out loads. Still had a bit of flicker but not as much. It just so happened I had an inline snubber on some old gauges so I put that on and it reduced it further. You could even make a blank piece with a small bore hole in the centre, say 2mm. That would help also.


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## Cptnemo14

joey24dirt said:


> I swapped the gauge for my DTP from air to glycerine and it did smooth it out loads. Still had a bit of flicker but not as much. It just so happened I had an inline snubber on some old gauges so I put that on and it reduced it further. You could even make a blank piece with a small bore hole in the centre, say 2mm. That would help also.


That sounds like an idea to try, I have a silicone sheet I could possibly try with. You think 2mm would be ok as the capillary tube is already about 2mm?


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## joey24dirt

That's 2mm through the whole tube straight to the gauge, where if you have a 2mm reducer going into a larger void after that it may help. I could be talking utter rubbish I'm just referring to a particular area on one of our sites where it's set up like that. Worth a try if you have something you could use


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## Cptnemo14

Well I think I managed to get it under more control...

i cut cut a small coin of silicone which is about 1mm thick and made a small hole in the middle, I then put it in the capillary tube and screwed it tight on the tee connector and away it goes. Still a slight flutter but not enough to cause a issue or need any further tinkering. :good:But time will tell lol.

thanks for your input


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