# Too much wobble?



## Dylan (Dec 5, 2011)

So having mentioned it a few times to others I decided to do the test on my Mazzer SJ in which you close the burrs until you hear the even whine, or if you are unlucky, what seems like a mis-aligned burr.

I heard the latter, so popped onto ebay to order one of those dial gauge thingys.

The gauge reads 0.01mm 0-10mm and goes from 0-100 marked every 10. It is difficult to hold the dial in one steady position as I simply dont have the clamps, but when held on the outer edge of the burr carrier (burrs removed) it flickers roughly 10 points (so between 10-20 on the gauge). It seems to flicker about the same amount, maybe slightly less, when held at an angle against the shaft of the burr carrier.

If I'm reading the gauge right, thats a 1mm wobble, I am not sure what the tolerances should be, but that seems like rather a lot...?

Edit - not the same gauge, but the same measurements.


----------



## DavecUK (Aug 6, 2013)

Dylan said:


> The gauge reads 0.01mm 0-10mm and goes from 0-100 marked every 10. It is difficult to hold the dial in one steady position as I simply dont have the clamps, but when held on the outer edge of the burr carrier (burrs removed) it flickers roughly 10 points (so between 10-20 on the gauge). It seems to flicker about the same amount, maybe slightly less, when held at an angle against the shaft of the burr carrier.
> 
> If I'm reading the gauge right, thats a 1mm wobble, I am not sure what the tolerances should be, but that seems like rather a lot...?
> 
> Edit - not the same gauge, but the same measurements.


I think that's actually 0.1mm wobble.


----------



## jeebsy (May 5, 2013)

10 x 0.01


----------



## Dylan (Dec 5, 2011)

Ahh yes, so I'm out by quite a bit, that doesn't sound as bad... So is 0.1mm wobble still a problem?

If its not then I'm guessing something is wrong with my burrs, or how they are seated as there is definitely an alignment problem.

Here is a video showing the sound of only one part of the burrs touching. I'm aware this must be very bad for the burrs but worth it to show what's happening I think.


----------



## El carajillo (Mar 16, 2013)

Dylan, you cannot hold the gauge steady enough to use it.You need a stand mounted on a piece of steel sat on top of the front discharge hopper.By the sound from your video there is a considerable amount of variation, either on the carrier or the burrs. My guess would be the carrier. P M me if you want further information. Where about's are you ?


----------



## marcuswar (Aug 19, 2013)

0.1mm wobble is definitely too much Dylan. I've managed to get mine to within 0.01 of wobble.

I seem to remember reading that a single "notch" adjustment of the grinder collar can be equivalent to roughly 0.015mm. If that's true then your burrs are wobbling through about 8 notches of adjustment !

As Frank has said, you really do need to clamp the dial gauge in some way, the values of movement being measured are just so small. Mine has a "foot" on it so I can just rest it across the top of the grinder and let the probe drop down into the burr chamber. Maybe you could fabricate something similar for yours.


----------



## urbanbumpkin (Jan 30, 2013)

Dylan said:


> Ahh yes, so I'm out by quite a bit, that doesn't sound as bad... So is 0.1mm wobble still a problem?
> 
> If its not then I'm guessing something is wrong with my burrs, or how they are seated as there is definitely an alignment problem.
> 
> Here is a video showing the sound of only one part of the burrs touching. I'm aware this must be very bad for the burrs but worth it to show what's happening I think.


I'm with Frank Marcus on this, you can't get an accurate measurement without a clamp.

That doesn't sound like the usual burr chirping noise.

Sorry to ask a daft question but are you haven't dropped something in there like one of the spring or a small screw. Sounds like something else catching.

Are all of the screws tightened up (particularly on the top bur)


----------



## Terranova (Feb 15, 2014)

You won't find any grinder in the world (incl. Tom's dsc running on 0,01mm) which does not chirp from one side when being at "zero point".

Although your grinder really sounds bad and I can imagine that something is wrong.

0,1mm is a lot, in particular axial, I wouldn't worry about 0,1mm radial play.

I am pretty sure that the blonding of your shots is much earlier than compared with a flawless running grinder.

You should take it apart if you are able to.

In your case I would compare the blonding with another middle class grinder, if there is a big difference, give the bad one as a xmas present to your relatives or so.


----------



## Dylan (Dec 5, 2011)

Thanks for the replies...

I was more or less aware that just holding the gauge was a bad way to go about it, but for the moment it was the best I could do. The 0.1mm play is the 'flicker' of the needle, something that is clearly observable and cannot be related to the movement of my hand, I tried to video it but it was too quick for my phone camera. I'm not diminishing the inadequacy of my method, but the flicker must be caused by the rotation, even if it is less accurate. I did mount the gauge with a hole through the plastic case it came in, not solid by any means, but a similar flicker was observable.

I have taken the whole thing apart multiple times before now, and I have used a screwdriver to lever the bottom burr carrier, whilst I would be surprised if this was the cause as I never put a lot of force into it it clearly is the likely culprit. I unfortunately read about better methods after the fact. I am trying to establish with the gauge if I have indeed buggered the shaft.

I have checked the burrs and how they are seated, I can find nothing wrong in this regard.

I will have another grinder to compare this to in the new year as I'm renovating an old commercial when I'm at home for Xmas, maybe not quite the same class as the SJ but close enough.

The biggest annoyance here is that this grinder has been a bit of a pet project, with doserless conversion, stripped paint and Auber timer fitted to the body. I eventually planned to sell it on but its not in a fit state like this. It would be a shame to have to assign it to scrap.

Perhaps it would still be ok for brewed :/


----------



## marcuswar (Aug 19, 2013)

Dylan,

When using the depth gauge on my RR55 I found that it was much better to take spot readings at various spots around the burrs (I took 3 readings using the burr screws as a guide) by slowly moving the burrs around by hand rather than running the motor. Doing it as static readings makes it much easier to establish which parts of the burr are the higher points etc. Trying to do this with the motor spinning was unrealistic as like you say all you see is needle flutter. It's also easier to keep the tip of the dial gauge on the very edge of burrs when turning manually as otherwise you can be registering the feathering of the cutting edges which also causes flutter.

Have you tried taking the burrs off and then measuring the base plate of the burr carrier with the depth gauge. This should help establish if the carrier is warped or if its the burrs that aren't fitted level.


----------



## Dylan (Dec 5, 2011)

marcuswar said:


> Dylan,
> 
> When using the depth gauge on my RR55 I found that it was much better to take spot readings at various spots around the burrs (I took 3 readings using the burr screws as a guide) by slowly moving the burrs around by hand rather than running the motor. Doing it as static readings makes it much easier to establish which parts of the burr are the higher points etc. Trying to do this with the motor spinning was unrealistic as like you say all you see is needle flutter. It's also easier to keep the tip of the dial gauge on the very edge of burrs when turning manually as otherwise you can be registering the feathering of the cutting edges which also causes flutter.
> 
> Have you tried taking the burrs off and then measuring the base plate of the burr carrier with the depth gauge. This should help establish if the carrier is warped or if its the burrs that aren't fitted level.


That makes a lot of sense, thanks marc, I'll look into making some sort of mounting plate when I get back to Manchester so I can go about doing this.

I had removed the burrs and was taking this reading from the burr carrier itself.


----------



## marcuswar (Aug 19, 2013)

If those measurements where from the flat base of the burr carrier then it sounds like you did "bend" the carrier when levering it off.

If you take spot reading by moving the gauge around the machine (as opposed to rotating the burr carrier) you should be able to ascertain if its the burr carrier that's warped or if its the spindle thats bent.


----------



## El carajillo (Mar 16, 2013)

marcuswar said:


> If those measurements where from the flat base of the burr carrier then it sounds like you did "bend" the carrier when levering it off.
> 
> If you take spot reading by moving the gauge around the machine (as opposed to rotating the burr carrier) you should be able to ascertain if its the burr carrier that's warped or if its the spindle thats bent.


Marcus I agree about "bending" the carrier but moving the gauge around will only reveal the same as rotating the carrier. Ie you are moving the gauge around rather than the carrier, it will not tell you if the shaft is bent. I doubt the shaft is bent, possible but unlikely.


----------



## Dylan (Dec 5, 2011)

I feel like it is more likely that I have bent the carrier than the shaft, at least this is my hope as its replaceable.

Hopefully removing the carrier and mounting the gauge against the shaft, then rotating the shaft will tell me if the shaft is bent.

I wont be able to figure this out until I get back to Manchester, so I'll update with any progress as and when.

Thanks for all the feedback so far, been very helpful.


----------



## marcuswar (Aug 19, 2013)

El carajillo said:


> Marcus I agree about "bending" the carrier but moving the gauge around will only reveal the same as rotating the carrier. Ie you are moving the gauge around rather than the carrier, it will not tell you if the shaft is bent. I doubt the shaft is bent, possible but unlikely.


When I say the shaft is bent, I'm meaning more its not running parallel to the burr chamber.If the carrier is flat then at any rotation around burr chamber the burr will be at the same height even though it will be a lower height when rotated 180 degrees. By moving the gauge around you'd see that independent of the rotation one side is always lower or higher. Having said all this, if this was the case then Dylan wouldn't be getting a wobble from a single position so I guess it isn't the case.

I think for a bent shaft Dylan would need to have the point of the gauge at 90 degrees to the rotation which will be hard to do with shaft inside the burr chamber. Another option would be to use one of those gauges with a hinged point. I think these work more like a stress gauge?


----------



## Dylan (Dec 5, 2011)

marcuswar said:


> When I say the shaft is bent, I'm meaning more its not running parallel to the burr chamber.If the carrier is flat then at any rotation around burr chamber the burr will be at the same height even though it will be a lower height when rotated 180 degrees. By moving the gauge around you'd see that independent of the rotation one side is always lower or higher. Having said all this, if this was the case then Dylan wouldn't be getting a wobble from a single position so I guess it isn't the case.
> 
> I think for a bent shaft Dylan would need to have the point of the gauge at 90 degrees to the rotation which will be hard to do with shaft inside the burr chamber. Another option would be to use one of those gauges with a hinged point. I think these work more like a stress gauge?


Even at an angle, the gauge should show some movement if the shaft is indeed skewif.


----------



## urbanbumpkin (Jan 30, 2013)

I think it's much more likely for the carrier to be bent. Carrier is relatively thin aluminium, shaft it steel.


----------



## Dylan (Dec 5, 2011)

Fingers crossed!


----------



## marcuswar (Aug 19, 2013)

I think if its bent then yes it will show some movement although if its enough to register at 0.01mm I don't know. If the shaft is straight but motor isn't parallel then I don't think it will show anything.

Anyway, form rereading all the previous posts I'd place my bet on it being a warped burr carrier rather than a problem with the shaft. At least this one is relatively easy to rectify


----------



## urbanbumpkin (Jan 30, 2013)

Just a thought. When you took the burr off did you line it back up when you put it back on?

There's 2 lugs on the spindle that need to go into 2 slots on the lower burr carrier.

Lug on the spindle just to the left of the black pen mark at the top in photo.


----------



## Dylan (Dec 5, 2011)

Indeed, yea I did have that lined up


----------



## bronc (Dec 10, 2012)

Sorry for hijacking your thread Dylan but I've been meaning to ask about removing the lower carrier burr alignment on my SJ for a while. I want to clean the room beneath it as I got the grinder second hand and never got to that part. Is there anything specific when installing it back? I saw that removing it should be done with three long bolts but didn't see anything about putting it back together.


----------



## marcuswar (Aug 19, 2013)

Putting the burr carrier back on is much easier than taking it off. In much the same was as tightening up a bolt is easier then removing a tightened bolt.

Just line up the lugs and drop it into place then screw on the top bolt while jamming the burr carrier with a wooden chopstick or clothes peg through the grind exit hole. Make sure you use something wooden or plastic to jam it NOT METAL.


----------



## Dylan (Dec 5, 2011)

bronc said:


> Sorry for hijacking your thread Dylan but I've been meaning to ask about removing the lower carrier burr alignment on my SJ for a while. I want to clean the room beneath it as I got the grinder second hand and never got to that part. Is there anything specific when installing it back? I saw that removing it should be done with three long bolts but didn't see anything about putting it back together.


Not a problem, thats what a forums like this is for.

Three long bolts is certainly the most widely accepted method that seems to be easy to implement and achieve, but it is still not ideal as it marks the area below the carrier. You must also be very careful to do it slowly and evenly.

Try heating the carrier as a first port-of-call, if you are able to do this others on the forum have said it will allow it to pop off with ease.


----------



## marcuswar (Aug 19, 2013)

As Dylan has said, try blasting it with a heat gun (the type used for paint stripping) for 10seconds or so and it pops off easily ... or at least it always has for me.


----------



## bronc (Dec 10, 2012)

Thanks for all the tips. I don't have a heat gun but maybe if I stick some tape at the end of the bolt it won't leave a mark? I also don't think I can fit it in the oven as some have suggested









EDIT: What size bolts do I need?


----------



## El carajillo (Mar 16, 2013)

Dylan said:


> Even at an angle, the gauge should show some movement if the shaft is indeed skewif.


I have not heard that expression in may a year "SKEWIF" nice one


----------



## El carajillo (Mar 16, 2013)

As there is only about 20 mm of shaft standing above the bearing I do not think the shaft is bent.

If you can mount the gauge on the side you can probably access the shaft through the exit shute. You can get spindle extensions for the gauge, the tip unscrews and you screw extension into position. You would be able to mount the gauge if you can borrow a magnetic stand with adjustable arm.


----------



## jeebsy (May 5, 2013)

Heat guns are about 8 quid from Screwfix. I'd offer to send mine around but it would cost more in postage than buying a new one.


----------



## michaelg (Jul 25, 2013)

jeebsy said:


> Heat guns are about 8 quid from Screwfix. I'd offer to send mine around but it would cost more in postage than buying a new one.


Also they're pretty handy if you want to dissolve your carpet with hot molten paint as I discovered to my dismay about 6 months ago! Still has got me ruled out of any future DIY so swings and roundabouts, eh?!


----------



## marcuswar (Aug 19, 2013)

michaelg said:


> Also they're pretty handy if you want to dissolve your carpet with hot molten paint as I discovered to my dismay about 6 months ago! Still has got me ruled out of any future DIY so swings and roundabouts, eh?!


LoL, my wife has done that to the bedroom carpet with an iron... maybe she's trying to get banned from doing anymore ironing ?


----------



## michaelg (Jul 25, 2013)

marcuswar said:


> LoL, my wife has done that to the bedroom carpet with an iron... maybe she's trying to get banned from doing anymore ironing ?


Sounds like it! Mind you, ironing is one thing in terms of housework that I am good at. I would rather iron my own shirts personally and love the steam generator irons. Best household innovation ever I think.


----------



## jeebsy (May 5, 2013)

michaelg said:


> Also they're pretty handy if you want to dissolve your carpet with hot molten paint as I discovered to my dismay about 6 months ago! Still has got me ruled out of any future DIY so swings and roundabouts, eh?!


Molten gloss on the skin was an experience I'm not in a rush to repeat


----------



## marcuswar (Aug 19, 2013)

jeebsy said:


> Molten gloss on the skin was an experience I'm not in a rush to repeat


Yep, been there and done that ...I now always wear some cheap disposable gloves if I'm doing any paint stripping. (I had to add the word "paint" into that sentence after reading it initially!)


----------



## El carajillo (Mar 16, 2013)

michaelg said:


> Also they're pretty handy if you want to dissolve your carpet with hot molten paint as I discovered to my dismay about 6 months ago! Still has got me ruled out of any future DIY so swings and roundabouts, eh?!


wAS THAT A DELIBERATE "PLOY" ????


----------



## bronc (Dec 10, 2012)

I managed to remove the burr carrier today. It was pretty easy with 3 M4 bolts although they left light marks on the plate below. There was a lot of trapped stale coffee underneath but other than that there was no damage.


----------



## marcuswar (Aug 19, 2013)

I'd recommend you get some emery paper and sand down those marks as the sweepers underneath the burr carrier can brush against them.


----------



## bronc (Dec 10, 2012)

The marks are barely raised so I don't think that will be a problem and if I decide to remove the carrier again I will make new marks


----------



## dsc (Jun 7, 2013)

Terranova said:


> You won't find any grinder in the world (incl. Tom's dsc running on 0,01mm) which does not chirp from one side when being at "zero point".


Why not?

Shame about mounting a magnetic base to the grinder is that there isn't really anything you can attach it to as the body is ali. I'd suggest a big lump of steel with the mag base on it and this whole lot mounted somehow next to the grinder, above it so that you can easily get the DTI where it needs to sit.

T.


----------



## Dylan (Dec 5, 2011)

So, just to cm back to this.

I had the opportunity to get a lower burr carrier at a good price, so I went ahead and ordered. It came yesterday and the difference in the wobble is substantial. Doing the same test with the dial gauge (holding it in my hand) there was no 'flicker' whatsoever with the motor running (visible anyhow). I also fitted new burrs, and now when they are tightened whilst running they make a much more normal sound, no more clearly obvious one side catching.

The new burr carrier had to be lightly hammered in with a wood chuck, so I wont be planning on removing it again any time soon.


----------

