Lower burr wobble

#1: Post by **wearashirt** » July 4th, 2016, 3:12 pm

Hi everyone,

I just wanted to ask if you think this is a legitimate wobble on the lower burr carrier. If so, is there a solution on how to fix it?

When I'm calibrating my grinder to the zero-setting, the burrs don't seem to start making contact equally on all surfaces -- there is "early chirping". Could that be the point of disalignment?

This is the video.

Grinder: HC-600 (Mazzer Super Jolly copy)

#2: Post by **TomC** » July 4th, 2016, 7:31 pm

It looks like it is, but the wobble is exaggerated by the head of the bolt and the washer. The burr mount doesn't appear to wobble nearly as bad, but does somewhat.

#3: Post by **Bill33525** » July 4th, 2016, 8:34 pm

The burr bolt on a K10 is offset from center on the shaft. Probably the same for your grinder.

#4: Post by **AssafL** » July 5th, 2016, 2:49 am

Shouldn't one use a simple lever dial indicator to measure the wobble (or runout)?

I find it difficult to assess wobble sans a probe. Even truing a bike is easier with a probe (even a pencil held in place with a rubber band helps).

July 5th, 2016, 5:04 am

Oh man, I don't know how to use one.. I've read about it in other threads. Is there a video somewhere showing how to use it with a grinder? But if there is a problem, can this be remedied?

July 5th, 2016, 5:06 am

Bill33525 wrote:The burr bolt on a K10 is offset from center on the shaft. Probably the same for your grinder.

I wonder if such a design could incrementally cause horizontal disalignment.

July 5th, 2016, 6:55 am

Isn't it weird that when I hold the burrs with my hands, press and rub them together, I don't here the "chirping"?

EDIT: Of course I won't -- they're perfectly laid flat against each other. The problem is in the carrier.

#8: Post by **AssafL** » July 5th, 2016, 2:24 pm

wearashirt wrote:Oh man, I don't know how to use one.. I've read about it in other threads. Is there a video somewhere showing how to use it with a grinder? But if there is a problem, can this be remedied?

There are many of Frank (Terranova) using a dial indicator.

A lever is a wee bit more involved if you want absolute readings as you have to calculate the cosine of the contact angle to the lever.

You raotate it by hand or very slowly.

July 5th, 2016, 3:46 pm

I was actually troubleshooting more profoundly a while ago, yet still macroscopically. I think I know what the problem is already.

The lower burr sits on an ring-embossment which supposedly fits against the bottom side of the lower burr. Well, the ring embossment, which is NOT a perfect circle, is also slightly eccentric with the axis of the rotation.

Any other ideas on how to solve this?