# Crushgrind Mechanism



## Graybeard (Jun 24, 2017)

Yesterday a lady from our turning club came over to turn a peppermill. She's made a challenge piece after every demo we've had since she joined the club and wasn't going to let this one go by.

Things went smoothly until final assembly when we tried to put the top on. The top would not slide down into the mechanism in the top. I've never had that happen before.

Has anyone had that problem? What do you think the problem might be? Any fixes?


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## DKMD (Jun 24, 2017)

Shafted or shaftless? Pics?

Reactions: Agree 1


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## Graybeard (Jun 24, 2017)

Sorry no pictures, she took it home with her. We cut the shaft down considerably but it still won't fit totally through the top portion. It was her first one and since she does a lot of turning and she's pretty set in her ways and does things her own way so I didn't say much. I did notice her tenons left a lot to be desired and the more she got into it the more wobble there was. I'm wondering if the top may be canted a bit off? Maybe the shaft hits the side of the neck instead of going through. I find the tops are tight to begin with so I don't think there's much room for error. It did fit before we seated it and she used my 7/8 inch bit which is what I always use.

Reactions: Agree 1


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## DKMD (Jun 24, 2017)

I'd guess you're right about it being off kilter. I've only done one of the shafted crushgrind mills, so I'm not familiar enough with them to trouble shoot one.

Reactions: Thank You! 1 | Agree 1


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## David Hill (Jun 24, 2017)

I've done both-- for me the shaftless are more than I want to do. I think y'all have already figured out the issue-- being a bit off (no pun inended, but there nonetheless)will do that.

Reactions: Agree 1


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## TimR (Jun 24, 2017)

Could it just be enough force wasn't used to engage the top mechanism to the shaft? I've not turned one in a while, but can recall them being pretty darn tight and needing a stiff arm to engage them the first couple times. On a side thought, any possibility that too much shaft stuck thru and was hitting "wood" in the top?


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## Graybeard (Jun 25, 2017)

Thanks for the comments. As far as pushing too hard she took a rubber hammer to the top before I cautioned her that the bottom of the mill might break out if you hit it too hard. It only went in as deep as the top of the piece where the narrow wire is around the top. After she drilled the 7/8 inch hole she drilled a 3/8 inch hole darned near through the top. 

I offered to use my band saw and cut out the top piece and make a new one as I have some of the original blank left but she's happy with it the way it is. The shaft only goes in a tiny bit but enough to engage the shaft. She said she'll never make another one. She's pretty driven to at least try every challenge.


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## TimR (Jun 25, 2017)

I just remembered...when that happened to me, I filed some sharp corners from the top of the shaft, made all the difference to install.

Reactions: Agree 3


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## Ray D (Jun 25, 2017)

I practically round the shaft end over, once I cut it off. I have never had one not go all the way in.

Reactions: Agree 1


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## Graybeard (Jun 26, 2017)

Ray D said:


> I practically round the shaft end over, once I cut it off. I have never had one not go all the way in.



Me either.


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## Spinartist (Jun 26, 2017)

Did ya'll glue the parts in like the directions say to do on crush grind mechanisms??

I found that sometimes to much glue stopped the "spreaders", which grip the shaft, from opening enough for the rod shaft to be fully inserted into the top.

My remedy was to take a small triangular file & gently file inside the top mechanism (#1 in next post) where the shaft goes just enough so the shaft can go in & use less glue.


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## Spinartist (Jun 26, 2017)

Crush grind mechanisms.
#1 shows "spreader" which holds shaft.
#2 shows fins to holds mechanism into top.

Directions say to glue #2 & below it into mill top. If to much glue is used & it gets onto #1 it can prevent #1 from opening to allow the shaft to fully seat.
I also cut the shaft & round the shaft top 3/16" above #1 gripper. If shaft is to long it can also prevent top from going on completely.

Reactions: Informative 3


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## Graybeard (Jun 27, 2017)

Thanks for the reply. I follow Chris West's directions which don't use glue. http://www.westwoodturnery.co.uk/Handout.pdf

Reactions: Like 1


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## TimR (Jun 27, 2017)

Here's how I do mine as well, without glue.
I didn't read thru all of Chris' instruction, but it appears to be quite detailed and takes into consideration turning/drilling/chucking to assure parts fit squarely. Mine does as well, and for those with short attention spans, in one page with a second sheet of figures.
https://woodbarter.com/threads/crushgrind-peppermill-instructions.19485/

Reactions: Like 2


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## Spinartist (Jun 27, 2017)

Photo above doesn't show the groove needed to snap the parts into the wood. I cut these grooves similar to what @TimR does in his illustration.


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## TimR (Jul 10, 2017)

We have our "home" peppermill packed away so I decided to make a simple one using plain wood (didn't even see the curl in the blank). 

I thought it would help to toss a few key pics in to explain how the approach I outlined helps assure a very true alignment between head and body, while also allowing the turning of head and body together if important or more convenient for your design. 

The key is to have a jig with a snug fit between the head and the body, and one for centering the taikstock end (bottom of mill), vs using a cone that could possibly split your mill.

This first pic is final shape, centered using plug jigs. The tailstock jig pushes against the shoulder of the bottom mechanism fit, so no concern with too much compression...though you do want to ease up when parting the head from its block. Friction alone keeps the head from turning relative to the body.



Next pics are close ups of jigs and where placed









This pic shows rounding/sanding done so you can easily (but securely) push the head onto the shaft.



Completed. No glue/epoxy for mechanism. Generals Woodturners finish.

Reactions: Like 4 | Great Post 1 | Way Cool 2


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## Graybeard (Jul 11, 2017)

First, Thanks Tim. Just so I'm clear, you don't turn a tenon on the top, rather you use the diameter of the top plug as a tenon? Also if I understand, you get a really clean parting cut or do you have to clean up the parting cut? Also when do you drill the top portion? I see the holes in the top and bottom are different as expressed in your jig? Again, thanks so much for your detailed response.


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