ER40 collet nut

Batmanacw

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I own Shars ER40 hex and square blocks. One of the two nuts is much more accurate than the other.

In the Square block the good nut holds consistently 0.0006" off center, which is an imperfection in the block and easy to correct. More importantly it holds nearly dead straight every time consistently. At 1" from the chuck it's 0.0002" off at most and usually less.

The other nut does not hold consistently or straight. I informed Shars and the graciously sent me a Tegara replacement nut 2 years after I purchased the block. Great customer service.

The new nut is better than the bad nut but not as good as the good nut. It is a bit more consistent but closer to 0.0005" off of straight every time. The new nut does the same thing in my Shars ER40 adjustable lathe chuck. 0.0005" off straight at 1" out consistently.

I would like to buy a better quality nut but I'm not sure what brand to buy for quality that won't break the bank. I'm trying to stick with solid nuts to avoid the issues with bearing contamination but I want better consistency.

What am I looking for?
 
IMO you are looking for a nut made by the inventor of the ER system - Rego-Fix. I have had your same frustrations and tried about 6 various brands of ER40 collet nuts including Shars, TMX, Maritool, and nothing comes close to the Rego-Fix.

This is the one I use on the lathe - it's ball bearing style: https://www.mscdirect.com/product/details/63080527
This is the one I use on the mill - non-ball bearing style: https://www.mscdirect.com/product/details/74514977 <- slightly better TIR

Hope this helps.
 
IMO you are looking for a nut made by the inventor of the ER system - Rego-Fix. I have had your same frustrations and tried about 6 various brands of ER40 collet nuts including Shars, TMX, Maritool, and nothing comes close to the Rego-Fix.

This is the one I use on the lathe - it's ball bearing style: https://www.mscdirect.com/product/details/63080527
This is the one I use on the mill - non-ball bearing style: https://www.mscdirect.com/product/details/74514977 <- slightly better TIR

Hope this helps.
I was trying to keep the price down. Ouch....
 
There are many factors as to the accuracy of any collet system, and it is usually an aggregate of all the parts. I assume the ER collets you are using probably have a tolerance of 0.0004-5" and the collet blocks also may not be on center. I have both ER40 and 5C collet blocks and at best they may be within 0.001-0.0005", I would not expect them to be any better than that. Techniks has both very good ER collets and also have a powercoat nut that is very well rated. One big issue is also proper torquing of the nut and also that the your are using the length of the collet to clamp. On my collet blocks I do not expect that level of accuracy and use standard nuts, on my R-8 and MT-3 ER holders I use the Rego-Fix bearing nut, all other bearing nuts I have tried have failed. I sometime do not follow that people want to buy the cheapest item and expect it to perform like a more expensive version that garantee's their specs.
Techniks 41940 ER40 PowerCOAT Slot Nut
 
There are many factors as to the accuracy of any collet system, and it is usually an aggregate of all the parts. I assume the ER collets you are using probably have a tolerance of 0.0004-5" and the collet blocks also may not be on center. I have both ER40 and 5C collet blocks and at best they may be within 0.001-0.0005", I would not expect them to be any better than that. Techniks has both very good ER collets and also have a powercoat nut that is very well rated. One big issue is also proper torquing of the nut and also that the your are using the length of the collet to clamp. On my collet blocks I do not expect that level of accuracy and use standard nuts, on my R-8 and MT-3 ER holders I use the Rego-Fix bearing nut, all other bearing nuts I have tried have failed. I sometime do not follow that people want to buy the cheapest item and expect it to perform like a more expensive version that garantee's their specs.
Techniks 41940 ER40 PowerCOAT Slot Nut

I chucked and rechucked a 1/2" dowel pin dozens and dozens of times. As I already stated my original post my square block is 0.0006" off center. With one nut it's very consistent and straight. It repeats over and over again.

I'm not expecting perfection from cheap tools. I'm simply optimizing what I have and looking for ideas on what to buy to make things better.

Your post seems to indicate that I'm ignorant of realistic tolerances or the quality of my tools. I am neither.

I just want to find a better nut and squeeze out a little better consistency. Once I have real consistency I can correct my blocks with my surface grinder and achieve much better centering of the collets. I cannot do that until I can reliably discern where center really is.
 
I agree with Rego-fix being very good. So is ETM and Techniks. These three lead the field and if accuracy is your goal then spend the money. A good Rego-fix solid nut should run near $40 on eBay.
 
I agree with Rego-fix being very good. So is ETM and Techniks. These three lead the field and if accuracy is your goal then spend the money. A good Rego-fix solid nut should run near $40 on eBay.
I wish! There is a bearing rego-fix for $92.
 
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