What makes ER collets good quality?

[StevSmar]

On another thread there was discussion on tooling up for a mill, and many opinions on R8 collets versus ER collets.

It seemed that “good quality” ER collets were considered quite useful, which then makes me ask “what’s good quality”?

I purchased these collets: Precision Matthews 1-26mm ER-40 collets for US$170, which claim to have:

• Precision Ground Clamping Surfaces, max runout .0005″
• Each Collet is marked with size for easy identification
• Collets are Hardened and Precision Ground
• Made from ASTM A29-93 Steel
• Guaranteed to Accuracy of Clamping to 0.0005″ or less

How will I tell if these are good quality?

 

[DavidR8]

I look for clean machining, no burrs anywhere, zero rust. I think the challenge is confirming the max runout. My 5C collets had that claim to accuracy but my collet chuck was not that accurate.
I have one ER20 Techniks collet that is visibly better than my import ER20s and its performance in my CNC router is audibly different.

 

[Susquatch]

Ditto what @David_R8 says. Burrs and poor machining are the kiss of death.

After that, I'd be testing their runout using a tenths dial test indicator starting with your spindle taper and each step out. All the tapers stack so you have to start with your spindle, your collet arbour, and then test the collets them selves with appropriate precision ground gauge rods. Each of the collets shouldn't add more than their spec to the holders. But if you know what you start with, sometimes you can install them to cancel out other runout.

You also need to check both runout at the collet and axial runout 2 or 3 inches beyond the collet.

It's a lot of work to qualify your collets, but it's worth it if you need it.

I think most folks who check them only check a few and then decide how many more they want to check.

 

[John Conroy]

That's the same ER40 collet set I bought and I'm happy with them. I haven't checked them all for runout but the ones I have checked have had less than .0005". Very nicely machined.

 

[Proxule]

Food for thought?

https://www.amazon.ca/AccusizeTools-Collet-Fitted-Strong-3350-0586/dp/B00SJEK6M6/ref=sr_1_14?hvadid=222088418305&hvdev=c&hvlocphy=9001283&hvnetw=g&hvqmt=e&hvrand=4505010460810844856&hvtargid=kwd-499372478872&hydadcr=2342_9636346&keywords=er40&qid=1680227225&sr=8-14

https://www.amazon.ca/12Pcs-ER40-Collets-Common-Size/dp/B07VGGFVTF/ref=sr_1_20?hvadid=222088418305&hvdev=c&hvlocphy=9001283&hvnetw=g&hvqmt=e&hvrand=4505010460810844856&hvtargid=kwd-499372478872&hydadcr=2342_9636346&keywords=er40&qid=1680227225&sr=8-20&th=1

 

[John Conroy]

Mine came in an aluminum case like the Accusize set and may be from the same source. I made a wood rack with a neoprene cover that is attached a mobile tool box so it be moved near the mill or lathe as I use them on both.

 

[Tom Kitta]

I actually never got a Chinese collet that was poorly machined.

They come in two common tolerance classes - AA and AAA.

The 0.0005 thou are the cheap stuff at AA grade, i.e. 0.01mm.

 

[Tom Kitta]

Food for thought?

https://www.amazon.ca/AccusizeTools-Collet-Fitted-Strong-3350-0586/dp/B00SJEK6M6/ref=sr_1_14?hvadid=222088418305&hvdev=c&hvlocphy=9001283&hvnetw=g&hvqmt=e&hvrand=4505010460810844856&hvtargid=kwd-499372478872&hydadcr=2342_9636346&keywords=er40&qid=1680227225&sr=8-14

https://www.amazon.ca/12Pcs-ER40-Collets-Common-Size/dp/B07VGGFVTF/ref=sr_1_20?hvadid=222088418305&hvdev=c&hvlocphy=9001283&hvnetw=g&hvqmt=e&hvrand=4505010460810844856&hvtargid=kwd-499372478872&hydadcr=2342_9636346&keywords=er40&qid=1680227225&sr=8-20&th=1

https://www.amazon.ca/dp/B09NP2N2CP/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B09NP2N2CP&pd_rd_w=Zb8NJ&content-id=amzn1.sym.88a70737-8341-4e83-b43f-2849bf84234d&pf_rd_p=88a70737-8341-4e83-b43f-2849bf84234d&pf_rd_r=K7JW15CZ41F8E57JJH56&pd_rd_wg=wyaKa&pd_rd_r=3c469b76-4664-4410-b712-a79bf8330bbd&s=hi&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzSFRMUEU3VjJRSEc4JmVuY3J5cHRlZElkPUEwMzAwOTYyMkpIUzdWTUtZQjNOWSZlbmNyeXB0ZWRBZElkPUEwMTU2OTc2S0taSTYwWkNUU0dWJndpZGdldE5hbWU9c3BfZGV0YWlsJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

around same price as PM. Quite cheap actually.

23 for 214 CAD. That is under $10 per collet. You will have hard time beating this by buying singles from say China direct.

Vevor does not have a ER40, just ER32 set - but nice and cheap as well

VEVOR 25 Pcs Collet Set ER32 Collet Chuck 1/16 inch-3/4 inch Holder Spring Collet Set for CNC Engraving Machine & Milling Lathe Tool (ER32) | VEVOR CA

Buy VEVOR 25 Pcs Collet Set ER32 Collet Chuck 1/16 inch-3/4 inch Holder Spring Collet Set for CNC Engraving Machine & Milling Lathe Tool (ER32) at cheap price online, with Youtube reviews and FAQs, we generally offer free shipping to Europe, US, etc.

www.vevor.ca

just 118 - and with some coupon magic its like 112.

 

[thestelster]

@StevSmar if you plan on using imperial size endmills or tooling, I would supplement your set with the imperial size of your tools.

Yes, they collapase down in size, but its better to use the nominal size collet. Case in point, take a 1/4" endmill and the metric collet that would accommodate it would be 7mm. But it's loosey goosey. It'll work, but you have to tighten the collet nut quite a bit.

Now take a 6mm end mill and put it into your 6mm collet. Perfect fit.

 

[Former Member]

All collets have specific ranges be it R8, 5C or various size ER collets, generally there is an overlap in their coverage as you step in sizing, ideally step down in size before maxing out.

As you get near the limits, you start to lose grip and increase run out, at worst you cause permanent damage. Another point is never fit a large size into a smaller collet, example 6mm is 6mm or smaller.

 

[combustable herbage]

@StevSmar if you plan on using imperial size endmills or tooling, I would supplement your set with the imperial size of your tools.

Yes, they collapase down in size, but its better to use the nominal size collet. Case in point, take a 1/4" endmill and the metric collet that would accommodate it would be 7mm. But it's loosey goosey. It'll work, but you have to tighten the collet nut quite a bit.

Now take a 6mm end mill and put it into your 6mm collet. Perfect fit.

I came across this site selling regular metric sizes but also 12.7, 6.35, 3.175 mm sizes, no other reason I can see but to better accommodate imperial sizes.

https://www.aliexpress.com/item/1005003406308779.html?spm=a2g0o.productlist.main.71.b1c66b992orfIf&algo_pvid=d4b2afcd-ff45-4b63-b2c2-38ae005e46c1&algo_exp_id=d4b2afcd-ff45-4b63-b2c2-38ae005e46c1-35&pdp_ext_f=%7B%22sku_id%22%3A%2212000025649073199%22%7D&pdp_npi=3%40dis%21CAD%218.5%218.5%21%21%21%21%21%40211be72e16802165241307516d0737%2112000025649073199%21sea%21CA%21700940613&curPageLogUid=r1jfUC2cWzmm

 

[thestelster]

I know many companies also offer half sizes in metric. But might as well get those imperial sizes you use most often.

I have a full set of metric ER40 with several half sizes, and 3/16, 1/4, 5/16, 3/8, 7/16, 5/8, 3/4, 7/8, and 1" in imperial.

 

[Susquatch]

@StevSmar - that's what I did too. My set is Imperial with a few extra metric ones. As @thestelster says, even though they are within the stated range it just doesn't feel comfy to gronk on the nut. It isn't a big deal to buy a few extra collets of selected sizes.

This might be as good a place as any to mention the ER Collet Nut indexing for other readers. ER nuts include an eccentric retaining collar. NEVER simply press the collets in and out of the nut. Yes, they will snap into place, but they are designed to be installed and removed by tilting and camming the collets in and out at a very particular clocked position on the nut. The better expensive nuts are marked, but most are not. I usually put a sharpie mark on the high spot. Some day I'll get a decent engraver. Looking into the nut, it's easy to see where the eccentric collar is - even on ER11. Sadly, many many a new ER user mistakenly thinks the collar is a machining error and "fixes" it. BAD IDEA!

Instead, the collar eccentric is deliberate. It is designed to hold the collet during the removal process so the nut automatically pulls the collet out of the taper. No hammers needed. It's actually a very elegant design.

 

[eotrfish]

ER nuts include an eccentric retaining collar

Should read "MOST ER nuts include an eccentric retaining collar"

I ordered a couple of Chinesium ER nuts a while ago and finally figured out why they wouldn't pull the collet out of the taper. Closer inspection showed that the retaining collar was in fact concentric with the rest of the features. Some Chinese machinist already "fixed" the perceived machining error. Too late to return them but OK to keep on the display shelf as a testament to Buyer Beware.

 

[Tom Kitta]

Should read "MOST ER nuts include an eccentric retaining collar"

I ordered a couple of Chinesium ER nuts a while ago and finally figured out why they wouldn't pull the collet out of the taper. Closer inspection showed that the retaining collar was in fact concentric with the rest of the features. Some Chinese machinist already "fixed" the perceived machining error. Too late to return them but OK to keep on the display shelf as a testament to Buyer Beware.

Wow, I got like a dozen ER nuts and so far none have had any issues. You must be unlucky.

 

[Susquatch]

Wow, I got like a dozen ER nuts and so far none have had any issues. You must be unlucky.

I got one ER11 with a spindle motor from China that was not done right too. Same as @eotrfish. I knew I was in trouble the first time I had to use a screwdriver in the collet slot to remove it. Fortunately, I got a proper nut with an ER11 collet set I got at the same time so it was no big deal to me. But I think he is right. It's something to watch for especially for someone new to ER collets.

 

[StevSmar]

Thanks for the responses everyone!!!!

Has anyone use a Collet Nut that has a bearing in it? I’ve read conflicting opinions on them, that the bearing is more likely going to allow the collet to spin, but it will allow the work to be gripped with more pressure.

I look for clean machining, no burrs anywhere, zero rust.

My cheap collets look like that, except for the slots which look a bit rough.

You also need to check both runout at the collet and axial runout 2 or 3 inches beyond the collet.

Good point, I’ll do that.

That's the same ER40 collet set I bought and I'm happy with them.

I’m glad to hear that. Because they seemed so cheap, I’ve been wondering what their quality is like.

Food for thought?

I’ve only bought one thing from Accusize, that was a positive experience so I’ll experiment with a few more.

They come in two common tolerance classes - AA and AAA…0.0005 thou are the cheap stuff at AA grade, i.e. 0.01mm.

That’s interesting, I’ll keep an eye out for that.

just 118 - and with some coupon magic its like 112.

Thanks for the vevor link, I saw that too, any magic is good!

if you plan on using imperial size endmills or tooling, I would supplement your set with the imperial size of your tools.

I was attracted to ER because of their range of workholding. But my suspicious side makes me think that using metric for everything will not be ideal…

As you get near the limits, you start to lose grip and increase run out, at worst you cause permanent damage.

My set just says “7-6mm“, “6-5mm”. It does make sense to use the “6-5mm” one for 6mm.

I came across this site selling regular metric sizes but also 12.7, 6.35, 3.175 mm sizes, no other reason I can see but to better accommodate imperial sizes.

Interesting they didn’t just put imperial labels on them…

I have a full set of metric ER40 with several half sizes, and 3/16, 1/4, 5/16, 3/8, 7/16, 5/8, 3/4, 7/8, and 1" in imperial.

Looks like after I practise more, I’ll be considering purchasing an imperial set to go with my metric set.

…the ER Collet Nut indexing for other readers. ER nuts include an eccentric retaining collar. NEVER simply press the collets in and out of the nut…

I’ve read that, though have yet to play with my collets.

Closer inspection showed that the retaining collar was in fact concentric with the rest of the features.

Interesting, it almost seems like they copied them without knowing how they work…

…I got like a dozen ER nuts and so far none have had any issues…

But I think he is right. It's something to watch for especially for someone new to ER collets.

That’s good advice. I like the cost of the import tools, but you often get what you pay for…

 

[Susquatch]

@StevSmar - apparently my memory was wrong...... I hate it when that happens......

So the number of slits in my R8 collets is 3 just as I remembered it. However, the ER32 collets are not 6 like I remembered, they actually have 16 slots.

Here is a photo of a Hardinge 7/16ths and an ER-32 7/16ths.

The bearing length on the ER32 taper is only slightly more than the R8 (roughly 20% longer), but has 16 ears that toggle at both ends for a greatly improved fit and more range on the size of parts it can accommodate.

ER40 will be longer and stronger yet. I don't have any.

 

[Former Member]

Thanks for the responses everyone!!!!

Has anyone use a Collet Nut that has a bearing in it? I’ve read conflicting opinions on them, that the bearing is more likely going to allow the collet to spin, but it will allow the work to be gripped with more pressure.


My cheap collets look like that, except for the slots which look a bit rough.


Good point, I’ll do that.


I’m glad to hear that. Because they seemed so cheap, I’ve been wondering what their quality is like.

I’ve only bought one thing from Accusize, that was a positive experience so I’ll experiment with a few more.


That’s interesting, I’ll keep an eye out for that.

Thanks for the vevor link, I saw that too, any magic is good!


I was attracted to ER because of their range of workholding. But my suspicious side makes me think that using metric for everything will not be ideal…


My set just says “7-6mm“, “6-5mm”. It does make sense to use the “6-5mm” one for 6mm.


Interesting they didn’t just put imperial labels on them…


Looks like after I practise more, I’ll be considering purchasing an imperial set to go with my metric set.


I’ve read that, though have yet to play with my collets.


Interesting, it almost seems like they copied them without knowing how they work…



That’s good advice. I like the cost of the import tools, but you often get what you pay for…

Quick answer Yes. Don't exceed the upper limit but the closer you are the better.

 

[eotrfish]

Has anyone use a Collet Nut that has a bearing in it?

I've used these Collet Nuts with internal bearing for decades. The two that I have are original ETM nuts - not Chinese copies. Haven't noticed any problem with the collet spinning or concentricity.