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ER32 collet chuck criteria for milling

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ericc

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#1
Hi. I was thinking of using my old horIzontal mill to cut pockets with an end mill. This will require some sort of collet. Recently, I purchased a SYIC ER32 collet at a garage sale. It looks like a pretty good one. Would a Banggood 3mt to er32 chuck work for this application? Low speeds and east The reviews on YouTube look pretty bad. This site has some positive ones. Would the run out cause problems with a good collet in it? Or would it be better to build one's own?
 

JimDawson

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#2
Any runout in the holder would transfer to the collet and then to the tool bit. But a small amount of runout may not make much difference in the end use, depends on the final accuracy that you require.

One other thing to concider is that when using a MT collet holder for milling, you need to secure the holder with a draw bar. Side loading (milling) with a MT holder will cause it to work it's way out of the spindle if not secured.
 

ericc

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#3
Thanks, Jim. I have a flycutter and a Randy Richard style shop-made dovetail cutter with one triangular insert that both wouldn't mind a little runout (like 0.005), but how about a 1/2" HSS endmill?
 

JimDawson

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#4
0.005 runout is quite a bit, but the final accuracy of the part is what really counts. Normally if I need to cut a slot that is on size, I use the next size smaller endmill and step over to final size. But, with 0.005 runout only one flute of the endmill will be doing most of the work. I would want a bit less runout. For most applications 0.0005 runout would be acceptable.
 

BaronJ

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Hi. I was thinking of using my old horIzontal mill to cut pockets with an end mill. This will require some sort of collet. Recently, I purchased a SYIC ER32 collet at a garage sale. It looks like a pretty good one. Would a Banggood 3mt to er32 chuck work for this application? Low speeds and east The reviews on YouTube look pretty bad. This site has some positive ones. Would the run out cause problems with a good collet in it? Or would it be better to build one's own?
Hi Eric,
I have and use a Banggood MT3 ER32 collet chuck in my mill for tool holding without any issue. The runout varies with the collet fitted, but thats down to the collets. I've found that the collets need a good cleaning and deburing before putting into service. All the ones that I commonly use are in 0.0001" range.
 

ericc

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#6
Hi BaronJ. That is pretty good accuracy that you experienced. Much better than what I gleaned from web searching. So, if I have a decent collet, it should be OK to get the lower quality chuck. I noticed that most of the Ebay sellers for this item are in China and have mediocre feedback. After seeing that monster thread on the "too good to be true" chuck scam, this looks kind of scary, especially if the seller's location is Chino(China).
 

ttabbal

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#7
For things that need accuracy like collets and chucks, it seems to be a bit "luck of the draw". I have and use Banggood insert holders, they work fine. But I've seen reviews all over the place for collets etc.. Some get good results, others don't. I suspect it's just poor QA. For a more mid-priced option I've had good luck with Shars. The lathe ER40 chuck and the R8-ER40 were quite good indicated against the taper. Not as cheap as direct from China, but they seem to have a better reputation for QA and the limited times I've purchased they have met the spec they published.
 

BaronJ

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Hi BaronJ. That is pretty good accuracy that you experienced. Much better than what I gleaned from web searching. So, if I have a decent collet, it should be OK to get the lower quality chuck. I noticed that most of the Ebay sellers for this item are in China and have mediocre feedback. After seeing that monster thread on the "too good to be true" chuck scam, this looks kind of scary, especially if the seller's location is Chino(China).
Hi Eric,

Using a 0.0001" test indicator I only see noise when reading inside the taper on the collet chuck. That noise is caused by stickiness of the stylus rubbing. Using a 12 mm slot drill in a collet, I might see 0.0003" or 4, and that will change simply by loosening the collet and rotating it a little.
I point that I did forget in my previous post, was use a ball bearing nut ! It makes it much easier to tighten up, as does a spot of oil in the nut.

Unfortunately all collets are not made equal, I've thrown a couple in the bin because I couldn't clean the harrage out from between the slits on the inside edges. I've also had one that had the two opposite slits missing !
And been told that it cannot happen ! Yea, "see those flying pigs".

I wish I'd kept it and taken some pictures of it, however Banggood sent me a new one, so no loss there.
 

mikey

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ericc, ER-32 chucks of high quality in an MT3 mount are rare. Lots of Chinese stuff out there but you sort of have to wonder how good a chuck is when it costs less than $30.00 for the chuck and nut included. You can't even buy a good nut retail for that amount.

The reason I raise that point is because it is well accepted that for every 0.0001" of runout you have, tool life decreases by 10%. This is because one tooth of an end mill is cutting more than the others as Jim said. If you have a chuck/collet/nut combination that has 0.0005" TIR then your tool life expectancy will be dismal.

So, what to do? If I was in your shoes I would buy a chuck from a seller that publishes specifications online. Then I would check that chuck's taper to see if the concentricity of the chuck falls within those specs. If it doesn't then you can send it back but if there are no specs then you have nothing to stand on. Say you buy one from Shars (claims 0.0002" TIR) and find it to be okay. Then you need to decide on a nut and collet set.

The nut can make a huge difference in the runout of the assembly. Cheap nuts can have or cause double or triple the runout of a high quality nut. Good nuts come from ETM, Rego-Fix and Techniks. Rego-Fix and Techniks both sell hard coated as well as ball bearing nuts. The Chinese ball bearing nuts are junk, at least in my experience.

The collets you use also make a big difference in runout. Rego-Fix, the originator of the ER system, is probably the world standard but ETM is also very good. The best ER collets for the money probably come from Techniks. Their collets are made in Taiwan and are some of the best collets you can buy at their price level. Centaur also makes some good collets but are pricier. Lyndex is also well known but Techniks specs are better.

Whatever you decide to get, consider spending some money and get good collets if you can find a good chuck and nut. That will give you the best chance at decent performance and tool life.
 

BaronJ

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#10
Hi Mikey

The reason I raise that point is because it is well accepted that for every 0.0001" of runout you have, tool life decreases by 10%. This is because one tooth of an end mill is cutting more than the others as Jim said. If you have a chuck/collet/nut combination that has 0.0005" TIR then your tool life expectancy will be dismal.
What a load of rot ! Most cannot even measure a tenth of a thou !
 

mikey

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What a load of rot ! Most cannot even measure a tenth of a thou !
Morning, Baron. I'm trying to decide whether I should be offended by the tone of this response. I assure you that I did not make up the information you quoted but perhaps you know more about it than Lyndex and Techniks so why don't you enlighten us so we can correct them?

And yes, I can measure tenths accurately.
 

ericc

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#13
Hi everybody. Very interesting. This definitely means that the specs are important. It may be more strict for carbide cutters, which I am not planning to use right now. For example, here is a link speaking about tool life. The general rule quoted is keep the runout less than 20% of the chip load.

https://www.cnccookbook.com/spindle-runout-measure-fix-tool-life/
 

mikey

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#14
I don't run a CNC mill. In fact I only have an old Taiwanese RF-31 and a Sherline 5400 mill but both have under 0.0001" TIR at the spindle and both use ER collet chucks that are quite accurate. Since I upgraded to better collets for both mills I can tell that my end mills last longer. However, one experience taught me the value of accurate collets.

I had to cut a Woodruff keyseat in the end of a cross slide lead screw. As you know, the proper fit is an interference fit and that requires an accurate cutter. Luckily, I was practicing on a piece of scrap 1144 steel and was using an import collet that I thought was pretty accurate - specs of under 0.0003"TIR - but the key was loose. I then tried the same cut with a Lyndex collet and got a better but still slightly loose fit. Then I switched to my Techniks collet and the same cutter cut an interference fit in the same material.

For most tasks we may not notice a difference between good and inferior chucks/nuts/collets but there are times when it really shows. I learned that cheap collets are fine for work holding on the lathe but for the mill, I prefer to use good collets.
 

BaronJ

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#15
Hi Mikey,

Morning, Baron. I'm trying to decide whether I should be offended by the tone of this response. I assure you that I did not make up the information you quoted but perhaps you know more about it than Lyndex and Techniks so why don't you enlighten us so we can correct them?

And yes, I can measure tenths accurately.
I agree that both you and I may be able to measure to these limits, but most on these forums are hobbyists and would have little ability to do so !

I certainly couldn't define tool life in those terms, not that I would be bothered about getting an extra dozen cuts from a tool that I may only use infrequently. I generally aim for accuracy of a thou or better, so a tenth is neither here or there.

Mitch, made a good point about normal tolerances due to wear and tear on spindle play ! Hitting tenths of a thou is very hard to do repeatably without precision machinery anyway. Making trying to achieve that kind of accuracy extremely expensive ! Way out of a hobbyist pocket.
 

mikey

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I agree that both you and I may be able to measure to these limits, but most on these forums are hobbyists and would have little ability to do so !
I dunno', Baron, I happen to know a lot of highly skilled "hobbyists" on this forum who are capable of doing professional level work so let's agree not to go there, okay? We wouldn't want to offend anyone.

I certainly couldn't define tool life in those terms, not that I would be bothered about getting an extra dozen cuts from a tool that I may only use infrequently. I generally aim for accuracy of a thou or better, so a tenth is neither here or there.
The point was that the accuracy of the tool holding system matters with regard to tool life. It's pretty well established and accepted throughout the industry and is certainly something even a hobby guy should be aware of, so I raised it. This has absolutely zero to do with the level of accuracy the user is working to. I don't know how to make this any clearer for you, Baron.

Have a look at the tips of the teeth of an end mill. See those little hooks? Typically, the wear you see is not even. One or possibly two will be worn more than the others and this definitely affects the function and accuracy of the tool. That asymmetric wear is an indicator of run out in the tool holding system, and you can be sure this extends to the sides of the end mill as well. How much of an impact this has on tool life, finishes or accuracy depends on the amount of wear that exists. In a hobby shop, tool life may be longer than in a pro shop but shorter life is shorter life as far as I'm concerned.

Your ability to measure how much run out there is or the accuracy levels you aspire to or even the amount of spindle run out the machine has are separate issues that have nothing at all to do with the fact that the more run out the tool holding system induces, the more asymmetrical wear there is and the shorter the tool life will be. That is what the collet makers are pointing out. I was doing the same thing. It is not "rot", or BS as we say on this side of the pond; it is fact.

We come from different cultures. Quoting something someone says and labeling it as a "load of rot" may be acceptable in your country but it will be seen as an insulting challenge here. Just some friendly advice.

As for me, in light of the above consideration, I decided not to be offended. Life is too short for that sort of thing.
 

mksj

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#17
Hi everybody. Very interesting. This definitely means that the specs are important. It may be more strict for carbide cutters, which I am not planning to use right now. For example, here is a link speaking about tool life. The general rule quoted is keep the runout less than 20% of the chip load.

https://www.cnccookbook.com/spindle-runout-measure-fix-tool-life/
Very nice detailed discussion on the subject. Thanks for posting. Tool like is a significant issue in production and CNC operations, and can significantly impact run costs. Typically in the hobbyist setting it is less significant/measurable because we are not pushing to the same limits as in production, and at least for me, I typically chip a flute from dropping an end mill long before I wear it out. Needless to say, rigidity and TIR are significant factors in tool life and finish tolerances. I will say that I have had significant TIR issues with lesser quality chucks and collets, in similar situations to what Mikey described above. As a self taught machinist, most of my work needs to be 0.001" or better, and setting up both my lathe and mill requires precision levels of 0.0001" resolution. I have a quite a few dial and test indicators, but I only use two (Starrett 25-511 and an a Compac 215GA), both which measure 0.0001". Both of my center finders for the mill needed to be setup to tolerances of less than 0.0004", I had purchased Shar's metric collets to set them up (both R8 and ER32). Both collets had TIR which far exceed these limits by quite a bit. I ended getting a PBA R8 collect and a Technics ER32 collet, which were far better. The ER chucks I use have a TIR of under 0.0001".

Precision is relative to the user, the machine, tooling and project requirements. I do not look at it as being a hobbyist, as most of my projects require finished tolerance of better than 0.001". I Also work with a number of other hobbyist that this also holds true. It is no more time consuming to do so, at least for me, in particular with the tooling/machines I use.

One of the features that makes the ER systems attractive is the system accuracy, relative to say an R-8 or 5C collets, and the range of clamping for the collets. The TIR with an ER system is a function of the collets, chuck and nut used (assuming the machine has minimal runout). If accuracy is not an issue then the whole discussion is a bit moot, use an ER Chuck you want. If you need accuracy, then get a chuck that specifies the tolerance limits and check it. There are many good quality ER chucks and collets at moderate pricing.
 

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#18
Hi Mikey,

I agree, lets not go there. I meant no offense, sorry !
 

mikey

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ericc

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#20
Since there is so much uncertainty with the online offerings, with the exception of Shars, I was wondering how hard it would be to get decent tolerances if one turns the adapter in house. It seems that the two main sources of error would be the chucking of the adapter, since it will have to be chucked to bore the tapered opening for the collet. The job could be done between centers, then carefully chucked on a parallel section of shank behind the area to be tapered. Would it be reasonable to get 0.0004 TIR with this sequence, assuming a good collet?
 
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