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[4]

Collet quality

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Maplehead

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#1
Hi All
I’ve been noticing that my 2MT collets have been starting to have an issue when I am tightening them in place with the draw bar. I hold them by hand firmly, with end mill in them and then as I tighten down and then go to use my spindle tool to final tighten the collet in place, they drop down a bit. However, my chuck with its 2MT collect never has an issue. This is becoming a PITA. I usually have to grab my pliers to hold the collet while I do the final tightening.
Is this a quality thing?
I got my collets from the Little Machine Shop. I run a micro mill that I bought from there. (And yes, it cuts steel.)
 

rgray

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#2
Solid morse tapers are self wedging. I have never used a split morse taper but one with the appropriate sized tool in it should fit the same as a solid.
Clean and dry and with the end mill or whatever in it...insert it into the machine with some speed and it should wedge right in and hold itself in place.
Is the drawbar preventing you from doing this? If so can it be lifted out of the way till the collet is in?
 

4gsr

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#3
Clean the threads on the drawbar with a die nut and clean out the threads on the collets with a tap. Also clean the bore of the spindle real good and the OD's of the collets and see if that fixes the problem.
 

Tony Pisano

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#4
Is the spindle keyed? I haven't dealt with that size collet, but the machines I've used with split collets have all had a small key to keep the collet from spinning as you tighten. Smoetimes the keys get worn if collets aren't properly seated and need to be replaced.
 

Maplehead

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#5
Hi All
Thanks for the replies.
This is the set of collets that I got.
https://littlemachineshop.com/products/product_view.php?ProductID=3491&category=
I’ve tried the above suggestions the best I could. The main collet giving me trouble is the 3/8’th one. That one gets the most use. The issue still stands. Maybe it’s just worn out in the wrong spot. I tried re-tapping it but I couldn’t get the tap to go into it. I’ll probably just order and set, or at least, another 3/8’th.
 

casca92

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#6
I sure don't have the vast knowledge that stored away on this board. but, may I suggest is that you replace the 3/8 collet with a mucher higher quality collet. I have been purchasing tooling here and there. As I have a better understanding of my needs and the crap tools float to the top. The better quality becomes more of an investment than an experiment
 

Maplehead

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#7
Forgot to reply to this.
Re-threading the drawbar and collet worked for me.
One last question: When I remove a collet, I fully unscrew the drawbar out of it before using my mallot to bang the collect out of the spindle via hitting the top of the drawbar. Should I instead leave the drawbar somewhat threaded into the collect when using the mallot?
 

Z2V

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#8
I loosen the drawbar about a turn then unseat it with a tap of the 1” brass plug I put on my wrench. I would think you could run the risk of damaging the thread on the end of the drawbar by unscrewing it first. Just my thought
 

Technical Ted

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#9
What I've found with my Chinese MT2 collets might be a different issue than yours, but you might find it somewhat relevant... I made a grinding fixture using my MT2 collets for sharpening the sides of end mills. I put the 1/2" one in and checked the run out with a dial indicator and a 1/2" dowel pin. It ran out between 0.002-0.003"! Way too much to sharpen the sides of an end mill. Seeing this, I put in a 1/2" collet I made years ago out of Inconel 600 (we used a lot of it at work and they scraped a lot of cutbacks - good, rugged and somewhat hard material). Anyways, the same dowel pin in my home made collet ran out about 0.0005"total.

Guess which one I'll be using to sharpen my end mills.

Ted
 

markba633csi

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#10
I've had to return both MT2 and BS9 collets to LMS for replacements- same problem each time- the big ends were machined too small and they sucked in to the spindle too far. These are Asian collets, same ones that are sold on Ebay, but I found that LMS has both the best price and return policy.
Mark S.
 

TORQUIN

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#11
Forgot to reply to this.
Re-threading the drawbar and collet worked for me.
One last question: When I remove a collet, I fully unscrew the drawbar out of it before using my mallot to bang the collect out of the spindle via hitting the top of the drawbar. Should I instead leave the drawbar somewhat threaded into the collect when using the mallot?
Yes, always have the draw bar engaging the threads, at least 3, but more if possible, when hitting it to loosen the collet. If you are all the way out the draw bar will bend the first thread, making it difficult to thread in the draw bar next time.

Chris
 
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