I have a Unimat DB200 with the typical 3-jaw chuck. I'd like to use ER16 collets, as they are about the right size for the machine and are compatible with the Unimat collet holder.
My question is why does the Unimat E16 collet holder use the 3-hole backing plate? I can fabricate an ER16 collet holder but I'd make one that threads directly onto the M12x1.0 spindle. Any downside to doing this?
I found a Unimat compatible ER16 collet holder on eBay, but it's $100+. I can fab one for a lot less.
Thanks. JMJ
Unimat db/sl owners: collet question
Re: Unimat db/sl owners: collet question
The best reason for using collets other than holding thin wall delicate parts is the collets accuracy. A threaded direct mount to fit your lathes spindle should work just fine. It does require some very careful measurements and fitting to the spindle. Then boring the correct collet taper after it's been confirmed that your getting a good repeatable fit and runout to the lathes spindle nose. Machining to fit tapered parts is very critical for both the diameter and the tapers depth. Even a .001" difference in diameter will change the collets location within the chuck by a lot. Caliper measurements aren't going to be close enough for this job by a long ways.
It's not an impossible job, but it's also not something you can do quickly. And if the chucks taper doesn't match the collets to a blued test fit then runouts could make the chuck useless. But if both yourself and your measuring equipment are up to it then yeah build one. If not then that $100 for an original Emco part is pretty cheap considering the time involved in making one.
My Emco Compact 5 lathe uses a 3 hole mount for it's original collet chuck, but on that lathe Emco chose to use bolts to fasten chucks to the spindle nose instead of threads. Hard to say exactly why they did the same for your lathe if the collet chuck needs to be bolted to a threaded back plate as well. But one possible reason might be because I think they also made a non gear driven dividing head for the Unimat size lathe and milling head. And my memory of it was they used the same design only smaller for the spindle on it to attach chucks with bolts that my lathe has. My little Emco mill uses a direct mount threaded spindle and threaded collet chuck and it works fine.
If it were me I think I'd want to use something like 4140 PH (Pre Hardened) steel for the chuck just for the better wear resistance it has.
It's not an impossible job, but it's also not something you can do quickly. And if the chucks taper doesn't match the collets to a blued test fit then runouts could make the chuck useless. But if both yourself and your measuring equipment are up to it then yeah build one. If not then that $100 for an original Emco part is pretty cheap considering the time involved in making one.
My Emco Compact 5 lathe uses a 3 hole mount for it's original collet chuck, but on that lathe Emco chose to use bolts to fasten chucks to the spindle nose instead of threads. Hard to say exactly why they did the same for your lathe if the collet chuck needs to be bolted to a threaded back plate as well. But one possible reason might be because I think they also made a non gear driven dividing head for the Unimat size lathe and milling head. And my memory of it was they used the same design only smaller for the spindle on it to attach chucks with bolts that my lathe has. My little Emco mill uses a direct mount threaded spindle and threaded collet chuck and it works fine.
If it were me I think I'd want to use something like 4140 PH (Pre Hardened) steel for the chuck just for the better wear resistance it has.
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georgepapa
- Posts: 8
- Joined: Fri Jun 26, 2015 6:49 am
Re: Unimat db/sl owners: collet question
Hi jmj,
Although I agree with pete, I would try my hand in the make of a directly screwed on holder but i would have a look in the market in case they do sell a reamer for the collet angle...
Hi pete,
I am also a proud owner of a compact 5 but have an mt2 holder held by an m10 screw drawbar, which i consider a potentially more accurate approach.
I have bought mine back in 81 being a satisfied unimat user and at the time it was the best buy though expensive. Trouble with such purchases is that one buys the best in the market expecting to enjoy its use forever and then, after half forever or so the company closes down or does not serve you anymore. Same thing happened with my Akai tape recorder e.t.c..
Regarding the divider I mostly use the unimat one (though limited to 24 teeth) since to use the compact 5 with more divisions i need to dismantle the chuck and at 75 years of abusing both myself and the lathes, i try to avoid it if possible.
Regards,
George
Although I agree with pete, I would try my hand in the make of a directly screwed on holder but i would have a look in the market in case they do sell a reamer for the collet angle...
Hi pete,
I am also a proud owner of a compact 5 but have an mt2 holder held by an m10 screw drawbar, which i consider a potentially more accurate approach.
I have bought mine back in 81 being a satisfied unimat user and at the time it was the best buy though expensive. Trouble with such purchases is that one buys the best in the market expecting to enjoy its use forever and then, after half forever or so the company closes down or does not serve you anymore. Same thing happened with my Akai tape recorder e.t.c..
Regarding the divider I mostly use the unimat one (though limited to 24 teeth) since to use the compact 5 with more divisions i need to dismantle the chuck and at 75 years of abusing both myself and the lathes, i try to avoid it if possible.
Regards,
George
Re: Unimat db/sl owners: collet question
Hi George,
Yeah I can relate about Emco no longer supporting these Compact 5's. Other than there cutting tools and the gear cutters, I think I bought every accessory Emco made for both the lathe and mill. It sure wasn't cheap to do that.
How come you have to dismantle your chuck for use on the dividing head? On mine the chucks are bolted on from the front.
Yeah I can relate about Emco no longer supporting these Compact 5's. Other than there cutting tools and the gear cutters, I think I bought every accessory Emco made for both the lathe and mill. It sure wasn't cheap to do that.
How come you have to dismantle your chuck for use on the dividing head? On mine the chucks are bolted on from the front.
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Cary Stewart
- Posts: 542
- Joined: Wed Jun 08, 2011 5:54 pm
Re: Unimat db/sl owners: collet question
The reason for the M12-1 threaded E-16 collet holders had back plates was to let the owner carefully machine the mounting spigot to just able to enter the hole in the collet holder. This is the same procedure that all the mounting devices except the sanding disc plate used. The back plate used on the DB/SLs was large enough to allow its use on the early Unimat 3 machines which have M14-1 threaded nose.
If you want a good well made ER-16 collet holder for your DB200 look at ebay "unimat". From time to time there is a fellow in England that makes direct mounting units. They are at a fair price and the shipping is not too bad.
If you have not yet done so I recommend that you join Yahoo Groups "unimat" as that is the special group for your Unimat.
Cary
If you want a good well made ER-16 collet holder for your DB200 look at ebay "unimat". From time to time there is a fellow in England that makes direct mounting units. They are at a fair price and the shipping is not too bad.
If you have not yet done so I recommend that you join Yahoo Groups "unimat" as that is the special group for your Unimat.
Cary
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Cary Stewart
- Posts: 542
- Joined: Wed Jun 08, 2011 5:54 pm
Re: Unimat db/sl owners: collet question
Pete,
The bolted on chucks allow the spindle to be reversed without danger. To reverse a threaded spindle to go clockwise would invite a very exciting event even on little Unimats.
Cary
The bolted on chucks allow the spindle to be reversed without danger. To reverse a threaded spindle to go clockwise would invite a very exciting event even on little Unimats.
Cary
Re: Unimat db/sl owners: collet question
Hi Cary,
Yeah I'm not enthused at all with threaded spindles and am surprised there being used even today at least on a few off shore lathes. Yes they work and have proven they do so for a very long time. There's just far better spindle nose designs available that are much more superior. I've only owned a Shereline that had a threaded spindle. The rest have some type of bolt system. Although I'd still rather they had used a D1-3 mount on my larger lathe. The threaded spindle is faster to change chucks of course.
Yeah I'm not enthused at all with threaded spindles and am surprised there being used even today at least on a few off shore lathes. Yes they work and have proven they do so for a very long time. There's just far better spindle nose designs available that are much more superior. I've only owned a Shereline that had a threaded spindle. The rest have some type of bolt system. Although I'd still rather they had used a D1-3 mount on my larger lathe. The threaded spindle is faster to change chucks of course.