# brass or emergency collets.for minilathe.



## dat2zip (Jul 7, 2004)

I have a need to make custom collets and I can't seem to find the softer brass emergency collets that you can get for the larger lathes.

Does anyone know where I can some for the HF 7X10 which I believe has a 3MT format.


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## PEU (Jul 7, 2004)

where can I learn or see how a collet is used? 

I cannot figure it out /ubbthreads/images/graemlins/twakfl.gif

Pablo


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## PhotonFanatic (Jul 7, 2004)

Pablo,

Decent explanation and some pic here:

http://www.mmsonline.com/articles/050203.html


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## wptski (Jul 7, 2004)

[ QUOTE ]
*dat2zip said:*
I have a need to make custom collets and I can't seem to find the softer brass emergency collets that you can get for the larger lathes.
Does anyone know where I can some for the HF 7X10 which I believe has a 3MT format. 

[/ QUOTE ]
Is that a 5C collet? If so look here: https://www.travers.com/catalog/catalog2.asp?ix=596505


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## dat2zip (Jul 8, 2004)

wptski,

Thanks for the link, but, the mini-lathe I have uses a different collet system. Mine is a 3MT format or 3 Morse Taper.

Wayne


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## gadget_lover (Jul 8, 2004)

WHat is a "brass emergency collet"? Is it one that you can drill as needed to hold a piece (or tool) in an emergency?

Daniel


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## wptski (Jul 8, 2004)

[ QUOTE ]
*gadget_lover said:*
WHat is a "brass emergency collet"? Is it one that you can drill as needed to hold a piece (or tool) in an emergency?

Daniel 

[/ QUOTE ]

Yes, if you have a odd O.D. say, you could drill/ream and and away you go!


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## wptski (Jul 8, 2004)

[ QUOTE ]
*dat2zip said:*
wptski,

Thanks for the link, but, the mini-lathe I have uses a different collet system. Mine is a 3MT format or 3 Morse Taper.

Wayne 

[/ QUOTE ]
Wayne:

Is that #3MT right in the I.D. of the headstock spindle? I have a RockWell 10"x36" and it takes a 4C collet which is right in the spindle itself.

O.T. Have you read this post of mine? http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Board=LED&Number=614699&page=0&view=collapsed&sb=5&o=&fpart=1


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## KC2IXE (Jul 8, 2004)

If it's a 3MT headstock, here is the route I would go - Call up someone like Sobel's and get a 3MT - 3C collet adaptor (it's an insert into the spindle) and a drawbar. (assuming you have at least a .75 thru hole) - then you can run 3c collets, which are meant for holding stock (hollow drawbar) - MT3 collets are for tools. I know you can get 3C emergency collets - heck, I have a couple of 3at emergency collets laying around!


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## dat2zip (Jul 8, 2004)

Hmmm, Little Machine shop has this handy 3MT to 3C adaptor.

http://www.littlemachineshop.com/products/product_view.php?ProductID=2244







Here a picture of some 3C collets at Littlemachineshop.






Quick question. From the images shown, I'm unclear exactly how the 3C collets go on the adpator. Do 3C collects screw on? 

Wayne


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## wptski (Jul 8, 2004)

[ QUOTE ]
*dat2zip said:*
Hmmm, Little Machine shop has this handy 3MT to 3C adaptor.

http://www.littlemachineshop.com/products/product_view.php?ProductID=2244






Here a picture of some 3C collets at Littlemachineshop.






Quick question. From the images shown, I'm unclear exactly how the 3C collets go on the adpator. Do 3C collects screw on? 

Wayne 

[/ QUOTE ]
Wayne:

The collet should go inside the adapter which has a pin or something that lines up with the flat on the collet to keep it from turning. The collet protrudes through the adapter with the threads sticking out and the end of the draw bar/handle screws onto the threads. You turn the handle, it pulls the collet back, it's split and collapses on your stock.

What I don't know or see is what keeps the adaptor from turning? /ubbthreads/images/graemlins/confused.gif Oh! It's tappered and that holds it I guess?


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## KC2IXE (Jul 8, 2004)

Bill's got it right on the money - the adaptor has an external 3mt which fits the spindle, and has a interior straight part with a pin, to fit the straight part of the 3c collet, plus a tapered part to fit the taper of the collet. The tube goes through the spindle, and screws onto the outside of the rear of the 3c collet (you can see the threads at the rear of the collets)

That will allow you to chuck up to 1/2" diameter parts "through spindle", and is a LOT more accurate than a 3 jaw chuck (a properly adjusted 4 jaw is still the gold standard, but it's slow)

The 3C taper is "self releasing" meaning that when you loosen the draw bar, it opens, unlike the MT3

3C was the standard "South Bend" collet for lathes that were not big enough for the 5c

Hardinge still makes them (among others) and are common used (be careful they are not sprung). The come by 1/64ths, and in round, square and Hex


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## wptski (Jul 9, 2004)

[ QUOTE ]
*KC2IXE said:*
Bill's got it right on the money - the adaptor has an external 3mt which fits the spindle, and has a interior straight part with a pin, to fit the straight part of the 3c collet, plus a tapered part to fit the taper of the collet. The tube goes through the spindle, and screws onto the outside of the rear of the 3c collet (you can see the threads at the rear of the collets)

That will allow you to chuck up to 1/2" diameter parts "through spindle", and is a LOT more accurate than a 3 jaw chuck (a properly adjusted 4 jaw is still the gold standard, but it's slow)

The 3C taper is "self releasing" meaning that when you loosen the draw bar, it opens, unlike the MT3

3C was the standard "South Bend" collet for lathes that were not big enough for the 5c

Hardinge still makes them (among others) and are common used (be careful they are not sprung). The come by 1/64ths, and in round, square and Hex 

[/ QUOTE ]
My RockWell 10"x36" uses 4C collets and sometimes need a little wack with hand on the drawbar to release! The 4C goes up to 3/4".


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## dat2zip (Jul 9, 2004)

I think the picture is playing tricks on my eyes. It still didn't make sense. I placed a call to littlemachineshop and talked to Chris over there. He basically said the same thing! /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/twakfl.gif

The only reason for clarification which I understand now is that I had a concern that I didn't want the collect to protrude out past the faceplate. If that was the case there would be poor mechanical stability which the minilathe is not very good to begin with.

I'll be purchasing it shortly and I'll feedback here how it works.

Thanks again.

Wayne


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## KC2IXE (Jul 9, 2004)

Wayne,
You'll LOVE using collets - MUCH nicer than a chuck


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## wptski (Jul 10, 2004)

[ QUOTE ]
*dat2zip said:*
I think the picture is playing tricks on my eyes. It still didn't make sense. I placed a call to littlemachineshop and talked to Chris over there. He basically said the same thing! /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/twakfl.gif

The only reason for clarification which I understand now is that I had a concern that I didn't want the collect to protrude out past the faceplate. If that was the case there would be poor mechanical stability which the minilathe is not very good to begin with.

I'll be purchasing it shortly and I'll feedback here how it works.

Thanks again.

Wayne 

[/ QUOTE ]
Wayne:

I never seen a mini-lathe in person but from the pictures it looks like it has a massive, wide chuck for a lathe that size. I can see why it may not be that rigid! Your way out from the end of the workhead spindle. My 3/4 jaw chucks for my 10"x36" probably aren't half as thick as the ones pictured.

What kind of mount is used on the mini-lathe? If it isn't a *******, you could probably pick up a smaller chuck. I guess that you'd hate to have a extra/unused chuck lying around?

My came with or I ordered a 4-jaw with it. I later bought a 3-jaw off the shelf locally. I think mine is a 1 1/2"-8 threaded mount if my memory seves me right this morning! /ubbthreads/images/graemlins/grin.gif


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## gadget_lover (Mar 1, 2005)

I was also somewhat confused about collets. I've looked into them some, and here's what I learned in terms the newbies can understand.

WHAT IS IT?
First a collet is an adapter with a hole in it for holding stock or tools. It's almost always used with a tool that has a tapered hole. This tool is known as a holder, closer or collet chuck. I'll call it a closer in this post, but the same applies to all three types. 

A collet is carefully ground to provide very exact tolerances very quickly. If you are building 5 parts in a row, a collet will allow you to quickly change from one to the next without having to readjust settings each time. A collet grips more of a rod than a chuck does, so it should mar the work less. It should also grip it firmer with less pressure.

The collet has slots cut in the sides that allow it to be squeezed tighter. The act of pulling or pushing it into the tapered hole in the closer squeezes it tightly against whatever it's holding. Each collet handles only one size of stock or tool. The hole is precision ground to provide very good contact (almost complete) for the full length of the collet.

Some collets (like the DA series and the ER series) compress down better while still remaining true. It takes only 11 ER32 collets to go from 3/16 to 3/4 inch. It takes a lot more (20???) 5C collets to do the same because each 5c is limited to a smaller range. 

The collet can be pulled (or drawn) into a closer by the use of a threaded rod that sticks out the back side of the closer. The collet has threads in the end that the rod screws into. This rod is called a "drawbar" and it typically has a nut or handwheel on the end that protrudes through the lathe's headstock. Some collets have threads on the outside, and they frequently use a "drawtube" to pull the collet into the closer. Collets with drawtubes allow long stock to protrude all the way through the lathe's spindle and out the other side.

The 3 C collets shown above use a drawtube. I'm pretty sure a 5C does too.

MT2 and MT3
There are some collets that don't use a seperate closer, but use the taper of the spindle, quill or tailstock to tighten the collet. The mt2 collets from littlemachineshop.com fit in the mt2 quill of the micro mill without an adapter. The drawbar comes out of the top of the mill. The collet is pulled up into the quill when the drawbar is tightened. To remove the collet, you simply back off the drawbar two turns and then give it a rap with a small mallet. This pops the collet out of the spindle.

To use a collet chuck with the HF 7x10, you'd buy a collet chuck with an MT3 taper. It will fit in the hole behind the chuck and hold itself in once it's been forced. Remove the 3 (or 4) nuts that hold the chuck to the spindle plate. Insert the MT3 taper into the hole after you clean the hole out. Use a drawbar to hold it tight.


Which collet style would you use?
There are 12 different basic collet styles, and around 100 different collets of various holder sizes listed in Machinery's Handbook. Some are made for a specific lathe, and others are general use. The choice of which to use depends on lots of things. 

You will see the Bison 5c collet chuck. This looks like a normal 4 inch chuck with a nose that protrudes. You insert a 5C collet and turn a chuck key just like on a 3 jaw scroll chuck. This turns a short threaded drawtube inside the chuck, drawing the collet into the taper in the nose.

Different lathes have different noses on the spindle. Some are threaded like the southbend). Others have an internal taper (like the harbor freight 7x10 using MT3). Some have fancy machining adapters designed for high production (CAT40?). You must make sure the closers you get fit your equipment.

Here's what I learned in shopping for a set of collets:

1) Start by finding which closer or chucks fit your equipment. You won't be able to use an R8 collet on a lathe with an MT3 spindle. An adapter may add as much as 4 inches to the length. It might also add to inaccuracies.

2) Make sure that the drawbar will fit. A HF 7x10 will only pass a drawbar up to 3/4 inches. A 1 inch drawtube will not work even if you can get a collet chuck that fits the lathe backplate.

3) Check the max size. A 3C collet will handle a maximum of 1/2 inch diameter, but it allows the work piece to extend down the drawtube. An ER32 will handle up to 3/4 inch and will also pass the work all the way through, but the drawbar for the closer may get in the way of passing work through. Some of the collets don't go down very small due to the design. 

4) Determine if you will need collets to hold square or hex rods. The ER type doesn't have a spec for square or hex parts, for instance.

5) look at the physical size. The ER32 collet itself is only 1.5 inches tall. The 2M collets I got (mt2 taper) are almost 3 inches tall. I would not be able to use them to hold a tailcap on the table of my mill.


What I selected;

I ended up with ER32 collets and a collet chuck with an MT3 shank for my lathe. It took less than 5 minutes to remove the 4 jaw chuck and pop the collet chuck into the spindle. I chose the ER32 because they will be used with my micro mill (only 8 inches between chuck and table) with a home built low profile closer.

I have a set of 2m collets for the quill of my micro mill. They also fit in the tailstock of my lathe, and in an adapter that clamps in the 3 jaw or 4 jaw chuck of my lathe. I have a simple 3/8 inch threaded rod to use as a drawbar.

If anyone needs pictures, let me know and I'll snap some.

Daniel


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## PEU (Mar 2, 2005)

I want to see the set installed, and a link where you purchased it. Thanks Daniel


Pablo


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## gadget_lover (Mar 2, 2005)

First a note about "ER collets", then I'll comply with Pablo's request.

The ER collets are a double angle type collet, with a taper on the back as well as on the front. Uniform pressure on the front forces it into the taper in a way that causes it to tighten uniformly along it's whole length. The collet has slots cut from both ends. This causes it to act like its hinged at both ends when it compresses.

The ER collet chuck is comprised of a shank, body and nut. The body has a tapered recess. The nut has a special lip that catches the groove around the collet, pulling it out as you unscrew it. The collet is inserted into the nut, then the nut is screwed onto the body of the chuck. The work is then inserted into the collet.


Here's a collet set and a collet chuck. I'll replace the link with pictures from my set later.






The number 32 in ER-32 indicates the collet is 32 mm across at it's widest point. The ER32 can handle stock up to 3/4 inch across. You can get ER collets in 20, 25, 32 and 40 mm. Each requires a different chuck.


I bought the chuck from H&H inductrial ( http://www.hhip.com/ ). They have collet chucks with several different shafts, all for $65 each.

I bought the collets from an e-bay aution.

You can buy the whole thing as a set. www.littlemachineshop.com carrys them as a set. I thought I saved about $25 buying the way I did, and I got 11 collets instead of 8. I looked at it just now and see the picture has 8 collets but the $159 buys the whole set of 11. Oh Well.

Daniel


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## gadget_lover (Mar 3, 2005)

OK, here's my collet chuck in use....

MT3 taper ER-32 in a Harbor Freight 7x10 mini lathe.

First, a 3 inch long, 3/4 inch diameter rod chucked in the biggest collet.







Then a side view. The collet chuck extends about 1/2 inch further out than my 3 inch 4 jaw chuck. You can see the collet nut could tighten down another 3 threads if the rod were a smaller diameter. That would make it 1/4 inch shorter. There is about 2 1/2 inches of rod exposed.







This is the business end of the assembly. The collet is basically flush with the edge of the nut when tightened.







You can see the taper of the collet when the nut is removed.






I think the arrangement for the collet slots is ingenious. The whole collet is essentially 16 1/8th inch shims held together by the metal at the ends of the cuts. Note, if you can, the eccentric lip next to the beveled opening of the nut. I've shaded it a light blue to make it easier to see. It's this eccentric lip that grabs the groove in the collet and pulls it out of the collet chuck's taper.






I used this collet today to turn a couple of 3 inch long 3/4 inch rods to .650 inches with a 2 mm wide ring exactly 5mm from the end. I was able to rechuck one of the pieces after determining the ring was 2.2 mm wide. It went in the collet nice and straight and I had the extra .2mm cut down in seconds. There was no sign of marring on the tube. Cool!


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## PEU (Mar 3, 2005)

ohh nooo, more money need to be spent...

Great explanation Daniel, now I definitively understand how the collets work.

So $153 for a 11 collets set, will look locally, but I bet prices here will be far expensive.


Pablo


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## gadget_lover (Mar 3, 2005)

Pablo has to spend more on new toys? Well, I guess my job here is complete. /ubbthreads/images/graemlins/smile.gif


Daniel (called a pusher by some)


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## wasabe64 (Mar 3, 2005)

[ QUOTE ]
*gadget_lover said:*
Pablo has to spend more on new toys? Well, I guess my job here is complete. /ubbthreads/images/graemlins/smile.gif

Daniel (called a pusher by some) 

[/ QUOTE ]

/ubbthreads/images/graemlins/crackup.gif

I've sitting on the fence about investing in a real collet set, thanks for pushing me off the fence.


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## gadget_lover (Mar 3, 2005)

Wow! That makes this a twofer! 

Both Wasabe64 AND Pablo are going down the path to ruin with me! 

/ubbthreads/images/graemlins/smile.gif

Now I just need a collet vise to use the ER-32 collets on my micro-mill. I might just have to make one. That would be fun!

Daniel


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## gadget_lover (Mar 5, 2005)

Just a follow up...

The ER-32 collet set I wrote about is not for everyone. Some folks will have almost no use for a collet, especially if they only use their lathe occasionally or only do the same part over and over.

If you are one of the latter, you might need only one or two collets. If that's the case you might be just as well off with collets that fit directly in the spindle of your lathe.

A case in point would be using a HF 7x10 lathe which has a 3MT (morse taper #3) built into the spindle. Many lathes have a spindle with a taper designed to hold collets or tools. If you only work with stock of one size (3/4 inch, for instance) you can buy a single 3MT collet with a 3/4 inch hole for $20 or so. No chuck is required and the drawbar can be a simple 1 foot piece of all thread ($2 at the hardware store) with a washer and a nut. 

To use an 3MT collet you simply remove the chuck and place the collet into the spindle hole. Insert your stock in the hole and screw a drawbar into the other end to snug the collet into the taper. That's all.

Daniel


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## gadget_lover (May 6, 2005)

I found that it's quite possible to make your own emergency ER collets for an ER series collet holder. The er-32 only goes up to 3/4 inch, but I wanted one to hold 9/10 inch bezels. I made one from a piece of 6061 aluminum tube.

The ER collet is easy to make. The taper towards the rear is 8 degrees, and the taper at the front is 30 degrees. The specs are in the Machinery's Handbook.

The slits were made with a standard wood cutting horizontal bandsaw. I only did 8 cuts (4 from the front and 4 from the back) but it appears to shut down nice and tight. I bored the hole before adding the slit.

It looks fairly good, I think.







Daniel


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## HarryN (May 6, 2005)

Nice work Daniel.


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