Home-made collet chuck and collets - some Q's

[arnoldb]

I've been keeping a growing "tools I need" list while building the Rocker and Fancy.

One of these needed tools is a decent way of accurately and solidly holding milling cutters and metal stock in the lathe headstock (Myford ML7).
Basically it boils down to "I need a collet chuck and/or collets". I researched various options, looked at prices and availability, as well as shipping to me here in Windhoek in Namibia, but cannot find anything to suit both my requirements and budget.

I can make MT2 collets, but they have the disadvantage of not having a through-hole for lengthier pieces of stock, as well as needing cutter shanks and stock to be a close tolerance to size.

My ideal would be ER collets and a spindle screw-on chuck. Some research on this showed that the normal ER series is not suitable for stock ?????.
I just cannot afford the commercially made screw-on chuck (or backplate mounted chuck) and collet set - for now.

So, It's down to:
1: Make my own "ER" (or based on that) chuck and collets.
If I do, the chuck body will be fine-grained cast iron - that should be OK?. The collets will have be from silver steel (drill rod)?? - hardened and then tempered to dark blue (spring) temper ? - I _think_ I have all the tools needed to do this, and can locally buy the stock - I'll just have to make a jig to slit the collets, but that could be recycled into a usable collet block.

2: Make MT2 collets with a drawbar? Will silver steel treated as above work?

3: Suffer in silence, each time set up the tool/work in the 4-jaw chuck (my 3 jaw has quite a bit of run-out) with the DI, and carry on like now? - I'm trying to save up to buy a mill; another couple of months and I can buy an ER chuck and collets from the savings, but then the mill has to wait for even longer.

4: ???

Any Yay's, Nay's, or suggestions will be much appreciated.

Regards, Arnold

 

[CrewCab]

Arnold, would one of These help, I've got one and it works fine, you could just use some threaded bar for a drawbar.

CC

 

[rake60]

My 9 x 20 lathe has an MT3 taper in the spindle.
I already had an ER32 collet chuck and set of collets
for my X2 mini mill so all I needed was a MT3 holder for
the lathe. Here's the story:
http://www.homemodelenginemachinist.com/index.php?topic=2239.0

The draw bar is just a length of all-thread a heavy washer and a big wingnut.
It works great for me. The depth of the MT3 holder is only about 4"
When the parts to be machined are small enough to call the collet holder
into service they are not usually longer than that.

Rick

 

[bentprop]

My ideal would be ER collets and a spindle screw-on chuck. Some research on this showed that the normal ER series is not suitable for stock Huh???.

That's the first I've heard of it!how is round stock different from a round milling cutter?
That just doesn't make any sense.
As for making your own,full credit to you if you manage it,but it seems like a lot of work for relatively little benefit.Mind you,with you being in such an out of the way place,it is a different story.If you ever need an odd size,you could make it up straight away,rather than having to wait a month for it to be shipped to you.
If you make a chuck to exactly the same spec as ER,you could of course always buy in extra collets later.
I have the ER32 chuck in my mill-drill,on a MT3 taper,but it never gets removed.I simply haven't found the need for them in the lathe.But i could if I ever wanted to,using an mt5 to 3 reducer.
If you have a vertical slide,you could do your light milling in the lathe,and hack into your mill fund to get the collet set.
It's a bit of an unfortunate "chicken and egg"situation for you :-\

 

[RobWilson]

Hi Arnold
you Could up make up a few 2MT collets in the common sizes for now and and copy the myford design for closing the collets allows full lengths through the collet.
regards Rob

 

[deverett]

Arnold

If it just for holding endmills and imporation of a collet chuck is too expensive, make up your own holder. They are quick and easy to do and will start you off until you can get the 'proper thing'.

Put a bit of 1" mild steel held in the chuck, drill a hole in the end and start tapping a draw bar thread (I suggest either 10mm or 3/8"BSW, but whatever you have. An aside: if making your own taper tooling, keep the drawbar threads standard!). Support the end with a centre and cut a 2MT. Leave about 1" - 1/1/2" of full diameter and part/saw off from the stock.
Remove from the chuck and put your new taper into the headstock and secure with your drawbar. Drill a hole for your end mill. If you have a machine reamer ream to the final size, if you don't, then drill in successive steps up to final diameter.
Finish by putting in a grub screw to impinge on the shank of your endmill.

Maybe not quite as accurate as a collet, but good enough for most of the sort of jobs you are likely to do.

Dave
The Emerald Isle

 

[arnoldb]

Thank you for the responses everyone

CC/Rick, I had a look at those; unfortunately, they fail my need for allowing extended lengths of stock through...
Bentprop - You're right with the "chicken and egg" thing... and yes, besides the time delay to get something shipped here, I have found very few online suppliers that are actually willing to ship to Namibia, and if they do, I pay as much for postage as the item costs...
Dave, thanks for the suggestion.
Rob, I've been thinking about the "original myford" principle as well... It might just be the easier way to go for me; any suggestions as to what metal I should use for the collets if I go this route ? I notice from the image you posted that the back end of the collet appears to be thinner than the rest of the taper - do you think this will make the collet clamp down properly for a bit bigger range than it's nominal size ?
Sorry for all the questions - I'm prepared to put a fair amount of effort into making this if the end result (subject to my machining skills) can justify it.

Kind regards, Arnold

 

[deverett]

Arnold

If you decide to go for the Myford type collet, be advised that they accept only the correct size of material. In other words, they do not have an extended clamping range like the ER collets.

There has been at least one article about machining them. I can't remember where, possibly MEW. I do remember that they were made in pairs nose to nose. Silver steel was used in their construction.

Dave
The Emerald Isle

 

[arnoldb]

Thanks Dave - I was concerned about the clamping range on those.

I think I'll go the whole hog, and just make a collet chuck and collets based on ER - in the long-term that might be the best solution.
Lots of work, but it should be fun (Am I the only masochist here? ;D)

Regards, Arnold

 

[deverett]

Thanks Dave - I was concerned about the clamping range on those.

I think I'll go the whole hog, and just make a collet chuck and collets based on ER - in the long-term that might be the best solution.
Lots of work, but it should be fun (Am I the only masochist here? ;D)

Regards, Arnold

Arnold
I made up an ER collet holder for my Thiel milling machine - 5MT shank, but being chicken, I bought the nut. These frequently come up on eBay. Item no. 380145020415 shows an example.

Dave
The Emerald Isle

 

[arnoldb]

Thanks Dave

Anybody interested in seeing build pictures ?

Regards, Arnold

 

[ozzie46]

Of course! th_wwp th_wwp th_wwp th_wwp

Ron

 

[Majorstrain]

I'll be lurking, 8)
I need to make one too. :bow:

Cheers
Phil

 

[deverett]

Thanks Dave

Anybody interested in seeing build pictures ?

Regards, Arnold

Arnold

I'm out in the Perishin' Gulf at the moment. When I get home in week's time, I'll get a picture and post it.

Dave
The Emerald Isle

 

[deverett]

Thanks Dave

Anybody interested in seeing build pictures ?

Regards, Arnold

As promised herewith some pics of my home made ER collet chuck. I only got home a few hours ago, so nothing more than a few basic shots.

I started out with a 2-1/2" diameter lump of steel. No idea of the quality, but it was the very devil to machine, even with carbide tools. The surface finish was achieved, after basic turning, with a file and emery cloth. Everything was 'blued' to check the fits and it turned out satisfactorily for me - not being a purist. There are still a few ridges that I could not get rid of and maintain size. Realise that this was made in the dark ages before I knew anything about this group!

I used the topslide to cut the taper - it is described as a 'Truncated 5MT'. First I set up a 5MT taper tool between centres to set the angle on the top slide.

I put the lump of steel in the 4 jaw chuck and centre drilled the end for support. I then cut the end down to accept the drawbar thread, which was cut on a trial and error basis until it fitted. Next the taper was cut and tried in the mill's headstock and 'made' to fit.

Fortunately, the taper in the headstock of my lathe is also 5MT, so it was just a case of putting the finished taper into the headstock while the internal taper for the collet was cut. The concentricity of the chuck should now be equal to the built-in accuracy of the lathe. The recess for the collet is about 1/8" deeper than where the collet is seen sitting in the nose to allow room for any contraction of the collet when it is tightned. Finally, I cut the collet nut thread. It is longer than required so that I would have been able to shorten the collet taper if I cut it too big. The through hole i drilled at 1/2", just to be able to pass long stock through it, but that's hardly necessay on a milling machine.

I haven't measured the runout, but I am happy with the way things turned out. Everything 'looks' to be OK. Like I said above, I'm not a purist!

Dave
The Emerald Isle

 

[Harry.]

This is an interesting project. Did you manage to make the collets you needed?
Did you use a caliper to measure an existing collet? What caliper did you use? I'm thinking about getting a vernier caliper, but there are so many brands. I've heard that Insize are good, have you ever used them?

 

[Apprentice707]

I have an old Super 7 which I have added to over the years (about 30 so far). I bought it secondhand and it came with a set of imperial Myford collets. They work reasonably well , but cost the earth these days even secondhand. I wanted a collet system to use on any of my small machines so I went for an ER25 system. The same as you I thought the collets and Myford holder were too expensive so I bought a set of collets direct from China and made the Myford threaded holder from 2.5 inch stock. It took a while but provided me with the experience of cutting internal and external threads in metric and imperial. I also bought the closing nut from China.
I had a quick look on E bay and didn't see any Chinese companies sending to South Africa, I am sure there must be one somewhere.

The collets and holder have worked out fine after many years of use.

Happy turning

B

 

[goldstar31]

The original poster has not posted for almost 8 years and my comments to Harry and co are to avoid the Myford collets although I have a set of Imperial ones. Frankly, they are fine for holding PRECISE dimensions but are liable to crack if undersize stock is used.

I have a set of home made ones made per Leonard Sparey in the Amateurs Lathe book but I instantly settle for 'Chinese' ER25 and ER32 from RDG in Yorkshire. I got to the daft stage in life where I want things to interchange between my Myford Super 7B, my Sieg C4- with n added vertical mill drill attachment, my mill drill, a Vertex dividing head which converts to a rotary table, a GHT small dividing head and obviously my Clarkson and the present Mk1 Quorn which might convert to take it to a Mark3 if I live long enough

We have no idea what will happen during this 2019 Coronavirus with the Chinese government having to spend billions propping up their economy but I would humbly suggest that others to 'get their act together' quickly.

My reading of a wider field than most!

And we Brits have Brexit and the other risk of a steel industry on or after the brink of collapse. Les Grenouilles are using their Verniers( a 'Hapsburg/ French design) to further alter the works.

enough to drive a soul to drink

 

[awake]

This is an interesting project. Did you manage to make the collets you needed?
Did you use a caliper to measure an existing collet? What caliper did you use? I'm thinking about getting a vernier caliper, but there are so many brands. I've heard that Insize are good, have you ever used them?

Harry, a bit of machining 101: A caliper is a very handy tool for measuring all sorts of things, as long as you keep in mind that its very best accuracy will be on the order of +/- .001" ... and if you are inexperienced, sloppy, or just moving a little too quickly, that might shift over a decimal point to +/- .010. Any twisting or "cocking" of the caliper will throw off the measurement significantly, so it takes some practice to learn how to get repeatable, reliable results.

That doesn't mean don't get them; they are invaluable for quick measurement, and they are capable of a number of different sorts of measurement, not just the outside diameter, but also the inside diameter and depth. Just don't depend on them for the highest accuracy.

You will get much greater accuracy with a micrometer. They are a bit slower to use, and less versatile - generally you need a different micrometer for inside diameters than for outside, and yet another micrometer for depth. (You can use telescoping gauges to take inside diameter measurements with an outside micrometer; that takes practice to get accurate measurements.) Even an inexperienced user should be able to get +/- .001" easily with a basic outside micrometer, and with experience you can shift that decimal point to the right, down to +/- .0001".

For either calipers or micrometers, you may have a "vernier" as part of the measurement markings. A vernier is simply a clever way of marking the tool such that you can subdivide the primary markings to very closely estimate the next decimal point or unit of measurement. On a caliper, the main beam may be marked at .025" intervals, and the vernier lets you resolve the last .025"; on a micrometer, generally you read the the barrel to get within .025", then read the dial to resolve the .025", then read the vernier to get to .0001".

Frankly, for a caliper, I wouldn't bother with a vernier; I'd get a digital. Even an inexpensive digital caliper can give decent results within the accuracy limits of what you can reasonably achieve with a caliper, once you learn how to use them properly.

 

[abby]

This is an ER20 chuck I made for my Pultra lathe from a piece of en24T. The nut was purchased off Ebay very cheap as were the collets , you can buy them one at a time as you need them.
It fits the headstock or the tailstock using tubular drawbars so stock up to 10mm can pass through , although ER collets are not ideal for long lengths.
I plan to make another which will screw onto the spindle and the drawbar will not be necessary.
A digital caliper may be accurate to 0.001 " but I defy anyone to get repeatable readings of that precision. If you are going to make your own collets and chucks then micrometer readings will be better and a plug gauge for internals.