Home Brew ER16 Collet Chuck

[PJW]

Hi Allen, I made two chucks, one on a Cowells & one for a Perris I am selling,on both machines I turned a mandrel true to the lathe I was putting the chuck on, on this mandrel I put a collet & clocked the top slide to run parallel to the taper, this seems to work as both chucks seem to work well & run true.
I made an ERE25 chuck for my larger lathe using the same procedure & have used this a lot over the last 18 months since I made it.
Give it a try all you can loose is a couple of quids worth of steel and a few hours. I am not a top engineer with letters after my name, I am just an old guy who got a lathe three years ago had a play on it joined the forum and ask when I am not sure,

Peter

[DTR]

Thanks for posting, PJW. I want to make an ER chuck for my mill soon and your WIP has given me some tips

[Mosey]

Great job! I put it on my list also, as I need a W-12 to ER-16 holder.
Funny how we fuss over a commercial collet system to make sure it is <0.0002" TIR, and then make one for ourselves on the lathe. I guess the best I could hope for on my lathe would be 0.0010" TIR without an internal cylindrical grinder.
Am I kidding myself?
Sherline shows how to recut the internal taper in their collet blocks on the lathe for higher precision.
This is a mystery to me.
Mosey 

[steve-de24]

Mosey,
have you got a link to the Sherline web page you refer to - I've looked for it without success.
Thanks in advance, Steve

[Twizseven]

Peter,

That looks very neat.   I think you should go into production.  There are quite a few Cowells around.  I've got a 1980's model and have the Cowells collet chuck (M14x1.5) (courtesy of Jo) but that ER16 looks very good and obviously has a wider range of collets.  Not tried thread cutting yet.  Just fitted it with DRO's and a new drive belt.  Out of interest what gear set up did you use to cut the thread?

Colin

[PJW]

Hi Collin, the thread for the chuck nose is a 1mm pitch, so on the Driver you have a 30t with suitable idlers and a 30t on the driven leadscrew gear. I found screw cutting quit a simple operation, the chart shows what goes where, do you have a copy of the Cowells screwcutting chart? I purchased a copy of the Cowells 90 handbook £6.95 worth the money. there are plenty of clips on youtube that will give you an idea, I do small cuts & take my time! if you have any problems, just shout out someone will come to your aid, i have had a lot of help from the forum members.

[Mosey]

Mosey,
have you got a link to the Sherline web page you refer to - I've looked for it without success.
Thanks in advance, Steve

I can't find it now, but it will turn up.
Mosey

[steve-de24]

Mosey, thanks for looking.

Colin,
if you want to cut the internal M14 x 1.5 thread (used to screw the collet chuck onto the lathe spindle) on your lathe rather than use taps then you will need a 30T gear on the headstock and 20T gear on the leadscrew with any two idler gears in between. (I'm assuming your Cowells has a 1mm pitch leadscrew like mine). This size of tap is a bit expensive.

Because you will have a limited view of machining the internal thread then I think that using a handle on the headstock spindle would be sensible - that way you can slow down the action and stop it whenever you want. Disconnect the motor from the mains and slacken off the drive belts if you are going to use a handle in the spindle - a belt and braces approach to safety!
Steve

[PJW]

Must make a handle, has anyone got a drawing of there handle?

[Jo]

Must make a handle, has anyone got a drawing of there handle?

  Which handle are you talking about.

Jo

[steve-de24]

Jo,
PJW is looking for a drawing of a handle to drive the headstock spindle of his Cowell's.
Steve

[Jo]

The Mandrel handle. I haven't drawn it up 

Jo

[sco]

GHT has a drawing for a nice one that uses an expanding mandrel to fit the inside of the headstock bore of his myford but could probably be scaled to suit.

I'm wary of fitting a handle to the end of such a small diameter headstock for fear of it getting knocked and bent.

Simon.

[steve-de24]

Jo,
do you know what thread is used on the left hand end of the Cowells headstock spindle?
Regards,
Steve
ps. Thanks for the photos.

[Jo]

do you know what thread is used on the left hand end of the Cowells headstock spindle?

I recall it as being a standard 3/8" by 32 ME thread, but there are only about 6 threads to attach to. The dog clutch arrangement means you can have the material full diameter through the headstock and this maximises the opportunities for catching your knuckles on the bit that is sticking out 

Jo