Model Engine Maker
Supporting => Tooling & Machines => Topic started by: PJW on January 31, 2016, 05:20:24 PM
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I started with a piece of mild steel 25mm x 35mm in my Prazimat lathe, I drilled, tapped& counter bored it to suit the thread on my spindle, I made two of these, one 14 x 1.5mm to suit the Cowells & one to suite the Perris I will be selling. I drilled through both pieces 31/64” then screwed the on to their nose threads making sure that they are tight against the shoulder.
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I next turned them true to the machines they would be used on, then turned the dia for the m19 x 1 thread with a run off for my single point threading. The 19 x 1mm is to match the nut I purchased! The threading was a simple job & was done in no time.
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I then returned prazimat to make a mandrel for one of the collets to slide on snugly. I left .5 mm on screwed it on to the lathe nose thread & finished it off on the machine it was to be used on.
I next clocked up the top slide to the angle of the collet side, I double checked this angle to make sure it would be right.
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Next stage was to put the partly made chuck back on and start to bore out the internal angle, I have an er16 chuck so I placed a collet in it to see how far it goes in, marked it & used this for a gauge. I bored the angle out to a fine finish & job almost done, the last job was to mill some spanner flats on.
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I am a tickler for tools and always interested in what others make. That turned out great and very useful............ :ThumbsUp:
Don
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Nice job Peter!
Simon.
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Thanks Don, I mentioned that i was going to make the chuck to sco (Simon) and he suggested I shared the build as it might be of interest. I was pleased with the finished product & it runs true so will get plenty of use if it is like my ER25's.'
Peter
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I love it, I bet it will be used a lot.
Holt
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Peter,
Thanks for the pics of your build, I've been thinking about kitting out my Cowells with ER16 collets and your posts make it look doable although I'll first have to get in a bit of practice with (new to me) internal threading. There is a series of videos on youtube of a guy making an ER32 collet chuck for his Boxford lathe which are worth a look although watch out for a mistake in part 2 which he corrects in part 3.
https://www.youtube.com/watch?v=8SV7lDiSXto
Steve
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internal threading?? I have never tried this yet myself, I purchased a nut of a well known auction site, the rest was done with a tap, have a go, if I can do it anyone can, nothing to loose is there!
Peter
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Peter,
I was thinking about cutting the internal 14x1 thread to attach the collet chuck to the spindle, I see you used taps for this.
I'd be buying the collet closing nut. Where did you get your collets and closing nut from? - I was looking at Arceuro which seem good value.
Steve
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My nut & collets are from china, I had a set ER25's from there two years ago and I have been pleased with them you have to wait a couple of weeks but I wasn't in a rush, they are so cheep you could throw them away if you have any trouble with them £10 a set, if I was making swiss watches I may need a little bit better quality,
Peter
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Nice work Peter, I made a similar chuck for my Emco Compact 8, only I made it for ER-32 collets since I use that on my milling machine. Very handy when turning round stock.
Thor
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Peter:
Great idea. I have some ER-20 collets for milling machine tooling. It would be nice to have a collet chuck for my Sherline lathe. I'll add this to the list of things to make.
Thanks for posting.
Hugh
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out of interest - how did you establish the true 8-degree taper? Most people who do this seem to spend a long time blueing and checking, then tweaking and re-cutting that tapered cone.
AS
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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
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Thanks for posting, PJW. I want to make an ER chuck for my mill soon and your WIP has given me some tips :)
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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 :headscratch:
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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
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Peter,
That looks very neat. :ThumbsUp: 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
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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.
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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
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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
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Must make a handle, has anyone got a drawing of there handle?
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Must make a handle, has anyone got a drawing of there handle?
:headscratch: Which handle are you talking about.
Jo
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Jo,
PJW is looking for a drawing of a handle to drive the headstock spindle of his Cowell's.
Steve
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The Mandrel handle. I haven't drawn it up :ShakeHead:
Jo
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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.
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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.
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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 :Doh:
Jo
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thanks Jo :LittleAngel:
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Mr Silky has a built in Handwheel that I have become very fond of using :embarassed:.
It may be an alternative for the Cowells but I fear it might work like a flywheel on such a small machine :-\
Jo
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When I made my ER16 collet chuck for the Taig, I used a pattern-follower method of cutting the threads. This lets me cut threads of any pitch:
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gerritv, I have seen similar approaches to thread cutting on the Taig (e.g in the link http://www.cartertools.com/brooketh.html), but none so simple or elegant as yours!
--Tim
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Hi Jo, you were right it is a 3/8 x 32ME thread, :ThumbsUp:
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[quote author=gerritv
When I made my ER16 collet chuck for the Taig, I used a pattern-follower method of cutting the threads. This lets me cut threads of any pitch:
Really neat, I've not seen that method before- so simple :facepalm: and so obvious ;)
Cheers,
Rod
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I've obviously had a long day and am feeling somewhat short on brain cells but cannot quite see how that thread following is working. :headscratch: Could a clever person elucidate a little.
Many Thanks,
Colin
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It looks like the carriage is being pulled toward the lathe chuck by the engaged threads of the piece held in the drill chuck, which seems to be mounted to the cross-slide. I've never seen it before, and it looks interesting.
I made a spindle hand crank for my lathe for cutting 3/4"-8 LH square threads, since my lowest 120 RPM speed was too fast for comfort and safety.
(http://enginuitysystems.com/pix/tools/Spindle_Crank.jpg)
(http://enginuitysystems.com/pix/tools/Spindle_Crank_1210_800p.jpg)
(http://enginuitysystems.com/pix/tools/Spindle_Crank_1225_800p.jpg)
(http://enginuitysystems.com/pix/tools/Spindle_Crank_1226_800p.jpg)
(http://enginuitysystems.com/pix/tools/Spindle_Crank_1272_800p.jpg)
You can see it in use in my video of the repair and mounting of my 6" 4-jaw chuck (around 12:00):
https://www.youtube.com/watch?v=fO_WpIo5gzs
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I think the tailstock is being dragged by the stud screwing into the job as it rotates. There is a bar low on the tailstock that is pushing the cross slide along. On many lathes you would have to disengage the leadscrew but the Taig doesn't have one, just a rack.
Well, that's what I see anyway,
Rod
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I've obviously had a long day and am feeling somewhat short on brain cells but cannot quite see how that thread following is working. :headscratch: Could a clever person elucidate a little.
Many Thanks,
Colin
I don't want to hijack the thread but
The tailstock is tied to the carriage. Taig has no leadscrew so the connected assembly just follows along the bolt that I used as the thread pattern. I learned this technique on my Unimat, which while it does have a lead screw also has a spindle that retracts. My web site has some more details: http://hobbies.psgv.ca/making-an-er16-collet-holder/
As PJW found, making your own ER chuck is not that difficult regardless of the lathe used. And the result is made-to-measure for your machine.
Gerrit
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Thanks for the handle pics Jo!!