Camlock chucks

[AdeV]

Me again with more silly questions 

Having made a moderately accurate ER32 chuck out of aluminium the other week, and determining that it improves the accuracy of my lathe by almost an order of magnitude (especially when it comes to turning tapers), plus the fact when I put the 3-jaw back on last night I had the devil of a struggle to get it to run even close to true (I think the chuck shrunk more than the lathe in the cool overnight weather, so it was a bitch to get the registration all lined up - normally it just slides right back on like it's been there all it's life), I've decided that I think I'd like to convert my spindle nose to a camlock system. This will basically involve making a thin-ish backplate with the camlock pins on it, which will remain on the lathe all of the time.

Then, in theory, I can just buy camlock chucks & fit them straight on without thinking about it. You may laugh now. 

So... firstly, what's the most common camlock setup to use? 3-pin? 4? 6? I plan to run chucks up to maybe 10" diameter (8" most likely), plus maybe collet chucks of unknown size etc. My spindle bore is 1.75" approx and my max RPMs are 670, so I don't see the need to run anything under a 6" chuck. I do want to get away from the tedious Edgwick chuck changing procedure. Now that I know my spindle is pretty good, I'm happy to bolt a piece of steel or cast iron up, turn it & never remove it again (hopefully!)

Any thoughts gratefully received on this subject (including, if applicable "for god's sakes don't go camlock!"  )

[AdeV]

PS: Its more important to me that whatever system I use, will mount as close as possible to parallel with the lathe; a smidge of runout I can handle by using a 4-jaw more often; or a 6-jaw if I go that route.

[Pete.]

The camlock pins are on the chucks, not the nose. The pins are not so complicated but I wouldn't fancy trying to make the retainers that go in the spindle nose.

[John Rudd]

Ade,
My SPG tools lathe uses the D1-4 method....I quite like the idea versus the M39 x 4 thread on my Chester 9 x 20 or the silly 6 mm stud mount method on my Sieg C3.....

Horses for courses tho'

However the pins are on the chuck not the spindle mount....but you do what works for you..

[Spurry]

My little Harrison M250 has a spindle bore of 35mm and a D1-3 nose, so would expect your size of lathe to accept a D1-4 or 6 without to much trouble.
The size you decide on will be governed by your supply of appropriately sized chucks, as much as anything.
The amount of work in a lathe D1-* spindle nose should not be underestimated. It's bad enough to try and draw one, without actually making it.
A very interesting build thread though, if you go ahead.
Pete

[chipenter]

Have a look at Tonys lathes site for camlock info http://www.lathes.co.uk/latheparts/page12.html .

[philf]

Hi Ade,

Have a look at http://www.model-engineer.co.uk/forums/postings.asp?th=90112 for an idea of how much work is involved.

I wouldn't want a lathe without a camlock fitting fwiw.

Good Luck.

Phil.

[AdeV]

Thanks all 

That ME thread suggests it's not all THAT hard to do, which is cool. And I have a die sink eroder to cut the square drive with     

Now my only concern is the depth a camlock backplate will add to the spindle nose; switching the pins to the backplate wouldn't work (obviously) as there's no way to mount the cam lock mechanism in the chuck itself... My spindle nose already protrudes further than most taper lock or threaded types, so the camlock needs to mount as far back as possible. This might restrict me to 3 pins (a D1-5 looks like it'd be a better fit for the size chucks I want to run, but until I've played around with some CAD, I'm not sure if I could make it all fit properly. I don't mind drilling some clearance holes in the Edgwick spindle flange to allow the camlock pins to come through the back of the backplate/mounting flange, but they need to be out of the way of the three mounting holes. I don't want to remove the flange from the Edgwick completely, just in case I utterly wreck it. Mind you, I guess I do have a complete spare headstock..... must check to see if that's got the spindle in it...

[mattinker]

Before you change chucks,maybe you could improve them by grinding the jaws; I seem to be having trouble attaching an image. The idea is to make three blocks that fit between the jaws so that the chuck can be closed tight and still allow grinding of what are usually the clamping surfaces. the holes and slots allow a little spring. You will need some kind of internal grinder to run this on the lathe!

[sparky961]

a

The idea is to make three blocks that fit between the jaws so that the chuck can be closed tight and still allow grinding of what are usually the clamping surfaces. the holes and slots allow a little spring.

Excellent tidbit.  I've seen it done with a ring in the back, but the ring gets in the way of most chucks.  This method wouldn't get in the way at all.  I'm assuming the idea is to turn it SLOW to avoid throwing the blocks.

[chipenter]

I have used both ring and plates but without the holes , the ring must not toutch the bore of the chuck , a quick test for the jaws is to lightly grip a piece of round hss in the chuck and feel iff it rattles .

[mattinker]

a

The idea is to make three blocks that fit between the jaws so that the chuck can be closed tight and still allow grinding of what are usually the clamping surfaces. the holes and slots allow a little spring.

Excellent tidbit.  I've seen it done with a ring in the back, but the ring gets in the way of most chucks.  This method wouldn't get in the way at all.  I'm assuming the idea is to turn it SLOW to avoid throwing the blocks.

Sparky,
I never had a block "throw", remember, they are clamped in by the jaws!

Cheers, Matthew

[RotarySMP]

The ISO 702-2 norm for the spindle nose has incredibly tight tolerances. Only 0.008mm (three tenths for fans of a base 12 system) tolerance field on the major diameter of the taper, which is a point in space you can't actually measure.  I had a thread discussion on this, and the way to gauge it is supposed to be a air gauge, but that will be just as difficult to machine accurately.

google "iso 702 download" there is link halfway down the page to a pdf download here on madmodder.
Mark

[sparky961]

I never had a block "throw", remember, they are clamped in by the jaws!

Yes, but the direction of centrifugal force is only countered by the friction between the blocks and the faces of the jaws, from what I'm seeing.  It seems that if you had a little too much spring built in, or too light a touch in tightening things up, it might launch one.

[awemawson]

It's a tried and tested method that's been in use for over a century ( like most things to do with lathes !)

To get good results you don't want light clamping anyway as the jaw teeth need to be in firm contact with the flanks of the scroll as they would be in normal use to get the same alignment.

[mattinker]

I never had a block "throw", remember, they are clamped in by the jaws!

Yes, but the direction of centrifugal force is only countered by the friction between the blocks and the faces of the jaws, from what I'm seeing.  It seems that if you had a little too much spring built in, or too light a touch in tightening things up, it might launch one.

Sorry mate, the spring action actually equalises the clamping action. The friction under pressure on these very light, near to the centre blocks is more than enough to hold them in place. Might I suggest that you try it? I certainly wouldn't advocate anything dangerous that I hadn't tried. This being said, I'm not responsible for anyone that doesn't tighten their chuck jaws when using this method!

Cheers, Matthew

[AdeV]

The ISO 702-2 norm for the spindle nose has incredibly tight tolerances. Only 0.008mm (three tenths for fans of a base 12 system) tolerance field on the major diameter of the taper, which is a point in space you can't actually measure.  I had a thread discussion on this, and the way to gauge it is supposed to be a air gauge, but that will be just as difficult to machine accurately.

google "iso 702 download" there is link halfway down the page to a pdf download here on madmodder.

Thanks Mark, I did that, looking at the document I do see what you mean. However, I think that if one were making a spindle nose from stock, you'd cut the major diameter to dimension, then set the cross slide over & cut the taper REALLY carefully, sneaking up on the final dimension until the cutter just about brushes the final diameter. Then you'd cut the pictured reliefs in.

Also, looking at that diagram, I think I'd be making a size 5 nose, which gives me a whopping +0.01mm /-0mm tolerance; so as long as I leave it a "gnat's todger" oversized, I'll be golden. Of course, whether I can actually turn anything to these sort of tolerances on a worn out 1950s lathe with wobbly chucks remains to be seen!

Matt - Interesting! I've having my chuck jaws ground before (John Bogs gave it a go on his surface grinder, some years ago), which unfortunately made no difference to the parallelism; which suggests the wear is in the scroll. Your technique would certainly give me accuracy at the given diameter, but given the scroll is obviously worn wonky (there's a tight spot at around 1.75" ish as well, which adds weight to this theory), I'd need to make a set of those for every diameter I ever wanted to cut accurately, and I'd soon run out of jaw! I could convert these from hard to soft jaws, of course, but it's all starting to sound like a lot of work every time I want to use the machine.... The camlock nose adapter sounds like a hell of a lot of really quite complex work too, but at least it's a one-off project which - done right - will give me accuracy for years to come... Well, maybe...

I'm a long way off starting this project yet... I need some more tooling & in particular some of those rather excellent "ultra sharp" inserts that Chronos/Glanze do. They're supposed to be for aluminium but I use them for pretty much everything these days 

[mattinker]

Adev

I thought of you the other day when I changed chucks on my Edwick, I'm left handed so the nuts that hold the chuck on are easy for me to get at!! For the heavy four jaw, I have a special block which has the way "grooves" that puts the chuck exactly at the height of the spindle, that doesn't make you left-handed though!!

I agree entirely, the wear is in the scroll, also in the teeth of the jaw, but, the grinding under pressure will help with bell mouthing. The eccentricity is is as you say going to vary depending on the diameter being held. This is a three jaw chuck! If you want accuracy, the four jaw is the only way to go! I f you do decide to abandon your Edgwick chucks and have one with both the the inside and outside jaws, I'd be very pleased to pay the postage and scrap value for it!

Cheers, Matthew

[AdeV]

Hi Matt,

Only got the inside jaws unfortunately, IIRC I've got a 2nd chuck which has the outside jaws on it, it's been a while since I looked. And I've got a 4-jaw. Problem with my 4-jaw is it doesn't hold parts straight. I can dial out the runout to less than a 10th, move the indicator an inch further in and it's wobbling like a Weeble. I could probably fix that with new jaws.... or get my existing jaws ground (again - I'm pretty sure it was the 4-jaw I was trying to fix). Again, I suspect it's worn out, a new chuck would make the most sense. Which brings me back to the camlock.... because then I can get a 3 & 4 jaw & swap them at will.

[RotarySMP]

what spindle nose does your lathe currently have? I was very temoted to make a camlock nose adapter for my Boley 4LV, as the threaded nose is a bit of a nuisance. It is a small lathe, so you couldn't go bigger than D1-3, but I couldn't make a D1-3 fit with the existing thread, without excessive overhang.
Mark

[AdeV]

It has a unique to the Edgwick nose - basically, a flat disc with 3 holes for mounting bolts to pass through, spannered up from behind. The chuck registers on the spindle, but there's no taper, so it relies on having pretty close to zero runout on the mounting flange.

There's a picture of it in the first post of this thread: http://madmodder.net/index.php/topic,12279.0.html Not a very informative picture though! I'll try to get a better pic later in the week.

My only concern with making a camlock nose is the stickout - I'll need to be able to remove it if i ever want to use the gap in the bed, for example; not that I've ever needed to yet...

[DMIOM]

.. I think I'd be making a size 5 nose....

Ade,

I'd commend D1-*  style for repeatability - my Chester lathe has a D1-5 spindle and I have a number of native D1-5 three and four jaw chucks, faceplates, dog-drive plates etc.; and several others (ER32, Jacobs rubberflex collet chucks, and a 6-jaw self-centring) that I've mounted to D1-5 backplates.

Should you progress with this in D1-5 form, and were running them on your CNC mill and new lathe, I'd be interested in one or two D1-5 receivers or 'noses' with a suitable flange or back mounting, so I can use them for ease of transfer of chuck-mounted work from lathe to rotary table or 4th axis on the mill.

Dave

[AdeV]

Hi Dave,

If I can make one to the required tolerances, I'd be happy to make some more, no problem 

How many pins does the D1-5 have? If I'm reading the diagram right, it's 6 pins, is that what yours have?

[djc]

I don't mind drilling some clearance holes in the Edgwick spindle flange to allow the camlock pins to come through the back of the backplate/mounting flange

If the pins poke through the existing flange, how will the cams lock onto them? Whatever you do will have to be almost entirely in front of the existing flange.

You have been pointed to the camlock specification. Draw up the pin and the cam in their proper relationship. Decide how minimal an amount of metal you can live with around the cam (the bit with the square hole in it). That amount will set the centreline of the cam relative to the face of the existing flange.

How many pins does the D1-5 have?

You do not have to use all six pins. Three out of six would suffice.

I need some more tooling & in particular some of those rather excellent "ultra sharp" inserts that Chronos/Glanze do.

Glanze inserts are not the best quality (toolholders themselves are good). The ones cutwel sell are branded and much better.

Have you considered finding a lathe with the appropriate spindle nose that someone is breaking and buying the spindle off them? All the work is done for you. I wanted to make a D1-3 adaptor for my rotary table and that's the route I went - buy a complete spindle and chop off the bit you don't need.

Before you settle on a final design, have a look at the chucks. Like with mill tooling, 40 taper is more common than 30 taper and thus is cheaper. I do not know how the prices of D1-4, D1-5 and D1-6 compare.

[RotarySMP]

If you already have a flange, what advantage are you lookig for with Camlock? Not fiddling with mount screws save a little time, but given a flange, you already have the FWD/REV safety aspect covered. If your flange is round and flat, then tight fitting chuck backplates should already remount with high reapeatablity.

The Camlock standard has such tight tolerances as it is designed for the chucks to contact both on the taper and similtaneously on the flange.

Ideally, the camlock spindle adapter should be hardened, and then ground. The clearance at the back of the camlock taper is to provide the run out space for the grinder wheel to run out into. This is why you can't measure this dimension directly. Even if you use a sharp tool without a nose radius, and dont have the undercuts, you are not likely to get repeatable measurements on the back end of that taper to within 8 microns.

Whether an unhardened, unground approximation of the camlock spindle will give significant benefit over the standard nose flange is debatable.
Mark