Gallery, Projects and General > How do I??
Camlock chucks
mattinker:
--- Quote from: sparky961 on October 30, 2017, 07:50:39 PM ---
--- Quote from: mattinker on October 30, 2017, 03:46:39 AM ---I never had a block "throw", remember, they are clamped in by the jaws!
--- End quote ---
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.
--- End quote ---
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:
--- Quote from: RotarySMP on October 30, 2017, 05:58:40 PM ---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.
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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 :thumbup:
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
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