Collet Stop

[eLuSiVeMiTe]

A stop on the drawbar has the same disadvantage that Dr Al identifies above: that if you push the stock onto it, the collet then slides on the stock as it tightens. So at the last squeeze of the drawbar, you are trying to move something in a tight collet. That cannot be good for stock or collet.

Fair point. Didn't read the other posts tbh

A collet closer was made for the L and would negate that issue as it's a lever action against the draw bar

 

[Agroshield]

ArcEuro sell the same one as Gloster, so there is a picture there as well. Put '5C collet stop' into Google images as there is a lot of things from which you can draw ideas there. See the Edge technology one for how to cope with differing diameter stock or stock with holes in (the rods are reversible). A very nice one is shown in the PM thread. There's one at GrabCAD that you could scale down.

For the half dozen that you do use, what size is the hole in the back end of the collet relative to its gripping diameter? Is there scope to loctite in a very thin wall bush that has internal threads such that they do not inhibit the through-capcacity of the collet?

5C Universal Collet Adjustable Backstop - Arc Euro Trade

Designed to fit any 1" bore 5C collet with or without internal threads.

www.arceurotrade.co.uk

Edge Technology 5C Collet Stop

Edge Technology 5C Collet Stop fits standard 5C collets with internal threads and is a must for multiple piece runs of small lathe parts.

www.allendale-metrology.co.uk

5C Collet Stop for Collets w/o Internal Threads

Have a number of Hardinge collets w/o internal threads. I am aware that Hardinge makes a stop for 5C's w/o internal threads... But looks like the hardinge stop takes up a lot of room on the inside of the collet. Anyone come up with a more compact stop design for 5C's? Thinking I may spend...

www.practicalmachinist.com

Free CAD Designs, Files & 3D Models | The GrabCAD Community Library

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grabcad.com

 

[James1979]

That edge one is very nice. I’m using 1/8 To 9/32 at the larger end. Maybe 1/4 occasionally. It you could actually loctite in a bush of reasonable wall thickness actually as the ID is around 3/4

 

[Rkweld]

There is a bunch of used 2804 collets on ebay at the moment, if you were wanting to modify one to have a stop and keep yours standard.

 

[James1979]

I think I have come up with something based on the input above. Thanks all, I will have a play in the workshop tomorrow and see what I can do.

The plan is, a bush tapped M12 bonded into the bottom of the collet. This will allow the collet to be used as normal as the ones I use are <8mm anyway. I am going to thread some all round bar to 12mm so it screws into the bush then put a locknut on it. Might have to make a knurled fastener rather than a nut but we will see.

Alu as its cheap, plentiful, and I can turn / profile the part inside the collet to whatever I need easily enough

 

[Agroshield]

Please consider the benefits of an M12* fine thread. A fine thread will have greater tightening power and smaller depth of cut (difference between major and minor diameters). A fine thread gives you better options on a draw tube as opposed to a draw bar. Maybe brass might serve better than aluminium as brass does not gall. You can bond the sleeve in before you tap it as then the collet wall will give support when tapping.

* or bigger - you might want to extend the system to your bigger collets. M16 x 1.5 is standard electrical thread so taps and dies are reasonable. 16mm and 5/8" are close enough to each other that tube choice is wider.

 

[James1979]

Very good points. I’ve made a few up in mild with 12x1.75 as that’s what to hand. I actually have a m16 fine tap so i may redo it and use that. I’ll order a die.

liking the idea of brass on brass though. Wonder if a drop of silver solder would work better than expoy

 

[mtt.tr]

This isn't a direct solution, but I use the dro,

 

[James1979]

This isn't a direct solution, but I use the dro,

I don’t have. It’s more to speed things up on the capstan. I’m doing runs of small (14mm Long x 6mm dia) parts at the moment. It’s just a way of getting them to length that’s as least fiddly as possible with my paws

 

[mtt.tr]

I don’t have. It’s more to speed things up on the capstan. I’m doing runs of small (14mm Long x 6mm dia) parts at the moment. It’s just a way of getting them to length that’s as least fiddly as possible with my paws

Ah capstan yes fair enough.

On the turret can you have a set to length stop?

 

[James1979]

Ah capstan yes fair enough.

On the turret can you have a set to length stop?

Yes I’ve made one up. To measure the stock. I see what you mean, use that in reverse as it were.

 

[Agroshield]

Wonder if a drop of silver solder would work better than epoxy

I am not sure if you mention this in relation to the bush/collet joint. The temperature for silver soldering would not be so good for the temper of the collet. For brass, soft solder would do. I would be looking for the Loctite with the lowest denaturing temperature and try to maximise the surface area of the parts in contact.

Most of the Loctites say 300 deg. F continuous but some are 450 deg., so they are the ones to avoid. To remove the bush, maybe heating the drawbar (induction coil?) with it screwed into the bush would have less effect on the collet than a direct flame.