1+

Though if you have a lot it may be easier to take round bar, turn the taper, over to the mill to do the 4 flats and then back to lathe and part off. This would save having to use the 4-jaw or find a suitable collet to hold the square.

Edited By JasonB on 22/07/2015 14:15:00

I would probably make them in 2 part using a self centring 4 jaw for the square plus small hole for the spigot I would leave on the pointed part – assuming that I could get 1/8" square brass and that being 0.013" under sized wouldn't matter. Or mill up the square bar 1st but in that case they may as well be solid.

John

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Use an overlong price of material, make them back to back and part off one from each end. Leaves a small stub of material but at this size material cost would be peanuts.

<——===——>

Jason's method is clearly the one to use Martin e.g. turn, mill & part off.

One suggestion to make milling the flats easier on your mill – would be to get an ER collet block (with a suitable collet) and use that to rotate the work squarely. They are not expensive and are very useful to have.

Regards,

IanT

This quite a small part,I would get a couple of lengths of bar, turn the cone on each end of each bar,then mill the flats in an index fixture,then part of.You then get four parts at a time rather than keep going between mill and lathe. I think a Myford 4 jaw only holds square bar 3/16 and up. Always avoid 4 jaw chucks on jobs like this if there could be a lot to make,too time consuming. If you try milling the flats first the square part is only 3.5mm across flats so turning after milling could cause the pointed end to deflect. If there was a lot to make it would pay trying out forming the taper with a wide tool rather than twidling the top slide handle a lot of times.

Pre-fabrication ?

Square stock , drill location hole to take cone/ flux / tiny fragment of silver solder inserted in hole.

Round stock for taper with tit ( sorry) on end.

Heat , cool , polish.

Martin, if (you do) you didn't have a mill, it would be just as east to put the square on by using a filing rest on the lathe, for some jobs this is quicker than transferring to the mill, and probably just as accurate as the original tips.

Wonder, are you going to nickel plate them to match the taps?

A Junior hacksaw would maybe be better than the Dremel.

Ian S C

Edited By Ian S C on 23/07/2015 11:16:30

Edited By Ian S C on 23/07/2015 11:18:46

It's probably just me but this seems to be getting terribly complicated in parts.

I'd stick the bar in my 3-jaw, turn the pointy bit (with top slide set over), take the work out and use a collet block (or other simple indexing device) to rotate it 4x whilst milling, return the work to the lathe and part off (with a rear tool post), pull another length out and turn another point. Ad infinitum – and no wastage!

If I wanted to be absolutely certain that the point was concentric to the square (within the limits I can normally work to) – I'd also use a collet chuck in the lathe, either by buying a second ER collet or moving the one I had with the work (a bit more fiddly but quite doable)

The only issue then is how good you want the other (parted off) end to be. On small work like this, the finish from a sharp HSS parting tool should be quite good enough.

IanT

I have such a milling set up available Michael but (at least on my lathe) I'd have to keep moving between the milling spindle and the top slide & parting combo – I can't have both mounted at the same time there isn't room. It does give a very accurate result because everything becomes a "first" operation, as the work doesn't leave the chuck but it's not convenient for multiple units with my arrangement.

Doing them two at a time as suggested would probably help with the overall time spent but not the total material used, as the 'bit' in the middle – required to hold the two 'ends' –  is effectively wasted.

For myself, time is not an over-riding concern but I sometimes only have a limited amount of material. Sliding the work out of a 3J, moving it to the collet block wouldn't take me that long and everything is ready to go every time.

If a vice stop was fitted, the collet block could be set and rotated pretty quickly and some kind of stop on the lathe cross-slide would allow the part-off length to be set too, as the saddle could be locked.

It's often not the actual machining that takes the time in my experience but setting up the machine to do it in the first place.

IanT

Edited By IanT on 23/07/2015 23:30:24