Making hexagon nuts on a rotary table & mill.

Hi folks,

For many years I've used a milling machine and a rotary table, the sort with T-slots.

As a long time clockmaker, I sometimes need to make hexagon BA nuts from brass bar. OK, I usually have done it the hard way, by filing, but there ust be an easier way to do it!

I’m sure there’s a way that I can attach a piece of round brass bar to the centre of the rotary table so I can just rotate it and mill the flats every 60 degrees without moving the X and Y slides.
I’m sure I saw a set of gadgets like angle plates with allen screws to centre the brass tightly, and similar screws with T-nuts. Might have been South Bend?

I know I could probably make some, but time is of the essence! What do you think?

Forget rotary tables a Hex Stevenson Collect,Chuck is what you want. ARC do them. Just made a load of ferrule nuts with mine. The square one is equally good and gets used more.

Dave

You can probably buy lengths of hexagon brass of the right AF for BA sizes. I have used the rotary table to make lots of custom nuts and bolts, but never as small as BA. You will need a method of getting the spindle exactly in line with the table axis. I cheat a bit and put a test bar in the RT centre Morse taper, and close the jaws of a three jaw scroll chuck gently on the bar before tightening the chuck down. Then I use an optical tool in the spindle to centre the end of the test bar. That gets me to about 0.002" tir which is good enough for most work.

Dave Smith beat me to it!

I made my own about the time that Arc started selling the John Stevenson version (Much better than my home brew!)

Depending on the length of the raw material the collet block can be horizontal for long stuff, or vertical for short.

Grip the bar in the ER collet. Mill one flat if horizontal, two if vertical.

Move block round one flat, mill next flat (s )

Repeat until you have a hexagon of the required size.

Or you cold start with hexagon bar of the required size, and merely drill, tap and part off!

Howard

Do you make pinions and wheels? Just use a similar dividing setup but an endmill to make the flats.

Easiest way is to mount your lathe 3-jaw to the rotary table and hold the stock in that. If you disengage the worm you can quickly spin it round and just use the graduations on the edge of the table and lock it every 60deg. Faster then having to keep resetting an ER block in a vice.

Depends on the size of 'hex' bar you need Phil.

I haven't been able to find very small hex-section brass bar, so if I want to make 14BA nuts (which are expensive) or 16BA nuts (which are unobtainable), then I have to make my own. It's a problem for me, as a scale G3 wagon can use a lot of these small parts. A 5/8th (pre-war) Whitworth nut is 0.7mm AF in Gauge 3 for instance.

One problem with thin materials is that they will simply move/flex if they are extended too far without support. One solution is obviously to only extend the material out a little but then this greatly extends the time required to make a usable length of hex bar.

My solution (whilst far from perfect) uses a hand shaper and works, although it's still not as fast as I'd like. As I need to get a uniform part thickness, I first machine the aluminium support to ensure it's perfectly level - which is much easier than trying to set a small part in a vice. The small Hex block is simple to turn after each cut and sometimes I just hold it in place - with a fore finger pressing on the part. No problem with a manual shaper but certainly not advisable with any form of rotary or powered cutter - although with a toolmakers clamp (as shown) a mill could be used.

My next experiment in this area will probably be to try a Hex draw-plate, using a small Allan key to make the hex-hole punch.

Regards,

IanT

Dave,

I’ve looked at these Stevenson thingies on ARC and they seem to be the better idea.

Old mart,

I’m sure I can get hex brass but i’d prefer to make my own from the existing bits of material with any size I wanted

Howard,

I’ve PM’d you but I don’t have an ER collet and I cannot understand how the Stevenson gadgets work – how are they gripped solid?

John,

Yes, I do, but very occasionally. I use a dividing plate on my Unimat lathe and move the motor to vertical with a home-made single point cutter.

Jason,

The problem is how to hold the stock in the rotary table, irrespective on how the is held.

Mike.

Edited By Phil Meaken on 16/03/2021 10:18:12

Surely that's your answer then - use an endmill rather than a single point cutter and a plate that gives 6 divisions.

Phil, did you miss the bit where I said mount your 3-jaw chuck to the rotary table, work then held in chuck

I saw it, Jason, but the problem would be how to hold the 3-jaw chuck onto the rotary table (the RT doesn't have a morse taper, BTW,)

Mike.

Edited By Phil Meaken on 16/03/2021 14:24:17

What is your lathe's chuck fixing?

That looks a good way of making very small hex barstock. Machining the ali 'bed' first to get a reference plane makes good sense. If you start off with round rod and do three faces you then presumably have to raise bed for the next three?
Is the cut taking place on the forward or reverse cutter stroke? In normal shaper usage it looks like the small diameter work could easily buckle as its pushed towards the indexing hexagon block.

Ian P

1 1/8 12 tpi, Jason. It's a 1947 Myford ML7. The morse taper shank can be removed from the headstock.

Mike.

John,

Unimat which I use to cut wheels isn't beefy enough to use milling cutters, and even it it was, it would take forever doing that.

Phil

I used to make nuts in the same manner as you however I now as suggested use hex collet's and hex bar, makes life a lot easier

H

It's cutting on the forward stroke Ian - but the cut is very light in these sizes. A finger helps prevent any lifting/buckling - but I wouldn't try that on my 7B. The angled 'shelf' (the hex holder is sitting on) can be moved to level the holder with the block's cutting surface - there's a clamping nut on the rear side of the block. In terms of the 3rd to 6th cut, you are correct to observe that either the cutter needs to be lowered - or (as I now tend to do) a thin shim inserted underneath - meaning the cutter height is unchanged (locked) for multiple lengths. The material is simply advanced by unlocking the grub-screw in the hex holder. You can't really see it but there is also a slight relief filed at the end of the material where the 'cut' ends - to help the tiny swarf slivers fall away.

There are other ways to do this work of course - just with a file for instance - but a hand shaper can make quite delicate cuts (with a sharp tool) and is well suited to work where you don't need to remove large volumes of material.

If I didn't have the shaper - just a lathe - then I think multiple lengths could be set on a shellac (wax) plate and faced - then turned and faced again. Using a heat gun and tweezers it would take six rounds of 're-setting' the lengths but you'd get a larger quantity of small hex at the end. Not sure if it would be any quicker but I think it would be possible with care. Larger hex can be done as others have suggested of course.

Regards,

IanT

Something like this fitted to the R/T's slots or onto a sub plate if needed. You can also get similar with a Unimat thread if you want to mount the smaller chuck onto the R/T

Thanks to all who've replied, but I think that the various answers weren't what I was really looking for; to clarify I'm going to start a new thread so this one can be closed.

I need to be able to get something that will clamp different sizes of brass bar and easily mill hexagons, squares or other different things (torx?) easily by just rotating the milling table.

As a newbie on here, is it possible for the Mods to lock this thread?

Thanks

Mike.

Edited By Phil Meaken on 17/03/2021 14:47:24

Mike,

I'll PM you about ER collets

Howard