[Fred Ming]

Greetings:

I have to put a flat, up to half the diameter, along the length of some pieces of 1/2 inch long, 1/8 diameter drill rod. I have milled a few, but haven't found a decent way to hold them for milling.

Any suggestions, please?

[NC Cams]

There are hand indexable, spin indexers for 5C collets.

Look into a Grizzly #G5649 and an appropriately sized collet...

EDIT

Hold them with the collet/indexer and then grind the flat with surface grinder. We made bullet proof allen keys for R/C car motors via grinding flats onto drill rod with this method.

END EDIT

[Fred Ming]

Thank you!

[Mcgyver]

at 1/8 there might be too much overhang for 1/2 length, but like NC says, the collet blocks are a quick and easy way to put squares, flats, hexs on the ends of turned work. if there is too much overhang, another good trick is to soft solder tricky little pieces to something large and easier to clamp. cut a small V in a small piece of mild steel, solder the DR in and then machine - take light cuts. keep your heat in check, if you get it too hot the piece you are soldering to will act like quench and start to harden it

[NC Cams]

Don't plan on taking all the metal off in one pass - it takes multiple passes.

We took 1" long pieces of drill rod and turned 0.090" dia drill rod into allen keys - the hex was about 0.080" long. The length you want migh make it a bit tougher - just go a bit slower and with light cuts.

Remember, light cuts and multiple passes should do it. Also helps to make the axis of drill rod parallel to the axis of the grinding wheel spindle and keep the rod parallel to the grinding axis as you feed the wheel across the rod.

It isn't all that hard to figure out once you can hold the rod steady with the spin indexer.

[pepo]

If you are not going to go past center and want to mill it I would drill and ream a hole in a set of soft jaws. Stand the jaws on end in the mill with the edges of course lined up and put this hole in just below the top of the jaws. Make sure you have something about .020 thick in between them when you do this. Now,lay them down and bolt them on the vise. On the first peice you will be milling the jaws and the part,after that the jaws will be cleared. For milling o-1 drill rod steel jaws would be much better. If you did this and made the peice 1/4" too long you could mill to the center or past and cut off the extra 1/8" on each end later. The two full diameter ends would keep the peice in the jaws. Grinding would be good also but heat must be controlled.

[Fred Ming]

Thanks for the suggestions.

I would give real money, which I try to avoid like the plague - to be able to buysome half-round 0.125" rod.

It gets worse. I then have to attach the 0.5" long pieces of half-round across a piece of 0.006 high carbon steel feeler gauge stock. ANY THOUGHTS ON THIS? I have been doing it with expoxy gel - it tacks it on there, and the load keeps it on - but it's not really satisfactory. WELDING would be nice, but can it even be done, what with the little pieces, and a piece so thin. Silver solder seems vaguely possible, but any excess material wopuld interfere with function.

Such a simple little part . . . glug.

[NC Cams]

Try sweat solder.

First you "tin" both parts with solder then you clamp them together. Then you reheat them - sort of like reflow soldering of SMT's on PCB's.

Minimal solder plus fairly strong bond potential.

[HuFlungDung]

There are small resistance (spot) welders available that would probably work quite nicely to weld the part on.

So far as milling is concerned, if you can spare a bit of extra length to the parts (and shorten them after), here is a method: take piece of keystock and drill and ream a 1/8" hole lengthwise down the center. Now, carefully mill a groove crosswise across this block, exposing the 1/8" hole down to one half of its depth.

Now, take the keystock and saw a vertical slit lengthwise, stopping when the cut enters the 1/8" hole from the bottom. (You may want to anneal the keystock beforehand, so it does not close up on you). The purpose of this cut is to make the keystock collapsible when clamped in the vise.

So if you start with pieces maybe 1" long, this will give you 1/4" of clamping length on each side of the cutaway area. Now you can produce the parts using this fixture.

Edit: whoops, I see this is much the same as what Pepo was advising. I didn't get it first read through

[Konrad]

You can hold the drill rod in a good vice, making a parallel first, so the center of the drill rod is about .002 to .003" above the jaw.
Konrad