DEALING WITH 4-40

[riversidedan]

wanting to make some small threaded rods with a 4-40 die and wanting to know whos had experience threading that small of rod.
will put the die in the chuck and rod in the TS chuck and have to force the rod in, the die is octagon so needs to go in the chuck.
anyway the setup is good just wondering whos messed with small rod threading////////



gentleman....................drill size for a 4-40 is .0890 or #43 the short steel rod to be cut is .0935 sound like its too big for the die??? and yes the rod is chamferd

 

[MrWhoopee]

First, make sure that the die is a thread cutting die and not a thread repair die. Hex dies can be either. Keep the stock as short as possible and chamfer the end "for ease of insertion". Since your are holding the die in the chuck you will have very little feel. It takes very little force to cut a 4-40 thread, but not much more to twist the stock off.

 

[extropic]

What is the length to be threaded?

What is the diameter of the length to be threaded?

What is the material of the rod?

How do you plan to advance the rod, into the die, at precisely the thread pitch? 1/40=.025" per revolution.

Based on what information you've provided in the OP, it not clear to me that your plan is the best way.

 

[T Bredehoft]

Today I was cutting 4-40 threads in brass, turned the 5/16 brass down to .110 for .250, (have the round die stock in a holder,) . I put an Aloris type boring bar on the tool post, put the die ups against the boring bar holder (to keep it square) and on the stub of brass, with the compound I put pressure on the die and turned the chuck by hand. Easy Peasy, When the die was half way onto the stub, I could turn it by hand, and spin it off. Did this a couple of dozen times, making thumb screws.

You'll want to get the proper diameter, (don't bet on .110, I just guessed, and be sure to start the thread true square. You don't want it wandering off to the side. In steel you'll want to use Tap Magic, and be sure your chips clear the die, don't jam up inside.

 

[Boswell]

just curious why you are choosing to put the die in the headstock? is it because of the length of the threads? To advance the tailstock and thus the material, you could potentially use bungy cord as a weak spring to put forward pressure on the material as it is threading.

 

[WobblyHand]

Little Machine Shop has a couple of calculators on their site. die threading They recommend the rod be turned to 0.1095" before using a 4-40 die. They also recommend a 30 degree lead in (chamfer) to make it easier to start the die. Getting the die to start square is the key. A good HSS die should cut well. Once started straight just make sure you clean out the die occasionally. I've followed their recommendations for other threads and it has worked out well. Their rule of thumb is rod size should be about 90% of the major diameter.

 

[silence dogood]

It is more fun to make your own. However, if it very long and a lot, you could get brass, stainless, or steel up to six feet long on the net. Look up Macmaster-Carr, Grainger, etc. on the net.

 

[riversidedan]

First, make sure that the die is a thread cutting die and not a thread repair die. Hex dies can be either. Keep the stock as short as possible and chamfer the end "for ease of insertion". Since your are holding the die in the chuck you will have very little feel. It takes very little force to cut a 4-40 thread, but not much more to twist the stock off.

whoopee the die pkg sez plumbling maint. and repairs...............thinking I got the wrong die>??? also when I look at the ID cutting surfaces inside looks like 1/2 arent thier and 1/2 are.......in other words the cutters are 1/2 gone

 

[riversidedan]

just curious why you are choosing to put the die in the headstock? is it because of the length of the threads? To advance the tailstock and thus the material, you could potentially use bungy cord as a weak spring to put forward pressure on the material as it is threading.

I put the die in the chuck to keep the everything straight

 

[WobblyHand]

You could put the die in a die holder (if you have one) and place it against your tailstock to keep it straight. Then the rod goes in the chuck.