Try using the die on a bit of mild steel. If it cuts ok it is probably the bit of silver steel that is the problem.

Hi Brian,

Firstly there is no need to make the piston rod out of silver steel, so you are making things far more difficult for yourself.

My guess is that the die is not lying flat in the die holder. A proper tailstock die holder is a better method, again making sure the die is inserted correctly.

The die may also now be blunt.

If the material is accurately dead central in the chuck or collet, then you can turn down the first section to 'core' diameter with a chamfer between core and OD.

Get some decent tapping compound. I use Rocol, usual disclaimer.

The correct closure of the die in holder can be tested by inserting a screw of known standard/size and same thread as the die into the die to check.

Cheers,

Julian

I have had silver steel that was much harder than normal, I heated it with a torch and let it cool slowly, made a lot of difference.

It's possible to sharpen dies with a Dremel, poke a cylindrical point through the circular holes.

Dave

All the foregoing advice is good. To which I would add,:

Chamfer the end of the rod, to help the die to start cutting.

Use lubricant (Rocol / Trefolex / Bacon Fat – Don't laugh, it works very well!)

Use a Tailstock Die Holder (Make one?) You are asking a lot to ask a M3 thread to drag the Tailstock along the bed. AND the Drill Chuck does not allow the Die to float to pick the rod.. The Tailstock Die Holders will be a relatively slack fit on the Arbor for just that reason.

Commercial Tailstock Die Holders usually have the ability to accept a variety of sizes of Dies.

I made myself a Sliding Tap Holder, to fit the Arbor for the Die Holder, for Tapping. Again, a slack fit to ease picking up the drilling. (Mine uses ER25 Collets).

Making your own tools is often time well spent, since you can make exactly what you want, you learn, and save money, (and in view of your location, time).

Hope that you get things sorted.

Howard

By simply not tightening the chuck jaws and allowing the die holder to rotate in the chuck, you can hold the die holder by hand while running the lathe or, with the lathe still, turn the holder to thread the rod. This assumes that the problem is caused by dragging the tailstock…..

That and some good cutting oil.

If the die is toast then replace the die and do the above.

Pete

for materials that chip easily rather than curl it is better to cut once with the die open and not twice to finish,

it may sound strange but that is my experience,

because if i closed the die up on brass or silver steel it tends to mutilate the bar and chew the whole thing up right down to the core depth of the die, not good i can tell you.

So if it looks ok after 1 cut and the part fits, leave it be.

Michael W

Can anyone advise on the correct way to cut a thread using the set-up shown in Brian's picture? I have the same type of die holder and am not clear on how it is meant to be used.

The die holder simply consists of a wide tube at one end to hold the die with a hollow narrow tube or shank at the other. The die holder doesn't have any arrangement that allows the die holder to move forward as the thread is cut. Nor is the holder obviously intended to be hand held.

A few ways of using the tool occur to me none of which seem quite right.

1. The drill chuck is wedged into the tail-stock so that it can't turn. The shank of the die holder is firmly gripped by the drill chuck. The tail-stock is unlocked and free to slide on the ways. Whilst the lathe chuck is rotating, possibly under power, the die is engaged with the end of the rod and the whole tail-stock pushed towards the lathe as the thread cuts.

2. Exactly as above except the tail-stock is locked and pressure applied by winding in the quill.

3. The shank of the die holder is loosely aligned by the drill chuck but not gripped by it. The die holder is held by hand and pressed on to the rod by moving the tail-stock. As the lathe chuck is turned by hand to cut the thread the die holder slides out of the drill chuck.

Methods 1 and 2 in my hands are likely to mangle the thread. Method 3 works but doesn't feel like "industry best practice"

I now use a more conventional sliding die holder. The way that's used on the lathe seems obvious in comparison to the simple type.

Thanks in anticipation,

Dave