Hints and tips for cutting small(ish) male threads with a die

Howard,
I can confirm that the die holder is on a sliding mandrel. I now have all the pieces in place to get this sorted.
Just need some shop time....

Having had a 40 year gap I am still using tallow (not the same batch), and I probably have enough to last me out. Is it worth me switching to one of the newer compounds or tapping fluid?

Brian

Brian If tallow still works, why change ?

Roy

Not if tallow works for you. Downsides of tallow are it can rot in the workshop - don't get used tallow in a wound - and it's not the most suitable compound available.

Although tallow is a reasonable lubricant and dirt cheap, it's out-performed by newer compounds containing extreme pressure additives that don't go off and work more reliably. The 'newer compounds' are hardly revolutionary modern ideas - they date back at least a century. Using a solid lubricant whilst tapping might help eject swarf, but I'm not sure tallow is stiff enough to be forced out and take swarf with it; I feel something more waxy is needed.

Deciding to replace a modern cutting mixture with tallow in hope a traditional material might be better would be a mistake - tallow isn't as effective. Depends on who you are and what you're doing. Taps and dies in my clumsy hands need all the help they can get! That said, faced with an empty spray can, I've successfully tapped threads with paraffin wax and Castrol grease - both worked.

Dave

Hi again Stuart. To make the centre screw, just grind or turn a point on the grub screw it is about 30 degrees and you should see the gap open when screwed in.

Best wishes

I recently had a similar problem trying to cut M3 and 5BA threads with a die. I used the tailstock barrel to butt the holder up to the work as I have done many times. The resulting threads were way off and binned.

The problem seemed to be with the 3 jaw chuck and the material not running concentrically.

I turned part of a length of ¼" bar to 3mm diameter in the same chuck and then cut perfect threads.

Serves me right for being lazy and not fitting my collet chuck!

One trick that nobody has mentioned is to make the piece you are threading slightly too long (too long by the thickness of the die). Then turn this section down to the root diameter of the thread being cut. This acts as a guide for holding the die straight when starting to cut the thread. It works when cutting threads in the vice as well. When your finished just cut the extra piece off.

MC

Before my lifetimes supply of Trefolex arrived Brian, I tried various alternatives. One of them which worked quite well was bacon fat - garnered after breakfast from the grill. It did go "off" after a few days and start to smell a bit but it was much better than dry cutting. Because of the pong it was also necessary to clean everything very well afterwards.

However Trefolex is a marked improvement..

Btw - although I use a cutting oil on my large drill press (& mostly drill holes from 3mm up) - on my smaller 1/4" drill (mostly 1-3mm holes) which is indoors, I use Trefolex instead. It seems to work just as well, it is easy to wipe just a little on the drill bit and it doesn't drip on the floor!

IanT

Bit of time in the shop today, initial conclusiion is that the issue was a dodgy die.
Brand new split die from Tracy Tools, stock turned to dead on size, no lead in taper, Trefolex.
Thread cut under power with no issues at all.