Carbide Tip Source

They might have it:

Products

Louis

 

Tungsten electrodes for TIG welding can be ground to a sharp tip. Try a welding supply house.

I think you can buy carbide drill rod in a variety of sizes. Try MSC.

 

Might need to be a bit more precise in your measurements to get one that really fits. Might also need to remove it and see how it's held in place.

"About 3mm" is also "About 1/8 inch" (3.2mm) and I can find carbide scriber replacement points, some plain, some threaded on the inner end, for $2-3 each, or possibly more or less with more shopping.

The cheapest ones seem to be a "standard" concrete scribe, with a carbide tip inset in a steel shank, which is threaded.


I would not exactly be shocked to find that some clever folks had adopted the same standard for endpins, but it would depend on your particular endpin.

This one claims to be 20mm x 3mm and a replacement tip for a "vibro-engraver", whatever that is. $4.49 - If you need it shorter and can't find the length you need, you could cut this down.

As far as I recall from learning to TIG weld in college, welding tungstens are NOT tungsten carbide, they are just tungsten, with or without a bit of Thorium or Lanthanum - the thoriated ones are a bit radioactive, so you want to give those a pass, but you may want to pass entirely if you want tungsten carbide.

I also found an 1/8" engraver point with a flat on one side, and a diamond tip (oh, the tone BS you could get into by claiming to hear a difference) for $59.

Another scribe with replaceable tips was described as a "jewelers scribe" and classed with "stone setting tools" on a jewelry supply website. Didn't see the tips alone there, and they are a bit vague about is is really 3mm or is it really 1/8" as they describe it as both (not quite possible.) That was $15 with both tips and a handle, one tip similar to the rest here and one with a smaller point section.

Should give you some more googling/shopping options.

 

I experimented with this for a bit. I found that the points like this - mine were made for grinding wheel dressing - are both expensive and delicate. Dremel engraver tips are expensive, and not nearly as hard as they claim. I think the best solution is to make a pin out of oil hardening drill rod (3' of 10mm O1 alloy costs 8 bucks at McMaster). Anyone with a metal lathe can carve the notches, thread if necessary, and make a point. Then you heat the end to incandescence with a propane torch and quench it in oil. If you have a power drill and bench grinder you can resharpen when necessary, but it will be less often than you might think.

 

They are hard, but they can be broken. I truly mentioned it only as a (poor) joke.