I thought it might be interesting to compare them.
- Halfords SIP Welding tips, 0.6mm or 0.8mm hole, M5 thread - 5 for £4.99
- B&Q, MIG Contact tips, 0.6mm or 0.8mm hole, M6 thread - 5 for £4.99
- Ebay, Tattoo tips, various sizes, no thread - 18 mixed for approx £10. can be bought singly.
Both the welding tips need to be carefully drilled out - typically 3mm - to within a whisker of the exit hole - so that the thin section is as short as possible.
The tattoo tips seem to be made by drilling a 6.8 or 7mm hole, then a 2mm? hole right through - then a tube of the required dimension is (brazed?) attached to bring the diameter down to the exit hole, and the tip shaped(guessing). From visual inspection, it looks like the 2/2.5mm hole extends almost all the way to the tip.
I think that if the excess tube is 'trimmed' it will form a good nozzle shape internally.
The tattoo tips need to be attached and/or the big hole in the side sealed. a few initial thoughts are:
- tap the internal diameter and screw in a standard reprap drilled bolt
- cut an 8mm thread in the outside and screw into a coupling nut or threaded block
- drill a 'heater block' like nopheads to 8mm and press-fit/solder/braze the tube to form a good seal.
Of course, if 0.6 or 0.8mm is too big for you, you can always use the nichrome wire/high temp solder trick to get a smaller exit hole.
Since solder is a generally softer, has anyone tried blocking the hole and drilling the solder with a small drill bit to get a 0.4 hole?