Sunday, 31 May 2009

Tips, Tips and more tips

I've recently ended up with a whole bunch of welding tips and some tattoo tips.
I thought it might be interesting to compare them.
From RepRap_bits
  • 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.
From RepRap_bits
Halfords are the smallest : an M5 thread, and a short body (18mm). B&Q have a larger M6 thread and are nearly 24mm long. Both welding tips are copper, and the tattoo tips are stainless steel. The tattoo tips have a long barrel, but a huge hole for a rubber band in the side. (white line is 3mm standard ABS filament)
From RepRap_bits
The nozzle holes are all similar sizes. the first two are 0.6mm Halfords. The next two are 0.8mm from B&Q. The tattoo tips come in various sizes. These are the two smallest round holes: I think they're designated R1 and R2, and look to be a similar size to 0.6/0.8mm. Some of the tattoo nozzles are much larger.
From RepRap_bits
The shapes are very different: the Halfords tip has the 'best' shape, a 45degree taper. The B&Q has a flat tip - it might cause the extrudate to stick, although it would be easy to reshape with a drill and file.
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.
From RepRap_bits

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.
I'll have a play with them (I've got 18, so plenty of spares) and see if anything works.

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?

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