Screw / nut blanks for threading with tap + die

Just wondering ...

Has anyone ever tried printing screw blanks on their Reprap - for subsequent threading with a die? Or similarly for a nut?

I know that some people have tried printing actual threads directly from their printer - but my impression is that this has limited success (especially for smaller diameters / pitches).

I don't have access to a tap-and-die set at present but might try this once I do.

D

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Semi-commercial engineering | Reprap diary

I print parts often that need to be tapped.

I print the hole to be tapped slightly smaller than the desired final tapped hole.

It works pretty well, but the threads cannot handle a lot at all, they are pretty brittle.

I do it more for prototyping than actual parts.

I've had pretty good luck with with printing the holes a bit smaller than final and shafts a bit larger than final. Carefully threading/tapping the part and then covering the whole thing with plaster. Let the plaster dry and then cook the whole thing in a toaster oven for an hour on 500 F. Let it cool and then bust the plaster off. Essentially I'm letting the plastic layers reflow into one solid piece.
It's a heck of a lot of easier and quicker to just chuck a solid piece of plastic in the lathe to begin with.

I print holes and hand tap them all the time. The trick is to use a spiral fluted tap, it pulls the plastic chips out as you tap and hand taps quite easily. I have had very little luck trying to use a conventional tap, it ends up jamming with plastic and chews the threads out. As far as strength it ends up just as strong as threads in a solid piece of plastic IMO.

I have tapped M8 nut prototypes printed with taulman 618 (it is explicitly stated somewhere on his site that you can tap it) by hand - works quite well, but my tapping technique seems to suck because I ended up with tilted threads. The person I originally intended these nuts for then tapped the final version of the nuts in a lathe with far better results. Now he is using these as lubrication free Z nuts without problems.

Interesting to read the ideas here.

I'm conscious that it probably doesn't make much sense - from an economic point of view - to fab own's one screws / threads a lot of the time (when machine screws are generally not particularly expensive). Having said that, it might be handy to print your own blanks if you need an uncommon length screw - and stuff like that.

D