Screws / Threading in Plastic and Steel

Discussion in 'Finishing Techniques' started by lensman, Sep 28, 2010.

  1. lensman
    lensman Well-Known Member
    I have an idea for a product, preferably in s/steel, but I suppose WSF or Detail might work. Part of the product will have a post into which I want to insert a screw.

    Does anyone have experience doing this sort of thing? I suspect that modelling the thread in s/steel is going to be out of the question, which means I'm left with the acrylic.

    Do you think that modelling the post with a smaller hole than the thread size would allow self-tapping when a screw is inserted?

    Any feedback appreciated.

  2. TimberWolf
    TimberWolf New Member
    Hi, self tapping is possible, I did it with Alumide. Just please be sure that the hole is not too small or the tapping will cause it to stress-crack. Maybe if your hole is more than a few mm deep, you could use a diameter about 0.5mm smaller than the screw diameter?

  3. lensman
    lensman Well-Known Member
    Okay, well that helps, thanks. And as I recall Alumide is either WSF or Detail with something else thrown in.

  4. If I recall correctly, Alumide is WSF with aluminum flakes (or some other form of aluminum) in it.
  5. brabantdental
    brabantdental New Member

    A thread is quite easy to insert post-production, very difficult to print functionally (especially the small sizes) in 3D.

    Seems like you would be much better off simply use a threading tap (preferably a blind-hole type) to get the threads in there after receiving the item.

    My suggestion would be to model a cilindrical hole with pre-drilling size for the desired thread size. M4= hole size 3.2 mm.

  6. ggurov
    ggurov New Member
  7. poobahuk
    poobahuk New Member
    I've some experience in this.

    I ordered a multi-part assembly in steel from Shapeways with 1.2mm diameter blind pilot holes, and 1.5mm clearance holes for assembly with M1.4 screws.

    I had to drill out all the holes to clean them up with a mini-pillar drill, but it wasn't difficult.

    I used a micro tap & die set I'd bought from Amazon to do the tapping, with a liberal application of generic 3 in 1 oil to the pilot holes.

    It worked surprisingly well, as with all tapping into steel, you need a delicate touch to avoid snapping the tap.