Tips on Bolt/Nut Design?

WorldWiz · 1 May 2013, 05:51

I have a model I'm preparing to eventually print, and it includes a bolt and a hole with screw threads designed for the bolt, and I'm looking for any tips, such as if I should make the hole 1 or 2 percent larger than the bolt to accommodate possible error in printing? Or if I should use the exact same model size for the bolt and the hole to get a snug fit? Other tips also appreciated. Thanks.

ely862me · 1 May 2013, 06:59

You should definitely leave some space between the bolt and nut,otherwise they won't work .
And also there is the printing resolution of the 3d printer .
If you check a real nut and bolt you will they are loose . You should try as you said with 2% difference and see how it runs then you can adjust .

Dave R · 1 May 2013, 10:02

There are specifications for internal and external threads. You might find it useful to look those up for the size of your threads and use those figures. What material will your model be printed in? Can it be machined? If so, it might make more sense to print the parts without threads and then use tap and die to add the threads.

WorldWiz · 1 May 2013, 11:12

@dave r said:

There are specifications for internal and external threads. You might find it useful to look those up for the size of your threads and use those figures. What material will your model be printed in? Can it be machined? If so, it might make more sense to print the parts without threads and then use tap and die to add the threads.

That's good to know. I'll check that out. I haven't decided for certain what material I'm using (though I'll probably opt for plastic until the price of brass printing goes down), but as this is just a hobby, I don't think I'll want to spend money on machining parts.

Dave R · 1 May 2013, 11:31

By 'machining' I just meant worked with tools. A tap and a die won't set you back much money and you don't need much more than that to simply cut threads. If the threads have to work well, you would be better off cutting them than trying to print them. Between SketchUp's faceted curves and the probably low resolution of the 3D printing process, you'll probably have a difficult time getting threads to mesh together smoothly.

An alternative that might work is to design the parts so hex nuts and threaded shafts can be inserted. It would be easier to know what would work if we knew what you're designing.

ely862me · 1 May 2013, 20:19

Excellent advices !
If the material of the printed parts is good enough(won't broke or chip) you could use a tap and a die(which would be like $10) and the outcome will be great !