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How to print male screw thread  

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Jim Hart
(@jim-hart)
Active Member
How to print male screw thread

I am using a SLS printer, and I want to print an object with a M2.5 male thread on it. I 'designed' this on Fusion 360, added a 2.5mm cylinder where I wanted the threaded portion. I then added the thread form - M2.5 x 0.45 RH, and the thread appeared on the cylinder. I then tried to print on the SLS, selecting the highest detail layer dimension. The threaded part is vertical on the plater. The object printed OK, the cylinder was just a smooth surface with no thread cut into it. A micrometer measured it as 2.47 - 2.48mm diameter. 

Am I being too ambitious in expecting to print such a small thread??

I could run a die down the cylinder but I don't have M2.5 die immediately to hand.

Any thoughts much appreciated

Jim Hart

Posted : 05/10/2021 9:56 am
ResPrint
(@resprint)
Active Member
SLS or SLA?

Hi Jim,

 

are you printing with a SLS or SLA printer? I wouldn't know for SLS..

With SLA (like Prusa SL1), imho it could/should be possible. I printed a threaded object, scaled it to a unknown dimension which is close to the thread you want. The cylinder turned out bent, but the thread looks fine, see attached image.

 

Posted : 05/10/2021 3:48 pm
Jim Hart
(@jim-hart)
Active Member
Topic starter answered:
SL! printer resolution limits

Sorry, that was a typo, I am using the SL1 printer and Elegoo, 'ABS like' grey resin. Pleased with the outcome apart from the missing thread. I think probably something I did wrong in the slicer (Prusa slicer), but I have no idea what. I just changed the layer thickness to the smallest hight = best resolution?

I did think that I was pushing the boundaries of what I might expect to come out, so it was a bit of an experiment, however would have been good if it had worked.

 

Jim

Posted : 06/10/2021 9:51 am
ResPrint
(@resprint)
Active Member

Two more thoughts on that:
1) Maybe the thread was not saved in your STL file? Do you see the thread in the prusa slicer?

2) Maybe there was an excess of uncured resin in the thread before post processing which wasn't removed?

Posted : 06/10/2021 12:50 pm
Stefan
(@stefan-3)
Eminent Member
only cosmetic thread?

I 'designed' this on Fusion 360, added a 2.5mm cylinder where I wanted the threaded portion. I then added the thread form - M2.5 x 0.45 RH, and the thread appeared on the cylinder.

i am not familiar with Fusion 360,  but many CAD applications "create" threads only as a texture / picture per default (for performance reasons), and not as the real geometry. Check if Fusion 360 has a option to create the thread as real geometry.

The slicer should also show clearly the thread geometry.

Posted : 06/10/2021 1:18 pm
Jim Hart
(@jim-hart)
Active Member
Topic starter answered:

Some good questions - 

the STL file does not show the thread, so I think the query about clogging with uncured resin is not the answer. I clearly need to investigate  Fusion 360 thread function. As a newbie to Cad and, especially, to 3D printing, I didn't know that a thread was not necessarily a 'real' geometry. I will investigate further, I would guess that Fusion does have the ability to generate a 'real' thread, it is an expensive programme .

Thank you both for the thoughts! Much appreciated.

Posted : 06/10/2021 1:32 pm
Jim Hart
(@jim-hart)
Active Member
Topic starter answered:
Fusion 360 and threads

Stefan, 

you were correct, Fusion as a default does NOT create the real geometry, it is 'purely' a texture. there is a check box in the Thread command to enable the full modelling. I now need to recreate my part with the thread fully modelled and then try printing. Many thanks, at least I have learnt something new!

Posted : 06/10/2021 1:58 pm
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