How to create large threads with low thread hight

[cyucelEJ2QP]

I've got two hollow cylinders of 42mm diameter and 0.8mm wall thickness (the whole thing to be 3D printed). I'd like to have one cylinder to screw into the other, forming a continuous tube.

I create cylinders and apply threads to them, but I am not sure how can I make individual threads less high without making inter thread distance smaller. Perhaps attachments will explain this better. 

If you please look at the cross section I shared, the problem I've got is that the wall thickness is too high (2.5mm), however to lower the wall thickness need to make individual screw threads smaller, but I don't want to change the distance between threads. 

If I change thread designation to M3x1.5, then I get the threads of the size I want but then I get them too close to be printed nicely.

Hope this all made sense.

[MRWakefield]

It sounds like you need a thread that's either 'stretched' or is truncated on the crest and root. For the stretched option you'll need a thread with a much greater flank angle than the standard Metric form. For the truncated option you'll need to add or subtract some amount from the crest and root values accordingly. For both of these options you'll need to create a new custom thread file. You'll find many posts about this if you search the forum.

You could also create the thread using the 'Coil' command, again, you'll find posts about this method on the forum.

If you could upload your f3d file that would help us to come up with a solution.

[cyucelEJ2QP]

Thanks for the answer, f3d attached.

[MRWakefield · Accepted solution]

I've attached an edited version as well as a custom thread file I've created. I've increased the flank angle to 80° (same as the DIN 40430 PG thread) with a pitch of 3mm and a thread depth similar to a standard metric 1.5mm pitch thread.

You'll need to copy the thread file to the Fusion 360 threads folder. This is easier said than done as this folder often moves when Fusion is updated. To make things a lot easier I'd recommend the 'ThreadKeeper' add-in to manage your custom thread files.

Hope this helps.