Acme thread into block

block2 Acme.skp (1.5 MB)

I need help finishing this item for 3D printin. Also a champher is requied at each side of the acme thead. Newbe that would apreciate any help tha tyou can give. Many thanks.

How did you create these threads? Do you need to be able to run a piece of threaded rod in this thing? What size are the threads supposed to be? What class? Are the Acme or Trapezoidal? How deep and at what angle do the chamfers need to be?

As it is now your model needs a bit of cleanup so that the block will be solid. The threads need to have their structure simplified. I would eliminate the nesting which will require unlocking the components
Screenshot - 5_17_2020 , 8_11_30 AM

I was working on something to show you how to model these threads and was about to cut them in the center of the block when I noticed that the blind holes aren’t equally spaced on the block. Is that correct? I’ll wait to find out before proceeding.

FWIW, from poking at your model I guessed that the hole is supposed to be for a 14x3 screw. Is that right?

Also for what it is worth, here is the setup waiting for the cutting to be done. I’ve drawn “cutters” for the chamfers and of course the “tap” for threading the hole. They are positioned in the block ready to go but you can see on the top that the chamfer cutter will get into the blind hole on the left. I can make the chamfers shallower but they aren’t very wide to begin with.

Edit: I also notice that the channels at each end are different in width. Is that by design? While waiting for you to come back I moved the blind holes so they are equally spaced and went ahead and cut the threads and chamfers.


I think I have upset the thing trying to move holes. the correct slot should be 6.670mm

Wide? On both sides? And centered? Like this? I guessed at the depth since they were both different. They are the same on both ends now, though.

What about the locations of the blind holes?

That is looking very good all holes are on the center line.

So here are the steps I followed after fixing the block, making a component, and ensuring it is solid.

I drew the threaded ‘cutter’ with the dimensions for internal metric trapezoidal threads for TR14x3. (I still don’t know what size you actually want so this is likely not right for you.) and made sure it is a solid component. Next I drew the cone shaped ‘cutters’ at the chamfer angle and made sure they were also solid components.

With the three solid components in place relative to the block, I used Trim from BoolTools2 to cut the block. You could also use Eneroth Solid Tools or even the native Solid Tools. I prefer BoolTools2 and Eneroth Solid Tools because they don’t convert components to groups but you may not care.

Thank you for that, the YouTube vid very helpful on how to do it but probably too complex for me at the moment. Could you email me, or upload the model and I will attempt 3D print and check for shrink rates and adjust scaling to suit.

I’m sorry. I didn’t keep the model since I didn’t get any confirmation that any of the dimensions were right.

Block & 14x3 Acme.skp (1.5 MB)

Hi Dave, I have had another go at this with your help but still cannot get this thread done. could you possibly help finnish this prodject for me. Many thanks,Paul

Here’s a finnished version (sorry, couldn’t resist)


You’ve got it so close it seems a shame that you don’t finish it. Explode all the sub-groups in side the screw component, draw in rectangles top and bottom to cut the screw off flat and make it a solid component. Make the cone shape a solid component or group, too. Then position them where you want and use Subtract from Solid Tools to subtract these things from the block.

Could you just talk me through the stage when cutting the tops on the treads.

I showed that in the video. Basically turn on Hidden Geometry. Select the rectangle and the screw geometry above and below the rectangle. Right click on it and choose Intersect Faces>With Selection. Then erase everything on the waste side of the rectangle and the outside edges of the rectangle. that should leave you with the flat end of the screw. Repeat on the other end.

Intersect both top and bottom. Then erase the surplus thread faces (Hidden Geometry off) and Solid Inspector 2 or Clean Up 3 will delete the lines.

Yes. I know how to make the solid screw component. I didn’t have as much for Solid Inspector 2 or CleanUp 3 to do as you show in your example. In fact when I was finished with the intersection and deleting, the screw was solid without needing any extensions.

Hi Dave,
Its seems funny that this seems to be so easy to make a thread solid for you guys but I am still struggling with this. I end up with just the face that I want as soon as clean the ends of thread that I don’t need. What am I doing wrong?
I have watch several vid’s and are more confused than ever. I have also realised that there are many guys that say they work with 3D but when it comes to make a finish model for printable they are lost also.

3d printed screw threads are brilliant, Paul, but I’ve found it a huge struggle. Your part is well designed because you have a decent number of threads and it will work well.
If you haven’t got Solid Inspector 2, I’d say get it. When you inspect your not-solid, use the Tab key (and X-Ray). It’ll will draw a red circle and zoom in to all the various issues. It taught me a lot.
What with a 30 degree overhang and 24 segment circles, you don’t end up with the exact same thing coming off your printer. Usually, I print a test block with the original thread scaled out in the X-Y plane as a series of holes and pick the one with the best fit. Or, I’ll just run a tap down the hole. Or, cut a notch in the end of the threaded stock to do a similar job to a tap.
I hope I haven’t confused you, and haven’t put Dave off as he knows much more than me. Besides, it’s my 69th birthday today and I’m not as sharp as I used to be. I have a lot of “senior” moments and don’t even know how to use the software properly. But I can do this. So, so can you. Is it worth the trouble? Absolutely.

Thanks for that, my excuse is that I’m 72 and try to keep my self occupied after having a stoke. So not so bad.

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