I could use a little help, I need to model some Acme threads inside a split nut using Vcarve. You can see in the picture what I am trying to achieve. The threads are a 5/8x4tpi.
Fusion360 has a built in thread tool. You can simply make a block, create a hole through it and apply the correct thread geometry to the hole. Split the block and export the object as stl or whatever you are needing.
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Thanks for sharing. Sounds simple enough, now I just need to teach myself Fusion. Thanks again.
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Jeff were you able get this completed? This split nut looks a lot like a piece I need for a legacy mill. I want to try and 3d print one, any information you can provide would be appreciated. Thanks
Eric Gantner
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Hi Eric, I’ve modeled and 3d printed a nut block like the ones openbuilds uses in their cncs… i did so using fusion360 and instead of modeling the block using the threading tool (it doesnt support acme) i imported the acme lead screw from grainger and used the combine function and “cut” away the threads from the block part using the lead screw as the “tool” it worked great when printed with enough threads and thin layers.
Eric
My hope was to create the halves for my Legacy as well. Unfortunately I did not make any progress. My hope was to be able to use my CNC to cut the grooves out of a solid block of material.
Are you sure about that? I’m not by a pc, but I’m pretty sure it does support standard ACME threads.
@EricRGantner or @JeffWimer What are the thread specs for your machine? If they’re not standard, you’ll probably have to draw them, or as Seth said, use a model of the screw and do a boolean.
Might be easier to just get a delrin block and the correct tap.
When I tried it i could only get NPC and Machine Screw Thread types. I googled it and found other posts about it on the F360 forum with replies from their staff saying that it couldn’t do ACME…
However I was doing the Trapezoidal ACME with a 4 start and and I forget the pitch, but not exactly a standard thread… the Grainger as the Model Source trick was pretty neat and got me more into using a “tool” to do the cut-away which I hadn’t done that much before, but I’ve use a few more times since … 
I looked into it a bit just now and It looks like it might be possible to use the Turning (4th axis) CAM tool to Cut a Thread in the Acme configuration, But Modeling it using the threading feature is limited to certain types… However One could sketch the profile of the thread and then loft it around a cylinder, however getting this perfect might be a pain…
Here’s the method for using the thread modeling tool though in case someone wants to try…
Fusion has standard ACME threads. Non standard threads or custom threads are tricky in Fusion. I hope they eventually add comparable tools for coils like those in Inventor, which is where I’d make custom threads.
Importing a 3d model to use in a combine is great in Fusion, but that only works if you can find the part in 3d. Traditionally, threads had no reason to be modeled, so there are a lot of cases where a 3d model might not be available.
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Neil,
This is what I found out. 5/8 dia 4 threads per inch, thread angle is 29° pitch is 1/4 inch.
Break break
Seth,
I only have VCarve Pro, and none of the other programs. Do you know if Fusion 360 trial version will allow me to do this? I figure one I go to export etc…. I will be denied.
Any input is greatly appreciated. Thanks
Eric
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F360 hibbyist license (free requires annually attesting to the rules of use) will let you do this
… the free version really has not much for limitations. They reduce how many files you can actively edit at once because only a busyness would need to edit 10+ models at the exact same time… and they limit use of the 4+ axis machining and neuter the rapid moves to only move at the same speed as the feedrate setting… but nearly everything else that you get for paying you get in that hobbyist license.
So yeah if you model it it’ll let you exporr as a stl and 3d print no problem…
I modeled a replacement dryer timer knob in free f360, exported the stl and sliced with cura for example…
Yeah, that’s not standard. Can you find any more specs? Single or double start?
Again, I’d look for a tap.
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Thanks for the info Seth, your know came out nice!
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Thanks all for helping out. I didn’t think that type of tap would be available. Now I need to find the materials to tap out. Not sure what durometer material would be best.
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Neil,
I will have to dig into into a bit deeper. Let me see what what I can find, or learn. More to follow. Thanks
Acetal/Delrin
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