Designing A Threaded Insert

[Im1in260m]

I'm trying to design a threaded insert because McMaster Carr doesn't have one for wood. I can't figure out how I have to go about it. I tried joining a coil to the outside of the cylinder and I put a regular 1/4 20 thread on the inside. But it just doesn't look like the item should. You can see the insert here. I have attached an f3d file of what I tried. I don't know what the inside diameter really is. I started with 1/4 inch then did the threads.  But how much material do I need to "cut" threads? I still have to look that up somewhere. I know the outside requires a 5/16ths " hole. So I assumed the base of the outside threads were 5/16 diameter. So I have to go to Lowes with my micrometer and get some measurements if I want accuracy. But for my purposes I don't need all that accuracy. I would just like it to be close.

Thanks for the info,

Scott

[jeff_strater]

This looks like a good start, @Im1in260m,

What are your plans with this?  Are you going to machine or 3D print it, or is this just for modeling purposes?  If you are going to 3D print it, then you probably want "real" threads on the inside.  If you are going to machine it, then you will have to look up how much material to leave for cutting threads.

The other couple of suggestions I have for you is to trim off your outside coil ends, using a pair of work planes, and re-cut your slot:

Then it looks more like the example that you gave.

Jeff

[HughesTooling]

If you make the coil longer you can use a revolve cut to fade the ends out.

And end up with this,

File's attached

Mark

[HughesTooling · Accepted solution]

The thread tool will resize the hole to the correct diameter, if you switch to modeled you can measure the core diameter.

One problem in your design was you use centre for the section position of the coil so it was to small on the inside diameter and filled in the threaded hole..

You should have used Outside and set a bit smaller than the Od.

Mark

[Im1in260m]

Thank you for your replies. All are very helpful. I'm gradually learning with your help. 

This insert will be used in several places in my CNBC router plan. I won't be printing. I'll just buy it. But I want my design to be as close to real as I can get. This morning I realized I could cut the inside threads out of the solid cylinder with a cap screw from McMaster. Then the inside of my insert would be exact. 

Thanks again for the input.