Thread milling

[Uncle Bob]

Thread cutters from Magnate (www.magnate.org).

Tool
No.
Degree
Cutting
Height
Shank
Dia.
Shank
Length
Overall
Dia.
Price

751 90 1/4" 1/2" 5" 7/8" $31.89
753 90 1/2" 1/2" 5" 1-1/8" $34.32
756 90 3/4" 1/2" 5" 1-3/8" $36.88

Sorry taht column labels did not paste correctly.

[bravesoul1950]

I have this cutter and the best price is from :

Interstate
3/4" Diam x 3/16" Width 3/8" Shank 60° Double Angle Cutter
High Speed Steel, Uncoated

https://www.mscdirect.com/product/details/03196052

There are other cutters from different companies, I just did a google search for my size and came up with quite a few sites selling them.

Joe

[martin54]

What bit you buy is dependant on the sort of work you want to be able to do with it, for most people a single form thread tool will be best as with only one cutting tooth it can be used to cut a range of different pitch threads. The angle also is going to be down to the threads you want to be able to cut. If you are cutting both internal & external threads for each project & don't mind them not being a particular existing thread form then it really doesn't matter what angle the bit is but if you want to be able to cut standard thread forms so you can use threaded hardware then you need to but a bit with the correct angle. The magnate bits while probably the cheapest I have seen are only available at 90 degree which may suit some people but for me in the UK most thread forms that I would use are 60 degree so a bit like the interstate bit mentioned is a better option.
Size matters as well because to cut internal threads the cutting head needs to fit in the hole
at 3/4" the interstate bit is good for threads above about 1" as there is a lead in & out when cutting threads, if you want to be able to cut smaller threads then you need to be looking at a different bit. There are some available but prices are on the higher end & each one will only cover a small range of pitches so do your homework before buying a bit

[bravesoul1950]

Martin,

Not being versed well in thread pitches I found your remarks very interesting and now I need to learn more. Thanks for your input.

Joe

[martin54]

Martin,

Not being versed well in thread pitches I found your remarks very interesting and now I need to learn more. Thanks for your input.

Joe

Joe, from what I can see on the internet then UTS is a 60 degree included angle the same as metric, this would mean that to cut any of the included threads that are in the thread milling form you would need a 60 degree bit.
As I said above if you are cutting internal & external threads to mate parts together like a box with a screw on lid then it really doesn't matter what bit you use

https://en.wikipedia.org/wiki/Thread_angle

[slowoodworker]

Hey all! It's not Christmas yet, and I actually got my boxes done for the grandkids! Thanks to advice from all you pros.
To get the lids to fit tight, I relieved the top of the female threads (tried the slot cutter on the male threads but felt more comfortable with this). The inside of the lid is dished -- and I had some trouble with that. the bit cut 1/8" outside the vector boundary. finally fixed it by using an offset(?) or allowance(?)

[mtylerfl]

Excellent work!

[gkas]

Really nice job. The lids are beautiful. I like the 0.5 TBN. It does a really nice job on the finish. I haven't got my lids to fit tight all the way down. More experimentation to do. Current projects put it on the back burner.

[scottp55]

Those boxes are Beautiful!!
Well Done!
And thanks for the pics of the jig!
scott

[martin54]

Those look great, much better than mine will if I ever get round to finishing them

Why the ? after 9/16" uts, guessing that might be because you are not 100% sure If you selected that size from the drop down list of threads & used a 60 degree thread mill then that's what it will be. If you used a 90 degree bit then it is not

I wasn't sure if your style jig would hold the lids properly so went with a threaded section on the jig for the lids to screw onto. Clearly your jig does work as you have used it

[slowoodworker]

Why the ? after 9/16" uts, guessing that might be because you are not 100% sure If you selected that size from the drop down list of threads & used a 60 degree thread mill then that's what it will be. If you used a 90 degree bit then it is not

I wasn't sure if your style jig would hold the lids properly so went with a threaded section on the jig for the lids to screw onto. Clearly your jig does work as you have used it

Thank you and others for the kind words. The "??" after "UTS" is because I wasn't sure of the initials. I did use a 60deg bit and the drop down menu choosing 9/16" threads.
The jig worked well for the blanks. I used oversized tabs to align them and had to tap the blanks into the jig pockets for a snug fit. For doing the top of the lids, like you I screwed them into threaded blanks that I tapped into the jig pockets. I also taped the lids to the blanks after one of my trial lids spun off during the roughing pass!
One problem I did have was a misalignment of the lid and base. I'm not sure what the problem is, but both boxes were the same. It may be that my CNC isn't as dialed in as I thought. It did take a lot of sanding to get the boxes to line up. ;-p