Thread milling ?

[JohnHaine]

Here's a photo of the tool with the number on the shank, hopefully you can get one from JB. If it would help I could post a photo of the modified tap but it's not very interesting, just an M8 tap with all the teeth ground off except one row. To find Richard's website to get the wizard look for Chestnut Pens.

[Clive S]

Here's a photo of the tool with the number on the shank, hopefully you can get one from JB. If it would help I could post a photo of the modified tap but it's not very interesting, just an M8 tap with all the teeth ground off except one row. To find Richard's website to get the wizard look for Chestnut Pens.

It would be interesting to see the tap. Here is the link :- http://www.chestnutpens.co.uk/misc/downloads.html

[Leadhead]

John - Thanks for the info. I actually just bought similar from Banggood. (SNR0013M16 Lathe Turning Tool Holder with 10pcs 16IR AG60 Inserts) Suited my budget at £15.31 with ten inserts included. It will serve to cut my teeth on. Will report on the efficacy.
I use many of their lathe tools and inserts and have found them good value for money. Have cut Titanium for instance,(gently) to good effect. I have no connection with them, just sometimes like relatively good cheapo`s for rarely practiced applications .
Confess this is more an interest in "how to do it" than actual immediate need. May need some foam.

[JohnHaine]

I just started with a chunk of bms.

[JohnHaine]

Tap.



If using a tap I think you have to mill down from the top. With a single point tool you can climb mill from the bottom of the hole.

[Neale]

Out of curiosity, how do you measure the effective diameter of the boring tool used for thread milling? I assume that you need this parameter for the CAM tool you are using? I have one of those internal threading tools for use on the lathe but until - eventually - I get my CNC mill conversion done, it's all a bit academic for me...

[Leadhead]

I simply drill a hole in some MDF about the size of the cutter dia. Harden it with CA glue and finish bore it with the tool. Then measure the hole carefully. This gives me my offset.

[Leadhead]

Should have said to be careful with various tool tip radii. These will of course vary the cutting dia and thus the depth of the form when trying to match an existing thread. Imagine a huge tip radius verses a tiny one. The V form would cut in different places. Start small and creep up on it.

[JohnHaine]

Best if you download and look at the little app that Richard has on the Chestnut Pens website - that defines the dimensions that you need. I measured mine by clamping the tool in a vee block and careful use of a digital height gauge, it was very quick. The app is designed for metric threads so it calculates dimensions from the standard formulas - it would presumably work for UNF, but I don't think it would for imperial 55 degree forms.

[JohnHaine]

One of the benefits of using a TCT threading tool or a tap is that it already includes the flat or radius. I just used the app, chose my fit class, and it worked.