[digits]

Hi guys, I am thinking about doing some thread milling to allow me to cut some large threads into parts. I don't want to spin the parts on a lathe as they are rather large and asymmetrical, so ideally I want them thread milled.

I have the thread-milling wizard in Mach 3, but what sort of cutter do I need and where (preferably in the UK) can I get one?

Cheers.

[dfurlano]

I use a single tooth cutter but the threads I cut are on the smaller side. I buy the cutters from Harvey tool in the US I do not know if they can be bought in the UK.

Here is an example.

[rharter52]

For large threads I use Advent carbide inserts,easy to use with great results

[DSL PWR]

I have a small single point tool that works great. I needed to do a 1.5" 6tpi in some .5" plate, and to get the .1" thread depth the little tool just couldn't do it as it can only go about .04". I couln't find a single point inserted mill that would go in a 1.35" hole with the correct depth of cut, so I made one

It takes a standard 60 deg turn face insert off of a lathe tool. I did have to grind the backside off for clearance.

[digits]

Cheers guys - is a boring bar single point enough to be any good - I do have a boring head I could try?

[DSL PWR]

The problem with most boring bars is the tip is way to the outside of the centerline. This will make the effective diameter of the tool much larger, and very out of balance. You will probably lack any kind of rigidity. If you have a boring head, and enough clearance it should work.

[Andre' B]

Cheers guys - is a boring bar single point enough to be any good - I do have a boring head I could try?

If you only have a few threads to cut it is hardly worth buying a thread milling tool, they can be very expensive.

I have cut internal and external threads with just a lathe type threading bar stuck in a end mill holder. You are going to want to check the heel clearance on the insert, maybe have to grind a bit off but I think with most bars and inserts you should be fine.

[warpedmephisto]

Another rather cheap solution that I have used in the past would be to take an old (or new) tap with the matching TPI and grind all but one tooth off and use that as your cutter. Or you could leave just one flute on the tap with all the teeth on it for a multi-tooth thread mill. Using a ground down spiral flute tap will reduce the cutting pressure on the tool and won't have as much of an interrupted cut.

Good luck!