Myford S7 George Thomas rear tool post, RTP

[Ray PopeParticipant @raypope26509]

Query regarding “special” tools

[Ray PopeParticipant @raypope26509]

I am building an GHT RTP. There is a requirement to make up a milling cutter with a 7 degree cutting edge to form the undercut sides of the groove which holds the parting off tool. Is there anyone out there who has built this RTP who has this tool that they can lend me?

Similarly, there is a requirement for a reamer with a depth stop and a cutting end shaped with a 12 degree included angle. Again, is there anyone out there who has made this toll who can lend me it?

Thank you very much.

All P&P on me

Ray Pope

[Clive Brown 1Participant @clivebrown1]

Afraid mine don't seem to be around any longer, but If no-one has them to lend out, and provided you have access to a lathe, the required cutters are quite simple to make from silver steel, hardened afterwards. GHT described them in his original ME articles.

The 12 deg reamer is basically a tapered D-bit, the 7 deg. cutter has 2 flutes formed with an end-mill.

[egaParticipant @ega]

Ray Pope:

I will send you a personal message; look out for your Inbox button (second from left at top of page) to start flashing.

[duncan webster 1Participant @duncanwebster1]

If this is how I imagine it you could form the 7 degree profile using a slitting saw, say 1/16" wide, slightly undercutting the vertical face. If this doesn't make sense let me know and I'll sketch it out

Edited By duncan webster on 28/10/2018 17:39:24

Edited By duncan webster on 28/10/2018 17:39:57

[egaParticipant @ega]

Posted by Clive Brown 1 on 28/10/2018 17:10:50:

Afraid mine don't seem to be around any longer, but If no-one has them to lend out, and provided you have access to a lathe, the required cutters are quite simple to make from silver steel, hardened afterwards. GHT described them in his original ME articles.

The 12 deg reamer is basically a tapered D-bit, the 7 deg. cutter has 2 flutes formed with an end-mill.

The drawing in GHT's Manual does indeed show two flutes formed by an end mill; looking at mine now I see I opted for three flutes possibly having in mind Len Mason's suggestion that odd numbers seem to work better. For milling slots GHT recommended slot drills over end mills for the reasons given in the same work.

[egaParticipant @ega]

Ray Pope:

Bumping your thread as it looks as though you may not have read my PM.

If you no longer want to borrow the tooling I will return it to store.

[ZanParticipant @zan]

The angled reamer is for cutting the plunger to locate the position of the post when indexing. It is common practice to make the reamer from silver steel, harden and temper it – a quick 20 min job. Then you make the mating part without changing the angle of the topslide. This ensures that the taper on the indexing pin will perfectly match the socket.

It is very important to get the blade perfectly square to the lathe axis or you WILL break that expensive blade.

A borrowed cutter will not be perfectly true and secure. I sold my GHT rear post after getting an inserted tip tool it works well and doesn’t get in the way.

[egaParticipant @ega]

Zan:

Good point about getting the tapers to match although I don't think it occurred to me when I made mine (or to GHT?).

I agree that the reamer is relatively straightforward to make but the OP clearly did not want to do so.

My objection to the majority of inserted tip tools is the overhang. That said, I am pleased with the ISCAR tangential parting tool I have on the other lathe; it is mounted in a GHT style RTP.

Ray Pope:

Still hoping to hear from you.

[egaParticipant @ega]

Ray Pope:

Just picked up your PM without problem and have PMd back. If you still don't receive my PM I suggest you tell me via this thread.

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