Diamond tool holder.??

[_Paul_Participant @_paul_]

Posted by chris stephens on 20/12/2014 23:47:14:Anyone else tried this tool for threading?

chriStephens

I have, I normally feed in using the compound set over to whatever angle the thread type dictates and it works fine but with two problems which stem from the quite steeply angled cutting face which make it difficult to line up the tool to the work using a conventional "thread gauge" and also the back face of the thread dosen't clean up so well as a flatter topped cutter when giving the final couple of "straight in" passes using the cross slide.

Does anyone else have a different threading technique when using one of these?

Paul

[VicParticipant @vic]

As much as I like it for conventional turning I won't be using it for threading.

I can't stand all that winding in and out so I'll be making one of these plus a grinding jig.

http://mikesworkshop.weebly.com/swing-up-tool-holder.html

[Ady1Participant @ady1]

As much as I like it for conventional turning I won't be using it for threading.

I can't stand all that winding in and out so I'll be making one of these plus a grinding jig.

A 10 pound vernier DRO on your cross slide simplifies threading because of its accuracy

You can skim down another couple of hundredths of a mm if required

[BazyleParticipant @bazyle]

Paul – you are not legally obliged to have the sloping top to the tool so you can grind it flat topped if you like.

A swing up toolholder is great if you are using a mandrel handle or have a lathe that reverses quickly but a retracting tool holder is better for a lot of purposes.

[VicParticipant @vic]

Posted by Ady1 on 21/12/2014 12:08:34:

A 10 pound vernier DRO on your cross slide simplifies threading because of its accuracy

You can skim down another couple of hundredths of a mm if required

That's another job on the list!

[_Paul_Participant @_paul_]

Posted by Bazyle on 21/12/2014 13:43:45:

Paul – you are not legally obliged to have the sloping top to the tool so you can grind it flat topped if you like.

Bazyle, using the Eccentric Engineering supplied jig and instructions will only produce a sloping topped threading cutter, what do you use to produce a flat topped one? do you have some type of custom jig?

Paul

[chris stephensParticipant @chrisstephens63393]

Hi Paul, with the flank feed (off set top slide) method, if you set the top slide to exactly half the thread angle all you need to do is align the leading edge of the tool with your thread gauge, the trailing flank is taken care of by the in-feed. It would help a little if you grind the tool slightly under thread angle to give some small amount of clearance. It also helps to not take very deep cuts to reduce any "steps" in the trailing flank. A final pass or two straight in only really works with a form tool type tool.

Hi Vic, how about getting a cross slide stop, it would help with your understandable aversion. I have an Eccentric style tangential type threading tool on a swing up tool, amongst many others including a copy of the Victorian original, which again works well. I seem to recall demo-ing it on the SMEE stand at Ally-Pally a few years ago, some of you might remember as it seemed to draw quite a crowd.

chriStephens

[VicParticipant @vic]

My Lathe isn't the most accurate (or rigid) Chris so on the rare occasions I've carried out single point threading I've done it on a "trial and hopefully no error" basis – or put another way I sneak up on it and frequently check progress with a suitable nut! I do have a cross slide stop, comes in very handy. I think the flip-up holder will make things much easier for me.

[IanTParticipant @iant]

I always understood that the top-slide should be set over at half the thread angle Chris

But then I started watching the videos of Marc Lecuyer (The Lazy Machinist in Canada) on YouTube and as a result (in future) I will be setting my top-slide at just under half the thread angle.

His explanation is that setting slightly "under" does no harm to the thread form but setting "over" (even slightly) does and that because it is quite hard to set exactly on the half angle – it's much better to set it "under". He goes through this in some detail here;

**LINK**

The rest of his videos are also very well worth watching by the way.

Regards

IanT

[BazyleParticipant @bazyle]

Hey, Chris, I remember that show. Our club stand was just over the aisle and I waited for the crowds to die down to see what was so interesting. Of course there was nothing as the crowd dispersed only when you stopped.

[ChrisHParticipant @chrish]

Recently have successfully done a large metric thread – 45mm OD x 3.5mm thread, both external and internal – following the instructional video's from Tom's Techniques. He advocates setting the top slide over to 30 degrees, not any other number, taking the vast majority out of the thread using the top slide and for maybe the last 10 thou (maybe more, forgotten already!) taking it with the cross slide so the tool, ground as a form tool, will form the final thread shape. All I can say is that it worked very well for me and no problems setting the cross slide to 30 deg any more than it would have been for 29 deg, easier in fact! But I do understand exactly what Marc L'ecuyer is saying. Will now watch more of his videos

Sorry, this post seems to have gone 'off thread' – no pun intended!

Chris

[VicParticipant @vic]

Thanks for that link Ian, I've seen it explained on paper but that was pretty good. Only problem is the scale on my machine is printed and got largely wiped off in cleaning. I'll have to make a 29° Angle plate!

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