Rear mount parting tool holder for Myford

[Lo-Fi]

I'm speechless. I can't believe how well it performs.

It's an absolute dogmeat build, born of necessity as I have some parts that need to be parted accurately in order to function. I remember there being a thread about it, but I can't find now.... Anyway!



I'm afraid no build pics, but it's all basic stuff. The pocket gives access to turn the bolt which picks up a T nut. the thing is located by a tang I milled in the bottom that's a good fit into the T slot. It puts the tool in perfect alignment with absolutely no fusting about with squaring it, which is quite a result. Material, I'm pretty sure is cold rolled.

I thought I'd try a stress test. Normally this type of parting op is a fear inducing nightmare. I just ground the end of the blade and honed, put on the lathe and went for it. Instant success! Beautiful chips, great finish, zero chatter and no jamming up. It's quite a wide tool too, I was sure I was setting up for failure, but it was all I had. Absolutely brilliant! I don't think I'll ever think twice about parting again.

 

[C-Bag]

Yup, that’s at the top of my to do list.

 

[woodchucker]

Yea, that would be nice. I would have to buy a new X slide. I might do that.
that's a lot of stick out though.

 

[keeena]

Looks nice to me and good to hear how well it worked.

Curious: when using that blade in your normal toolpost does it have the same rake as the rear toolpost? When I've used those in my QCTP they are angled up (positive rake). Your custom mount is neutral rake. Just wondering if that is also helping and/or if it was a conscious decision.

Can you leave it semi-permanently installed or will it interfere with regular turning ops? I had been thinking of doing the same just so I could leave a parting blade installed and ready to go whenever I needed it...seems like that could be convenient.

 

[Lo-Fi]

I don't think I've tried with this blade, it's way wider than I'd ever consider workable. However, I've tried all sorts of blades with all sorts or angles with many holding schemes on the tool post. Nothing has been terribly successful. I was fully expecting to find that the neutral rake is a problem, milling off the slot I have and starting again with some rake. The excessive stickout was simply a "let's see how far we can push this"!

For some jobs I probably can leave it installed, but the cross slide isn't really long enough for it to not potentially get in the way or worse, much as it would be great to be able to just leave it. Maybe I'll design MK2 to be quick install, though. If your lathe has a long cross slide I can't see why you couldn't leave it. If you wanted to get fancy, a mini turret with parting tool and chamfer tool would be awesome!

 

[benmychree]

The hold down on all turret lathes that I have had anything to do with are all drilled down through the whole height of the tool post, the hex head being much easier to access that a fastener inside that pocket. Best is to have the T nut permanently attached to a stud and use a nut on top of the tool post, this I say, because the thread length in the T nut is relatively short and subject to rapid wear. Best to make the stud and T nut integral and use a thicker than normal nut on top.

 

[Lo-Fi]

Can't disagree with any of that, but... I didn't have any long M6 bolts or studding to hand and my ancient English lathe won't cut metric threads (which I must sort out). I also didn't fancy my chances of drilling a 6.5mm hole that long accurately without a lot of faff, so the pocket was quicker. It gets the job done and leaves a load of meat in the top of the tool post to either redo the slot for the parting blade (not needed at it happens) or for other auxiliary tools like a chamfering bit, so I'm kinda happy that circumstances pushed me that route. I'm quite sold on the utility of rear mount tools now, so I'll be drawing up MK2 with improvements and many more gizmos!

A parting op on an actual part was just as smooth:

 

[jwmay]

Rear mounting a parting tool ... if you can

I am moving this discussion on rear mounting a parting tool to this thread rather than continue to hijack another one. In this thread, I noticed that @NC Rick had t-slots running the length of his cross slide and suggested to him that he consider making a rear mounted parting tool. For those...

www.hobby-machinist.com

Here's one! Looks like somebody knows what they're talking about eh?! Congrats on your dogmeat project. And thanks for sharing it, along with that phrase. I can't wait for someone to ask me about something at work. Whatever it is, I'm gonna call it that. Lol

 

[mikey]

@Lo-Fi and @jwmay, just catching up on your posts and am glad your tools worked out for you. Such a simple thing, yet it makes parting so much easier. Makes you wonder why the lathe makers didn't bake it into their designs.

 

[jwmay]

I'll never go back!