# Rear mount parting tool holder for Myford



## Lo-Fi (Oct 15, 2021)

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.


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## C-Bag (Oct 15, 2021)

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


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## woodchucker (Oct 15, 2021)

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.


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## keeena (Oct 15, 2021)

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.


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## Lo-Fi (Oct 15, 2021)

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!


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## benmychree (Oct 15, 2021)

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.


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## Lo-Fi (Oct 15, 2021)

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:


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## jwmay (Oct 16, 2021)

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


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## mikey (Dec 24, 2021)

@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.


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## jwmay (Dec 24, 2021)

I'll never go back!


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## Lo-Fi (Dec 25, 2021)

Me either! For such a simple thing it could have saved hobbyists buckets of blood, sweat, tears and ruined parts over the years. 

I did some bronze parts the other day, used it to do the hogging. That thing can fair shift some material! But the best thing is it fires the inevitable spray of chips downwards!


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## mikey (Dec 25, 2021)

Yup, one of the few things in life to which there is no downside. 

If you haven't tried it, increase your speed. This really reduces the feed force required when parting. All you need to do is feed so there is a slight positive resistance to the feed. The chips will curl off, the cut will go smooth and fast, your accuracy will improve and the finish will be great! Keep it lubed as you feed in and you're going to love it.


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## Lo-Fi (Dec 25, 2021)

With you on all of that. Lovely curls that drop out because gravity. 




Even tackled parting tool steel! The HSS stays sharp for a crazy long time too.


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## mikey (Dec 25, 2021)

Yeah, the tool holds an edge for a long time. Interesting, eh? I think this is because there is no rubbing below the cutting edge. The tool is working like an orthogonal tool. The upper surface of the tool is all rake so chip flow is enhanced. 

Regardless of why the tool stays sharper longer, it does.


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## FOMOGO (Dec 25, 2021)

Nicely done. It's on my list, though I've gotten much better at it in the conventional mode on my old Atlas. I think much of that was from adjustment, and getting everything as rigid as possible. Mike


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## woodchucker (Dec 25, 2021)

I don't have a problem usually, so I'm sticking with a frontal attack, easier to measure too without a DRO.


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## mikey (Dec 25, 2021)

woodchucker said:


> I don't have a problem usually, so I'm sticking with a frontal attack, easier to measure too without a DRO.



Ahh, Jeff, if you only knew how good it can be ...


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## woodchucker (Dec 25, 2021)

well I'm not doubting. But Until I buy this http://mlatoolbox.com/S-4382.html I can't.
I do want it, I have a taper attachment that has a bad cross slide, it was broken, and brazed. Then I found out about the gib screws that were stripped out and broken out.  The braze was ok, just a little bent, and I can deal with, the gib screws I sent out to a guy that does cast iron welding for me.  I didn't want nickel for this, but because I had wanted nickel on the other piece our wires got crossed, then the nickel wound up  on the other dovetail (fixed).. A real mess. drilling through nickel rod is... well tough... tapping it is tougher.

So if I do the mla slide, I might give it a try, until then... I don't have the means... so I'm sticking with what I got... which isn't giving me a problem now..


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