Myford rear toolpost

[GrottoParticipant @grotto]

Thanks for all the helpful comments.

The parting tool, inserts, and toolpost were a package deal, so I don't think that changing the parting tool will fix the issue.

Unfortunately I couldn't find a supplier here in NZ to get the item from, otherwise it would be easy to fix.

I'll ask around and see if I can find someone local with a mill who can have a crack at it. I've been meaning to go along to the Model Engineering club for ages, so this is a good incentive.

Supplier has offered a refund or exchange, but wants the toolpost back to see if it's out of spec., so can't really complain too much about service.

It works very well despite being 2mm high, which surprised me, as 2mm off centre on the front tool post would not work at all.

[HopperParticipant @hopper]

Have you tried using the other end of the parting tool holder? The notch may be in a slightly different position. Or a different carbide insert?

[Jon GibbsParticipant @jongibbs59756]

It looks to be the same rear toolpost they use for their HSS parting blades so it's clear the fault is with the parting blade/tip.

**LINK**

I would buy a HSS blade locally and send them the parting blade holder and tip back for replacement at their cost or if you're determined to keep it all, I'd grind/draw-file the bottom 2mm off the told holder and make a fixture similar to the one in the above post to make up the missing 2mm of height in the holder.

If you go the HSS route then I can thoroughly recommend the mod I made in the above post. I've parted 2" on the narrower 3/32" blade without any trouble at all and never put the old 5/32" blade back in.

HTH

Jon

[Ian HewsonParticipant @ianhewson99641]

Hi IanT

Never said it was the wrong tool for the job, just wrong tool for the toolholder.

The holder is not designed for that particular tool, not the fault of the seller unless they said it would fit.

[IanTParticipant @iant]

You might be right Ian

In Grotto's photos it does look as if his tool holder is sitting further back in the slot than (I think) mine does – which suggests that his slot is a bit deeper than mine (sorry I can't measure mine at the moment). So maybe this particular block was made for a different type/style of parting tool. It's hard to tell.

However, I do have a block & tool holder set that looks pretty much exactly the same as this one and it works very well on my old Super 7. So usable versions of this design do exist and hopefully Grotto's problem is not a common one. I hope you find a workable solution to the problem Grotto – good luck..

Regards,

IanT

[Howard LewisParticipant @howardlewis46836]

What you seem to have here is an EXTREME example of Tolerance build up.

The arguments about who / what is to blame do not solve the O P problem., and returns/replacement look to be costly and time consuming.

It is unlkely that every toolpost / tool combination would set the tool tip exactly on the centreline of every Myford 7.

If everything could be made that precisely, there would be no need for adjusting screws on Q C Ts would there?

For what my advice is worth, hoping that you will only need to do it once for your lathe, this is my suggested way of dealing with the problem:

1)Measure the height from the face of the Cross Slide to the Centre.

2)Measure the height from the Cross Slide to the tip of the Parting Tool.

3)Note the difference.

4)Turn two dowels to snug fit in the T slot in the Cross Slide.

5)On the centreline of the key in the bottom of the toolpost, drill / tap two holes, as far apart as practicable. Make them deep enough that the outer ends can be drilled / reamed, at the same positions to take the newly made dowels.

6)Alternatively, drill / tap the rear face of the Toolpost., in two places, near to the bottom.

7)Make up a bright M S plate, at least 6mm thick, and drill clearance for the fixings chosen for the above tappings.

The plate should be made so that it hangs below the bottom of the Toolpost, to locate against the rear face of the Cross Slide..

7)Set the toolpost in the four jaw chuck, as near on centre as possible.

8)Face off the key,

9)Turn off the lower face of the toolpost, the dimension noted earlier.

10)After deburring, and cleaning, fit the two dowels, or the locating plate, to the Toolpost, and fit to the Cross Slide.

The dowels, or the rear locating plate should bring the tool to the same alignment as the original key.

The tip of the insert should now be at the lathe Centre Height.

Do not be surprised if subsequent tips, especially if from another manufacturer, differ slightly from this Centre Height. Everything is made to dimension which has a tolerance.

Tolerances allow interchangeability, but do not guarantee absolute precision.

Heres to trouble free parting off!

Howard

[Neil WyattModerator @neilwyatt]

This is just musing, but perhaps altering the parting tool something like this could drop the height by 2mm whilst keeping the fit in the toolholder. I have probably exaggerated the angle, and I realise that it will change the angles at the tooltip, but less work than modifying the holder.

.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 14/12/2015 12:59:04:

What you seem to have here is an EXTREME example of Tolerance build up.

The arguments about who / what is to blame do not solve the O P problem., and returns/replacement look to be costly and time consuming.

It is unlkely that every toolpost / tool combination would set the tool tip exactly on the centreline of every Myford 7.

If everything could be made that precisely, there would be no need for adjusting screws on Q C Ts would there?

.

Well-put, Howard

As the old saying goes: "If you can't make it exact, make it adjustable"

… Which leads me to the [possibly contentious*] thought, that we need a design for an adjustable toolholder for inverted, rear-mounted, tools [and not exclusively parting tools].

… Perhaps someone with experience of 'production' lathes could advise ?

MichaelG.

.

[*] The difficulty, of course, is the risk that adjustablity will compromise stiffness.

[Neil WyattModerator @neilwyatt]

> just cut 2mm off the bottom of the blasted parting tool and get on using it.

I doubt the design has enough spring to grip the body of a much narrower tool.

> a design for an adjustable toolholder for inverted, rear-mounted, tools

Slap a QCTP on top of a rear mounted pillar?

Neil

[Swarf, Mostly!Participant @swarfmostly]

Neil,

Do you mean one like this:

Best regards,

Swarf, Mostly!

[The Merry MillerParticipant @themerrymiller]

Hello Grotto !!!

Below you will see some pics of the rear toolpost that fits on to the extended cross slide of my Myford ML7-R

It uses the standard Myford boat tool that you can adjust to the centre height without much/any trouble.

If you can get hold of one of these all power to your elbow.

Len.

[LambtonParticipant @lambton]

Neil have you "moderated" my recent post?

[GrottoParticipant @grotto]

Posted by Hopper on 14/12/2015 04:22:55:

Have you tried using the other end of the parting tool holder? The notch may be in a slightly different position. Or a different carbide insert?

Both ends give the same height unfortunately

[GrottoParticipant @grotto]

Posted by Neil Wyatt on 14/12/2015 13:46:06:

This is just musing, but perhaps altering the parting tool something like this could drop the height by 2mm whilst keeping the fit in the toolholder. I have probably exaggerated the angle, and I realise that it will change the angles at the tooltip, but less work than modifying the holder.

.

I reckon this would be a good solution, but I'm not confident I'd get the angle/width exact enough. Maybe if I had more experience

[GrottoParticipant @grotto]

Posted by Ian Hewson on 14/12/2015 10:15:37:

Hi IanT

Never said it was the wrong tool for the job, just wrong tool for the toolholder.

The holder is not designed for that particular tool, not the fault of the seller unless they said it would fit.

I'm not blaming/dogging the seller, but the whole unit came as a package specific for the ML7.

[Alan JacksonParticipant @alanjackson47790]

I made a base with a slope so that the upper part can slide to the right height.

Alan

[Mark P.Participant @markp]

IMHO rear toolposts are a vexation to the spirit, all the ones I’ve used just get in the way eespecially on a smaller machine. I tried one on my WM250 after I’d ripped the back of my hand open on the parting blade 4 or 5 times I used it as a paperweight, as I said just my opinion but each to their own.
Mark P.

[VicParticipant @vic]

Nice Job Alan!

[Martin KyteParticipant @martinkyte99762]

That's not a Myford rear tool post that's a rear toolpost mounted on a Myford and as built it's clearly not adjustable for centre hight.

Martin

[KWILParticipant @kwil]

Martin is so correct.

Apart from a slight advantage in having the "parting tool available all the time", I have never found the need to fit a rear mounted tool, much of the hype for such tools is over stated.

A properly set up blade + insert on the normal front QCTP works every time (for me) on all my lathes, large and small.

Now argue about that.

[Clive IndiaParticipant @cliveindia]

Posted by Grotto on 15/12/2015 00:58:49:

I'm not blaming/dogging the seller, but the whole unit came as a package specific for the ML7.

If that is the case, I think you should return it.

So far, there has been several solutions for you – Neil Wyatt has given you two and Merry Miller has a practical solution, with many others taking part. So it boils down to two options with the skills/equipment you have I think – either modify the tool or change the holder. If you keep it, the tool can easily be modified. If you do not have the skills/equipment to modify the toolpost, then you have to change it.

Kwill and Martin make a good point and I can see what they mean – there is little time saved and it gets in the way sometimes, but having got it, I use this (excuse me for not cleaning it)….

Edited By Clive India on 15/12/2015 11:42:05

Edited By Clive India on 15/12/2015 11:42:47

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Alan Jackson on 15/12/2015 10:23:24:

I made a base with a slope so that the upper part can slide to the right height.

.

That's very neat, Alan

MichaelG.

[VicParticipant @vic]

That's very nice Clive, even if too dirty to be posted in good conscience! No really, I like it!

[EmgeeParticipant @emgee]

This RTP may be like Alans, made by a toolmaker many years ago, could have been from plans I'm not sure. I find it very useful for grooving and parting without problems.

2 more pictures in my Album.

Emgee

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Edited By Emgee on 15/12/2015 17:45:01

[Neil WyattModerator @neilwyatt]

Posted by Lambton on 14/12/2015 16:41:16:

Neil have you "moderated" my recent post?

Not that I am aware of, I haven't deleted anything and if I have edited a post it will say so at the bottom.

Neil

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