Quick release rear tool post

[Philip RoweParticipant @philiprowe13116]

I've recently bought a Dickson style quick release rear tool post to supplement my GHT rear parting tool which is a great bit of kit but I feel that to be able to use other tools, for example chamfering, rounding etc would be advantageous. When it arrived I was disappointed to find that it sits about 25mm too high, I have a Super7 and I suspect this particular tool post was made for the Myford 254 with the greater centre height. I know that I could return it but there're not that common and it is something that I've wanted for a long while, so my intention is to cut 24mm off the mounting block and then machine the last 1mm either in the lathe in a 4 jaw or maybe flycut it in the mill. Before I attack the casting with the bandsaw can anyone see a reason why this won't work.

Unfortunately in the photo below the difference in height between the font and rear tool posts doesn't show but I can assure you that it is 25mm. Thanks in advance for any assistance. Phil

[Philip RoweParticipant @philiprowe13116]

[DC31kParticipant @dc31k]

Please excuse the foolish question, but are you aware that the tools in the rear post would be mounted upside down?

Thus, in order for the cutting tip to be at centre height, the body of the tool will be above that of the one in the front toolpost. If you use a tool that completely fills the Dickson holder, the bottom 'shelf' of the rear holder would be the same level as the top shelf (the part that contains the square-headed screws) of the front one.

I would suggest that before you slim it down, do a mock up with a tool in a holder on the rear post and confirm what, if anything needs removing to position the cutting tip at centre height.

[bernard towersParticipant @bernardtowers37738]

Yes looks a bit tall my base casting is 1.654ins.

[Swarf, Mostly!Participant @swarfmostly]

Good afternoon, Philip,

I agree with DC31k's advice to do your research thoroughly before performing any irreversible cuts!

Some time ago, I bought a Myford-Dickson rear tool-post that was labelled as being for one version of the Myford 254, the 254S if I remember correctly.

Like you, I planned to reduce the height of the base casting to make it suitable for my ML7. But a shorter base appeared on eBay and I bought that. I can't get to the workshop right now but, when I can, I'll try to measure the relative heights of the base castings and report back here.

I would also suggest that the Myford-Dickson rear toolpost is intended for use only with a special inverted parting tool-holder whch holds the blade with a significant downward slope. That is the only tool-holder I intend to use with mine – I am not at all sure that the device is intended to take tools that don't have that slope.

Take care before making a premature and irreversible modification!

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 07/11/2022 17:03:55

[Martin KyteParticipant @martinkyte99762]

Like this one

[peak4Participant @peak4]

I'm not sure whether this helps or not.
When I bought the Warco 720, a Myford S7 clone, it came with two unnamed Dickson style toolposts and 8 holders.

I made a raising block for the rear, so I could use it with an inverted 12mm carbide insert slotting tool, as well as my normal 10mm insert tooling in the inverted position.
I can also use my normal tooling the conventional way up, and still get centre height OK, for use running the lathe in reverse. As an example I could use an internal threading bar, on the reverse side of the workpiece to cut away from the headstock.

This will of course depend upon the height of your actual QD tool block.

In my case, both the toolpost and the raising block are nominally 1½" high; in reality I think they are about 10 thou over.

Bill

[old martParticipant @oldmart]

The rear toolholder I made for the Smart & Brown model A is only for inverted cutting off blades, but if I decided to use conventional lathe tools, they would be held at the standard height and the lathe run in reverse. But the threaded spindle can also be securely locked if required. I do use left hand boring bars frequently in the standard toolpost with the spindle in reverse to get a better view, and left hand internal threading bars which enable a right hand thread cutting away from the chuck.

 With your difference in heights, be careful before doing any major modifications. Remember that if you cannot lock the threaded spindle you would not be advised to run in reverse so the tools will all need to be inverted. The tips, however will be at the same height, so the underside of a 12mm shank tool will have to be 24mm higher when it is in the rear toolpost.

Edited By old mart on 07/11/2022 19:54:11

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