Mini Lathe Parting Tool Holder

[JohnS]

Hello Guys
One aspect of using my 7 x 12 Mini Lathe that always gives me big problems is when it comes to parting off. I believe it is quite normal procedure on big boys lathes to have the parting tool mounted in its own holder at the far side of the bed ways - presumably to provide greater rigidity. Seems to me that its the lack of rigidity in mounting the parting off tool in the QCTP that may be contributing to my problems.

If the tool could be mounted directly onto the carriage this would surely improve the situation. If that is the case I would imagine one (or more) of our members may have already come up with a solution. If so I would very pleased to hear about it - and a photo or drawing of the modification would be very welcome.

JohnS

 

[DickDastardly40]

John,

If you attached a rear parting tool to the carriage similar to a moving steady rather than the cross slide (if I understand you correctly), you wont be able to move it in and out. It is in my experience bolted on the cross slide (if you have Tee slots) upside down at the rear and you part with the lathe running forwards and wind out the tool.

If your cross slide is not slotted then drilling it and tapping so you can fit one is an option.

I believe the job is not trying to ride over the top of the parting tool which is why you get an improvement in rigidity. Happy to be put right on htis.

Al

 

[Bogstandard]

The main reason a rear parting tool works so well is because it eliminates a lot of the areas that cause lack of rigidity. By mounting directly on top of the cross slide you are eliminating the compound slide and toolholder which on smaller machines are prone to flex a little when the heavy cutting pressure of parting is put onto them.

You might find that a much thinner blade will overcome some of the normal parting problems. I have ground up 1mm power hacksaw blades before now, for use on one of my earlier lathes and that overcame my problems completely.

But if you want to carry on looking at rear toolpost parting holders here is a site that shows one that can be modified to suit.

http://iwr.ru.ac.za/~iwdf/lathe/reartool.html

Hope it helps

John

 

[chuck foster]

the rear parting tool idea is great one, i used to part off from the front and the parting tool would chatter and then break!!!
when i got my 9" south bend it had no cross slide so i made one using plans from a model engineer mag. from the late 60's.
it looks like this.

and the other side

just to give you an idea how good this style of tool holder works here is a pic of a part for a parcell and weed engine i'm building. it is a block of cast iron that is
1" x 1 1/4" x 1" and the turned or round part in the middle is .550" ( and it is off set to one side).
i think this has to be one of the nastiest things to turn but the rear parting tool made the job real easy.

so if any one is thinking about a rear tool holder i would have to say.....stop thinking about it and do it!!!

if any one needs the plans to make the south bend top slide to accommodate the rear tool holder just email me and i will send you a copy.

now get out to the shop and build one!!!