Qctp (quick Change Tool Post)

[John3198]

Hi everyone.
I have just purchased from Chester Machine Tools, UK, a DB10 Super Lathe and I also bought the T1 QCTP kit to replace the machines original tool post. I know I have to modify the QCTP to fit, my question is can anyone who has done this provide me with the dimensions and any info that will assist me in doing this myself. Thank you in advance. John.

 

[Paul in OKC]

What part do you need to modify? I am not familiar with what you have, but most modifications are to the T-nut to fit the slot on the compound. Outside of that, need more input.

 

[John3198]

What part do you need to modify? I am not familiar with what you have, but most modifications are to the T-nut to fit the slot on the compound. Outside of that, need more input.

Hi Paul, thanks for your reply. I know you have to bore out the holder to fit the base on the original post on the compound, then the post that fits into the new holder has to be trimmed down and bored out and tapped to slide over and screw onto the the original post. I received the attached pic that shows what is required, but I would like dimensions to work to that have not been given. The holder part is obvious and the post I get the gist of what is required, I had just hoped that someone has done the same on their lathe and could give me some tips and dimensions on how to tackle it.

 

[Paul in OKC]

Ah, well, with out having a similar set up afraid I am not much help. Good luck!

 

[T Bredehoft]

How about.... you show us the compound on your lathe, (without any tooling on it,) in a photograph, and another photo with the various parts (that need modified) of the QCTP. Maybe among us we can figure out what needs to be done.

 

[Ulma Doctor]

Hi John,
i have not attempted that conversion, but if you'll humor me i may be able to help a little.
by your photo, it appears that you need to bore the new post to fit a larger center stud.
you start by measuring the stud.
then dependent on the hardness of the toolpost, attempt drilling to a clearance size for the stud were going to use.
it could be bored and/or reamed , possibly countersunk or plunge cut with a milling machine as well- if you have the inclination
if the toolpost is very hard you may need to perform a series or grinding operations or consider EDM.

 

[John3198]

Thank you, I have now sorted it, the person who sent the pic thought he had attached the spec sheet! He contacted me and sent me the specifications I need to complete the task. Thanks again.

 

[casca92]

9x20 jet lathe BD920N model
remove old 4 tool holder
the new 14mm stud that comes with QCTP will need to be drilled with a 17/64th drill bit about 3/4 length of the 14mm stud * I drilled from short thread side as bottom *
next you will need to tap the hole 8mm about 1/3 the new hole length you just drilled.
there should also be a 2x2 inch spacer * I tried to included spacer when I mounted QCTP on but seemed to high, so removed- which will leave plenty of threads sticking through top of holder, added some washers so wouldn't have to tighten so far . * going to add a threaded hold down with a handle to remove need for wrench *

hope this might help I tried to locate a stud all ready drilled and tapped. if you pay for $300 model it comes done and ready. economy model no such luck.

 

[Wreck™Wreck]

I may be missing something in your question but you have the lathe? You have the toolpost?

You then have every possible dimension at your fingertips in the real world by measuring them. This is preferable to relying on a third parties quite often sketchy numbers, you can't go wrong when you have the actual parts in hand.

I hate to bring this up, but.

The quick change tool post is not the most rigid method of holding tools merely the most convenient method for a hobby machine, I have long considered these a root cause in many of the "help with parting" threads. Conventional wisdom tells you to extend the tool out as little a possible, the question is from exactly where is this measured. From the center of the mounting bolt? From the center of the T-Slot? From the Center of the Compound Slide?

I would venture to guess the if measured the cutting edge of a tool mounted in a lantern post is closer to the mounting bolt center than a tool mounted in a holder which is then mounted to a QCTP which is screwed to the compound. A 4-way tool post is more rigid yet a screaming, bleeding PITA to set tool heights on, so is the lantern holder when using more modern square shank inserted tooling with negative rakes.

 

[DavidT]

Thank you, I have now sorted it, the person who sent the pic thought he had attached the spec sheet! He contacted me and sent me the specifications I need to complete the task. Thanks again.

Hi John, Would you be able to post the spec sheet that you received. I have just bought the same lathe and have the same problem.