Harold Halls QCTP

Evening,

I'm planning to make a quick change tool post following Harold Hall's design for use on my Warco GH600. I started off by re-modelling the design slightly larger than the original as I thought that would be sensible considering that the GH600 is just a little bigger than a Myford 7. I increased the base block from 50mm square to 75mm square and then made other appropriate changes.

I am at the point of ordering some material and just started to doubt if the scaling up was necessary for my lathe? The GH600 is not all that much bigger than a Myford 7 but a little more powerful.

Am I doing the right thing or just making the job harder and more expensive?

Thanks

Dan

Dan, I have just finished the same QCTP with 12 toolholders and I uprated the base to 70mm square and made other revisions to sizes to suit. Totally sold on it, so very pleased I did it, in fact was considering writing an article for submission to MEW I've been so pleased. I think it may be an under rated type of QCTP because of it's unorthodoxy but I don't think you will be disappointed.  An internet search will produce another engineer who built one and then verified the repeatability of removing/replacing a tool holder with very acceptible results.

Chris

Edited By ChrisH on 09/12/2020 17:27:22

Hi Chris,

Thank you for your feedback, reassuring to hear from someone with experience of this design. Did you take any photos as you went through the project? What lathe do you have your tool post installed on?

Dan

Dan - my lathe is a Weiller LZ280, a quality German lathe from the late 1960's early 70's now well used but still in good condition/. Acquired it when a boat repair firm went bust nearly 20 years ago. Tool height from bed is 125mm, so bigger than a Myford!

I made 12 tool holders, not yet ground all the tools up to fit yet mind, adapted some holders to take a specific tool and otherwise standardised on 3/8" tool steel. The first 4 tool holders were made from a length of bright steel a bit bigger all round than the tool holder size but I saved some money by buying a 300mm length of black steel cutting it in half lengthways and making 8 tool holders from that machining a bit off all round. By planning the machining and machining all holders in pairs in stages one after the other I got all 8 holders exactly the same size. There are only a couple of crucial (measurement-wise) stages to do but by thinking the machining sequences through before starting and especially how I was to do the crucial bits the actual machining went quite quickly and and accurately and without drama.

Good luck.

Chris

PS - I have added a family photo in Albums

Edited By ChrisH on 09/12/2020 18:33:14