Gallery, Projects and General > The Design Shop

QCTP

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andyf:
Hi Chuck,

If you are going for the Norman Patent type, you might consider this one http://mikesworkshop.weebly.com/novel-quick-change-tool-post.html which takes two tools in each holder block, with independent height adjusters for each tool.

I doubt if a standard "4-way" type could be easily adapted so as to vary its height. You need a thick (around 1") post for it to clamp on to securely, and there isn't enough metal in between the four tool slots for a correspondingly big hole.

Andy

bp:
A while ago I made a pillar and clamp-on toolholder style QCTP.  One of the reasons was to eliminate the tool overhang from the top slide and as a result increase rigidity, and provide better parting off.  These requirements have been met. 

Anyway I wouldn't use aluminium alloy for the toolholder, it simply isn't rigid enough although others will no doubt disagree.  Also I made "my" pillar as large as possible to increase clamping area and to increase the seating area onto the compound slide.  The pillar ended up at about 35mm diameter.  My toolholder used 12L14 (free machining) steel 35mm nominal diameter for the pillar, and 25mm slices off of 50mm x 50mm bar for the toolholders (all 14 of them)
cheers
Bill Pudney

Metalman:
I wonder Jonny if you have misunderstood Harold Hall's QCTP. It is easy to look at the photographs on his website and think that it is a half round key locating in a half round groove, which of course it is not.

The inner member has in fact a flat on the top so that the outer just locates on the sides rather like a mini inverted dovetail assembly and should locate very well.

Another very important consideration that he mentions on his web site is that the location has a much greater length to width ratio than other designs, that he comments are about 1:1. I estimate the difference to be in the order of 4:1 for his design compared to the 1:1 that he mentions for other designs.

The main consideration for the design, published in MEW issue 50, is that it is quick to make and at a push can be made in the workshop that does not posses a milling machine.

Kenneth

Jonny:
Ken, what happens when one material is softer than the other and or when it starts to wear. That will be the first time its used.
Even if both parts are same metal one will wear the other rapido.
Looks slow to change as well as tolerances have to be tight making alignment and fitting a chore. Will egt better over time with wear.
In saying that should be better than any dovetail push out type.

Wedge type pull in as in Dickson far the strongest.

Doc:
Here is a set of drawings for the one I put together and built for my lathe.

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