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QCTP
Jonny:
Had a quick look at that Bill, looks the worst of the lot.
Hate to think what the rigidity is like and also the repetition when changing over.
The Dickson style of toolpost is far the best, support against the tool post. Unfortunately i gave a large one away and now only a T02 a bit on small side with 1 tool holder.
I normally use for convenience the chinese dovetail and will have to change. I have noticed for weeks trying repetitive stuff swapping and changing tool holders over, i cant maintain dimensions. The reason the toolposts are flexing, if its pushing against one dovetail, its got less grab on the rear in the case of boring, therefore comes out undersize.
You can physically see the toolpost veer off when knurling.
AdeV:
I built a piston type (http://madmodder.net/index.php?topic=3453.0), and in practice I find it works very well. It helps to have the toolholders to be a fairly tight sliding fit over the dovetails, otherwise it's possible to end up with the piston acting as a fulcrum allowing the tool to rock in the horizontal axis - not fatal, but you need to be aware of it, and of how the cutting forces are going to affect it, and make apprpropriate allowances. On the other hand, get a nice snug fit and there's no noticable movement when you operate the cam.
If I were to make another one, I'd probably have a go at a wedge type, although I do have most of the bits for another piston type...
jgroom:
Hi Chuck.
I built one of Mr. Stevensons' toolposts several years ago. It was a bit huge at 3" square for my little 9"SB so I dropped it to 2.5" square.
It still feels a little large, but it's extremely stable.
I built a smaller one I found in Home Shop Machinist (can't remember the issue date) to get in a little closer to the chuck.
Both work very well.
Any Loftquist has a very nice looking compact toolpost, http://www.statecollegecentral.com/metallathe/MLA-23.html. The drawings for it have also appeared in HSM (May-June 2006). May have to build one for the fun of it. :dremel:
I've never used an Aloris style piston type post so I guess I'm no help on that front, but I've never had a problem with the wedge type.
Cheers
Jeff
BillTodd:
I made this Hardinge style one for my HLV_H. Inspired by this design on the HMEM site:
http://www.homemodelenginemachinist.com/index.php?topic=5153.0
Bill
Chuck in E. TN:
Thanks for the input so far. I have collected a couple of plans and pasted them into a word document to study further. I still lean to remaking the Mert B./ Ralph P./Norman Patent variety. The first one I made was from 6061 aluminum block on a steel cylinder. I cut the clamp slot with a hand hack saw, but that was before I had a 4x6 band saw and some decent slitting saws.
Any other ideas floating out there?
One more question. The standard 4 way Chinese tool post, any clever mods to make it more useable, like adding height adjustment?
Chuck in E. TN
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