Piston or Wedge

[curtis cutter]

I believe many of you fairly accurately know my competence level. I would maybe place myself at a .25 on a 1-10 scale with an 11 being a Harold...

With the above thought in mind, I currently have a piston type QCTP using AXA holders and if I were to come across a wedge type TP would there be any advantage in this design for me?

[warmstrong1955]

I changed my piston style to a wedge years ago. Main reason, was the piston, when making interrupted cuts, would come loose. I was always having to slap the handle to keep it tight, to the point where I even broke it. I have never had the wedge come loose, even turning ugly nasty flame cut things, turnig them into round things.
The other thing I noticed later, was the wedge has a much better repeat-ability. The piston could miss by a thou or two when changing tools one time to the next.

Bill

[curtis cutter]

Thanks Bill.

Does the piston type draw down and away from the TP and task better then?

[warmstrong1955]

Wedge type draws down as you tighten it.
Piston just pushes out from the center line of the mounting bolt.

After owning both, I don't know anything the piston style does better than the wedge....besides costing less.


Bill

[SteveM]

When the piston pushed out, the toolholder is wedged on the dovetails of the toolpost, so it is supported by two surfaces.

The wedge pulls in, so the toolholder is wedged between the dovetails AND the face of the toolholder, so it is supported by four surfaces.

Now, with all that said, I had a generic wedge toolpost and it was a piece of garbage. I eventually sold it and went back to my Phase II piston toolpost which was actually better.

I eventually got a Phase II wedge and it's great.

I actually have a very old Aloris piston toolpost. It's so old that it has the dovetail on only one side, and the height adjustment was by a little screw that stuck out the bottom of the toolholder. Got it in a deal with a bunch of other stuff and figured I'd use it for something.

Some have commented that the Phase II is not made as well as it used to be. I can't comment on that - I got mine used.

Steve

[Harold_V]

Aside from using an indexing square holder, my greatest experience is with the KDK post, which is also a wedge design. I was quite impressed with them, and used several sizes. One of them was on a 42" Dean Smith Grace lathe. Heavy holders, not fun to change, but up to the task.

H

[NP317]

My new lathe came with a piston-type QCTpost.
I replaced it with a wedge type before doing any lathe work.
~RN

[Richard_W]

Aside from using an indexing square holder, my greatest experience is with the KDK post, which is also a wedge design. I was quite impressed with them, and used several sizes. One of them was on a 42" Dean Smith Grace lathe. Heavy holders, not fun to change, but up to the task.

H

Harold its my understanding that KDK is no more. I like the Dorian tool post better now that I have used one for awhile. Although both Aloris and Dorian are good. Just my new preference.

Richard W.

[Harold_V]

I understand the KDK to be gone, too, Richard. The last time I used one was in 1967. The shop in which I worked is gone, as well (United Precision Manufacturing, in Salt Lake City, Utah)!

I've not experienced the Dorian. Must be pretty good.

H

[curtis cutter]

Thanks for this discussion. I think I will keep eyes open for the wedge type I think.

BTW, I typed AXA but meant BXA and I could not find how to edit my post. Am I missing an option button somewhere or is there a time thing involved?

[Mr Ron]

I was tempted to buy a piston type, but after reading about the pros/cons of both, bought the wedge type and happy I did. Now before buying anything, I do the research as much as I can so I don't make a costly mistake. This forum is a great place for such research.

[Harold_V]

BTW, I typed AXA but meant BXA and I could not find how to edit my post. Am I missing an option button somewhere or is there a time thing involved?

Thanks to the edit feature being abused by one reader, it has been removed from the board, although moderators still have the ability to edit in their respective fora. That said, if one wishes to edit a post, simply inquire of a moderator.

H