QCTP questions

[kvom]

The lathe I'm using at school is a CXA size, and what I believe is called a "wedge" type. There is a steel wedge in one of the dovetails that locks against the tool holder.

The toolpost of the lathe I just bought is AXA size, and is what I believe is called a "piston" type. In any case, there are two rectangular plates on the flat of two dovetails that press against the tool holder. It would seem that one could mount a holder on either of the two sides with the pressure plates, so I'm assuming that you might be able to mount a facing tool on one, then a turning tool on the other without reorienting the toolpost itself.

Am I on the right track here? Any significant differences between the wedge and piston types?

 

[ksouers]

Kirk,
Having two tools on the post at the same time will cause interference with each other. You can only have one tool at a time. The QCTP is to make it easy to switch tools, so it's really no big deal to swap them out. Having two positions on the post makes it easier to change from say facing or turning tools to boring tools without much hassle.

I have a piston type tool post and I've found that I need to have a couple shims handy. Some of the tool holder's dovetails are a tiny bit loose and can wobble a little. I just stick a shim or two in the dove before tightening up.

 

[SmoggyTurnip]

I wondered for a long time why there is 2 places to mount tools on the QCTP. After all you can put your boring tool on the same side as the turning tool just by rotating the post 90 degrees. Then I realized that the Handel that is used to secure the tool holder would stick out in front and get in the way when using the boring tool that way. So I guess the 2 positions give more flexability in the position of the handle.

 

[kvom]

I knew that the tp would hold only one tool at a time.

The wedge type post I'm using at school can tighten my moving the handle in either direction. When I get the lathe home I'll see how this one works.

 

[GailInNM]

Kvom,
I have used both piston and wedge type tool posts. I currently have a wedge type on my lathe.

I think that the wedge type are a little more rigid as the holder is bearing on 4 surfaces instead of 3 on the piston type, but the difference is too small to make any real difference unless you are planning on doing a lot of heavy hogging cuts. I have not noticed any difference for the type of work I do. The other difference is that the wedge are generally more expensive.

The piston is a little easier to use in one way. The wedge gets in the way when cleaning off the surface that the height adjusting nut when mounting a toolholder. Not enough to be bothersome however. The piston type is smooth in that area so there is no place for chips to hide.

Gail in NM,USA