Im looking at geting a QCTP for my 9x20. My question is wich is better, the wedge type, or the post type?? An explaination for why would be good too!
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QCTP question
- Thread starter jpfabricator
- Start date
Wedge. Wedge has better repeatability and is held in by expanding the dovetail the entire length of the toolholder. Piston just have a rod that comes out to push the toolholder away from the base and jamming the edges of the holder into the dovetail. This piston only contacts one spot on the holder.
Some would debate the merits of the two, I will not. I had a piston style at one time, it was cheap and poor fit on the dovetail. Every time I used it the tool holder would pivot on first contact and change the cutting angles, height, etc. I since bought a better wedge style that is much better fit on the post and the wedge cams tightly and the tool holder does not move. Different makes and style so no direct comparison.
I like the wedge better than the cheap piston.
Pierre
I like the wedge better than the cheap piston.
Pierre
Both work. The wedge is more rigid over the whole range of adjustment. I have both. The wedge is much nicer and generally not that much more expensive. The piston post I have is an A2Z CNC toolpost and it has a rather small piston to bear on the holder. One with a larger bearing surface would even out the differences a lot.
Get the wedge type. We hear of folks trading up to the wedge but have you EVER heard of someone who had the wedge type "upgrading" to a piston?
One might argue the potential differences in rigidity, but I can think of two additional deal breakers nobody seems to mention that would keep me from switching to a piston:
1. Both kind accept tools in two positions, 90 degrees apart. BUT, when tightened, the tool post handle ends up in a different position (at least it did on the one I tried) - I find that irritating.
2. Should you ever get into making your own holders, having them draw in against the flats of the holder and the post will make life much easier. All you do is make the dovetail just a bit too tight, and grind, mill or lap the flats to adjust the fit.
One might argue the potential differences in rigidity, but I can think of two additional deal breakers nobody seems to mention that would keep me from switching to a piston:
1. Both kind accept tools in two positions, 90 degrees apart. BUT, when tightened, the tool post handle ends up in a different position (at least it did on the one I tried) - I find that irritating.
2. Should you ever get into making your own holders, having them draw in against the flats of the holder and the post will make life much easier. All you do is make the dovetail just a bit too tight, and grind, mill or lap the flats to adjust the fit.