Help me buy a QCTP

[arvidj]

I know I have a wedge 400 and several tool holders in a drawer in the basement. If you're interested I can take some pictures and we can talk.

[Pete O]

I'm back and I'm interested! Please let me know the details, keen to see photos too of course.
Pete

[arvidj]

I'll take some pictures and post them this evening. Or we can take this semi-off line and I can PM you the pictures. I'm not sure which you and\or Ed would prefer.

[EdK]

(04-07-2016, 12:39 PM)arvidj Wrote: I can PM you the pictures. I'm not sure which you and\or Ed would prefer.

It doesn't matter to me but I don't think you can PM pictures. Links to pictures yes. But then I may be wrong.

Ed

[Pete O]

Probably best talking dollars by PM (or is it only us Aussies who think that money is private?) but I'm sure others would like photos.
Pete

[arvidj]

I never installed or used the tool post so my memory of the details were a little cloudy.

The good news ... I finally posted the pictures ...

The bad news ... it is a piston, not a wedge tool post ... the heavy duty boring bar holder does not go down on one side of the tool post [gets caught on the piston] ... and it is heavy so shipping to Australia could be expensive.

Anyway ... it is the "standard starter set", the tool post, a parting blade holder, Knurler, boring bar holder, heavy duty boring bar holder and turning and facing tool holder.

   

   

The discoloration on the tool post seems to wipe off. The tool post has never been mounted or used so it appears to be the protective grease that has discolored.

   

And here is the "strangeness" of the heavy duty boring bar holder. All the other holders fit without any issues so I am assuming that a little cleanup with a file will make this one fit both sides. I don't have a need for the tool post so have not bothered to try to resolve the issue.

   

   

PM me if you ... or anyone else for that matter ... is interested.

[Pete O]

Still interested Arvid, will PM re your price.
Never having used a QTCP, can someone educate me on the advantages / disadvantages of piston vs wedge type? I'm sure it is mostly about accuracy, but what degree of accuracy are we talking- and is it about repeatability or about actual movement during an operation?

[f350ca]

A QCTP is all about convience Pete. The wedge type is supposed to repeat better, maybe if you washed the tool post and the holder each time you mated them you'd see the difference but in a shop environment, don't think it matters. I have a wedge type Dorian CXA on the Summit and a home made piston type on the Hardinge. You'd never be able to change out a tool and rely on the DRO to cut what it says on either. Both seam ridged.

[Sunset Machine]

I can only comment on the piston type. It doesn't mount the holder exactly the same each time but it also doesn't seem to matter a whole lot, I'm not sure why that would be a problem. Coming to size with HSS, a few tenths isn't out of the question. Rough .020 over, one finish pass .010 over, then to size.

You might see an advantage when you assemble the tool holder to the post, the piston needs a wiggle until it drops in, sometime invisible gremlins prevent it and a puff of air clears it. I'm guessing that a wedge might have a better feel, a more positive action. I don't think it could be any more rigid, but maybe they are.

I have a lantern and a 4-way on a South Bend. The QCTP lives on a Logan but if there's any amount of work to do on the SB the toolpost gets moved over to it. There's that much improvement, even with the piston type.

[PixMan]

The accuracy of one style over the other is not a factor in most cases. Only when you have fitted a very good DRO that stores tool positions and you need to depend upon those for repetitive parts is it an issue. I have never trusted a manual lathe to repeat to zero (Hardinge HLV and chuckers excepted) but then I don't find myself making more than one of anything very often. Even if I did and trusted the machine AND the DRO to repeat, I'm still a guy who with stop the machine and measure.

You have to be doing some really demanding work to find the differences between wedge and piston types, or the tool post itself (regardless of design) is just of such poor quality it won't ever work well. The one Arvid shows sure looks like a good quality one and may just need a good tear-down, lube and rebuild to get the two pistons retracting to the same point.