Phase II+ piston style tool post question

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jmarkwolf

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Skip to the last sentence for my question, or read on for my sordid tale of woe.

I wanted some more BXA tool holders for my Grizzly G4003G lathe, and I wanted another tool post to use for temporarily clamping to the web of the ways, for purposes of attaching my Skyhook when changing out lathe chucks. I didn't want to use my regular tool post and carriage due to the moment arm imposed on the tool post and carriage by the Skyhook and chucks.

I thought I'd be clever by buying a "name brand" Phase II+ piston style Chinese tool post and holder set, comparing the new tool post to my "no-name" tool post that was supplied with my lathe, keeping the better one on my compound, and deploying the other one for "Skyhook duty".

When I completed fabricating the nut, and locked the tool post down on the compound, I discovered that the cam lever was jammed tight against the body of the tool post and couldn't turn. Apparently the sleeve that allows the the cam lever adequate room to turn, is a skoche too short. I turned a 0.030" thick shim washer and inserted it between the body and the flange nut and all is well.

Then I discovered that the cam does not rotate smoothly, and sometimes binds. Feels like sand. I decided then that this new Phase II+ tool holder would likely be doing the "Skyhook duty". I checked to make sure that the Skyhook would fit the Phase II+ dove tail and indeed it does not. The dove tail on the tool post would need to be shaved. Then just for fun, I checked to see if all the tool holders fit the Phase II+ tool post and indeed they do not. 2 out of my 10 tool holders would not slide on at all, and a couple more were pretty darn snug.

Pretty disappointed in my "clever" $239.00 purchase decision, I decided that the Phase II+ tool holder was a great candidate for disassembly to see how these things work. I removed one cap screw from the piston, expecting the piston to drop out, but it's spring loaded and won't come out. The screw on the other piston won't unscrew at all, and continues to spin as though the nut on the other end is spinning with the screw.

It's not clear from the exploded diagram how these pistons and screws are supposed to come out. Can anyone steer me towards info, hopefully video, on how to dismantle one of these things? Not finding much on Youtube nor the web.

Toolpost_disassembly.jpg
 
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All piston-type QCTPs are built the same way. Here's how I've disassembled mine:

Turn the knob until one of the pistons is at its furthest extension. Grab the piston with a pair of vise grips on the edges, so that it won't retract when the knob is turned. Then turn the knob until the other piston is as far out as it will go. The center section can then be lifted out with the knob. Once it's out, you can see how the eccentric is "captured" by one or the other piston no matter which way it's turned ... unless you can keep a piston from retracting against the eccentric.

With the center section removed, you can grab the (round) inner part of the piston and keep it from turning while unscrewing the SHCS that attaches the (rectangular) piston face.

It looks like you've managed to remove one of the piston faces already (which is more than I could do before going thru the exercise above). So you're nearly there! At this point, you can rotate the knob to extend the "other" piston, use a screw to pull outward on the inner piston you've exposed, then lift the center out.
 
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Update:

Right you are Hman. Thank you. I did as you described and it came right apart.

And as I suspected I found a lot of oily muck inside. They certainly never put it through a parts washer after manufacture. It looked like it had been in service a few years, not fresh out of the bag. I cleaned it out good and re-oiled it with fresh oil and it is much smoother operation. The cam is still a little stiff at one clock angle however. Like there's a "wobble" in the cam and it's dragging at one spot.

I also examined the fit of the 2 tool holders that don't slide on. They hang up hard at the transition at the top of the dovetail (see pic below). This area is ground 0.004" lower apparently to make it easier to start the tool holder. But the 2 tool holders will not go any further than this transition.

I also compared the overall height of the dovetail between this Phase II+ and my original Grizzly tool post. The new tool post is ground about 0.020" higher, which would explain why some of the tool holders won't slide on.

At this point I don't know if it's worth any more effort to fix. I don't have a surface grinder to shave some height of the dove tail. Thinking about returning the set to Travers. I'm really disappointed in Phase II+. I thought they'd be better than this.

There might be an honest to goodness Aloris in my future.


Toolpost_dovetail.jpg
 
There are reasons why Chinese tools are cheaper to buy. Much of it is related to quality control and quality assurance, which is often (always?) skipped over, to lower the manufacturing costs. Same with cleaning up the gunk. Also in not testing each unit with go/no go tool holders to make sure they meet standards. Instead, they leave that up to you. Send it back and demand another one, or for your money back. My Phase II BXA tool post has worked fine from day one, 5 years or more so far.
 
I decided that for $239 it wasn't worth packing the tool post and all the tool holders back up, paying for shipping and maybe suffering a "re-stocking" fee, so I decided to try and grind the face of the dove tail down a little on my 12" disc sander.

I took the tool post all apart again and adjusted the disc sander table good and square to the wheel and proceeded to carefully grind the faces down just to the level of the "starting grind" (about 0.005").

After cleaning it all up up again and re-assembling all the tools slide on nicely and it works better than ever.

At the very least it will work fine for holding my Skyhook.

It was educational learning how the tool post works, but so much for my idea that "name brand" Chinese tooling would be more righteous than "no-name" Chinese tooling.
 
It's a crapshoot. I've bought several qctps from China Frank at CDCO. They all worked. Some were better than others. For the price I didn't expect aloris quality. Seems like they were a lot cheaper than the one you bought, but that was a few years ago.
 
I almost bought from CDCO as well, but like I say, I was hoping the "name brand" Chinese Phase II+ would be better than the "no-name".

Learned my lesson.
 
CDCO sells the Bostar QCTP's for about half the price of the Phase II and they are WAY nicer. I've tried both.
 
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