G0768 QCTP adapter

Kenny G

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This is corresondence I have had with a vendor over a product I recently recieved want to get your opinions.
HI


My name is Ken and have a concern about a recent order














this order included









4157​

Quick Change Tool Post Set, 0XA for G0768





This is my concern on mounting the QCTP as described It was apparent that the new stud did not have a press fit it would turn in the boss /bushing when tightening and even more when loosening.





1542659346476.jpeg


This is the stud sent


with the tool post mics at


9.984mm























1542659346723.jpeg


This is the original at 10.010mm. This is apparently enough difference that there isn’t a true press fit.























My second concern is with the spacer











1542659346809.jpeg


diameter of the boss 17.55mm



































1542659347501.jpeg


diameter of the bore is 20.53mm



































1542659348160.jpeg


showing the disproportionate fit allowing the spacer to float when trying to adjust .





























I’m not sure what I want to do about this but I don’t feel this is adequate for a rigid and stable system. I I think I like the QCTP being steel , wedge etc. but now I’m not sure. I can make my own adapter stud and spacer for the QCTP which was what I had originally planned on doing. What can you suggest I do , all my past dealings with your company have been very satisfactory.





Ken





This was the response from the company rep.





“Ken


Use the spacer as-is. The loose fit doesn’t affect the function.


Knurl the base of the stud to make it “stick” in the hole.


Those lathes seem to vary from batch to batch. We’re trying to make parts that will fit them all. We’ll probably knurl the next batch of studs.”


I know I kind of left myself open by asking what I should do. What would you do? I don’t really agree that the spacer is completely functional as a sloppy fit doesn’t do much for rigidity. Do you think that it is right that a accessory sold as an adapter should then need to be adapted? I have chosen not to include the company although some here will probably know them as a respected supplier.
 
Hi Ken,

I would simply make my own tool post holder and know that it was done properly right from the start.
 
The tool post is supposed to turn freely and wiggle a bit when the large top nut is not tightened down. Tightening the nut down locates the tool post rigidly. My Phase II BXA tool post and all the other Aloris copies I have seen work the same. I have no issues with using my tool post, and consider it to be working correctly. What is it about the one you rec'd that causes you concern operationally?
 
I have both AXA and BXA QCTPs. Neither of them is a press fit between the post and the ID of the QCTP. Matter of fact, there's about .020" clearance on the AZA and about .010" on the BXA. I don't use a spacer on the adapter (model 3712) I bought for for my 9x20 lathe, but it doesn't have a boss on the lower end of the post.

In any case, the location and stiffness of the QCTP on the lathe is independent of the fit on the post. It comes from contact between the bottom surface of the QCTP body and the top of the compound slide. In your case, that will include the top and bottom surfaces of the spacer. The pressure of the nut at the top of the post holds the QCTP firmly against the slide and friction prevents movement. In some cases, the top of the slide might bow upward slightly in the center because of the pressure. If this happens, the frictional area will be reduced and the QCTP can unexpectedly rotate. I've relieved the center of my AXA on the bottom surface (as shown in the photo) to maximize the friction on the periphery. Everything works well and is very secure.
kHPIM5659.jpg
 
Unlike the AXA, BXA, etc QCTP studs, this stud is only threaded on one end. The other end has a round head meant to fit a counterbore in the bottom of the 768 compound. The OEM stud was apparently a light press fit into the compound. Enough so that it grabbed slightly to permit tightening the QCTP nut. The new stud is .026mm smaller than the OEM stud so no press fit. The spacer is meant to seat the QCTP above the boss on top of the compound and although a sloppy fit is less than pleasing, it won't affect the operation.

How to cure the loose fit of the new stud? You can make a new stud that fits properly. You can build the bottom of the stud up with silvweer solder or braze and turn for an interference fit. You could knurl the new stud to increase the diameter. You could epoxy the stud in.
 
The tool post is supposed to turn freely and wiggle a bit when the large top nut is not tightened down. Tightening the nut down locates the tool post rigidly. My Phase II BXA tool post and all the other Aloris copies I have seen work the same. I have no issues with using my tool post, and consider it to be working correctly. What is it about the one you rec'd that causes you concern operationally?
It's actually the adapter that is the problem the stud to replace the original is not a press fit (the original was)so when trying to tighten against the compound it will spin and the spacer is way oversized to fit on the boss. The actual tool post is ok as far as I can tell. The original stud that came with the machine was a little to short to use with an OXA tool post due to the boss on the compound so this is compensated with a spacer to fit under the QCTP. Hope I am clear
I can and will make my own adapter but I orderered the set that was specifically advertized for the 0768 so it's a little disconcerting that the adapter seems so far out of spec.
 
It's actually the adapter that is the problem the stud to replace the original is not a press fit (the original was)so when trying to tighten against the compound it will spin and the spacer is way oversized to fit on the boss. The actual tool post is ok as far as I can tell. The original stud that came with the machine was a little to short to use with an OXA tool post due to the boss on the compound so this is compensated with a spacer to fit under the QCTP. Hope I am clear
I can and will make my own adapter but I orderered the set that was specifically advertized for the 0768 so it's a little disconcerting that the adapter seems so far out of spec.
OK, sorry, it mounts a bit differently than mine does. I can now see the issues you are having. I am guessing you can send it back for a refund, modify it yourself to your needs and expectations, or maybe there might be more ideas coming in this thread on other and perhaps better ways to deal with it.
 
RJ you are absolutely correct that is the problem. Maybe I'm being a little picky but I just feel that when I order something it should work as advertised.I could have ordered the QCTP form other vendors but since they advertised this as a solution I figured that I would circumvent the need to do the adapter myself and put it into service sooner.
 
No, I don't think you're being too picky. You just want the product to work, and it won't without you fixing it first.

The sad part is, this is all too common. Poorly executed product or service, often by people who only know one small component of what they're supposed to be providing, and nobody to stand up for the ultimate performance. From tool posts to telephone poles, everything is outsourced six ways to Sunday so that nobody really knows who did what part anymore. Or to what specification.

The beauty, of course, is that because there are so many layers it is infinitely easy to say "not me, it was the other guys who did their part wrong...". And so on down the line until the last poor fool in the chain, the consumer, throws up his hands and walks away. Too tired, and too frustrated to even want to play the game anymore.

How very sad indeed.

-frank
 
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