QCTP holder

I will not even attempt to widen the slot. Doing so accurately is probably beyond my skill level and I would then have a non-standard/modified compound. Who knows what problems that might create down the road. I probably misspoke using the term "T nut." Here is a sketch of the compound slot.
compound slot.jpg

And here is what I am thinking of making to replace the carriage bolt. I left off the threads. Too hard to draw quickly.

t nut.jpg

My T nut would be a 1/4 x 15/16 x 2" with a 5/8 threaded post. The post will either be welded in place or screwed into a threaded hole in the base plat.
 
mickri, that is what I had in mind too. I think I can easily fab that
 
Well, as I said in the beginning, the BXA is too large for an Atlas. And costs more to operate. But people new to machining seem to have the notion that a BXA is somehow superior to an AXA and will make them a better machinist. It isn't and it won't.

Most vendors of QCTP's will list tool posts that will work out of the box with an Atlas. Some are more expensive than their cheapest offerings and some aren't. But before investing in a QCTP. you really should make sure that you know what you are getting. It is, after all, not a trivial expenditure.

As I have said before, people who have bought a BXA for their Atlas usually fall into two groups - those who will admit that they wish that they hadn't and those who wish it but won't admit it. Virtually every time that I have written this, on average 2.3 people reply that they bought one and are glad that they did. I am too polite to make an honest reply to that.


On the subject of using a carriage bolt instead of a T-nut and stud to secure the TP to the compound slide, the short answer is "DON'T". Sooner or later, you will probably break the T-slot out of the top of the compound. Plus the square part of the proper carriage bolt is not made for preventing rotation in a slot. It is tapered to allow it to easily cut into the wood that it is made for use in. This means that the square part is initially in contact with only a few thousandths of the lower part of the slot. And after a time you will start to notice dings in the lower part of the sides of the slot as the bolt cuts into it. You will never see this from a proper fitting T-nut.
 
wa5cab, I may eventually get to agree with you. Can you tell me the size of your AXA center bolt? From the bit of research I did last night it appears that it would only be 1/16 smaller than my 5/8 bolt, which wouldn't really leave enough meat for a t nut in my 5/8 slot. I appreciate your input.
 
What you need to hold the BXA base unit to the compound is a nut. The larger thenut, the stronger it is. The head of a carriage bold will be nowhere near strong enough. neither will 5/16 thick steel. (maded to fit the entire slot) will be what you need. The tighter fit the the better/stronger it will be. Ideally the screw would be tapped into the compound but that isn't a realistic solution. Unless you use a full sized T nut, you won't be happy with your lathe.
 
Robert thanks for the heads up on carriage bolts. I don't think that I will experience those problems because I milled the flats on the bolt to just under 5/8 and used my mill to flatten the head and to square off two sides of the bolt to fit in the bottom 1" x 3/16 slot. I have a rather beefy boring bar holder that came with my lathe and a 4 way tool post holder. The nut on both of those is no bigger than the head of the carriage bolt. I haven't made a proper nut because I don't have a piece of steel to make it out of.
 
I just sent a note to the CDCO folks to see what they recommend. I may end up going with the AXA. Don't say anything wa5cab!!!
 
The CDCO folks got back to me:

"Actually the BXA Bolt threads is metric M16 x2. so the bolt diameter should be 16 mm . Our AXA Bolt threads is M14 x 1.5 , so the bolt diameter should be 14 mm , but BXA is much better for 12" lathe like yours. If you use AXA, the holders will always at the top position , no big room for the cutters up down adjustment. Maybe you can consider to cut the BXA bold diameter a litter smaller to try it."

So two comments: (1) their comment about the tool holders always being in the top position is one reason I went BXA to begin with and (2) it sounds like they are suggesting that I modify the bottom part of the bolt by reducing the diameter and re-threading, which I did consider. I'll be in Tempe for a week so I'll have time to consider options.
 
Yes you could just make a flat threaded piece instead of a t-nut- don't modify your compound slot
I was going to put in a vote for AXA but you pulled the trigger too soon LOL
mark
 
Thanks markba633csi. That's was one of my thoughts as expressed in a previous reply, so we are on the same page. It was good enough for the lantern style post. I do ultimately want to come up with a t nut solution but don't want to let perfection get in the way of good enough for now.
 
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