Bxa Or Cxa Quick Change Tool Post?

G

gwade

H-M Supporter - Silver Member
H-M Supporter - Silver Member
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Jul 15, 2014
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I've recently acquired my first lathe which is an antique LeBlond 14. LeBlond informed me it ws shipped in 1920. It's in pretty good shape and has the drive modified and a modern 1 HP motor installed. I was told by LeBlond that it was very similar to the first Regal 15's. My question is what is the best size QCTP for this lathe (looks like both would fit based on centerline dimensions)? I am leaning toward the CXA because I have some larger tooling that I got with the lathe. But if BXA is all I need then it would save me about $100 based on import tool pricing and even more in the long run as additional tool holders are acquired. Any/all advice would be appreciated.
 
Question on this topic for those with more experience than I have.

Will the larger post be more rigid?


Daryl
MN
 
You should be able to run either. BXA is recommend for 10"-15" swing, and CXA is for 13" to 18". Strictly from an economics standpoint, you need to weigh the cost of the tooling you have and will need to purchase in the future with the $100 difference. But that's not taking into account what it is that you plan on using it for and if you really need the extra rigidity of the CXA and heavy tooling. Industrial shops may need it, will you be more of a job shop or a hobbyist?
 
The old lathe is/will be used for hobby and repair of farming equipment. No commercial work. Is it feasible to mill down insert holders (such as 1" square down to ¾"x1") so it would fit in an oversize BXA holder? I have a 1" Sandvik triangular insert holder, a 1" holder for a stand-up threading insert, etc.
 
For the CXA I would first check the distance from the top of the compound to the spindle center and then get some dimensions of the tool holders to see if there is enough space for the large insert holder shanks to work with your lathe. Some holders may bottom out before the tool can center. Personally I wouldn't base my decision on one insert holder (unless you have a box full). The BXA is plenty rigid for most work. Either way a good quality wedge type is preferable.
 
Hmm! I think you are right about the 1" tools being above centerline. I think the dimension from compound to centerline is only about 1.4" but will confirm tomorrow. If so I will order the bxa set. Another side question if you guy's don't mind: What type/size parting tool do people with the bxa tool holder use? Look's like the provided holder in the set is for a ⅝" tool which seems a bit rare.
 
gwade said:
Hmm! I think you are right about the 1" tools being above centerline. I think the dimension from compound to centerline is only about 1.4" but will confirm tomorrow. If so I will order the bxa set. Another side question if you guy's don't mind: What type/size parting tool do people with the bxa tool holder use? Look's like the provided holder in the set is for a ⅝" tool which seems a bit rare.
Click to expand...

My opinion is that a QCTP and standard blade holders are not particularly well suited for parting operations. In some cases it will work OK but eventually its limits of rigidity might rear its ugly head. If you check out some of the threads on parting and chatter you will see some of the DIY tool posts and holders that members here have come up with.
 
A common problem that a lot of newbees make is not correctly setting up to part. If you just throw a parting blade in a QCTP (or toolpost), have the compound at the common 30*, extended off the cross slide, the tool will not be bearing directly down for maximum support on the carriage, and it will deflect and catch. Get the carriage directly under the tool with as short of plunge as possible.
 
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