CXA QCTP on the PM-1440GT

Great write up, 12" long chip strings obviously are not perfect but at least they break and are not rats nesting and whipping you to death. .010 feed sounds fine, maybe bump the speed up a hair or try a little deeper cut, sometimes a change of just a couple percent in speed, feed or depth of cut will make the difference. I know a guy who does very fine work, he sometimes puts the tool a hair below center in an effort to set up a repetitive job so to get a better chip or finish. On heavy roughing cuts I sometimes pause the feed to break the chip and let the insert cool a second, I don't run flood. IMO CNMG is one of the easiest inserts to dial in for good chip breaking. I have been happy with Korloy ones I get off ebay out of China, a couple bucks an insert either polished for Alum, or coated for steel.

For taking huge roughing cuts on a lighter weight lathe, nothing beats a cobalt HSS bit with positive rake and some back rake, tan to light blue chips. With low cutting forces you can really go to town on depth of cut.

Great photos in your post, excellent work
 
Wow Jay. That looks great. Very nice work and thanks for sharing. Picking up my 1440GT tomorrow but I have a looooong way to go to catch up with you. Quite inspiring though.

Cheers

John
 
Great write up, 12" long chip strings obviously are not perfect but at least they break and are not rats nesting and whipping you to death. .010 feed sounds fine, maybe bump the speed up a hair or try a little deeper cut, sometimes a change of just a couple percent in speed, feed or depth of cut will make the difference. I know a guy who does very fine work, he sometimes puts the tool a hair below center in an effort to set up a repetitive job so to get a better chip or finish. On heavy roughing cuts I sometimes pause the feed to break the chip and let the insert cool a second, I don't run flood. IMO CNMG is one of the easiest inserts to dial in for good chip breaking. I have been happy with Korloy ones I get off ebay out of China, a couple bucks an insert either polished for Alum, or coated for steel.

For taking huge roughing cuts on a lighter weight lathe, nothing beats a cobalt HSS bit with positive rake and some back rake, tan to light blue chips. With low cutting forces you can really go to town on depth of cut.

Great photos in your post, excellent work

Thanks Doubleeboy,

I agree the CNMG inserts are fairly easy to dial in. For roughing stock diameter not to a shoulder I like the SNMC inserts. After installing the solid base I tried running the cutter at the same feed & speed as before and instead of producing small chips as it did with the compound I just got a big fat string and a better finish. I just bumped up to the next gear and feed rate to get the long curls. I have not tried any other settings yet as I didn't want to waste any more material.

I haven't played around with HSS for heavy roughing on this lathe. I may give that a try. I generally only use HSS for custom cutters. I've ground a lot of HSS over the years and for whatever reason generally dislike doing it. Kind of odd since I enjoy regrinding drill bits by hand. Go figure.
 
Wow Jay. That looks great. Very nice work and thanks for sharing. Picking up my 1440GT tomorrow but I have a looooong way to go to catch up with you. Quite inspiring though.

Cheers

John

Thanks John. Congrats on the new lathe. Be sure to post pictures!
 
I counter bored the top of the tapped hole .100" deep the same diameter as the 8mm socket head cap screws so they would lock in to the cross slide.

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Jay, can you clarify why you counterbored the tapped holes? The block covers them when it's installed. Is this so you can plug the holes with short cap screws when the block is removed and the compound is put back on? Thanks for the post. Using Mitee-bites to jamb-lock the QCTP is a great idea. Curious how they worked out and if you had to go to a large size to get the anchoring force you need.
 
Jay, can you clarify why you counterbored the tapped holes? The block covers them when it's installed. Is this so you can plug the holes with short cap screws when the block is removed and the compound is put back on? Thanks for the post. Using Mitee-bites to jamb-lock the QCTP is a great idea. Curious how they worked out and if you had to go to a large size to get the anchoring force you need.

The SHCS are only threaded at the end. The un-threaded body protrudes past the bottom of the hole in the solid base. By counter boring the threaded holes on the cross slide to the same diameter as the screw body the un-threaded body acts as a pin vs just relying on the thread alone to keep the solid base from being moved under a heavy load. When the solid base is not installed I'll use button head cap screws to plug the holes.

The Mitee-Bite clamps are working so far. Time will tell.
 
You give me something to strive for Jay. Great write up.
 
Did you prep your cross slide at all?
How do you dial in squareness of the post with the Mitee Bites?
I'm not familiar with them.
 
Did you prep your cross slide at all?
How do you dial in squareness of the post with the Mitee Bites?
I'm not familiar with them.

Other than drilling holes in the cross slide the only thing I did was run a stone over the mating surface to check for burrs or high spots.

The head of the screw for the Mitee-Bite is ground eccentric so as you turn it the brass hex is pushed against the part. The hole for the screw is drilled a pre-determined distance from the part to be clamped. I used the Mitee-Bite clamps because I had them otherwise I may have done something different.
 
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