Parting Woes Solution?

Catcam said:

The original set up spun the chuck ( clockwise) so the hacksaw blade was in tension . this is a stable and preferred mode of operation. Your set up, with the chuck spinning anticlockwise puts the blade in compression which can cause the blade to buckle/ break. But if it works , it works.

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Agreed. There's a reason why hack saw frames have tensioning screws.

Even with the teeth in the "proper" direction, I look at that set up and have to ask myself, "What could possibly go wrong?" ymmv

Tom

Ozwelder has a good list of the basics of parting.Lathe rigidity and type of tooling play and big part in being successful.I have found that using carbide insert parting tools,flood coolant.and slow feed to be the best way to go but HSS tooling with the proper chip breaker ground will do a good job also.The flood coolant seems to cool the tool and wash the chips out of the groove that may jam and break the tool.The more mass the lathe has the better to absorb the chatter and vibration of the parting operation. My 2 cents---Glenn

Changing the flexi top slide to a solid plinth made all the difference in mine.
Parting is now a joy and threading at 90 degrees is also not a problem.

I've been just holding the hacksaw in my hands for thirty years.

I part off regularly now in many materials and will offer the collection of what I have learned from others and do myself:
Work close to the chuck or collet- more rigid!
Extend parting tool only far enough to get through work- more rigid!
Use a proper tool holder- made for supporting the parting tool
Run lathe at lowest RPM
Hand feed in with confidence and feel how the machine responds- If I feel and see a consistent cut I keep going, if it tends to jump in irregularly I just stop and reassess my setup- that is always what happens right before a tool breaks! If you get resistance in the feed NEVER keep going- sure sign it is about to break.
Use lots of coolant
Haven't broken a parting tool in a couple years now... but I probably just jinxed myself!

Small LATHES have to much flex to cut easily with a parting tool. I've made thousands of cut offs with parting tools , the best ones are the biggest oldest turret LATHES. The machines most hobby machinist have just aren't rigid enough to keep the tool from flexing , it can be done but it takes extra care to be as strong has you can make it. I've been toying with a build in my mind to build a roller support to stiffen the tool or holder it would extend or clamp to the ways or like the Hardinage lathe off the head stock itself. It's tuff to keep a knife blade stiff putting force behind and above . There's no panacea in the parting world. The other option I've thought is a rotary tool with a good slitting saw mounted in a qctp . Drop cut and go. I see this as about the best option for small lathe owners. My thoughts only

I machined a one piece parting holder a while back to reduce the flex and get the blade closer to the tool post. Of course I made a video


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