# Parting Woes Solution?



## savarin (Nov 21, 2016)

I just saw this (pun intended) and thought it may be of use to those who have problems parting.
I rather liked it.




I couldnt think where to post this so please move if necessary.


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## Christian Poulsen (Nov 21, 2016)

...just when I start thinking I've seen it all!...


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## wawoodman (Nov 21, 2016)

I think it's pretty damn ingenious, considering how much trouble beginners (like me) have with parting off!


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## chips&more (Nov 21, 2016)

What the heck! That's one for the books!!!


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## Christian Poulsen (Nov 21, 2016)

well yes, from what I see it looks pretty safe and it even has adjustable cutting pressure! (smiley face here)...so ifn' one doesn't have a good parting/cuttoff tool and holder and/or doesn't have the speeds and feeds down for cutin' off...why not this!


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## 12bolts (Nov 21, 2016)

All it needs now is a small crank running of the leadscrew to provide some reciprocating action and spread the wear

Cheers Phil


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## ndnchf (Nov 21, 2016)

My success with a parting too greatly increased when I switched from the old lantern toolpost to a QCTP and parting tool holder.  But there are still time when I just need to saw something off and use a hand held hack saw.  For small pieces, this is pretty clever, simple and effective little tool.  I like it.


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## 4GSR (Nov 21, 2016)

Sometimes when parting off in the lathe using carbide tooling, I'll stop the part off so it leaves a nub about 3/16" in diameter.  Next I'll take my hacksaw, part it the rest of the way off with the lathe running.  Haven't tried it at full diameter.


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## chips&more (Nov 21, 2016)

My 14” lathe is big enough, ridged enough and powerful enough to part without the typical problems. It’s those Murphy ones that I worry about. I will usually take my project out of the lathe and over to the power bandsaw cut-off instead of risking a blade catching or compound breaking or soiling my underwear or some other bad thing…Dave.


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## ndnchf (Nov 21, 2016)

Intrigued with the idea, I went out to the shop after dinner and cobbled one together from  scrap I had laying around.  Pretty easy to make.  It seems to work pretty well, but needs a stronger spring than I have to replicate the downward pressure sawing by hand gives.


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## Christian Poulsen (Nov 21, 2016)

...looks like this op/set up is catching on!...I wonder if the original got a patent? (We better lawyer up!)...smiley face here


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## Bill Gruby (Nov 21, 2016)

If your spindle has the chuck screwed on I would suggest you do NOT try this. The original has the spindle running in reverse. The teeth on the blade set to cut that way. One snag of the blade and you could wear the chuck.

 "Billy G"


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## ndnchf (Nov 21, 2016)

My set up has the spindle turning normally and the saw is arranged so the teeth cut properly. But good point about a chuck unscrewing if going the other way.


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## Bill Gruby (Nov 21, 2016)

I saw that the second was correct and only the original was going the wrong way. Kudos for the build on yours.

 "Billy G"


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## Tozguy (Nov 22, 2016)

ndnchf,
may I ask which way the saw teeth were facing?
how often did you have to lift the blade to clear chips? or do you just crank the slide back and forth a bit while it is sawing to clear them?


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## ndnchf (Nov 22, 2016)

The teeth are facing away from the toolpost so they cut against the rotation.  I just cranked it back and forth a bit.  It is slow.  I used a 32 tooth blade.  An 18 tooth would be better and a stronger spring.  I mounted the blade to a piece of 1/2" square stock with an 8x32 screw and lock nut.


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## Wreck™Wreck (Nov 22, 2016)

Bill Gruby said:


> If your spindle has the chuck screwed on I would suggest you do NOT try this. The original has the spindle running in reverse. The teeth on the blade set to cut that way. One snag of the blade and you wear the chuck.
> 
> "Billy G"


If you can release a threaded spindle with a hacksaw blade you are a better man then I am. I once owned a threaded spindle machine and unscrewing the chuck took considerable effort if it had been in use for several months or years.


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## Bill Gruby (Nov 22, 2016)

With all due respect Wreck, read on please.If that blade jams or bends the teeth will jam or bind. If they jam the spindle could come loose.

FWIW, I have a spacer washer on my spindle between it and the chuck. This makes for easy removal of the chuck after long periods of use. A set up like the first one with the spindle running in reverse will have the chuck loosen and come off if that blade jams.

I leave you with this phrase, "Just because you haven't seen something happen, does not mean it can't happen.

 "Billy G"


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## Tozguy (Nov 23, 2016)

And there is always the wisdom of using a locking mechanism on a screw on chuck probably conceived for guys like me.


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## Wreck™Wreck (Nov 24, 2016)

Bill Gruby said:


> With all due respect Wreck, read on please.If that blade jams or bends the teeth will jam or bind. If they jam the spindle could come loose.
> 
> FWIW, I have a spacer washer on my spindle between it and the chuck. This makes for easy removal of the chuck after long periods of use. A set up like the first one with the spindle running in reverse will have the chuck loosen and come off if that blade jams.
> 
> ...


I have actually spun a 20" 4 jaw chuck off of a threaded spindle, I fully understand the outcome of such a thing happening.


However in my initial post I was wondering if one may actually unseat a threaded spindle with a hacksaw blade and a spring.


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## Tozguy (Nov 24, 2016)

I vote yes, given enough time and vibration, some will. Some won't, maybe, but which ones?


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## Bill Gruby (Nov 24, 2016)

Without mixing words any further than this post, the answer is, I don't know either but I damn sure don't want to find out. I posted the warning as a precaution.

 "Billy G"


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## Christian Poulsen (Nov 24, 2016)

Wreck™Wreck said:


> I have actually spun a 20" 4 jaw chuck off of a threaded spindle, I fully understand the outcome of such a thing happening.
> 
> 
> However in my initial post I was wondering if one may actually unseat a threaded spindle with a hacksaw blade and a spring.


I could see it happening if that hacksaw blade set up jams and crams ifn'n the chuck is turning in the "unscrew" direction without a "lock" (just like anything)...By the way, good catch to whoever caught that (somewhere above)


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## Bill Gruby (Nov 24, 2016)

Safety is our primary concern on this Forum along with helping  in any way we can. It wasn't hard to see in the first video that there was an accident waiting to happen. That is why it was brought to the attention of all. My sole purpose was to show what was going on and what could happen. I would not feel right if something happened to one of you and I had not said something. I would hope the rest of the membership felt the same.

 "Billy G"


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## Wreck™Wreck (Nov 24, 2016)

I appreciate your lessons about safety, carry on all.


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## Garththomas (Nov 25, 2016)

I imagine an operation like this would be a pretty low rpm operation


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## Ozwelder (Nov 25, 2016)

For goodness sake. 

Take the time to learn and do it properly or line up a good eye doctor.
Theres a good reason you haven't seen it elsewhere. Its just plain dangerous and an accident  just waiting to happen.
I am saying whats on my mind rather than remain silent and  hear of someone getting hurt.

Guys,as they say it ain't rocket science. I regularly part off with HSS through stainless 303 and on occasion 316.

Ok these comments do  apply to non production amatuers . I am not a jobber, so time is not a factor for me.

Observe the basics.

* Part off at center height
* Part off square to the axis of the work -check set up  AND that compound  setting is on zero.
* Set up for the minimum of  PO tool overhang - half diameter of work + a smidgin
* Ensure the rigidity of your tool holder and tool post
 * Use a constant (cross) feed
* Where necessary use a lube - on stainless mine is a sulphur base lube
* Sharpen the HSS tool as per info available -its there on the net
* Watch for the curl shape of the swarf that comes off the steel -  the shape, size and texture tell you so much .Most times with a lot of steels  comes off like a cursive writing "C" and usually is very shiny at the cut face.

I am certainly no machinist, merely an amatuer of some  8 or nine years experience but decided  very early in my machining hobby to learn about using HSS. It has paid off in terms of economy  versatility and not needing a wide selection of carbide cutters and tool holders.
It took a bit of  time , effort and study plus chatting to an old timer and I was parting off trouble free with HSS within 6 months.
I hope this can help someone. Experienced machinists feel free to jump in and add something I may have missed.

Regards
Ozwelder


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## Mariah (Jan 4, 2017)

My QCTP puts the parting blade off to the side and that results in things tipping and the blade digging in, mini lathes do this to keep your adrenaline drained...been there done that more times than I care to remember!  My way of ending this problem was to turn the holder and parting blade upside down and use reverse for parting.  If the tool digs in the blade tips away from the cut, this saves my parting blades and my adrenaline is back to normal!  This worked so nice I drilled and tapped a hole on the blind side of the holder to set the tool height quickly.


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## Catcam (Jan 4, 2017)

savarin said:


> I just saw this (pun intended) and thought it may be of use to those who have problems parting.
> I rather liked it.
> 
> 
> ...


Novel and it uses up the broken blades you have laying around. May well work


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## Catcam (Jan 4, 2017)

ndnchf said:


> My set up has the spindle turning normally and the saw is arranged so the teeth cut properly. But good point about a chuck unscrewing if going the other way.


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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## higgite (Jan 4, 2017)

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.


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


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## Professor64 (Jan 17, 2017)

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


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## savarin (Jan 17, 2017)

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.


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## Silverbullet (Jan 17, 2017)

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


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## StuNY (Jan 18, 2017)

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!


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## Silverbullet (Jan 18, 2017)

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


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## jdedmon91 (Mar 11, 2019)

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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