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View Full Version : diy spring toolholder, the answer to parting problems



janvanruth
02-13-2016, 12:17 PM
simple, effective and cheap
this guy made his own
as he made his own lathe, his own mill, (nearly)all his tooling, all out of scrap
check out his channel and be sure to leave the end mill sharpening ficture to the last!!!!!!

https://www.youtube.com/watch?v=oxY0xG-pbo4

Carm
02-13-2016, 12:27 PM
He is a crafty mechanic.
The fact that he has prosthetic hands is mind boggling.
One of the songs appears to be about no need for pity.
No pity from me, he epitomizes the human spirit.

janvanruth
02-13-2016, 12:42 PM
He is a crafty mechanic.
The fact that he has prosthetic hands is mind boggling.
One of the songs appears to be about no need for pity.
No pity from me, he epitomizes the human spirit.

S**t, now you ruined the surprise.

Illinoyance
02-13-2016, 12:56 PM
Used to be fairly common.
http://www.ebay.com/itm/ADJUSTABLE-TOLL-BIT-HOLDER-PARTING-OFF-AND-TOOL-POST-LATHE-/121888545217?hash=item1c61

Carm
02-13-2016, 01:06 PM
S**t, now you ruined the surprise.

Oh! Sorry 'bout that.
But I don't think that should matter at all, the work speaks for itself.

awemawson
02-13-2016, 02:25 PM
Nice - he now just needs to learn how to grind a chip breaker into his parting tool :)

Mike Amick
02-13-2016, 04:04 PM
Would be cool to learn the story behind his disability. Those black carbon fiber fingers are almost sinister.

Edit : Not saying they ARE carbon fiber ... Just struck me that way.

janvanruth
02-13-2016, 04:39 PM
lost them 35 years ago in a bomb accident

plunger
02-13-2016, 04:43 PM
Is there any more info on this guy.

Peter.
02-13-2016, 04:47 PM
Well, I'm impressed.

janvanruth
02-13-2016, 05:30 PM
https://www.youtube.com/channel/UC87Ga2R7IghA26_0mPjicHw

Mike Amick
02-13-2016, 08:15 PM
lost them 35 years ago in a bomb accident


See that !!!

That's the beginning of a totally interesting story.

Tim Clarke
02-13-2016, 09:25 PM
This man needs to join us here, he'd be most welcome, not to mention admired!

Doozer
02-13-2016, 09:34 PM
I don't think the holder made the difference.
The HSS blade with the holder has a positive
rake grind to curl the chips, and at an angle
no less, which twists the chips and shoots them
sideways, as not to jamb the kerf.
The original blade is a brazed carbide, with no
geometry or surface prep what so ever.
So no wonder the HSS blade (with the springy
holder) works well. I would like to see that
first bit put into his holder and see the results.

--Doozer

imp
02-13-2016, 09:43 PM
This man needs to join us here, he'd be most welcome, not to mention admired!

YES, and YES! My own bomb accident happened when I was in 8th. grade, attempting to make Berge's Blasting Powder. Mortar and Pestle mixing, suddenly WHOOSH, 2nd. degree burns to the face and stirring-hand. The event convoluted my then-evolving new-found almost-adulthood. Story for someplace else, if anyone cares to hear more about it, but the bottom line is, it explains how and why I went on to be self-taught in many of the skills I am grateful to have acquired. imp

fixerdave
02-14-2016, 12:07 AM
Just curious... what's the theory behind the springing holder?

I ask because I've often wondered why people complain so much about parting. My piece of junk seems to part without issue, and I've no idea why. It's the cheaper version of the piece of junk Chinese 3:1 machines. I mean, it's got a 16" swing. The whole thing flexes and chatters all over the place, but I can part an inch or so of steel. A bit of chatter at the start, but once it starts cutting, so long as I keep spinning the cross-feed, it keeps going. Maybe it's because my whole lathe is a big spring :)

Now, today, just for fun, I tried to part 3" of mystery steel. That did not go well, but I knew I was pushing it. Way too much stick-out on the parting blade and even the slowest speed was too fast. I was just testing out a modified tool holder; still not happy with it.

David...

J Tiers
02-14-2016, 01:11 AM
I also part off with whatever piece of HSS with a grooving type grind comes to hand first. never use a regular cutoff tool. No issues, it just works, hand feeding the tool not using auto crossfeed.

I had lots of trouble before converting the Logan to 3 phase.

Still, that type tool is on my list, as it ought to improve cutoff even a bit more.

PStechPaul
02-14-2016, 01:34 AM
Last month I had some trouble parting some 5/16" tool steel. I think a thinner blade would have been better, and less stick-out, but the holder I used was too close to the chuck:

http://enginuitysystems.com/pix/tools/Parting_2675.jpg

http://enginuitysystems.com/pix/tools/Parting_2677.jpg

The problem I was having may have been from the cutting edge having insufficient rake and it may have been work-hardening because it was rubbing. It may have been O-2 or W-2. It seemed to cut OK and then suddenly grab and chatter.

phil burman
02-14-2016, 09:57 AM
Just curious... what's the theory behind the springing holder?

I think the theory is that it is self regulating regarding depth of cut and therefore risk of grabbing. The greater the force on the cutter the further it swings down and away from the work piece, thereby reducing the depth of cut and consequently the force and the risk of grabbing.

Phil:)

JoeLee
02-14-2016, 11:34 AM
I don't think the holder made the difference.
The HSS blade with the holder has a positive
rake grind to curl the chips, and at an angle
no less, which twists the chips and shoots them
sideways, as not to jamb the kerf.
The original blade is a brazed carbide, with no
geometry or surface prep what so ever.
So no wonder the HSS blade (with the springy
holder) works well. I would like to see that
first bit put into his holder and see the results.

--Doozer It's the tool holder that makes the difference. With out the slight give or spring action as so called, once the chatter starts it's difficult to stop, we have all experienced it before. The spring action breaks the vibration. Not a new idea.

JL..............

J Tiers
02-14-2016, 12:01 PM
Rake MAY help, or not, but it does tend to make the re-sharpening almost impossible without "cropping off" a chunck of the blade....

None of the HSS tools I use for parting off have any topside rake at all. If you create good conditions for parting, you will not need it. That's why those "old fashioned" tools never have it. A grind that foilds the chip inwards in a "V" is good though, it helps get rid of the chip.

Close to the chuck, blade dead parallel to the feed, on-center, with some oil. should work. Works much better on 3 phase, of course, because chatter control is possible.

Yes, the flexible tool swings away instead of digging-in. Dig-in is what causes chatter. Normal cutters dig in, swing down until the increasing force is able to break off the chip, then pop back, digging in again even worse, swing down , pop back..... over and over. The spring tool swings AWAY, reducing the chip, so it breaks the cycle, and avoids the chatter.

PStechPaul
02-14-2016, 06:02 PM
Here is a video that clearly shows the spring action during parting:


https://www.youtube.com/watch?v=vB-9P8G7n48

To some extent, this may be what happens if the cutting edge of the tool is placed slightly below center. The cutting force pushes it down along the tangent of the cut, and that positions it further away.

Here is a discussion on parting techniques where this is referred to as a "gooseneck" holder:
http://www.armurerieduroi.com/pages/lathe/lathe_cutting_parting.html

metalmagpie
02-15-2016, 10:13 AM
Here is a video that clearly shows the spring action during parting:


https://www.youtube.com/watch?v=vB-9P8G7n48

To some extent, this may be what happens if the cutting edge of the tool is placed slightly below center. The cutting force pushes it down along the tangent of the cut, and that positions it further away.

Here is a discussion on parting techniques where this is referred to as a "gooseneck" holder:
http://www.armurerieduroi.com/pages/lathe/lathe_cutting_parting.html

Not only is that video shot at an angle where you can't see the tip, the tool isn't even a spring type.

metalbender
02-15-2016, 12:07 PM
Looks like it is a spring type, by the amount of movement. Too much mass in there to flex that much. Details would be seen from the other side of the holder.

brian Rupnow
02-15-2016, 12:31 PM
My two cents worth--My old 10 x 18 lathe gave me fits when parting off. Chatter, broken tools, stalling the machine. Scared me right to death parting off. It had a tall rather skinny top-slide arrangement held in place by two 6 mm bolts which were loosened to turn the top-slide on it's central axis to take an angled cut. My new 12 x 24 lathe is much more robust, and although ultimately the top slide is still held in place by two bolts. they are 12 mm bolts. and the topslide has greater base area to be clamped by those two bolts. My parting off tools are the same.--My parting off issues have gone away completely. I am sure that on the small lathe, the entire topslide and tool-holder were springing, being sucked into the cut, then bouncing back, then being pulled in again until it would pull in, snag the tool, and break it. The new lathe is solid as the rock of Gibralter. That is the only difference.---Brian

EVguru
02-15-2016, 12:39 PM
I run my parting blade upside down and the spindle in reverse. The whole tool post & top-slide assembly then gives spring tool geometry.

A rear toolpost is the same idea.

Carm
02-15-2016, 12:44 PM
I run my parting blade upside down and the spindle in reverse. The whole tool post & top-slide assembly then gives spring tool geometry.

A rear toolpost is the same idea.

You dyslexic mebbe?

plunger
02-15-2016, 12:48 PM
My iscar parting tool with a 2mm blade will cut threw that diameter in 15 seconds flat.

jackary
02-15-2016, 12:53 PM
No spring mounting here
https://www.youtube.com/watch?v=S8HvS13L7MU
Alan

DR
02-15-2016, 12:58 PM
The guy should have the tool closer to the chuck, always part off as close as possible to the chuck or collet. He also shouldn't have that much unsupported bar sticking out the back of his spindle, potentially very dangerous.

I only watched the very first of the video, not enough time for a long video now.

Black_Moons
02-15-2016, 05:25 PM
Just curious... what's the theory behind the springing holder?

I ask because I've often wondered why people complain so much about parting. My piece of junk seems to part without issue, and I've no idea why. It's the cheaper version of the piece of junk Chinese 3:1 machines. I mean, it's got a 16" swing. The whole thing flexes and chatters all over the place, but I can part an inch or so of steel. A bit of chatter at the start, but once it starts cutting, so long as I keep spinning the cross-feed, it keeps going. Maybe it's because my whole lathe is a big spring :)

Now, today, just for fun, I tried to part 3" of mystery steel. That did not go well, but I knew I was pushing it. Way too much stick-out on the parting blade and even the slowest speed was too fast. I was just testing out a modified tool holder; still not happy with it.

David...

Simple. You stick to 1" work and likely close to the chuck. People who have big problems parting usually show them working on 2"+ stock. Bandsaw/hacksaw/anything with a nice tooth set is much better for that thickness.

Parting more then an OD or two away from the chuck is just a recipe for trouble.

Also, Parting more then an inch or two, without widening the groove several times as you work your way down, is just asking for trouble as the chips just love to jam in such a deep parting. Grinding side relief into your parting tool can also really help. (Yes, this means that after sharpening it N times, you have to cut the entire area you side relieved off... but parting blades are cheap compared to stained underwear replacements)

Note, you can part bigger pipe/hollow parts, just make sure the depth your cutting is not more then 1/2 to 1" deep before you widen the groove.

PStechPaul
02-15-2016, 06:57 PM
Here is a video that shows a lot of things that you should not do, and it ends with the carbide tip (from a circular saw blade) breaking off, along with a lot of vibration, runout of the work, and the lathe appearing to be made out of rubber:

https://www.youtube.com/watch?v=DiQNwZifpj4

In his second video, he shows another piece of the saw blade welded to a 3/8" bar, and running upside down in reverse in his mini-lathe:

https://www.youtube.com/watch?v=MAoy6eHYo2Y

Edwin Dirnbeck
02-15-2016, 09:30 PM
EVERY GOOD LATHE HAND HAD ONE IN THE OLD DAYS.
Not so much for parting ,but for holding form tool such as inside and outside radius tools ,before the age of cnc.If you have a 2 inch diameter part sticking out of your chuck 4 inches and no center allowed and you need to put a 1/ 4 in outside corner radius on it. Did this many times .It would squeel like a pig but it would stay put in the chuck.You could then file and polish to finish the part. Edwin Dirnbeck

PStechPaul
03-02-2016, 12:27 AM
Here is a video showing the use of a spring tool holder for threading:


https://youtu.be/rbgJpF1KoEI

And the swarf is edible!

vpt
03-02-2016, 07:43 AM
Like the idea of the paper towel tube over the leadscrew.

Joel
03-02-2016, 10:33 PM
Like the idea of the paper towel tube over the leadscrew.

I use a shower curtain rod cover. Cost a buck, covers as much of the leadscrew as I want and fits tightly so it easily clears the half nut.

vpt
03-03-2016, 07:54 AM
Here is a video showing the use of a spring tool holder for threading:


https://youtu.be/rbgJpF1KoEI

And the swarf is edible!


haha, this was great!

dalesvp
03-03-2016, 11:31 AM
I've been watching this thread with keen interest as I'm in the middle of a difficult parting. Perhaps someone can give me some pointers to make this cut happen easier and safer. I had to make a cut in the stock more than twice as wide as the tool so it would cut one way, turn it over, then cut the other way. Gradually scrapping out the bottom of the cut. The OD of the part is 15". There does not appear to be any way to get a standard cutting tool fitted to this set up. Here are a couple of photos.

http://www.svpwiki.com/imagesDynasphere/IMG_2319.jpghttp://www.svpwiki.com/imagesDynasphere/IMG_2320.jpg

Paul Alciatore
03-03-2016, 02:19 PM
Just wondering, could you cut from the inside?




I've been watching this thread with keen interest as I'm in the middle of a difficult parting. Perhaps someone can give me some pointers to make this cut happen easier and safer. I had to make a cut in the stock more than twice as wide as the tool so it would cut one way, turn it over, then cut the other way. Gradually scrapping out the bottom of the cut. The OD of the part is 15". There does not appear to be any way to get a standard cutting tool fitted to this set up. Here are a couple of photos.

http://www.svpwiki.com/imagesDynasphere/IMG_2319.jpghttp://www.svpwiki.com/imagesDynasphere/IMG_2320.jpg

dalesvp
03-03-2016, 03:18 PM
There's not enough clearance between the jaws and the place where it needs be cut. It is 'cutting' - but it is more like shaving a few thousandths at a time.

PStechPaul
03-03-2016, 04:52 PM
It might be better to do a rough cut with a saw and then finish facing the piece in the lathe. Or maybe clamp the piece on a milling table with a rotab and use a small slitting saw. The finished cylinder looks like it will have rather thin walls and would be easily distorted, so final machining operations might require making an insert from plywood or similar material so it can be gripped. That might also work for parting on the lathe, as the cutting edge pierces the thin wall of the piece.

gzig5
03-03-2016, 05:14 PM
It think that I would fixture a grinder with a cut off wheel to the compound and cut it off that way. The cut will be clean, will put the least amount of stress on the setup, and be least likely to catch and rip the work out of the chuck. Protect the ways with towels and tin foil, of course.

garyhlucas
03-03-2016, 06:27 PM
I think I'm going to throw a piece of steel in the CNC mill and make a cutoff holder with the spring action just to see how it works. Should be a simple job, all done in one setup using one tool.