Author Topic: Gang Parting Tool For The Lathe  (Read 940 times)

Offline gtermini

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Gang Parting Tool For The Lathe
« on: May 26, 2017, 11:49:56 AM »
I routinely make loads of these 2 3/8 X .2 thick Teflon discs for a cushion in a concrete sample moisture extraction press. They are nothing critical, and are time consuming to part off one at a time. I could do about 60 an hour with set up and turning the rough bar stock to size. I had some time before the next batch need to go out, so I invested some effort in a tool to cut four at a time. Teflon is soft and expensive, so I was shooting for minimum kerf. The blades are 1/2 x 1/16 set about 3/16 staggered so the discs part off in order from the end. I still need to blunt the tops of the blades back from the cutting edge so the quit rubbing and cutting where they're not supposed to. A cnc lathe could still whip my ass on this job, but for my current situation, this is way quicker than before.

I had measured up a toolholder in the past, so I milled a dovetail in a block to drop on the toolpost so I wouldn't have to screw with center height everytime. The clamp plates were layed out in autocad to get the spacing correct, They have four 1/4 NF clamp screws and two 1/4 dowel pins to keep the straight.





Greyson

Offline slip knot

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Re: Gang Parting Tool For The Lathe
« Reply #1 on: May 26, 2017, 05:39:02 PM »
pretty sweet. Teflon comes with its own cutting lube too. lolx
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Offline rvannatta

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Re: Gang Parting Tool For The Lathe
« Reply #2 on: May 26, 2017, 10:40:44 PM »
I routinely make loads of these 2 3/8 X .2 thick Teflon discs for a cushion in a concrete sample moisture extraction press. They are nothing critical, and are time consuming to part off one at a time. I could do about 60 an hour with set up and turning the rough bar stock to size. I had some time before the next batch need to go out, so I invested some effort in a tool to cut four at a time. Teflon is soft and expensive, so I was shooting for minimum kerf. The blades are 1/2 x 1/16 set about 3/16 staggered so the discs part off in order from the end. I still need to blunt the tops of the blades back from the cutting edge so the quit rubbing and cutting where they're not supposed to. A cnc lathe could still whip my ass on this job, but for my current situation, this is way quicker than before.

I had measured up a toolholder in the past, so I milled a dovetail in a block to drop on the toolpost so I wouldn't have to screw with center height everytime. The clamp plates were layed out in autocad to get the spacing correct, They have four 1/4 NF clamp screws and two 1/4 dowel pins to keep the straight.

 

 

Greyson


Instead of using  a parting tool,  have you considered making a multi-bladed  hack saw---   consisting of  several  traditional hack saw blade bolted together with machine screws  (with the blades
spaced with washers.     Hack saws cut  very very straight  when your work in in a  lathe rotating fairly slowly.    I will even  take my power hacksaw and  chain it to the carriage of my big lathe
when I need to cut things exceptionally square.   a hack saw can't go crooked if what you are cutting is rotating.     I suggest the hacksaw as the kerf is even less than the parting tool.

Offline DeadNutz

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Re: Gang Parting Tool For The Lathe
« Reply #3 on: May 27, 2017, 12:57:05 AM »
Nice parting tool. I used to part off lots of urethane for tooling and some cut like butter while different durometers would give me fits. I have never used hacksaw blades on the lathe but I did have to stop guys from dressing turning parts with a file that had no handle on it.

Offline gtermini

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Re: Gang Parting Tool For The Lathe
« Reply #4 on: May 27, 2017, 01:03:43 PM »
Nice parting tool. I used to part off lots of urethane for tooling and some cut like butter while different durometers would give me fits. I have never used hacksaw blades on the lathe but I did have to stop guys from dressing turning parts with a file that had no handle on it.

A file with no handle on the lathe is right up there with leaving the key in the chuck.

Hacksaws are hell on lathes too. My old South Bend 9 at home has a few scars under the chuck from somebody cutting parts off with a hacksaw and plowing away right into the front way.

The hacksaw blade idea has the gears in my brain turning. That particular big Monarch doesn't have reverse on the spindle, so the blades would have to be hung from above the work to drag cut and not dig in. I'm parting these at 700 rpm and about a 2 thou cross feed and the discs get warm and swell almost enough to bind. I would think the hacksaw blades would need to be held in tension to keep everything straight.

Greyson

Offline rvannatta

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Re: Gang Parting Tool For The Lathe
« Reply #5 on: May 28, 2017, 12:50:10 AM »
Nice parting tool. I used to part off lots of urethane for tooling and some cut like butter while different durometers would give me fits. I have never used hacksaw blades on the lathe but I did have to stop guys from dressing turning parts with a file that had no handle on it.


A file with no handle on the lathe is right up there with leaving the key in the chuck.

Hacksaws are hell on lathes too. My old South Bend 9 at home has a few scars under the chuck from somebody cutting parts off with a hacksaw and plowing away right into the front way.

The hacksaw blade idea has the gears in my brain turning. That particular big Monarch doesn't have reverse on the spindle, so the blades would have to be hung from above the work to drag cut and not dig in. I'm parting these at 700 rpm and about a 2 thou cross feed and the discs get warm and swell almost enough to bind. I would think the hacksaw blades would need to be held in tension to keep everything straight.

Greyson


I get reverse in my bit lathes because they have old pick up transmissions in the gear reductions.

I wasn't sugggesting   a saw with no handles.    I would make a way to hold it.

What I've usually done to cut things is to use a power hack saw  (band saw actually)     we have a light duty one that I can chain to the carriage with a couple of chains an binders
My solution has been if the cutting direction ended up the same as the rotation of the lathe    (which depends on which way you put the power hacksaw in.)   I either run the headstock
in reverse or other times,  -I put the rotation  of the lathe deep in the backgears..... and let them go the same direction...--- the saw speed with greatly overrun the rotation speed
so it all happens.   You do need to manage the  saw pressure to keep things straight


RE"   screwing up the bed with  stray saw cuts:

                I manage incidental damage to the lathe bed with    "Lathe boards"


I regularly  put a bunch of these in position around the lathe  so if something falls or drops it won't ding the bed.

Similarly when  I'm changing chucks,   I prefer positive control over the chuck,  and use a chuck hanger with a rotating bushing on the end which I can clamp in the chuck.
as I have a threaded spindle,   as I have a hard time just grabbing up a chuck and screwing it on the headstock without some help.

Latheboards in use as a safety device





Here's a very small power hacksaw cutting   a driveline to length.







Offline pepi

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Re: Gang Parting Tool For The Lathe
« Reply #6 on: May 28, 2017, 06:52:41 AM »
Good idea

Greg
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Re: Gang Parting Tool For The Lathe
« Reply #6 on: May 28, 2017, 06:52:41 AM »