How to Mount Parting Tool

With the tool pictured, I can see how one would mount it upside down.

My HSS parting tool is part of the AXA holder and the angle of the tool is built in. And it would point the wrong way, though I could rotate the tool post to fix that, at the cost of putting the tool further away from the chuck. I would also have to remove the height adjustment to mount it upside down...

Just curious if there's a way to try it with my setup. I'm guessing it is better to use my carbide parting tool if I want to do this as it's a normal tool I can just flip over.

If running the tool behind the work, don't you need to run in reverse or upside down?
 
4ssss said:
A lot of the problems in cutting off on a lathe have to do with the speed of the spindle. As you get closer to the center, the speed of the cut increases, so slowing it down helps quite a bit. That's where a VFD is helpful. I normally keep my motor pulley on the faster side, so my slowest spindle RPM I have is around 550 without the back gears. I'll start at that speed, and around 1/2 way thru I'll re-sharpen the tool, and drop the speed down maybe 30 % with the VFD. Adding an angle to the tool (longer at which side of the cut you need to save) allows the cut off part to be held a little longer so you end up with a reasonably burr free part that you cut off.
Click to expand...

Huh? As you approach the center (smaller diameter same time per revolution) the surface speed decreases. For simplicity sake: On a 3in diameter part at 1000 RPM you have a surface speed of about 785.4 SFM. At the same 1000 RPM with a 1in diameter part you have a surface speed of about 261.8 SFM.

(Pi(D") X 1000) / 12 = SFM

If D1 > D2 then SFM1 > SFM2

I'm not great with a lathe so I don't always know how to apply that to the feed for the best cuts, but the math is pretty simple.
 
ttabbal said:
With the tool pictured, I can see how one would mount it upside down.

My HSS parting tool is part of the AXA holder and the angle of the tool is built in. And it would point the wrong way, though I could rotate the tool post to fix that, at the cost of putting the tool further away from the chuck. I would also have to remove the height adjustment to mount it upside down...

Just curious if there's a way to try it with my setup. I'm guessing it is better to use my carbide parting tool if I want to do this as it's a normal tool I can just flip over.

If running the tool behind the work, don't you need to run in reverse or upside down?
Click to expand...

You can make or buy one like this: https://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=31&Itemid=45. I think @ddickey has one and @Ken from ontario made one.

If you rear mount the tool then yes, it has to be mounted upside down and you use it with the lathe running in the normal direction. Unfortunately, most lathes do not have a T-slotted cross slide that would allow you to mount a separate tool holder to the bed of the cross slide. My Sherline and Emco lathes do and a stand-alone parting tool holder mounted to the back side of the cross slide is the way to go on these lathes. It makes parting a routine non-event.

If it is of any interest, I wrote my Sherline tool up here: http://www.machinistblog.com/rear-mounted-parting-tool-holder-for-sherline-lathe/
 
Interesting. Thanks Mike! I do have T-slots on the cross slide, so I could try something like that. Though it would be a lot easier to make with a mill.. :rolleyes:

I did try flipping my carbide parting tool over and run in reverse. It does seem to part smoother in aluminum. That tool limits depth to about 1", but it shows that the idea could work well for an HSS blade as well. Not that I do a lot of parting on thicker material.
 
Bob La Londe said:
Huh? As you approach the center (smaller diameter same time per revolution) the surface speed decreases. For simplicity sake: On a 3in diameter part at 1000 RPM you have a surface speed of about 785.4 SFM. At the same 1000 RPM with a 1in diameter part you have a surface speed of about 261.8 SFM.

(Pi(D") X 1000) / 12 = SFM

If D1 > D2 then SFM1 > SFM2

I'm not great with a lathe so I don't always know how to apply that to the feed for the best cuts, but the math is pretty simple.
Click to expand...


Agreed, I have my VFD set up with a slider potentiometer on the cross slide to increase the RPM as it approaches centre - right at the centre it should be infinite, but my lathe will only go up to 2500 :(

It parts just fine with power feed and either HSS or inserted-carbide tools, but it's a heavy, rigid lathe*, and the "near constant" surface speed makes facing a lot better, more consistent surface finish, and turning different diameters is quicker not having speed changes.

Dave H. (the other one)

*13x30 but well over 4000 pounds
 
ttabbal said:
Interesting. Thanks Mike! I do have T-slots on the cross slide, so I could try something like that. Though it would be a lot easier to make with a mill.. :rolleyes:

I did try flipping my carbide parting tool over and run in reverse. It does seem to part smoother in aluminum. That tool limits depth to about 1", but it shows that the idea could work well for an HSS blade as well. Not that I do a lot of parting on thicker material.
Click to expand...

I meant T-slots that run the length of the cross slide like this. It makes mounting accessory tool posts simple:

3-494.jpg


Have a good look at that ForR parting tool holder. You can make that with your milling attachment and a drill press. Or buy it - not that expensive.
 
ddickey said:
I have pics if you want them of the FoR holder and the one I made.
Click to expand...

I would like to see what you have. It is always helpful to see what people have done.
 
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