Lathe Dynamic Rough/Chip Thinning Calc

[champshire]

I have been kicking around playing with a new tool path that I have never used before in the Lathe Suite. Dynamic Rough. I understand the concept, it's HF Milling but for lathe. I want to try it, and even have tools and inserts here to make it work (I think, famous last words). I want to plug in feeds/speeds/doc and compare it with traditional grooving in this case. I would hope it would be faster but I want to see proof of concept before cutting chips.

My hold up is how to figure feed/speeds. I know I would be thinning the chip, so I can increase feed. Is there a calculator online that I can use to figure this out?

I also have a milling project where I want to try the same type of thing, using a copy mill as a HF mill. I would need to figure out the proper chip load for that as well.

Thanks in advance guys!

Do you guys have any suggestions on what to use to calculate this? In the past, with dynamic, I just click the little check box for RCTF and life is good. I don't have that option in this case.

[neurosis]

I see nobody has responded to this one.  Have you talked to the tool mfg?  I would imagine that they could help?

I would assume that it's the same formula used for button mills but not being a lathe guy, I'm just guessing on that. 

[gcode]

I tried these toolpaths using a Ø.750 button tool on big VTLs.
The operation was a deep irregularly contoured facing profile.
The toolpath ran really well, ripping the metal out, using one tool
to do what took a left and right hand DNMG to do old school and it was super easy to program.
I had to drive it really hard to break the chips though.
The tool and the machine were OK with that, but my experiment was a failure.
The tool squealed too loudly.
You're thinking, what a bunch of pussies, use some hearing protection.
That was not enough.  150 yards away at the other end of the building
it was loud enough to be painful. Standing near the machine, it was simply
too much to be endured no matter what kind of hearing protection you used.
I don't know how many decibels it was, but I have no doubts it exceeded OSHA's
limits for a workplace.
 
 

[mkd]

i worked at a place where a guy was going at it on a VTL with a 3/4" trigon in a gcode=scale part.
 Taking a 400+ sfm at .022 in/rev at .700" per side the noise was deafening yet the chips were flowing like a garden hose.
 That was the last part that lathe transmission ran  

[champshire]

Thanks for the feedback guys. I'm going to look pretty hard at trying this. I already have the inserts and holders here. My Sandvik tech guy will be in tomorrow, so I will sit him down and dive in.

In my head, HF Turning has to be faster and have better chip control (I battle chips using a square groover) than just a standard grooving tool path.

You never learn if you don't try something new!

[gcode]

The toolpaths are great
My experiment failed because the button cutter had to be over a foot long to clear all the features in the part.
Once we had the feeds and speed running hard enough to break the chips the tool was buzzing like
a tuning fork.
It's possible I could have designed and welded up a more rigid holder, but the first try was so painful
all cooperation and interest in my experiment were gone.

[__]

The toolpaths are great
My experiment failed because the button cutter had to be over a foot long to clear all the features in the part.
Once we had the feeds and speed running hard enough to break the chips the tool was buzzing like
a tuning fork.
It's possible I could have designed and welded up a more rigid holder, but the first try was so painful
all cooperation and interest in my experiment were gone.

That's a common problem with those button cutters, they generate far too much vibration and noise, I saw a programmer trying to plunge with one on a 6 ft diameter part, the vibration snapped the 2 inch holder clean off.

We went with a left and a right hand tool after that, to use something like a button cutter, I think some kind of a custom tool with an insert on the left and right and a void in the middle would work better or a small button cutter, the large contact width/area is the issue with those tools.

Reducing your rpm could reduce the vibration, but that can increase the load/pressure on the tool as well. It's challenging to account for the vibration caused by additional stickout..

[champshire]

Update: Worked with my Sandvik vendor and we figured feed/speed/doc. Looks like, for the area I am cutting, it will be slower to dynamic by about 90 seconds per Mastercam. I may try it anyways, in hopes of better chip control.