[How do I?] How do lathe tools not hit on the back side of tool?

A

awaqa909

Registered
Registered
Joined
Jan 28, 2017
Messages
52
I'm asking more for CNC... The machine knows the X and Z of the tool, but how would I tell it to z down on this back side of this example part? I'm sure this drawling has errors... No idea if those angles are actually 45 deg. We have VNMG 331 (.016) and DNMG 432 inserts. I'm thinking I would tell the machine to drop down after the radious of the tool? I'm trying to learn conversational and don't know any really G-code atm...

290769
 
On the presumption I understand what you are doing...
I use a manual lathe at home, but understand mainly how a CNC generator might go after this.
It looks like you are making something akin to a knob, just not with rounded corners.
YouTube here looks similar, but rounded

For this you would use a straight on tool, which with a several passes will create this profile. The back relief is the most important feature. The strategy is multiple paths to remove most of what you don't want until you can make the "money" pass that is he final contour.
 
I haven't done any CNC lathe work but on the CNC mill, the CAM program knows the profile of the tool and tool holder and the geometry of any fixturing. It has a rule to avoid any interference with the part or fixturing when it generates the G code.

On a lathe, I could see this as being more complicated as the tool and tool holder can be oriented at various angles and the CAM program would have to know the non-cutting geometry as well but presumably it would function in the same way
 
I would say that it depends on your CAM software. Some will probably warn about this, some will leave it up to you to ensure the tool doesn't crash. You could do an air cut or try it on something soft to ensure it isn't going to crash before you cut your stock.
 
Manually jog it around your cuts and keep track of the coordinates. That will determine the limits of your rapid moves.
 
This is the way I would make this part. I think the angles are 45°, missing a dimension to get the front one, but it looks correct.

Flip it over and do the bulk of the work on the front for tool clearance and strength of the part. Then part off.

290796

1553016939793.png
 
Last edited:
JimDawson said:
Flip it over and do the bulk of the work on the front for tool clearance and strength of the part. Then part off.
Click to expand...

That would be especially handy if it happened to need a threaded hole in that end of it. Parts that look like that often do.

Tool shapes must be entered in my cnc lathe so the control knows what it's working with. If I remember it's a 1,2,3 or 4. Right, left, centered and ?
I don't even remember.
Aslo nose radius entries.... maybe that was the 1234 .. Once done it's not needed as long as I leave the tool there and my lathe has 2 turrets so 14
tool spots. So nothing I have to mess with very often. If I do need to ....out comes the books.
Once those things are done then offsets are done.
 
Just out of curiosity, why are you not using CAD/CAM to write the G code? I use Fusion 360 for the lathe.

The other option would to run is as shown in your drawing then use the parting tool to cut a series of overlapping ''grooves'' on the 0.5 portion. A very efficient method of removing material on a CNC lathe.
 
Conversational should have canned cycles . Face and turn the front end and angle . Part the .500 diameter to 1/2 " width or so and leave .010 for finishing . Use a reverse profileing tool to do the back angle , then your other profile bar has room to finish the .500 diameter .

You are going to have different tool attack numbers as well has both tool nose radius comps .

If that back angle is not critical , just run a contour cycle with a profile bar and tweak the beginning of the back champher to suit . The G41 wouldn't pick this dimension up .

Run a dry run if you can or you may even have a graphics page . Not sure .
 
tcarrington, this is a great example of what I'm trying to figure out.
JimDawson, that looks good. What program is that?
It looks like I forgot to mention that this part was more of a example and something that I might try to machine if I can ever get to that part.

I've got a hobby license for Fusion 360, have only started the program a few times and haven't learned the basics. Work has Mastercam, but someone it kinda learning to use it from what I hear. I was thinking learning to program the machine at the machine would be a better way for me to get my foot in the door and maybe move up to CAD/CAM. I've been wanting to climb the ladder but have been slow to do so.

I finally started learning the Mitsubishi lathe, with NAVI conversational and am having quite the difficulty. I don't understand the "pattern" and am struggling with tool data,(it's actually very minimal, but I can't figure out the angle of the back of the insert "back relief"? for the tooling that we have, so I thought I would just learn G-code, but I think I will still have issues with tool data..or I would have to compensate in the G-code itself, though trial and error.(I know very minimal G-code)
 
You must log in or register to reply here.
Back
Top