Corner rounding end mill problems

[Franke]

I am a vet who has taken on a new job as a design programmer using Fusion 360. I work at a small shop with about 25 Haas mills and lathes. It is a "learn as you go" situation. I am not a machinist or programmer by training.

I am trying to put a radius on a square block about 8" long which I have in a vise and must turn four times. I must put a radius on each arris of the block. All of the toolpaths seem to be working but my corner rounding end mill has been a nightmare. I have been fooling with the pilot diameters and height offsets for days. When I get the tool correct for coming down one face then when it turns the corner to go round the end and down the other face the pilot gouges the material at the point of tangency perpendicular to the vertical face. It looks good along one face but is completely wrong for the opposite face in the same plane. This happens even when I use a dedicated tool model for each face of my part/turn of the stock in the vise.

I am desperate for a solution. Any help will be warmly appreciated.

 

[kustomizer]

I would likely finger cam a part like that in the first place just to keep in practice but I am the odd one out here.

 

[gustafson]

Milling the entire outline first, right?
Sounds like an offset/part size problem rather than a tool diameter problem

 

[nihilistic]

What do you mean you have to turn it four times? Is the part too big for the mill or something?

 

[edwin dirnbeck]

Please give the length ,width and heigth of the block.How is the block being machined to size AND squared up and what are the tolerances? Do you have a good solid end stop when you reposition your block? .003 or.004 size difference and a few thousands out of square can easily add up and cause gouging. Edwin Dirnbeck

 

[gustafson]

If you are corner rounding all 12 edges with corner rounding EM, it would take 4 setups. Top Bottom Left Right. One would usually interpolate the sides to avoid excess handling

 

[Mtndew]

I have been fooling with the pilot diameters and height offsets for days.

Why? There is only 1 pilot diameter and 1 height offset.

A) is the block already milled to the correct length and width? I assume yes but you never know.
B) Are you hand programming this or using Cad/Cam software?
C) Are you using Cutter Comp? If so, program the tool for the diameter that the pilot is and comp accordingly. Z Zero can either be the end of the tool or the end of the radius, your preference.

 

[Mtndew]

It looks good along one face but is completely wrong for the opposite face in the same plane.

My first thought is that your datum isn't set the same as what you programmed it to be.

 

[Franke]

What do you mean you have to turn it four times? Is the part too big for the mill or something?

I am actually qualifying four faces before putting down other toolpaths. When I get a properly sized 1.98"X1.98"X8.00" piece I then do some contouring. The last thing I do on each face is put the radii on. So my actual piece is more complex than my initial description. I actually turn it eight times in the vise. But the only problem I am having is with that corner rounding end mill.

 

[Franke]

My first thought is that your datum isn't set the same as what you programmed it to be.

I am using a fixed datum in the work envelope that I have modeled in Fusion. Then I am using the WIPS system and the Renishaw probing templates with the WCS override function in Fusion to transfer my static datum at the corner of the fixed jaw of the vise to populate the cells in the work offset registry for each subsequent WCS.

I suppose there could be an issue with the Renishaw macros or some calibration issues with the stylus of the spindle probe. But I set the job up carefully and adjusted the stylus until there was no runout when I spun it.

Any ideas would be helpful. I have been at this for less than a year and am not an experienced machinist.

 

[Franke]

Why? There is only 1 pilot diameter and 1 height offset.

A) is the block already milled to the correct length and width? I assume yes but you never know.
B) Are you hand programming this or using Cad/Cam software?
C) Are you using Cutter Comp? If so, program the tool for the diameter that the pilot is and comp accordingly. Z Zero can either be the end of the tool or the end of the radius, your preference.

M.
Adjusting the pilot diameter of my modeled tool is the only way I know to pick up the point of tangency perpendicular to the spindle axis. Adjusting the height offsets is the only way I know to pick up the point of tangency in Y. As I am running the tool around the entire part, once I get these correct for the first side I expect that it should not change as my tool goes around the part ... as long as the tool stays in a fixed plane. But, sadly, as I turn the corner and come around the end of the part the tool plows into the material as it comes down the side parallel to the side it was adjusted for. The tool does not seem to work for the edge in the same axis and plane of the one where it was previously working well.

 

[Franke]

What do you mean you have to turn it four times? Is the part too big for the mill or something?

Turn it in the vise. I dont have multi-axis machines.

 

[Franke]

Please give the length ,width and heigth of the block.How is the block being machined to size AND squared up and what are the tolerances? Do you have a good solid end stop when you reposition your block? .003 or.004 size difference and a few thousands out of square can easily add up and cause gouging. Edwin Dirnbeck

E.
The piece prints out at 1.98X1.98X7.812" with .xxx +/- .005. The end stop is solid. I use a shell mill to take it down from initial 2.000" stock by turning four times. Once it is a rectangle I turn it four more times in the vise and contour, drill tap etc. The last toolpath on every face is the CREM. I take it around the entire part. But it will be fine on one arris and when it turns around the end it gouges.

Can't think what to do ....

 

[MCritchley]

Cheat the tool up and away from the face a few thou. Don’t try to get it perfect, whats the tolerance on the radii?
Also use a flared corner rounding endmill from Harvey tool. I use 6 different sizes each with a .107 pilot diameter. Easy to get right on the first try.

 

[edwin dirnbeck]

E.
The piece prints out at 1.98X1.98X7.812" with .xxx +/- .005. The end stop is solid. I use a shell mill to take it down from initial 2.000" stock by turning four times. Once it is a rectangle I turn it four more times in the vise and contour, drill tap etc. The last toolpath on every face is the CREM. I take it around the entire part. But it will be fine on one arris and when it turns around the end it gouges.

Can't think what to do ....

What is arris? what is CREM? Edwin Dirnbeck

 

[edwin dirnbeck]

It sounds like the only side that comes out "perfect" is the side that is up against the fixed vise jaw.If this is true,then your problem might be tolerance build up. Edwin Dirnbeck

 

[edwin dirnbeck]

I didnt get

I would likely finger cam a part like that in the first place just to keep in practice but I am the odd one out here.

Yes ,I didnt catch the FINGER CAM right away.If the problem is consistent ,why not just change the x or y or z values ? I am used to working with old junky machines,that seldom do what they are suposed to do. Edwin Dirnbeck

 

[nihilistic]

What is arris? what is CREM? Edwin Dirnbeck

Corner Rounding End Mill. I dont know what arris means I think it might be some kind of obscure circle geometry reference.

I feel like there may be something in his programming that he isnt modeling right or his work offsets arent correct. I can't really tell because we dont know what the final shape is supposed to be. If its just an edge break then really he could just run a single line and move in in manually and do each edge independently if he cant figure out the CAM. If there is a radius then just program a radius with lead ins/outs and move it in until it hits. That would be the get it done, figure it out later method.

OP have you tried drawing the endmill and loading it as a custom tool then generating your cam?

 

[Nerdlinger]

can you 1) post the code and tell us 2) the pilot diameter and 3) corner radius of your corner rounding mill?

Assuming you are trying to get the full radius of the cutter your cut depth should be equal to the corner radius of the cutter and your code should be making a rectangle equal to the size of your block with the value of your cutter diameter in your offset page equal to the pilot diameter of your tool. Does that make sense?

 

[Larry Dickman]

I think arris is fat finger for axis.
I'm not following what the problem is. It's not April 1st is it?