Rest Machining Question

[richardsalzman]

Below, I have a 1/4" end mill with a 2D adaptive followed by another 2D adaptive with a 3/16" end mill but for some reason there is a small area highlighted in yellow that does not appear to be machined away.  I set the tool diameter for the second 2D adaptive to 1/4".  Any suggestions as to what is wrong?

I also experienced a bit of chatter on the 3/16" end mill.  It is a 1" long end mill so I purchased a shorter one.  I am using feed optimization and wondering if adding multiple depths (like two passes) would this help reduce chatter?

Thanks.... Richard

for 3/16" end mill:

File:  https://a360.co/431F55v

[a.laasW8M6T]

Hi

the Rest machining in 2D adaptive isn't stock aware so it makes a best guess at what stock may be left over from the previous tool. it works OK sometimes but isn't the best

You will get better results using 3d adaptives rest machining

I would select the pockets as a machining boundary for the 3 da adaptive and let it do the work for you

[podging]

1in flute on a 3/16 endmill is on the long side. I'd only be using that for a finish pass when you want a specific aesthetic. Also it needs close to full flute engagement or it will chatter horrendously.

Adaptive toolpaths have effectively a minimum radius that they can do. If you try to use a .1875 endmill to adaptive a .198 dia fillet it will leave extra material on the wall. You can decrease the material remaining by decreasing the Minimum Cutting Radius in the passes tab, but if you decrease it too much it will cause chatter and more wear on the tool.

I usually add 10% to the simulated endmill for rest machining, so instead of .25in, .275in.

3d adaptive will do most of the work for you, but it will also take longer to calculate. 2d adaptive take more effort to learn, but they can be faster to program.

[Laurens-3DTechDraw · Accepted solution]

I'm pretty sure that the issue you are having is because of the Minimum Cutting Radius on the first roughing operation.

Because of that, it will not cut as deeply into the corner as the next operation is expecting. So it would be smart to add the minimum cutting radius*2 to the tool Diameter in the second roughing operation. So you end up with 0.3".

The chatter you experienced may be because it was cutting far too wide initially, as there was more stock still to be machined than the second roughing operation expected. With these updated value's that might already be a lot better.

[richardsalzman]

Thanks for all the nice tips.  I usually use 3D adaptive so I forgot that 2D needs more guidance.   Laurens, I understand that you are saying the first roughing operation did not cut into the corner deep enough, but I do not follow what you meant by:

So it would be smart to add the minimum cutting radius*2 to the tool Diameter in the second roughing operation. So you end up with 0.3".  Where did the .3" figure come from?

Richard

[programming2C78B]

1/4" tool + 2x 0.025 min cut radius

[richardsalzman]

I thought the min cutting radius was supposed to be match that of the previous tool.  Are you saying I need to take the previous tool and add the .025 to give it a bit more clearance so the tool does not go so far into the corner?

[programming2C78B · Accepted solution]

I think you're confused on how this works

you rough a pocket with a 1/4" tool with .025 min cut radius (this really should be smaller)

On your next toolpath, the Tool Diameter in your Rest option should be 0.3 or even higher.  Rest on 2D toolpaths only figures out what inside corners are to be machined.

All of this is avoided if you just use 3D adaptive though....

[richardsalzman]

Thanks... I typically use 2D for simple outside corner geometry and 3d most of the time.  Thanks for the clarification.

Richard 

[richardsalzman]

ok, I swapped the operation for 3d adaptive, but there is an extra tool path at the top.  What is causing this?

[programming2C78B]

Your depth of cut options. Easiest is to set the Top Height -.001 from Model Top. 

[richardsalzman]

Thanks.. I thought of trying that but I thought I was cheating.  I thought I had set something up incorrectly.