Dynamic Area Mill Toolpath

[Bill H]

I have a arc-shaped slot that I want to machine with trochoidal motion, so I'm  trying to use a Dynamic Area Mill toolpath.  The slot is 0.38" wide and I'm using a 0.25" endmill.  I've tried every combination of parameters I can think of, but MC won't generate trochoidal loops - only arcs parallel to the slot's walls.  What am I doing wrong?

[jlw™]

Upload a file?

 

I'd probably use plain old dynamic mill instead of a surface path.

[Micromoldmaker]

 

What am I doing wrong?

Just a guess: maybe use a smaller tool as your .25 em doesn't have the room to dance.

[shazam/TPP]

what version of Mastercam? have you tried peel mill? X9 offers dynamic peel and the old version of peel and try to reduce your min toolpath radius, and bare minimum on your stock to leave on walls. hth

 

ps. since your end mill size is so close to the slot width, change your back feedrate to be the same as your initial feed also

have zero micro lift

[Colin Gilchrist]

As others have mentioned, your endmill is simply too big for the slot you are cutting, to be used effectively with "Dynamic" or "Trochodial" style motion. The reason is that the tool needs room to swing both and entry, and an exit arc.

 

Try using a .1875 or .125 endmill. (Believe it or not, the smaller .125 endmill is better suited to the task.) Dynamic or Trochodial style motion is most efficient at 2:1 depth to diameter ratio, or greater. You need to take advantage of the flute length. I see a lot of people trying to use "HSM" machining techniques, but using the same depth of cut values they are used to using for "normal" full immersion roughing.

 

For me, one of the goals of applying HSM techniques like this is to reduce the number of depth cuts needed. We get this result by using smaller diameter tools, with longer flute lengths.

 

I find that the limit of the tool and path is found around 4:1, depth to diameter. So beyond that ratio, you really have to slow the paths down due to deflection.

 

Try using a .1875 diameter tool, setting the "Corner rounding radius" to "3%", and the stepover to "10%". Set your Stock to Leave to ".005". That should work, even with the .25 endmill.

 

My guess is that your Entry motion is just trying to "ramp" the whole thing, so you don't see any "dynamic" style motion. Look at your entry parameters. Try using a "Helix", set your helix radius to .002, and that should show you where the issue lies. (the "Dynamic" path will try and plunge somewhere near the center of the slot, not at one end).

 

As others have said, try 2D HST > Peel mill.

[Bill H]

Thanks, everyone, for the helpful suggestions.  It was the entry parameters that were causing the problem - the helix was too big.

 

Another question:  How can I control the point at which the entry helix is located?

[jlw™]

When selecting geo, click on point then pick your start point, then go back to chain and pick your chain. Then if you want an exit point pick another point after finished chaining.

[Bill H]

jlw - Perfect.  Thank you!

[CJep]

Thanks, everyone, for the helpful suggestions. It was the entry parameters that were causing the problem - the helix was too big.

 

Another question: How can I control the point at which the entry helix is located?

Don't use helix, create a arc segment in the center of the slot that follows the shape of the slot geom. Switch entry over to custom entry chain and select. The tpath will ramp in following the chain geom and you can adjust the width of the slot it will cut while ramping to depth.