Pencil cut, partial area

[Thee Rickster ™]

This 'bugs' me.

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I finished with a 1/4" ball, and Waterline rest with 1/8" ball.

 

The rads on the part are .08" to .1"

The waterline rest cuts does its job properly, cuts everywhere it should.

 

The pencil cut skips key areas that I need to machine.

 

Does anybody know how to force MC to pencil cut where its supposed to?

 

Any help will be greatly appreciated.

 

Rick

[peon]

I see that on occasion too Rick and it sucks!! Did you add a value in the "overthickness" box? If not, plug some numbers in there and see what happens.

[Thee Rickster ™]

Always do, and tried different integers like always to see if it will take.

.005, then.010, then .015then, .02, then gave up.

 

My standard is always .01"

 

Well I got surface finish leftover to work with tons of retracts but at least it did not

miss areas....I got scallop rest to work also now I just have to worry about

cutter deflection now as i cant get it to climb mill in the

direction that i need and control like pencil does. ...dang

[peon]

Try a bitangency angle of 179. and see what it does. May or may not help.

[Nils N]

Maybe a bit more set up but how about trying 'blend' to finish the radius's. I use it a lot because I don't like the tool paths I get with pencil or left over.

[Thee Rickster ™]

it took 10 times longer to crunch and still missed 15 % of the areas to cut.

better but in no way acceptable

[Thee Rickster ™]

Nils, i don't think i have the time or energy to figure out how to

use blend over an entire mold base.

 

Thanks all, but I had to move on.

[MotorCityMinion]

Rick, you can get scallop to work in climb only by increasing the the surface area to be machined, lets say by 110%, either direction inward or outward, using boundaries. Then trim the tool path to the areas you want to cut. I trim it just a little bigger than what I need to overlap and get a decent blend. You can also create some dummy surfaces to include in the tool path to help out. This method can also smooth out some of the spikes (sharp moves) that usually arise in a scallop path.

 

SF Blend can easily be confined to small areas and works well with depth limits. This is one of the older tool paths that will do what the HST won't.

 

 

[Thee Rickster ™]

It would take an hour to segregate the boundary areas to trim my paths.

 

You shouldnt have to spend that much time getting a workaround path for the bugged one.

 

when pencil works, it does it perfectly even on 10 x more difficult geometry then

i am using today. when it decides not to work i try

'surface finish left over' and 'scallop rest' and see which of the two is closest to the pencil.

 

usually its the rest paths that error and the pencil works...go figure

[Scott Lundin Shopware Inc.]

Playing with overthickness and bitagency settings in the pencil path as mentioned usually takes care of it. However I have seen where surface finish pencil just wont do certain spots. In these cases I have switched to the HST pencil path and for some reason it has created complete tool path. Not sure why.

[heavychevy2155]

Can you suppress the hole or fill it, you have the 2 Radii together there and it may be throwing it off. Just a thought.

[?Mark]

Try plugging in 1/2 of your tool's diameter in overthickness field....

hth

[Thee Rickster ™]

Hi all, been too busy to check this thread out.

 

I tried all the ideas and the winner goes to Mark @ PPG.

1/2 the diameter in the over thickness fixed it.

 

May be it is the difference between the fillet size and the rad of the cutter.

Left over worked and scallop rest worked, they obviously must calculated the path

differently.

 

Thanks for all the ideas!

:old forum cheers: