Ramping moves for rounding wizard?

[myxpykalix]

In the indexer tools for rounding a blank I put the following info:


8544

I'm using a 1/2" straight flute endmill and for some reason when it plunges down it feels like it is going to jam up and stop. It's even hard enough that it loosened the piece in the chuck.
and based on what i input its only going down 1/8th inch.
Is there any way to ramp that first cut down? Once it gets going its fine. I have tried it at speeds of 13,000 to 21,000 with similar results. My Z speed is .50

[bill.young]

John,

The first move the flattening routine makes is a ramping move... it lowers from the safeZ height to the cut depth as it spins one revolution and then turns another revolution at that depth so that it's a consistent depth.

MZ, 1.25
MY,0
M5,,0,0.9375,,360
MB,720

Are you starting with a 1" radius round blank, or is it a square blank so that the 1" measurement is from the center to the flat side? If it's a square blank then it's really 1.41" from the center to the corners and that should be your rough radius setting. You are actually cutting almost a 1/2" deep in your first pass when it spins down to cut depth.

There are lots of options..here are some:

*) The best way is to change the rough radius to 1.41 and the Bit stepdown to something larger than your current setting. If you change the bit stepdown to .3 or so then it will make partial-depth passes that will cut the corners off (at twice the Finish Pass bit Stepover to speed things up), and then round the blank at the final depth

*) You could edit the plunge part of your file so that it plunges in several spins. You'll also need to change the MZ move because your safez is calculated above your rough radius and your rough radius value is wrong. Maybe something like this which does it in 3 spins:

MZ, 1.75
MY,0
M5,,0,0.9375,,1080
MB,1440

*) create a file that cuts the points of the square off on the Indexer before turning. It would basically have to:

1) Zero the B-axis with one of the flat sides facing up.
2) Turn 45 degrees
3) Plunge the Z-axis to a safe cutting depth
4) cut along the blank from one end to the other. You may have to do a couple of passes wide to cut off the corner
5) rotate 90 degrees and repeat. Continue 'til all the corners are cut off.

Then round the blank normally with the Virtual tool

*) Cut the corners off your blanks before putting them on the Indexer so that they are 8-sided and then set the rough radius to the new "largest radius" which is down to 1.08" for an octagonal blank

*) You could try slowing the indexer move speed down, but it's still a big bite. Might work, might not..

Bill

p.s. The tooltip that appears for the Rough Radius text box explains how to set it for a square blank.

[myxpykalix]

Bill,
I had not thought about the real depth when it hit the corners like you explained. Using your example "If it's a square blank then it's really 1.41" then how would be the best way to calculate different size radius's using that theory? (say if i had a 2" or 3" blank)?
What i measure is a square blank from center to flat side.
Should i measure from opposite corners diagonally ,divide and use that as my radius?