on topic (imagine that)

Today I switched on high speed rapids in the cam, it basically adds radius's to the rapids...but it chokes. It chokes because it tries to
position itself exactly at every point thats a rapid. Starts, moves to the next point, stops, starts, moves to the next point, stops, starts... etc.. etc... etc... Around an arc.... thats a lot of start and stop points. The machine has no optimization for rapids. Seems most machines don't. So, seems the preffered way is to program rapids as feedrates. All cam systems have that option. So I programmed the feedrate for rapids to the actual rapid feedrate, and even without the high speed radius added, it rapids faster. It doesnt stop and start like rapids point to point. Seems more continuous.
Big improvement.
***************
Next note: CNC look ahead vs PC look ahead.... Machines today have lookahead for corner control. This way they will slow down in corners, etc... The problem with this is the lookahead values on machines are usually short. Lets say they look ahead 20 blocks. Sounds like a lot... But cut a football on a cnc, set the tolerance to .0001, and you will get 100 blocks of code in .005 of an inch of cut. That means the machine will start to slow down .005 away, or a lot less actually, and still bang in the corner...not as bad, but it will still bang. The computer on the other hand can be set to infinate lookahead. Output feedrates to slow corners by up to 50%. This way it will start to slow down when its best for the corner since the computer knows about the corner at the beginning of the program, not 20 blocks away or less like the machine.
***********
Next note:
(nevermind, the wife just walked in with my six pack! SeeYa'll)
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And that cam would be?

And that machine & control would be?

why settle for a six pack when you can have a keg?
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wrote:

And that cam would be?
cough...cimi(a)tron

And that machine & control would be?
creative... weird azz machine

why settle for a six pack when you can have a keg?
because I know my limits lol
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On 7/17/2010 8:55 PM, vinny wrote:

Creative Evolution? Like these guys? http://www.geonicsinc.com / AWESOME control IMHO. Ran several retrofitted machines back in the mid to late 90s with Creative retrofits.
The owners (George and Todd) are AWESOME folks!
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It's the spindle housing warming up and growing away from the column. Same reason the Z moves.
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