On Saturday, June 02, 2012 06:55:30 AM John Thornton did opine: > I just pulled that feed rate out of my ear, assuming if you actually > tried to cut you would replace it with a feed rate that worked for you. > > John
The 45 I made had very poor quadrature, but the bits I ordered from MCT arrived when it was about 1/2 done and that generated some nice straight slots. I had ordered a 5 pack of 1mm's and a 5 pack of 1/32 (0.3125"). I had a 53% duty cycle with the 45. So I set up, using the backplot, adjusting that code's slot count until I had what looked should be good quadrature and adjusted the slot lengths so that a straight line Y move of .400" from the X centered on a slot about 3 down from the index, passed thru the center of the index slot, and .800" up from the starting point was sitting about 1/4 of a blank below the slot 3 up from the index. That turned out to be 50 slots. With the much stiffer pcb mills, and with the difficulty in centering this .018" thick alu on the spindle tail, I will cut the next one at 50 slots, from the brass plate as its thick enough to ride the top of that thread in the spindle & stay centered much better. It turns out that with the opto's in a straight line mount, on .4" centers, the slot lengths for the AB circle are about .020" less if the slot is to pass the center of it over the opto's as I had, with the longer slots, to set the opto's inward in order to get the AB ring out of the index channel. This was putting the AB opto's at the inward, and more distorted from bit flex ends of the AB slots. So I'll put a 1/32 mill in when I go out today, put the heavier brass under the bit & give that a shot. If encoder mode 0 doesn't work, I can always go back to mode 1. I am thinking part of my instability is the storage effect of the 10 uf filter on the output stage of Arturo's C41 interface screwing with the correction rates, so that will get swapped for a .1 uf mylar before I give up and goto mode 1 again. I am not at all happy with the encoders velocity output characteristics, one of the instability items is that at low speeds, it doesn't output anything at under 2 or 3 rps! Then it kicks in and bangs the hell out of things, regardless of what I set the min-velocity pin to, including down to .125 last night. .125 is well below the minimum speed I get just by clicking the fwd button, that is about .5 rps. IMO I ought to get a valid but low velocity reading from it just by rocking the chuck by hand but I don't. > On 6/1/2012 5:44 PM, gene heskett wrote: > > John T.: I did a short pass with your code, cutting 2 slots. Feed > > way too fast, the slots were badly S shaped from bit flex. It sure > > looked like a good idea though. Thanks. > > > > Running a .7" feedrate, it is gradually straightening out the bottoms > > of the slots. I also went down to a 45 cycle wheel with the > > narrowest slot for the one under construction now, but my calipers > > are telling me I'll have to pull the opto's together by at least 50 > > thou to get good quadrature. Dunno if I can bend then that far or > > not. We'll see when this one is done. I'll see what the duty cycle > > is as I'd druther go up than down. I couldn't pull them far enough. So the experiment continues with a 50 slot wheel and a 1/32" mill today. Thanks John. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> I think it's a new feature. Don't tell anyone it was an accident. :-) -- Larry Wall on s/foo/bar/eieio in <10911@jpl- devvax.JPL.NASA.GOV> ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
