Welcome to the Parallax Discussion Forums, sign-up to participate.
doggiedoc wrote: »
I'm eager to see the video when that comes to fruition!
Roger Lee wrote: »
That took a lot of effort just to haul it to UPENE 2012. Big and massive bot.
You could have taken the easy way and brought photos/videos, but you took the hard way.
I want to say THANK YOU.
absolutely great, impressive machine.
DiverBob wrote: »
Got 15 new Parallax HB25 motor controllers in the mail!
idbruce wrote: »
This is the first time I took a peek at this thread, and I must say that your project is very impressive, with the addition that your videos are outstanding and very informative. Not that my opinion matters much, but I would have to say that you are an extremely intelligent and highly talented individual.
I thought I was fairly intelligent until I found this thread, but now I feel stupid
photomankc wrote: »
Bob, if you don't mind saying, what ended up being the fix for the reaming issues you were having? I assumed that the numbers you gave were a mistype (.6235 -> .672) and you meant (.6235 -> .627). I know in most instances 0.0035" oversize on a ream is disaster but It would have had to swinging like a boring bar to cut 0.048" oversize! I have found that despite the claims of flexible self-centering, that the only way to get accurate reams was to mount them in a good collet chuck, not a drill chuck. Every time I have used a drill chuck the results have been poor. There are plenty of times where it didn't matter that much but when it does the only way I can get close is with a collet and even then I always seem to cut close to 0.0005" oversize. Reamers are fiddely things and not my favorite tool, I much prefer to bore the holes when the tolerance is tight.
I was just curious though what ended up being the issue.
Ken Gracey wrote: »
Bob, I know I asked before but have you tried flood coolant on these CNC processes? I think you'll be really impressed with the finish quality, absence of material galling, and increased feed rates.
You have so much patience to undertake such a long-term project. I wish I had that ability.
DiverBob wrote: »
Believe it or not, those were the actual numbers I got on the hole. Lots of chatter and the cut hole was very ragged. I've used reamers before on other mills but this was the first time on a CNC.
I did a lot of experimentation with different speeds and feeds and in every case the hole ended up too large, sometimes by a significant amount. The reamer itself is HSS and 0.0005 undersized for the bearing. I use a good quality R8 collet and the mill is fairly rigid. I couldn't detect any vibration in the workpiece while using the reamer either. I couldn't find any help on the Internet machining sites that I hadn't already tried and was ready to just program the end mill to cut the hole instead. As a last resort I tried manually feeding the reamer in the Z axis and manually turning the reamer by hand. This method actually worked pretty good although I modified the turning by hand to using a socket and ratchet which sped up the process quite a bit. Since the hole is only 0.215 inches deep it takes less than a minute to do it this way.
I think if I changed the motor speed v-belt to the lower pulley that I could duplicate the slower speed but it would take more time to swap pulleys for each part than to just do it by hand. The lowest speeds possible using the standard pulley don't have enough torque so the that limits the low end speed. This is a work around but until I do some more experimenting I will stick with what works! I figured that I only have 18 holes per leg to ream!