CNC Joinery Machine (edging up on a gloat)


I haven't finished it yet; but since posting last I've been busy. I did some redesign and re-cut all of the baltic birch parts - then redesigned the y- and z-axis motor mounts and routed them out of 1/4" x 3" x 3" 6061T6 aluminum angle. They're a bit more robust than the 3/16" two-piece originals, and the 1/4" stock let me tap all the bolt holes to eliminate a dozen washers and lock-nuts.
I hacked the four-axis controller (I'm always nervous about cutting PCB traces and adding jumper wires to make it behave differently than the designer intended); and now two of the control channels are driven by a single pair of inputs - which ensures that the two x-axis motors will forever march to the beat of a single drum (and in the /same/ direction!)
I made up the four cables that run from the controller to the motors; and mounted the y- and z-axis motors. I installed a downloaded copy of TurboCNC on the shop PC and spent a day trying to learn enough to do a reasonably correct configuration. I'll probably be tweaking the operating parameters for some time, since I /think/ I'm only allowing the steppers to run at a little less than 2/3 full speed.
Today I coupled the x-axis (only) lead screws to their motors, plugged the data cable in to the PC printer port, started TurboCNC, took a deep breath, and turned on the power. Not even a wisp of smoke - and no hot wire smell. Phew!
I put TCNC in "jog" mode and told it to jog 10" in the +x direction - and it /zoomed/ exactly 10", with a smooth acceleration, steady full-speed (at a parameter-controlled maximum of 14000 steps/second), and smooth deceleration. My calculator says that by holding it back to 14000 steps/sec it's only moving at 175 inches/minute; but I think it'll handle 20000 steps/sec (250 inches/minute). I want to tell you though, that the 14kc whine was music to my ears!
Feeling encouraged with this initial success, I told TCNC to run one of the sample g-code part programs. The program was to raise the router (+z motion), move to the starting point for a cut (+x and +y motion), lower the router to the cutting depth (-z motion), cut a 1" diameter circle (+/- x and y motion) at 10"/min, and return the router to the original position (-x and -y motion). Even though the y- and z-axis leadscrews weren't connected, I think it ran through the whole sequence correctly.
I was so wired I had to take the rest of the day off. Now I need to tear it all down for painting - then do a re-assembly and installation of a trim router to do some actual joinery.
Life seems good when things work the way they're supposed to. I /will/ post a gloat (with photos) when I've successfully cut the first dovetail joint.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/JBot.html
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Morris Dovey wrote:

Congrats.
I've done some stuff with steppers and control systems, and it sure feels great when it all works properly.
Chris
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Morris Dovey wrote:

A stepper motor that moves at 14000s/sec? Wow. Even if it could, wouldn't it lose all torque?
Maybe I'm thinking of a different class of steppers. :) I just found one that claims (with lots of disclaimers) it can do 10000, and costs $1200.
er
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Enoch Root (in 2tidnQuo7vWsb8fZnZ2dnUVZ snipped-for-privacy@forethought.net) said:
| Morris Dovey wrote: | || I put TCNC in "jog" mode and told it to jog 10" in the +x || direction - and it /zoomed/ exactly 10", with a smooth || acceleration, steady full-speed (at a parameter-controlled maximum || of 14000 steps/second), and smooth deceleration. My calculator || says that by holding it back to 14000 steps/sec it's only moving || at 175 inches/minute; but I think it'll handle 20000 steps/sec || (250 inches/minute). I want to tell you though, that the 14kc || whine was music to my ears! | | A stepper motor that moves at 14000s/sec? Wow. Even if it could, | wouldn't it lose all torque? | | Maybe I'm thinking of a different class of steppers. :) I just | found | one that claims (with lots of disclaimers) it can do 10000, and | costs $1200.
I'm not a stepper guru. The controller is set up to drive the motors in half-step mode, so I guess that's really 14000 half-steps/sec. That sounds to me like the equivalent of 7000 full steps/second. It appears that, as best I could tell, I'm not losing any steps at this speed - which encourages me to bump the speed up a bit more.
When the bit is out of the wood, I want to find how fast I can move to the start point for the next cut; and when I'm actually cutting I'll want to find out what kind of speed is possible and reasonable. My lead screw approach is roughly equivalent to gearing the motors down 12x, which trades off linear motion speed in favor of a 1/4800 inch linear motion increment and 12x more "oomph" than I'd get from a direct drive setup.
The steppers are spec'ed deliver 200 in-oz of torque and, since I bought these for a full order of magnitude less than $1200/ea. Still, they appear well-made and more than adequate for the job I want them to do.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Morris Dovey wrote:

Ah, no doubt it's microstepping the motor.
[schnibble]
er
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Busy? Understatement?
[ berinteresting update snipped for brevity]
Got to love it when a plan comes together.
My CNC ambitions are more certain than ever, but the time-line is very foggy due to the failing health of both my parents (both 85) but I get a vicarious pleasure watching your project take shape.
Aluminum seems like such a natural material for CNC work. I use a lot of it my jigs/projects. I can't wait to see the end result. Will you paint or powder-coat? The 'look' of the finished product will certainly help sell it. (Be bold!)
Godspeed!
r
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Robatoy (in snipped-for-privacy@nr-tor01.bellnexxia.net) said:
| || I haven't finished it yet; but since posting last I've been busy. | | Busy? Understatement?
/Fairly/ busy. I feel like I'm dealing with a whole lotta learning curves at the same time - and there's this nagging feeling that I'm spending too much time spinning my wheels (working my backside off without making much foreward progress.) Perceived progress seems to come in big jerks. I'm much more used to proceeding at a steady pace with a considerably greater confidence in my own abilities.
| [ \berinteresting update snipped for brevity] | | Got to love it when a plan comes together.
:-)
| My CNC ambitions are more certain than ever, but the time-line is | very foggy due to the failing health of both my parents (both 85) | but I get a vicarious pleasure watching your project take shape.
I understand. My parents have been gone for quite a while and I still miss 'em. Good on ya for taking the time to treasure their lives. If the time line gets to bothering you, you're welcome to drop in to try out the CNC machinery here. We're not /that/ far apart.
My camera is still at the Nikon repair center. The repairs are free (which is much appreciated) but I'd really like to have the camera back so I can share some pix.
| Aluminum seems like such a natural material for CNC work. I use a | lot of it my jigs/projects. I can't wait to see the end result. | Will you paint or powder-coat? The 'look' of the finished product | will certainly help sell it. (Be bold!)
The best things I can say about aluminum is that it's cheap, readily available, and doesn't make red-brown rust. It likes to glob up on cutting edges when it gets warm and the shavings definitely aren't user-friendly (I've just learned to stop brushing the chips away with my hands.)
I'm coming to appreciate brass more and more - although it does make green rust and its shavings aren't friendly either - and I dunno if I'm looking foreward to working with steel or not. Interestingly, my appreciation for wood has grown considerably during this project.
Bold? How about burple? Actually, I think it'll probably end up with a high-gloss medium-light gray - even though the current trend seems to be decorating tools to resemble fashion sneakers. Hmm, am I displaying signs of becoming an old fuddy-duddy? (Probably.)
| Godspeed!
Thanks. It's interesting/fun to develop stuff like this - though it does seem to want to proceed at its own pace.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/JBot.html
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wrote:

Exciting stuff, Morris! Would be great to see some pics now, but if too much hassle I guess we can wait.
Keep Plugging, J
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Joe (in snipped-for-privacy@4ax.com) said:
| Exciting stuff, Morris! Would be great to see some pics now, but if | too much hassle I guess we can wait. | | Keep Plugging,
It /is/ exciting, Joe. The hassle is in having my camera at a repair center 1000 miles away and not being able to shoot new pictures to share. I could probably pull the Rolliflex out of retirement and use film; but I keep thinking that the digital camera will be back before I could find film, get a couple of good shots, have prints made, and fiddle with my old scanner...
I absolutely guarantee that I'm more impatient than you are! :-)
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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Joe (in snipped-for-privacy@4ax.com) said:
| Exciting stuff, Morris! Would be great to see some pics now, but if | too much hassle I guess we can wait. | | Keep Plugging,
My camera has returned from its California vacation (thanks to the good folks at the Nikon service center) and reported for duty in the shop Thursday morning. You're invited to follow the link below to some more recent photos.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/JBot.html
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