G-man, that's an interesting idea using Delrin with a lead screw. For some reason I can't visualize it for a ball screw especially trying to involve bearings.
It would be nice to see movies of your machine. I will make some videos of mine soon to share.
Komputer Numerically Kontrolled (KNK) Router
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Hey Kam,
If you check out this link, and look at the leadnuts, that is basically what I have made, except I use a small hose clamp rather than a spring:
http://www.dumpstercnc.com/
Maybe I'm missing something obvious about a ballscrew that wouldn't work with this kind of leadnut. I'm too tired right now to get a good picture of a ballscrew set-up in my head.
G-man
If you check out this link, and look at the leadnuts, that is basically what I have made, except I use a small hose clamp rather than a spring:
http://www.dumpstercnc.com/
Maybe I'm missing something obvious about a ballscrew that wouldn't work with this kind of leadnut. I'm too tired right now to get a good picture of a ballscrew set-up in my head.
G-man
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Head Monkey
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Looks very nice man. Excellent work!
Everything I know about snowboard building, almost: MonkeyWiki, a guide to snowboard construction
Free open source ski and snowboard CADCAM: MonkeyCAM, snoCAD-X
Free open source ski and snowboard CADCAM: MonkeyCAM, snoCAD-X
Very elegant end result. Man, those are some honkin' big motors on those big ol' lead screws. If that machine should ever have a burp in it's code, it seems the machine could cause some real damage to itself. Do you plan to run some limit switches? I had to disconnect my switches due to so some annoying false activations, I think caused by some static interference from my dust collection hose. I'll probably try adding some smoothing caps to the limit switch connections on the board, but until then, I have to keep a pretty close eye on things while the machine running. I've only had one time when the machine 'went postal', but it seemed like it took an eternity for me to get to the emergency stop switch. My motors are too small to cause too much real damage, though. Your's, on the other hand, look quite formidable.
Are you going to make a door with a big carving of the 'ski builders' logo? Okay... silly question... of course you are.
Great job.
G-man
Are you going to make a door with a big carving of the 'ski builders' logo? Okay... silly question... of course you are.
Great job.
G-man
G-man:
True -- the motors are strong; but they were free and I've limited the current (torque) to minimize damage. Besides, they only look big and intimidating ... once you get to know them, they are soft and kinda cute
.
Static? Wow, I'm surprised. Are your switches close to the air ducts? Are you using a pull-up or pull-down resistor to keep the signal from floating? I would assume that the control board would have something like that. What about ground loops? Large current returning to ground can cause weird behaviors. What about some sort of de-bouncing circuit?
I have not added any limit switches yet. Will consider both the board/software-level and a special back-up shutdown.
True -- the motors are strong; but they were free and I've limited the current (torque) to minimize damage. Besides, they only look big and intimidating ... once you get to know them, they are soft and kinda cute
.Static? Wow, I'm surprised. Are your switches close to the air ducts? Are you using a pull-up or pull-down resistor to keep the signal from floating? I would assume that the control board would have something like that. What about ground loops? Large current returning to ground can cause weird behaviors. What about some sort of de-bouncing circuit?
I have not added any limit switches yet. Will consider both the board/software-level and a special back-up shutdown.
Hi Kam,
Yes, the board has 10k pull-ups, but for some reason, a lot of folks report false limits with this board. It seems that a small capacitor across the connection on the board usually fixes the problem. I've also read posts where operators have similar problems with other boards, also fixed by adding the capacitor. I was getting my false activations only when the router was running and the dust collection was also running. I'm just running a large flow shop vac for dust collection... a little hokey, I know, but it seems to collect pretty much all the dust that I generate. Over the past month of some pretty active cutting, there's only a slightly noticeable layer of dust on horizontal surfaces right next to the machine. I still wear a respirator any time I'm close to the machine when it's running. Anyway, when I'm running a pen device, rather than a router (I almost always pen test any new code file before doing any actual cutting), I never got the false activations. I only got them when the router and the dust collection were running, and only at a specific point in the x-axis travel where the dust collection hose did this little flop-over and ended up a couple of inches from one of the limit switches. Now, a complicating factor here is that the power cord for the router is cable tied to the vac hose, so the problem could either be static electricity in/on the hose, or it could be electromagnetic interference from the power cord. I recently re-routed the dist collection hose so it doesn't flop-over near the limit switch, but I haven't reconnected the limit switch lead to see if I still get a false activation at any time during a code run. Maybe I'll do that tonight.
Ground loops or de-bouncing circuits???... dang... looks like have some more stuff to learn about.
Oh... here's a weird scenario that I came up with last night while watching the machine run. What would happen if power was lost to the router, or a router just simply gave up the ghost, while cutting a code file? The bit would stop cutting, but the machine would continue to feed the non-rotating bit into the work piece. The expensive bit would almost certainly break off and the work piece would also get messed up. I haven't read about a safety circuit that would sense some sort of change in router current draw, or some other parameter, and thus shut down the machine before the router bit came to a complete stop, but maybe such a circuit is available. What do you think? Any solutions come to mind?
Thanks for your thoughts regarding my false e-stop activations.
G-man
Yes, the board has 10k pull-ups, but for some reason, a lot of folks report false limits with this board. It seems that a small capacitor across the connection on the board usually fixes the problem. I've also read posts where operators have similar problems with other boards, also fixed by adding the capacitor. I was getting my false activations only when the router was running and the dust collection was also running. I'm just running a large flow shop vac for dust collection... a little hokey, I know, but it seems to collect pretty much all the dust that I generate. Over the past month of some pretty active cutting, there's only a slightly noticeable layer of dust on horizontal surfaces right next to the machine. I still wear a respirator any time I'm close to the machine when it's running. Anyway, when I'm running a pen device, rather than a router (I almost always pen test any new code file before doing any actual cutting), I never got the false activations. I only got them when the router and the dust collection were running, and only at a specific point in the x-axis travel where the dust collection hose did this little flop-over and ended up a couple of inches from one of the limit switches. Now, a complicating factor here is that the power cord for the router is cable tied to the vac hose, so the problem could either be static electricity in/on the hose, or it could be electromagnetic interference from the power cord. I recently re-routed the dist collection hose so it doesn't flop-over near the limit switch, but I haven't reconnected the limit switch lead to see if I still get a false activation at any time during a code run. Maybe I'll do that tonight.
Ground loops or de-bouncing circuits???... dang... looks like have some more stuff to learn about.
Oh... here's a weird scenario that I came up with last night while watching the machine run. What would happen if power was lost to the router, or a router just simply gave up the ghost, while cutting a code file? The bit would stop cutting, but the machine would continue to feed the non-rotating bit into the work piece. The expensive bit would almost certainly break off and the work piece would also get messed up. I haven't read about a safety circuit that would sense some sort of change in router current draw, or some other parameter, and thus shut down the machine before the router bit came to a complete stop, but maybe such a circuit is available. What do you think? Any solutions come to mind?
Thanks for your thoughts regarding my false e-stop activations.
G-man
G-man sounds like you should be running a ground cable for your dust collection hose.
Mine runs up over a beam and down to my planer it makes my hair ( the few I have left) stand on end when i walk under it.
Keep thinking I should probably ground the sucker.
sam
Mine runs up over a beam and down to my planer it makes my hair ( the few I have left) stand on end when i walk under it.
Keep thinking I should probably ground the sucker.
sam
You don't even have a legit signature, nothing to reveal who you are and what you do...
Best of luck to you. (uneva)
Best of luck to you. (uneva)
Ha! Same with me... to the few I have left. I'll try your grounding idea if I continue to have problems after I reconnect the limit switches... and maybe I'll just do it to stop my hair standing on end when I walk under the hose. Thanks very much.makes my hair ( the few I have left) stand on end when i walk under it
G-man
It's not clear to me how one would 'ground' a plastic hose considering it's an insulator, for example charges on the surface of the hose are not free to move, so wrapping wire around it would not do much good, only for the charges which are in contact with the wire.
The static electricity seems a little strange to me, but nothing is impossible, I suppose. Have you shielded the switch return wiring? My encoder cables are shielded as the large motor current wires running nearby can inject noise. Also, if people have reported the problem at the board level, then it seems to me that additional bypass caps may be needed on the +5V supply points on the board -- I'd add a few big ones (10-100 uF, electrolytic type) in parallel with a few smaller ones (ceramic type), 0.1uF-0.01uF, from between +5V and ground to minimize any pesky high-frequency transients. Also, since the false activitation happens when the router and vac is on, there's a possibility that the large current can cause the voltage to fluctuate, affecting the +5V supply to your pull-up, etc. The router and vac motors are inductive loads and can also be another problem. But then again, it's hard to tell without really looking at it close up with a scope or probe.
It would be interesting to see if you've fixed your problem by separating the charged hose.
OK, I just realized it's 1:30 am and that last paragraph I wrote probably makes no sense. Also, I'm certain it came from the dream I was having while falling asleep typing away on the keyboard....
Yeah, I know...it just keeps on going. Too bad one can't make a living just learning professionally. I'd be all over it....Ground loops or de-bouncing circuits???... dang... looks like have some more stuff to learn about.
The static electricity seems a little strange to me, but nothing is impossible, I suppose. Have you shielded the switch return wiring? My encoder cables are shielded as the large motor current wires running nearby can inject noise. Also, if people have reported the problem at the board level, then it seems to me that additional bypass caps may be needed on the +5V supply points on the board -- I'd add a few big ones (10-100 uF, electrolytic type) in parallel with a few smaller ones (ceramic type), 0.1uF-0.01uF, from between +5V and ground to minimize any pesky high-frequency transients. Also, since the false activitation happens when the router and vac is on, there's a possibility that the large current can cause the voltage to fluctuate, affecting the +5V supply to your pull-up, etc. The router and vac motors are inductive loads and can also be another problem. But then again, it's hard to tell without really looking at it close up with a scope or probe.
It would be interesting to see if you've fixed your problem by separating the charged hose.
I was thinking about building a small watchdog robot using one of those Carnagie Melon vision boards, coupled with image recognition software to track and monitor the router's spindle speed and deflection. As you know, if you lose power, the bit will slowly come to a stop, while at the same time the x/y/z stage will continue to move cutter. Because the cutter is slowing down, its cutting ability diminishes and thus the forces between the material and bit increases causing it to deflect. So, by measuring both the spindle rotation and deflection, you should be able to back out whether power loss has occurred to router. The bit deflection can easily be related to the force/moment applied to the cutter and you can then shut things down before permanent damage will occur....maybe such a circuit is available. What do you think? Any solutions come to mind?
OK, I just realized it's 1:30 am and that last paragraph I wrote probably makes no sense. Also, I'm certain it came from the dream I was having while falling asleep typing away on the keyboard....
Kam,
Interesting point regarding grounding the plastic hose. I've noticed that sometimes when I vacuum with a shop vac, sawdust/debris particles start to build up on the hose in little 'projectile/static like' formations . When I go to wipe them off, I feel these little mini-shocks on my hand/fingers from the hose, and I figured that I was providing some sort of 'ground' for the positive static charge. I'm the first to admit that I don't understand these things very well, so there are probably other forces at work that I'm unaware of. And, I may well have been completely off on my initial assumption that it may have been static electricity that was causing my problem. If I had it to do over again, I would simply run only the router, or the vacuum (not both at the same time) and see which caused machine to experience the the false e-stop conditions. The condition always occurred at the same point in a base material cut-out (just when the vac hose [with router power cord tied to hose] flopped close to a limit switch). The limit switch wiring is shielded and grounded at the board. I have the machine on a 30 amp circuit. I'll hook up the limit switch circuit in the next day or so, and do a couple of dry runs to see if the false activations still occur now that the hose and power cord have been re-routed.
Thanks again for the thoughts. The machine is running just fine for now. I know, though, that I should get those limit switches back to operating correctly before too long. I've paid those kind of prices too many times before.
G-man
Interesting point regarding grounding the plastic hose. I've noticed that sometimes when I vacuum with a shop vac, sawdust/debris particles start to build up on the hose in little 'projectile/static like' formations . When I go to wipe them off, I feel these little mini-shocks on my hand/fingers from the hose, and I figured that I was providing some sort of 'ground' for the positive static charge. I'm the first to admit that I don't understand these things very well, so there are probably other forces at work that I'm unaware of. And, I may well have been completely off on my initial assumption that it may have been static electricity that was causing my problem. If I had it to do over again, I would simply run only the router, or the vacuum (not both at the same time) and see which caused machine to experience the the false e-stop conditions. The condition always occurred at the same point in a base material cut-out (just when the vac hose [with router power cord tied to hose] flopped close to a limit switch). The limit switch wiring is shielded and grounded at the board. I have the machine on a 30 amp circuit. I'll hook up the limit switch circuit in the next day or so, and do a couple of dry runs to see if the false activations still occur now that the hose and power cord have been re-routed.
That's okay... I'll just wait until 1:30 this morning to read it, and it'll make perfect sense.OK, I just realized it's 1:30 am and that last paragraph I wrote probably makes no sense. Also, I'm certain it came from the dream I was having while falling asleep typing away on the keyboard....
Thanks again for the thoughts. The machine is running just fine for now. I know, though, that I should get those limit switches back to operating correctly before too long. I've paid those kind of prices too many times before.
G-man
Grounding... I think it would be as simple as running a bare copper wire around your duct hose and grounding this to the chassis of your dust collector.
But I've yet to try it
There's a ton of info here.
http://billpentz.com/woodworking/cyclon ... lectricity
I'm pretty sure I remember G-man linking to this site a long time ago,
(Perhaps my memory is going with my hair)
hope this helps
sam
But I've yet to try it
There's a ton of info here.
http://billpentz.com/woodworking/cyclon ... lectricity
I'm pretty sure I remember G-man linking to this site a long time ago,
(Perhaps my memory is going with my hair)
hope this helps
sam
You don't even have a legit signature, nothing to reveal who you are and what you do...
Best of luck to you. (uneva)
Best of luck to you. (uneva)
Hmmm... that article does look familiar. Sure is a boat-load of information. I saved it as a bookmark for future reference. I did read the section regarding static electricity (way down towards the bottom of the page [section F], for anyone interesting in finding it). My stationary ducting is ABS, rather than PVC, as discussed in the article, and I'm not sure what plastic the 2 1/2 inch vac hose is made from. I've noticed that the rigid vacuum 'wand' attachments can really build up a big static charge and collect a lot of airborne dust. It's interesting that the article recommends first wrapping the ducting with a piece of aluminum tape, then attaching a grounding wire to the tape via a bolt. It seems that the adhesive backing on the tape would function as an insulating barrier to the conduction of the static electricity... but, who knows. Maybe I'll have need to try it out here soon.
Thanks, sammer, for the link. Your memory seems to be pretty darn good.
G-man
Thanks, sammer, for the link. Your memory seems to be pretty darn good.
G-man