Steel C-channel Build - Questions and pictures

[olskool]

Hello everybody! I've been reading for a while, and building for a shorter bit. I've got a xylotec 425oz stepper kit, running Mach 3 demo software. I'm currently building the gantry and have the x axis and the main frame constructed. I'm very much not a plans person, so we will see how poorly this will work out. I'm looking to cut wood and nothing else.

I doubt I'm that different than many people on here, but I am honestly building this because I thought it would be fun to build. I have no immediate need for it. That might come in handy seeing as it'll take me another year or so... ; )

Ok, here are a few pix
this is the original frame I tried 2.5' square


this is about 4x2.25'


this is a closeup of my test bar positioning/leveling piece.


I've got a ton of questions, but the main reason for my post is to show where i'm at and to ask a mach 3 question.

I'm getting stuck at 120 rpm jogging right now. I've heard a wide variety of causes, but I have switched computers and played around with a lot of the settings. I'm a bit hesitant to switch too much stuff around because I am still learning what it all does. Could this be a jumper issue? Is that going to be my max speed? Is it because it is just the demo software? Is there a god?

I have loved watching all the other builds, and learning that there are way more 'build it because I can' type geeks out there that I ever imagined. Thanks for everyone's help. past, present and future!

To follow along more easily, you can check out my blog at blog.tinyenormous.com I hope to see you there!

[rustamd]

Is Mach3 not alowing higher in/min? If so it might be kernel speed. Change it to 35000 or 45k if your computer can handle it.

[wcarrothers1]

Don't know if it applies to steppers but if you are hitting your max speed I'm guessing you are trying to drive faster and it's faulting?

Based on voltage to my servos my max speed before they fall to far behind and the geckos fault out because they can't keep up. Can also fault if the acceleration rate is quicker then what the servos can accelrate at..

So maybe able to get some more speed if your faulting durring the accelleration point.

Could also be running out of pulses though to (ie kernal speed)

How ever everything has a limit. might also be able to find what your screws RPM is calculated to be (there are charts the screw makers have for that) basicly a factor of length size and the slap they start having when spun. You might find that your already at that point anyway and would not want to spin them much faster. Also torque loss the faster you spin with steppers typicaly have slower top speed anyway.

[olskool]

Thanks guys (or gals) for the tips. I'm gonna mess around with the kernel speed. I'm not on a fast machine by any means. I think it's got a 1ghz processor in it.

wcarrothers1- I agree everything will have as limit at some point. I'm just hoping the limit is somewhat higher. I have 10 tpi 1/2 in acme screws, so at max 120 rpm, i'm looking at 12 ipm max, right? That sounds like a really slow machine to me.

Maybe the answer is to buy a faster computer, but doing that makes me think that even expensive (to me) 2 or 4 start acme screws could be a cheaper option. Either way, tweaking the kernel speed is a free and easy way to see if it could be fixed in software.

Isn't there something about if I'm half stepping vs 1/4 vs 1/8 with kernel speed issues? I think I remember someone saying that 1/8 step used 2x more cycles than 1/4, and would result with a slower max speed. I seem to remember a lot of confusing math that then followed and scared me away from the forum for a day or so...

Can't wait to start making sawdust...
My CNC, Motorcycle, Homebrew and more blog.

[rustamd]

what microsteps are you runing at?

[olskool]

rustamd- I'm running a xylotex driver. The highest they support is 1/8th. I think that is what it is shipped in, and what it currently is. I'm not at home right now, but i'm fairly certain it's 1/8th

[rustamd]

than your max speed should be 132 IPM

[Regnar]

"than your max speed should be 132 IPM"

This is what I get with the same settup. 10tpi Leadscrew with Xylotex Board and 269oz steppers.

[olskool]

well i'm stumped! I just checked. the xylotex is in 1/8 mode, I have tested the software at all three kernel speeds and only the sound that the motors make changes. I consistently get a fluctuating value between 119.0 and 120.0 rpm.

Is this user error? The only way I know of changing the speed is to up the rate% by hitting the arrows above the rpm readout. This flashes red at me, and then continues to do no change whatsoever. I can get a higher rpm if I hit two jog keys at once, but I'm pretty sure that's cheating...

I really wish the mach 3 forum was set up like this one! All of my efforts over there end up in frustration. it's got a terrible search function, and I can only ever find individual posts. sigh.

Well, i guess i'm off to go poke around a bit in mach 3 forums. Wish me luck! and thanks for all the help thusfar.

Checl out my (lack of) progress here

[rustamd]

What steps per inch do you have set?

[la_coterie]

Try holding down shift while pressing the jog key