Just for reference, I am running approximately 8100 steps per units (inch), velocity of 120, accel of 7 and a step and direction pulse of 5. I am running Chai's (linearmotion2008) screws and 5056D drivers.
The position of those last 4 dip switches (off, on, on, on) are responsible for your microstepping value. In your case it would be 1/2 stepping (if I am reading the chart correctly). If this is the case, your steps per unit would be in the 200 x 2 x 5=2000 steps per unit. I would think you would get a bit of resonance at that value.
Chai's ball screws, I don't know what you mean by microsteping my pulse/rev is 400
Edit, what do you recomend I should set it to?
Last edited by mr.andaya; 12-16-2012 at 07:06 PM. Reason: You too fast lol
Gotcha, I'll work I it when my wife gets back. I'll post my results. How fast are your rapids with it set like that?
Thanks
-joe
120ipm
The microstepping value (the last 4 dip switches, sw5, sw6,sw7,sw8) needed to be known to get the correct steps per unit. In my calculation 200 (steps per rev of your stepper) x 2 (your 1/2 step microstepping value) x 5 (the number of turns of the leadscrew to travel 1 unit an inch in this case) =2000. If you microstepping value was 1/10 for example (this is the only available value of a G540) your calculation would have been 200 x 10 x 5=10000 steps per unit. I hope that helps more than it confuses.
A 1.8 degree stepper requires 200 steps if full stepping. Because your are half stepping it requires 400 for a complete revolution. 1/4 stepping would have required 800 etc. These values are to smooth out the movement and or minimize resonance. Resolution can be more accurate too or smaller increments theoretically. I am using 1/8th.Originally Posted by mr.andaya
@fastest1 hey I ran ur settings, wow haulin ass lol. My gibs are a little tight(brand new) so the motors miss a few steps. I turn it back down slower, what do you run on ur dip switches?
Thanks
-joe
I was running 300-330 during the test. That was hauling ass! What is remarkable, is that is slow compared to the big stuff. I read of guys approaching 2000ipm IIRC. I know that you can drill a hole in your table really quick at 80ipm if you think your offset was right and you let down your guard!
The last 4 switches are set up,up,down,down. The first 3 vary depending on whether it is the X & Y or Z.
It will take a while to get it adjusted well. Pay special attention with gib tightness and use a dial indicator to sense movement of the carriage to assess gibs tension. Tight is not the solution, smooth is. Dont forget to lube well on all moving surfaces. Personally I use a qtip or small brush to lube all surfaces. I will get around to the auto oiler 1 day.
Cool thanks, It seems fast with the machine not bolted down lol. My gibs arnt super tight but "snug" I figure I'll be adjusting and re adjusting soon. I wanted to Cnc it while manual oiling it, then make the nessery brackets and such for the oiler.
-joe
Understood about the future desires. Dont watch any Hoss conversion stuff, it will reroute your plans daily! LOL
Also try playing with the accel values of the steppers, the ramping of the speed as the carriage moves will vary with different values as will the song. The song of the steppers is hypnotizing and with experience will tell you a bit about the performance.
Yea I've been looking at his site for the past few weeks, I'm like treadmill motor, 4th axis, 5th axis..... I want it all.... Lol
Tool changer? Power drawbar/TTS? Laser? Printer? He is up to something right now! The guy is a dynamo.
A lazy man does it twice.
Ina do the power drawbar with the tooling forsure.
I just want to thank everyone for the help, last night I finished my nema34 z axis mount using the 2 axis's(manual Z) and will be finishing the conversion this week.
Thanks again guys
-joe
Fastest, can you elaborate a little on the use of a dial indicator to assess gib tension?
Thanks
adrian.
Adrian, Sure. I tried to find the thread that elightened me. At the time I was missing some steps (and might be still during some code but it is not mechanical and only occurs when running a CamBam file. Save that for another day.
My original approach to gib adjustment was to just snug the screws up to insert the gib further into the pocket. As long as I could still move my machine and it felt rigid I was happy. During my pursuit of the missing steps. I thoroughly went thru my mill numerous times. I read a thread by Bjones, BRad or BAM (they all might be the same person) though that is irrelevant. He/they described a technique in which a dial indicator was installed on your carriage touching the side of the X table. Adjust the gib til there was no movement of the indicator when rocking the table. Do it in many places up and down the travel of each axis. Not too tight, just when the indicator stops moving. Repeat for each axis. After doing this your machine will run very smoothly. Tight is not the solution. Smooth movement is not easily achieved with tight gibs. The difference on a manual mill is night and day too. The information might have been there all along. But I thought tighter was better.
I hope that made sense.
A much better way to adjust gibs is to measure the backlash, tighten the gibs slightly, then measure backlash again. As you tighten the gibs, you should find backlash decreases slowly. You will reach a point where backlash suddenly increases greatly. The correct setting is just BEFORE this happens.
Regards,
Ray L.
Thanks Ray.
I assume you mean backlash in the axis perpendicular to the one that you're adjusting the gibbs on, right? So if I'm adjusting the gibs on the y-axis, I'll measure the backlash on the x-axis?
Just one question (if my assumtion above is correct);
Why would backlash increase when the gibs get "too tight"?
adrian.
No, I mean ON the axis you're adjusting. When the gibs get too tight, friction increases dramatically, and the bearings, ballscrew, ballnut, belts, couplings all become springs, and it takes much more force to make the axis move, which creates backlash as everything "winds up". Try it, you'll see.
Regards,
Ray L.
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