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hey everyone, haven't been here for awhile but need some advice. I have a gantry machine with ball screws on X&Y axis directly driven by 820 oz steppers, I haven't been able to run the machine at more than 50% of slow jog without it stalling and jerking, it then misaligns the gantry. My question is this, is there something I missed or is there insufficient torque by these motors and do I have to use timing gears and belts. Any help would be appreciated.
There are lots of varibles here. My geuss is you have alignment issues.
I also had racking issues and found that my linear guides were not aligned accurately enough. After a lot of measuring shimming check more measuring and shimming and slective loosinging and tightening of bolts then more shimming it is working great.
My machine has lower powered steppers than yours (540 ozin I think) and is also direct driving my ball screws which have a 16mm pitch. I intentionally choose a coarse pitch to keep the motors spinning slow for more torque. Machine travel is around 40" x 60" so not smalll but not teribly large either. Larger machines are harder to get everything in alignment.
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What pitch are the screws?
What are the specs on the motors?
What voltage are you running them at?
What drives are you using?
What is your acceleration set to?
What speed does it stall at?
How fast are you trying to go?
How big is the machine?
How heavy is the gantry?
In most cases like this, the culprit tends to by large, high inductance motors that just aren't capable of spinning very fast.
Hey- I'm not to bright when it comes to electronics so I don't know if this is the right info. DQ860MA is a type of two-phase hybrid stepping motor driver, The drive voltage of which
is from 24VDC to 80VDC. lt is designed for use with 2-phase hybrid stepper motor of all kinds
with 57mm to 11Omm outside diameter and less than 8.0A phase current. This circuit that it
adopts is similar to the circuit of servo control which enables the motor run smoothly almost
. Average current control, 2-phase sinusoidal output current drive
. Supply voltage from 24VDC to 80VDC
. Opto-isotated signaf I/O
a Overvoltage, under voltage, overcorrect, phase short circuit protection
a 14 channels subdivision and automatic idle-current reduction
o 8 channels output phase current setting
. Offline command input terminal
. Motor torque is related with speed, but not related with step/revolution lnput voltage 24-8OVDC
lnput current <64
Output current 2.84-7.8A
Consumption Consumption : 80W; lnternal lnsurance : 10A
DC Voltaqe 5V 7.5V 12V 13.5V 15V 24V 2W 48V
Voltaqe Tolerance !2o/" tzola t1% t1% !1olo tl% t1o/o t1olo
Rated Current 50A 404 29A 26A 234 14.6A {34 7.34
Gurrent Ranqe 0-50A 040A 0-294 0-26A 0-23A 0-14.6A 0-134 0-7.3A
Ripple&Noise(Max. lS0mVp-p l50mVp-5 l50mVp-1 1S0mVp-p l50mVp-p lS0mVp-p 200mVp-1
240mVpo
Line Requlation t0.5% r0.5% r0.5% r0.5% tA.5o/" r0.5% !0.5o/" i0.5%
Load Reaulation tl% tlolo !0.5% r0.5% r0.5% r0.5% r0.5% t0.5%
Rated Power 250W 300w 348W 351W 348W 350.4W 351W 350.4W
Rated Power 74o/o 79o/" 74% 80% 78% 83% 83% 84%
Voltage Adjust
Ranqe
4.5-5.6V 6-9V 10-13_2V 12-15V 13.5-18V 2A-26.4V 26-32V 41-56V
Voltaqe Ranse 90-1 32VACI1 80-264VAC 47-63H2;255-370VDC
AC Gurrent 4.54t115V 2.54/230V
lnrush
Current(Max.) 254t115V s0A/230V
Leakaqe Current <3.5mAl240VAC
Overload
Protection 145-145% TYPE: OUTPUT CUTOUT AG Restart
Over-voltage
Protection 1154/o-135o/o
Over-temperature
Protection
RTH3>50C FAN ON,345C
RTH3>6OC FAN ON,SsO"C
FAN OFF, >8OC
FAN OFF, >85C
oUTPUT CUTOUT(s-I5V)
oUTPUT GUTOUT{2448V)
Temp.Coefficient 10.03%/c(0-50"c)
Setup.Rise,Hold
Part No.: 85BYGH450D-007 single shaft
Frame Size: NEMA34
Step Angle: 1.8 degree Voltage: 6.4V Current: 2.0A/phase
Resistance: 3.2 Ohmlphase
lnductance: 15 mH/phase
Holding torque: 6.3N.m 892o2-in (with Bipolar Connecting)
Rotor inertia: 36009-cm2
Number of wire leads: I
the ballscrews are 25mm 5lead table travel 48 x 48, gantry weighs about 68# , the gantry moves easily when not hooked up to ballscrews. when jogging without the gantry connected I can hold the ballscew and almost stop it from turning. I would like to be able to cut at 200 and rapid at 400 to 600 - hope this helps
.
The biggest issue is your choice of motors and ballscrews.
What is your power supply voltage? Probably 24V-36V? That's typical of all the poor performing packages you find on Ebay.
Your motors have 15mH inductance. Ideally, you want motors with an inductance of 2-3mH. To get the best performance from those motors, you'd need a 120V power supply.
But even if you had that, your screws will limit your speed.
400ipm = 10160mm/min
You'd need 2032rpm to reach that. The bigger the stepper, the slower it's maximum speed. The higher inductance, the slower the speed. You have big, high inductance steppers. I'd be surprised if you can even get a usable 500rpm from them.
You'll never see 400ipm with stepper motors and those screws, unless you use a belt drive to spin the screw 3-4 times faster than the motor. To get the speeds you want, you really need screws with a minimum lead of 10mm, or even 20-25mm.
You'd also be much better off with a low inductance motor in the 450oz range. Ideally rated close to 6 amps.
thanks for the input, does anyone have any suggestions as to where to get the best motors for this, I'd like to keep the ballscrews I have for now. also what would be the best for timing gears 1 to 6 ?