XX-Axis Gantry negative direction drift

captain wrote:

Hi BigJohnT

Not quite sure what you mean is that the setp stepgen dirhold and ~dirsetup value in Hal which is 15200

It is connected to the parallel port

It's not the stepper test but a program which runs up and down the X axis with the same X coordinates that is from 0 to 260mm offset on the Y axis by .3mm at each pass and varying Z depths between 0 and 18mm, a program I wrote in CamBam using

3D Profile Machining Operation horizontal scan-line

.

alan_3301 wrote:

I see now that they recommend the 7.3 amp with 3 motors, and a 12.5 amp supply with 4 motors.

Could you direct me to that site as my supplier in Australia is still advertising the kit thus:-

1 x G540 Geckodrive Stepper Controller
1 x PS-01 7.3A 48V Linear Power supply
1 x SW-01 Emergency Stop Switch
1 x SW-06 IEC Power socket/fuse/ switch
1 x CB-10 IEC Female Socket
2 x RL-04 48V coil 20A SPST Relay
4 x SM-03 387 oz.in Bi-Polar Stepper motors

cheers

1500 ??
i would be expecting something around these values
it would not harm to try them , ( good call JT )

step 1000
stepspace 2500
dir hold 500
dir setup 500

one way to check the drives it just to move it to another axis and see if you get repeatable results , if the suspected drive is faulty then the fault will follow across to the new axis
ok on the power supplys , i'd just go and change the power supply for a 12A one or higher .

you dont need to match a power supply to electronics , stepper drives just dont need them .

i suspect your problems are a combination .,.. change the power supply , and then look at reconfiguring your hal files .
as Rick has said changing your setup gearing , drasticly changes the setup , so you need to re-configure .

one way to prove is to say remove your z axis driver , and just run the machine in x & y and re configure hal .
once you have that correct then add the Z .

if your not careful you will end up chasing your tail .. and no doubt be as confused as hell .
i have not used Geko drives , so i'm not familiar with their suggested timings for that particular model , however the one's quoted will get you close
and in the ball park . but no doubt someone with 540's will be able to post timings that work .

Rick G wrote:-

O.K. but keep in mind the new gear ratio requires more torque from your motors to move and hold the gantry.

Thanks I realized this and and will get a bigger power supply.

cnc basher wrote:-

one way to check the drives it just to move it to another axis and see if you get repeatable results , if the suspected drive is faulty then the fault will follow across to the new axis

This I have done see earlier and the driver is certainly sus.

I used Stepconf Wizard to reconfigure so the config can't be too far out, I think I need to sort out the hardware issues first, then I'll let you know my results.

cheers

note : you say the step timings are 15200 ???

note that even stepconfig gives these default timings for a geko 540
so either the above is a typing error , or your miles out ... which would account for some problems

steptime 1000 ns
step space 2000 ns
direction hold 200 ns
direction setup 200 ns

although i would be more willing to use a steptime of 2000 ns & 700 ns respectively as it has been noted the default values are tight

O.K. but keep in mind the new gear ratio requires more torque from your motors to move and hold the gantry.

Thanks I realized this and and will get a bigger power supply.
/quote]

I was wondering if with the new gear ratio your motors have enough torque to reliably do the job even with a larger power supply.

Did you check the current resistor on the driver that seems to be the problem?

Rick G

Hi All

The value I gave was the Hal file entry:- setp stepgen.0.dirhold 15200
setp stepgen.0.dirsetup 15200

The other values are:- setp stepgen.0.steplen 1
setp stepgen.0.stepspace 0

How these figures are arrived at I haven't a clue, the Driver Timing Settings in the Stepconf Wizard preset for the Gecko 540 are as cncbasher says, that is

steptime 1000 ns
step space 2000 ns
direction hold 200 ns
direction setup 200 ns

Rick G, yea the current resistor on the driver checks out fine thanks

I do need to sort out the hardware issues first, I am sending the driver off testing with Gecko and have ordered another power supply.

cheers

OK, got an additional power supply and replaced the G250 driver which appeared low with a G251.
I removed the 3 good G250 drivers from the Gecko 540 and wired them with the new G251 to a new MB-02-V6 break out board, so I now have a 7.3A power supply driving the two X axises motors and another 7.3A driving the Y and Z axises.

Got as far as holding and jogging, still trying to sort out the homing and limits.

The holding is vastly improved, Testing the 387 Oz/in motors ( bush style spring scale and g clamp on axle) + - 16 lbs @ 1 3/8in = +- 352 Oz/in as compared with the +- 4 lbs @ 1 3/8in = +- 88 Oz/in and 46 Oz/in on the bad drive.

What I still don't understand is why there was no voltage drop with the lack of power.
(I'm pretty stupid when it comes to electronics) as I'm sure my high school physics back it the day says if you don,t got current you sure got voltage drop.

Thanks cncbasher, alan_3301 and all for the in-put.

Hi back with the good news.

I ran my previous test for one and a half hours and approx 45,000 lines of G code and got negligible drift on the X axis.

I have run the stepper test on all axises as was suggested in

Y axis negative direction drift. Help!

linuxcnc.org/docs/html/common/Stepper_Diagnostics.html

I am now back to running X at 12,000 mm/sec, with Y running at 9,000 mm/sec and Z at 4,800 mm/sec with between 0.08 and 0.2 mm out across all the axises which is excellent for a home made 1,220 x 2.440mm gantry router running on belt drives, I think,

Thanks once again to all for the support.

Cheers