Xcarve losing steps in y axis bad

[RalfFerly]

ok understood however when there is a tool load during machinging that does create much added force on the machine…so air cuts dont have all the extra forces …

thaks when i get time i will investigate with your advice cant do it now too cold out

[RalfFerly]

do you know what default x y z power pot is on the gshield? what does inventables set it at or is it just random?

[RalfFerly]

and like i said my cheap 3d printer and cheap laser engraver have never ever lost steps …they use same type system and i use them many many hours especially 3d priner

thats comparing a $100 machine to a $1600 dollar machine…the $1600 machine should be in theory more reliable

[RalfFerly]

i didnt know thqt larry very interesting drivers get current all the time and not on demand…when needed…that seems wasteful and unnecessary wear and tear on the drivers to me…

[RalfFerly]

haldor i dont believe it is the speed of the machine as i was only moving at 25ipm and lost steps on the 2nd pass doing a cutout in plywood at .025 depth

and i slowed my rapid down substantially so that when it goes to first mahining point it takes its time ni9ce and slow and did not lose steps going to first point…it lost steops this last test during the slow machinging process

but we will see who knows what the issue is

i appreciate all your help

[JohnChamplain]

do you know what default x y z power pot is on the gshield? what does inventables set it at or is it just random?

Setting the stepper motor current limit

The potentiometers on the gShield are setting the Vref (Voltage Reference) level on the TI stepper motor driver chips. This determines the current limit for the driver. You can measure this voltage at one of the potentiometer pins (see photo) and adjust it to obtain a given current limit. Use great care as the potentiometer pins are very close to other components and it is easy to short the pins together with your meter probe. Really bad things happen. The gShield (version 5) uses a 0.1 ohm …

[HaldorLonningdal]

i didnt know thqt larry very interesting drivers get current all the time and not on demand…when needed…that seems wasteful and unnecessary wear and tear on the drivers to me…

Steppers are very different from a standard brushed electric motor.

The power need to come from somewhere, an idle/non-rotating brushed motor require nothing - because it is doing nothing, and you can spin it easily by hand. A stepper motor at “idle/non-rotating” is forced by the driver to stay put and will resist hand turning. This require power.

Your stepper based 3D printers and laser do the very same.

[RalfFerly]

thanks for all the info…im going to try to tinker with it today a bit doing some testing and changing and adjusting

one noe though

if i have machine disconnected powered off…and i push the gantry back and forth at a fairly high feed rate, at the right y motor area there is a grinding sound …not the entire way but just random as pushing.

[RalfFerly]

thanks haldor now that you mention that, it makes sense

the steppers need power all the time to keep position

[HaldorLonningdal]

if i have machine disconnected powered off…and i push the gantry back and forth at a fairly high feed rate, at the right y motor area there is a grinding sound …not the entire way but just random as pushing.

Disconnect power AND disconnect the belts one way or the other, so the only thing that would cause friction are the wheels. Motion should be smooth with uniform friction.

[RalfFerly]

problem still not fixed…

haldor thank you will do that when i get time

earlier i did some mechanical and elec troubleshooting i found some very loose screws as i suspected that were on the right y motor terminal so i tightened them and ran machine about 16 inches back and forth on y axis via easel

with no issues about 20 diff cycles so i decided to run a cutout program

i ran the program using 1/8 bit .025 deep at 25ipm…i babysat it…it ran great for about 7 passes and then on the 8th pass about half way through it decided to do an out of path move so i unplugged immediatley the out of path move was not z issue and im not sure if it was y or x …because it stopped for a couple seconds and then crazy took off on wrong path…

oh well…will keep troubleshooting when i have time

thyanks

still losing steps apparently

[HaldorLonningdal]

still losing steps apparently

Untill you measure Vref voltage of your drivers we won’t be able to tell if its set too high or too low.
When you have the time.

[RalfFerly]

hi haldor since weather was nice out today i was abel to get outside and test vref

x 1.05
y 1.09
z 1.15

these values were never changed…stock settings

what should i do increase them or are these values ok?
i think larry mentioned they should be higher?

[RalfFerly]

here is my theory on the vref on my machine

since mine is a late 2015 early 2016 model back then they offered nema 17 as standard and you had to upgrade to nema 23 if u desired

i bet the gshield driver vref stock setting was calibrated for the nema 17 motors?

according to some othe posts voltages of 1.2 or so would be ideal for the neam 17

i have nema 23

im waiting ot hear back fif i should increase voltages…on all 3 or just y ? given the voltages i provided

it seems they should be about 1.9v each?

[AndrweJerman]

I had the same problem with my 2015 unit which I too bought used. I eventually resolved the issues, which were multiple, but realized that I really needed to upgrade to a new controller so I just recently completed the Demon Controller. I hope to have it in service next week with new 269 oz steppers.

By the way, what spindle are you running?

[HaldorLonningdal]

x 1.05
y 1.09
z 1.15
these values were never changed…stock settings

Increase to 1.4V per axis, any change?

Vref (Y) = 1.09V => 1.36A current limit / 2 motors = about 0.7A per motor
24V x 0.7V = 16W

Your Nema23 steppers can take up to 2,8A each, while the gshield can as a theoretical max wth active cooling provide 2,5A. But in terms of reliability 2A is max with active cooling, providing a little headroom.

Bottom line, the gshield is unable to take your steppers to the max and that is before we consider the two Y-motors sharing a single driver. The Controller for instance have 4A capacity per driver, and 4 drivers => the Y-steppers can have one driver each.

[RalfFerly]

Dewalt 611

Hey haldor i adjusted vref for x y z to about 1.7v

I got ur message after

I ran a cutout program about 1 hr 3/4 plywood and had no issues

Maybe that was part of my problem since day 1…my machine has lost steps on several occasions since i have owned the machine …the loose connections at the y motor prob didnt help lol

Thank you and larry etc…i hope this helps…we will see

Should i leave at 1.7 or drop it a bit?

I have nema23

[RalfFerly]

Design flaw …if you cant take advantage of full capability of the motor why offer the motor?

Poor design period.

What they should have done if their designers were using common sense is to offer the nema23 and include a more compatible driver board with it

[RalfFerly]

this is what i tried to machine for my friend…and luckily i was able to save it by flipping it ovver and not show all the lost step boo boos

so its a left handed hockey player now…not a righty lol

[RalfFerly]

here is the boo boo side