I am coming back to you because i am facing a new problem with Estlcam that i just noticed now.
2 days ago i had to do a job with the CNC wich required me to drill 500 holes on a table, each holes spaced between them by 30mm center to center.
When i started the job i noticed just by my eyes that the spaces between them were not 30mm, i grabed my ruler and i measured 37.5mm. So i stopped everything and cre-checked and controled everything during hours and making tests again… At the moment i am writing this i did not find why this happens.
Here is all i checked and what i can say so you can help me:
My file is a DXF, i checked the spacing and it’s ok: 30mm center to center
Checked in Estlcam to by displaying the grid in mm with a pitch of 10x10mm. Okay i have 3 graduations between my holes, center to center.
My hardware is Ramps 1.4 in 1/8 step resolution with Nema 17 1.8deg. 200 steps per revolution, 16T pulley and 2mm pitch belt.
Using Estlcam to control my Ramps 1.4 with the following settings: XY at 1600 step/rev (200 @ 1/8), 32 mm/ revolution (16*2)
Now the measures:
When i make 1 revolution manually on X or Y axes by placing a mark on the pulley, i am measuring a traveled distance of 32mm so i guess it’s
okay
When i send the command : X30 Y30 to the CNC wich should move the machine of 30 mm on each axes, i am measuring a traveled distance of 37.5 mm
exactly on each axes !
So what the hell i am missing ??? Cause i am scratching my head since 2 days without finding why… :(:(
Please if someone can help me that would make my day… even my week !
Hi there,
It may just be possible that there is a mismatch of belt to pulley.
You may have a 2.5mm pitch belt and a 2mm pitch pulley or vise versa. I had that and it took a while to find! Your error is 25% which ties in with 2 to 2.5. Check carefully!
Good luck
I also turned around that K factor of 1.25 but did not thought about a belt or pulley problem…
The problem is that when i make a manual full revolution i can measure 32mm (16tooth x 2mm) of travel so the picth should be fine no ?
Do i have to set anything in the Basic Settings section when i use Estlcam firmware to control the Ramps 1.4 ? i tried to change CNC feed unit from mm/s to mm/min just in case that it could be the problem but nothing changed in the traveled distances when i change this parameters…
Matt,
I do not think so. If the steps per mm are set correctly and the stepper drivers are also at the required setting, then Estlcam will do the rest.
A 20 tooth pulley will also give a 25% error if it should be 16 tooth!
I printed T5 pulleys for my cnc machine and found that the diameter of the pulley had to be correct with regard to the number of teeth otherwise an error would creep in.
I’m sure you will find out where the problem lies and look forward to the answer.
The only thing that bugs me is that 1 revolution gives me the correct 32mm travel… so why when i send a command like X30 Y30 the CNC travels for 37.5mm ???
I will do this indeed but i do not have access to the CNC at home
So i am gathering informations so i can solve the problem tomorrow.
Do you think that if my travel distance is correct when i manually make 1 full revolution, the problem can exist when i send a travel command ?? How could this happen ?
I ordered one of these shields. Can you tell me how to set up the 4th driver for my second motor on the y axis?
And what should I select under Pin Layout? Estlcam, i guess?
@Ryan better to wire the steppers in parallel. I have a pair on MPCNC X & Y that measure 12.5 ohms each, set the total current at 0.8A (0.4A through each one) with a 12V 4A supply. great travel speed, nothing gets hot. I found when I ran about 0.8A through each one they really got got after 1/2 hour or so. Drivers stay very cool also.
The steppers I sell can individually max out the drv8825 stepper drivers, when wired in parallel they each get about half the desired Amperage and are not as powerful as when wired in series and can each get max amps, almost doubling each steppers power output. Wiring in parallel works just fine but with larger steppers you are not using your steppers to their maximum potential.
@Ryan@Vicious1@Christian I took your advice and ordered a CNC shield and an Uno. Plenty cheap on Amazon $23 including 4 DRV8825 driver boards.
I finally realized ESTLCAM uses its own motion control (not GRBL) and simply supports the pinouts of the CNC shield (GRBL 0.8).
I think I like this better than the RAMPS1.4/MEGA2560 I was using. At least spindle control now works as expected. Haven’t tried the probe yet, but limit switches work OK. Machine movement seems somewhat smoother than before but could be my imagination.
So far, a tidy solution, smaller and easier to deal with for CNC routing. thanks…bb
@Ryan I suppose if your steppers are low impedance (3-6 ohms), high current and you are running out of current available on the driver, then you don’t have much of a choice except to put them in series. I don’t see anything wrong with that approach.
My NEMA17’s are 12.5 ohms with a max current rating of 1.4A. With a 12V supply max current will be only 0.9A each, (1.8A for two in parallel) and that’s about as much as the DRV8825 will source with forced air cooling. I found that I didn’t need nearly that much current for good operation and the motors would get too hot after a while even just resting. Running at 0.8A for the pair (0.4A each) everything runs cool without a fan. In theory, I should probably use a higher supply voltage which should make the motors accelerate faster, but I haven’t had a speed problem.
So it depends on the situation how best to connect.
I personally prefer parallel as the back EMF tends to help the motors stay in sync. I’ve come to think this is better than using separate drivers.
