Me too! Same way. Connect the A+ and A- to see if the stepper engages (turns more difficult than without the wires connected), if so, no harm done to the stepper. See also Mark's video at the time stamp where he is checking the wires of the steppers for connecting. I used the TB6600 stepper motor drivers from Ebay (China origin). But think will go for other ones to replace these. Too vulnerable apparently.

 

Did you ever get an answer for this? I'm trying to get mine all calibrated up so I can really start chewing through some materials.

So far my settings are giving me accurate measurements when testing the X and Y axis out. My Z is acting a little squirrely. If any of your masters could look at my config that I posted on my DropBox https://www.dropbox.com/sh/ll69wwon389gxbp/AAAVQ5lxE9SHIQcHdA2hpnepa?dl=0 that would be awesome. As for the "Squirrely" Z axis, Here is what's going on. When I start a job, it brings the Z axis up, moves over into the work area (It does this really really slowly I might add. It takes a few minutes to move the gantry. Slowly ramps up to a velocity of 50mm/minute until it gets to where it needs to drop the spindle??? Really confused on this) Then the Z goes down into the workspace, but goes down way too far, and bottoms out on the bed. This is even after I have set the safe Z distance in tgFX. Jogging the Z manually, and it stops itself at my pre-measured distance ok. If I pause the job, manually move my Z up, and resume, it goes about it’s business fine. I figure it’s got to be some sort of weird configuration / faulty end user issue, but I’m at a loss of where to start. I have some limit switches enroute, but they won’t be here for about a week. I plan to use them as limit, and limit/homing sensors. Do you think that would help my cause out? I should note that my Z motor is a NEMA 17 0.9 degree motor.

 

Stepper=generator when you turn it by hand, I knew that! Even when I pushed the gantry forward just a little, I was aware of that effect. No smoke though when I did it. Anyway, I dare to call myself quite stupid by knowing it, realizing it and still doing the dumb thing. Now, you all can call me stupid for it, I just cleared the way.

Which brings me to the question to you all; how can a stepper motor driver be protected against this feed back of power into the board? Not being really into electronics, I believe a diode or so should do the trick?

 

@ Rhinofart, I calculated it again and again, the settings for the GT3/3mm pitch belt with 20 tooth pulley and Nema 23 at 1/8 micro steps should be 26.66667 and for the Z with ACME 8mm Lead screw 2mm pitch direct drive (through flexible alu coupling)and with Nema 23 should be 200 steps/mm.

CNC USB controller software has a handy calibrating tool that can help to fine tune this even more. The calculation is the theory, but the measurement in real life is the true value. Calibration with calipers and precision ruler learned me that the X (shorter distance than Y) is only a couple of hairs off, while the Y had a bit more that needed correction. The Z calibration I did a couple of times to be sure, and the value came there at 199,69 or so. I rounded it up to 200 steps/mm.

Hope that helps a bit?

 

Hey David.
Thanks for the quick reply. I'm using Sketchup to create the part, and SketchuCAM to generate the gcode. I just finished doing a "Successful" job on her. Didn't have the spindle running. It worked well except for the time it's taking to get the tool out into the work area, and moving from one cutting section to the other. I have a YouTube video of it uploading right now, and it should be available on Youtube when it's done processing. I'll add the gcodes that went "sideways" to my Drop box listed above. The files with the Prefix "Borked" were the failed ones. Lots o shapes was the job from the youtube video, and Measurement Testing was just 2D (X & Y only) In the Youtube video, the job starts as soon as you see the spindle come up off the board, and then at about minute 6, the job actually starts it's cuts and such.

 

Hey Prauk, that did help me out a lot. I'll delve deeper into it tomorrow after work. It's 1:30AM for me right now, and I have to get up at 6:30 for work (and to check out that super rare lunar eclipse that's going on at sunrise. Moon is setting while sun is rising. Blood Moon I think they call it.

 

Rhinofart, 5mm/min is slower than a dead turtle! Try 500/min as a starter. I jog with 3000/min and use 500/min and up for cutting. 5mm/min is about 30cm an hour! Which controller are you using? Your Z is making way too much noice. Grease the ACME and make sure the ACME is lined out properly with the bearings top/bottom!.

 

I just receive my CNC xPRO drivers and connect it to the motors and had my first movements (nice little creature). Have to do some tweaking in the steps per unit and will try to jog the machine. The motor did not suffer any damage. The only thing I notice was with the 26.66 steps per unit the machine was moving very slow, don't know it was this or something else.

Thanks,

 

Put the center of your router bit (or a pin point) just above the table, put a ruler at 0 exactly under the center parallel to the axis you're measuring, jog the axis you're measuring on the screen for a decent distance (about 300mm) and reed the distance travelled according the screen, now look on your ruler if the distance there is the same. If so, the 26,66 steps must be correct. Otherwise, re-calibrate or recalculate.
Speed of movement can be set in all kinds of different screens in your software. For example, jog speed can be 3000 (pretty fast for a small OX!), travel speed (for homing etc.) can be 1500, and cutting speed can be anything between 100 and 3000 (depending on cutting depth and material you're cutting).

 

I would make a video to show this, if it were not the case that one of my motor drivers blew up. Have to wait for a new one to make the vid.

 

Robert, since you have the same motor drivers as I have and one of mine blew up yesterday, do you think it is possible to have two steppers on one of these TB6600 and set the driver at 4.5A to compensate for the load of the two? The slave stepper can be connected with the A- and A+ on the B- and B+ of the driver to have reversed motion? Thanks in advance for your help.

 

OK now I'm officially lost trying to configure the Grbl. I did manage to jog the machine using different steps per mm from 26.67 to 1600 steps. My confusion is all the other parameters seem confusing for me. First time using mm and this software. Can some one show me how to configure the Grbl to use it.(basic parameters) My machine is 1500 x 750 and using a 1/2" acme screw as z axis.

Thanks,

Alberto

 

Thank you for the help David! You're pretty darn knowledgeable if you ask me! ;0) I'll check into those settings when I get home, and put the family to bed. One bit of clarification though. Did you mean, to type G00 X100 Z30, or did you mean X100 Y30?

 

Many stepper drivers incorporate the necessary diodes to protect the driver chip against the back emf but even then it would be unwise to manually rotate the connected stepper at a fast speed.

Tweakie.

 

Yep, see what you mean. Here is a picture of the TB6600 I'm using now. I see no diodes in there, do you? If possible this year, can somebody help me with the question about connecting 2 steppers to one motor driver? The one that is in the picture?

 

It can be done but I wouldn't suggest it as the motors would be under powered.
For the cost of them drivers I would just buy a new one.
A key factor when working with these drivers is to never change dip switch settings while powered or unplug motors because it will burn up

 

Thank you Robert! The last sentence I can fully agree with (now, after screwing 1 driver up!). Just hooked the 2 Y axis up to one driver and it seems to work. Tomorrow morning I'll give it a more extensive try and testing. Now I have your attention; do you think I can partially compensate the under powered situation by cranking up the amps to 4.5 (max of the board)? Or would that result in too much amps going to the motors and blow them up? Thanks for helping.

BTW, of course I will buy a couple more. But since they take a month for delivery, I would like to go on with things. Your previous advice about having a driver for each motor was a very good one! It means that you can stay in business by jury rigging the thing until new ones arrive.

 

Yes you can crank the driver to full blast, it's just going to run a little hot.
Your motors should handle it just fine

 

Yes they are built into the IC but still not good enough for protection, same as the older TB6560 hence the diode array on them chin boards

 

Each stepper motor needs it's own driver.
Basically, connecting two steppers to one driver used to be done years back when steppers were only operated in full or half step mode. The advent of microstepping made this practice unsatisfactory as they can quickly get 'out of step' and the software 'gantry squaring routines' will not work to correct the situation.

Tweakie.

 

Thanks everybody for the answers. I'll give it a try with higher amps. Since it's only temporary until the new drivers arrive it might just last for a month.

Tweakie, where can I find the gantry software squaring routines in the CNC USB controller software? Didn't see that one passing by. The hardware is square right now (somehow that last 0.35mm disappeared today while moving up and down for testing???). But I'm always interested in an extra software solution for it. Busy with 3d printing some extra gadgets for the OX. Will be posted (after testing) in my build under files. G'night ya all!

 

You need to contact Planet CNC or check out their forum for the answer to that.

I use Mach3/4 and 'gantry squaring' is done as a macro (part of the 'homing routine') and I am sure Planet have the same or a similar routine which you would be able to use.

Tweakie.

 

For anyone who was helping me out (thanks for being patient and helping me learn), or for anyone who cares my OX is now working beautifully. I had to do a little more calibration with the help of the TinyG guys, and the thing that fixed my issue was.............. I swapped out my power cable between my 12v power supply, and the TinyG board. The only wire I had in the house long enough, was some 16 Gauge speaker wire. Anyway, I get full speed movements from G0 commands now as well as G1. This weekend, I start chewing through wood, acrylic, and some aluminium.

 

Congratulations Rino!

How long did it take you to get your ox running?
From receiving the last part until now?