wires, wires, everywhere wires.

[Mike Wenman]

Ok..so I have this homebuilt 3-axis (3 motor) CNC that has been giving me fits and even when it does decide to play nice, the limited cutting area (18.5" Y x 37" X) just isn't doing it for me on some things I need so I have built a table with torsion box to hold a full sheet of 3/4" MDF (49" X 96") and am building around that. Other than the Z axis using a 1/2"-10 5 turn 2 start acme screw, the Y and X will be chain driven.

Wiring the
Y and Z up are no problem, but now with the wider table, will require 2 X axis steppers instead of 1 so here is where I'm getting stuck.

I have ordered another motor and driver to add into my system.

I "should be able to put both drivers onto the breakout board where pin 2 is step and pin 3 is direction and of course power to the drivers is no problem there, but the catch for me is the actual wiring of the motors themselves to the drivers.

With just 1 motor I was wiring in pairs as this:

Red-White / Blue-White to A+
Red(solid) / Blue (solid) to A-
Green-white/ Black-White to B+
Green(solid) / Black (solid) to B-

When I jogged the axis in the + direction, this would move the gantry from left to right in a + direction. (when standing at the side of the table)

now, when adding the 2nd stepper, which will be on the opposite side of the other, are they wired the same as indicated above or do I wire the greens/blacks to A+ / A- and the reds/blues to B+ / B-

a quick guess at this is yes to swap the pairs to the diff spots otherwise with them both turning the same dir, this will result in twisting of the gantry.

Thanks again.

Mike

[John McClanahan]

Mike, what software are you controlling the steppers with? If it is Mach 3, you can / should set the extra driver up as a slave drive. Look under the config menu. Also, if the direction is wrong, it can be reversed in the software.

John

[Jerre Griffin]

My mill uses 2 steppers for the X axis. It is wired exactly as if it was only one motor. Both sets of stepper wires sent to 2,3 BOB same colors etc. This has not been a problem. I thought about slaving via Mach3, but the manufacturer of my kit said not to worry about it and so far (6 months) it has worked flawlessly. It also leaves open 8,9 for the A axis.

Jerre

[Hennie Helberg]

Mike,use the second x-axis motor as a slave swap the wiring around as you described it but don`t attach them to the gantry. Stick some form of needle onto the shafts of the motors.If you jog your x-axis (gantry) to move to a x+ direction the needles should show that one shaft turns clockwise and the other anti clockwise.Hope it helps,for more tech stuff go to the MechMate site you should pick up some info as we run two motors on the x-axis gantry.

[Jerre Griffin]

Mike

I should have said, wire both motors identical to their respective drivers (in my case keling) just run the step and direction from 2 and 3 on the BOB to both drivers. I am not sure why you would want the stepper shafts rotating in opposite directions. Mine rotate together in the same direction. This has been working fine for 6 months. My machine is 2 x 5 and the gantry is MDF.

Jerre

[Dave Johnson29]

I have ordered another motor and driver to add into my system.

Mike,

You are opening a can of worms for yourself. Trying to get two motors to step at the exact same time, rate and distance will require great faith and a good heap of black-magic. The most likely outcome will be even less power as the motors fight.

I have built MANY CNC machines over the years ranging from Sherlines 2-1/2 ton milling machines. On the two occasions I I was devoid of good sense and I tried double motors I think that was when I lost most of my hair.

The only two solutions as far as I am concerned, are, a single bigger motor or gearing the existing motor and running it faster. Maybe a third is a combination of bigger motor and gearing.

There are some (very few) designs available online that use two motors but caveat emptor.

[Mike Wenman]

oh goodness...I thought I had hit the post button, but apparently it didn't take on my latest response...

Ok..I have purchased the BlackToe hardware kit that some of you may have read/heard about on a build your own cnc website. I already had plans for a small 20" x 40" of his, but it just wasn't working out for me. This new table uses a full size MDF sheet for the table.

I already had a 3 motor / driver kit from Keling that uses 425 Oz/in steppers so ordered and just received another stepper and driver of the same as this new CNC calls for 2 steppers on the X-axis directly opposite of each other.

Many others have built and are running this setup with no problems and the size of the table definitely fits the bill for me even though this is a hobby system.

I am using Mach3 and kind of understand the cloning/slave aspect of setting up the software but not really.

As mentioned before, these motors have 8 wires which I have as follows:
A+ A- B+ B-
Red-white RED Green-white Green
Blue-white Blue Black-white Black

Step and Dir are connected to pins 2 and 3 of the B.O.B

Do I connect the new Driver also to Pins 2 and 3 of the B.O.B or to where A or C axis would go on pins 8 and 9?

if to 8 and 9, then In Mach3, I think I can just check a box to change polarity, but if also connected to 2 and 3, then I would have to "reverse" wire by making my A's to B's and B's to A's correct?

have searched and searched the web but no luck seeing any diagrams so I can get a visual.

Goodness..when is this snow and cold going to go away so I can get out for a harley ride or atleast some good fly fishing? Atleast then I wouldn't be couped up inside asking all these questions.

Speaking of questions, I have one in regards to fly fishing..how do you all catch them little bugers? I didn't have any luck last fall..they sure are elusive critters..not one fly caught..just a million and 2 skeeter bites and a fish or three, but no flies..darn! :P

[Jerre Griffin]

Mike

I also have the Blacktoe. You can use the 8,9 pins for the new keling driver. Then you would need to slave the drive in Mach3. I am planning to add an A axis so I want the 8,9 pins for that axis. When I asked Patrick about the dual motors, he suggested that both Keling drivers for X axis be connected to the BOB via 2,3. The motor wires to the Keling drivers should be identical for both steppers. They will both go the same direction of rotation. If you reverse one motor you will skew the gantry and create a mess. This can also happen if you lose steps on one stepper and not the other. I don't know if slaving with 2,3 and 8,9 will have any chance to prevent non coincident movement. In practice this has not been a problem when running jobs. I do check for coincident motion with a right angle across the table before each set up of the day. Has not been a problem, but I check each time.

Jerre

[Jerre Griffin]

Mike

On another note, I wore out the aluminum rails in 6 months, so I changed to 3/4 angle iron on all axis. Just so you might want to do this during a build rather than disasembling the unit after you wear them out.

Jerre

[Mike Wenman]

Jerre,

Thanks much. I'll just put the new driver on pins 2 and 3 and wire the new motor up exactly how the other one is. Still don't see how that will allow one to turn CCW as the other is turning CW, but if it works, it works...lol

Mike

[Jerre Griffin]

Mike


The shafts do not spin in different directions except when called for by your gcode.. Unless you have a right and left hand thread screw,( the screws shipped by Patrick are from McMaster and are identical 1/2-10 5 start if you took his recommended package). Just set up as Patrick advises and you will be OK.

Jerre

[Mike Wenman]

I am not using the lead screw version (v2.1) but am building the upgraded chain driven version (v2.2) On v2.2, the motors are not at the end of the table, but are on mounted on the gantry sides opposing each other.

If at the end of the table, yes, both motors turning CW would move the gantry along the axis the same, but with opposing motors, it is like the rear end of a car. if you jack the back up and turn one tire CW, the other side one turns CCW

This is the reason, I believe, I need to swap the A's with the B's

Mike

[Jerre Griffin]

Mike

Patrick addresses this in a post on his forum. Basically on one side of the gantry the chain goes over the sprocket and the other side it goes under the sprocket. I guess this is because of the locations of the motors. Sorry for the confusion, I thought you were using leadscrews. There are a lot of answers on Patricks Forum relating to the build you are doing.

Good Luck

Jerre

[Mike Wenman]

So I've been trying to cut pieces for my new 4 x 8 machine using my small 20" x 40" machine and since it's inception, it has been nothing but UNRELIABLE and still continues to be that way regardless of how many times I have taken it apart, put it back together, and even cut all new pieces and put it together.

It will either plunge down when only supposed to go -0.125 or after I have drilled a hole down to -0.75 it will not raise up correctly or all the way then go ripping through the piece to the next spot.

On some ocassions when the system appears to be running fine, say when doing a profile cut with even a horrendously sloooooow feedrate of say 10, instead of staying on path at each pass around the perimeter, it will slowly and gradually reduce the piece in both length and width soooo, I'm inquiring if anybody that reads this forum lives in or near Colorado Springs that has a full size table that would be willing to assist me in getting my parts cut. I have .dxf files and also .NC cut files for use with CamBam to generate gcode. It's all cut out of 3/4" MDF.

Thanks.

Mike

[Rob Wright]

Mike -

A quick tip on how I cut my Joes 4x4 on my small Solsylva that had the same ailments that you describe:

Only peck the holes to a depth of 0.125

Only do a single profile cut to 0.125

Then cut them out with a jigsaw, and use a bearing patter bit in a router table to follow that good 1/8"profile cut that was done with the router. You can do then use a drill press to finish the smaller through holes with the correct dia bit. Use the same method to cut out large internal holes by removing the build with a forstner bit and jig saw and use the router table again to clean it out.

Hope that helps you out some. I know how frustrating it can be trying to cut out parts on a small machine that is not cooperating