ramkitty x3 conversion

[ramkitty]

I have gleaned enough information to begin my cnc conversion build. The components so far are as follows.

Grizzly G0463 mill
CNCFusion deluxe kit (on order)
Keling KL23H286-20-8B 425 oz/in stepper on x&y
Keling KL34H295-43-8A 900 oz/in stepper on z
TB6560 3 axis el-cheapo stepper board. I bought it long time ago and am finally putting it to some use.
Currently I am using a xantrax desktop adjustable power supply at 24v

I also bought the estop and some cheap microswitches for homing from keling. The estop is feels really cheap but it was 10$.

I knew how to use cad before and I taught myself solidworks. I then taught myself mach3 and watched many videos on its use and operation. Next was learning solidcam which I am reasonably comfortable with.

After learning cam I figured I would wire up the board and configure mach3 to use it. I was able to input a GCode file and could see the axis led lit as the machine was moving.

Today I received the steppers and wasted no time to wire them up Bipolar Series. I started with the x axis stepper and configured it to move based on 1/8 micro stepping. Success was had after a little bit of toying around and figuring out how many shaft revolutions I should get per inch of movement. With that done I repeated the process for the y axis with no troubles. Moving to the large z motor I wired it up and was having issues, the motor appeared to jitter which I determined to be resonance. Increasing the acceleration seemed to solve the problem.

Next I will have to wait for my screws to arrive to modify the machine and in the mean time I will set up my switches and think about an enclosure. I will not tweak the motors too much until I get them on the machine and make some measurements.

[doorknob]

Good luck with your build.

I'm curious as to why you decided to wire the steppers as bipolar serial. Was it due to wanting to reduce the maximum current draw by the motors? The trade-off would seem to be reduced max speed capability due to the voltage constraints on your power supply and on your TB6560 board.

[ramkitty]

First of all I do not know what most people are doing but my controller board is limited to 36v but it recommends 24v for nema23 motors. Also the current is limited to 3A on the chips (3.5A peak) and the nema 34 motor I have runs at 3A in series. I could run the nema23 motors in parallel and still be in spec but I do not know enough about the tradeoffs of the different configurations. It was my understanding that series has more torque but less speed (and current) as I do not have the machine hooked up I do not have a physical example of how fast (or slow) my setup will be.

[ramkitty]

cncfusion kit has shipped

[Johann ohnesorg]

You got a real mill. So please get a real motor controller. Get a real power supply, too. You limit your motors and therefore your speed with this cheapo driver and the miserable "power supply."

[ramkitty]

The cnc fusion kit has arrived. The build will start comming together.

I understand that the motor controller is subpar, I had it on hand and its more of a proof of concept unit. Once I have a working setup it will be replaced with a better unit.

I do not understand your comment on "miserable power supply". This is a lab supply having accurate regulation in voltage and current with capacities well under the maximums of the unit.

[skullworks]

Most people run power supplies up towards the top end of the controllers capacity.

Using the baby Geckos (G251's) and a Kelinginc KL5010 50V 10A with the motors wired Bipolar parallel for maximum performance is hard to beat.

For your setup I think the same would serve you well. G251's for X/Y and a G203V (or a G201X if your brave) to run that big Z stepper.

Many users opt for a 48V switched power supply and it has proven to work, I just like using liner power.

That and having silent steppers when the machine is not in motion make things even better.

[ramkitty]

I understand but I am running at the top end of the controller, I read that anything over 24v could damage the controller even though it is rated to 36. I am also limited to 3A which is why I chose to go with the bipolar series rather than parallel. I retain full torque at the cost of speed. The power supply and controller are not meant to be permanent and will be replaced eventually, earlier once I see how pitiful they will be based on other peoples comments.

[photomankc]

You're losing a large amount of the stepper's performance at 24v. Those 425's are 80v motors as I remember so in order to get the rated performance from them in a chopper drive you need up around 80v to drive them. Picking the motors and drivers is something where you either want to really know what are doing and understand all the theory in it or stick to the packages that are normally used for that machine.

I had those 425's and they were dogs at 50V so I doubt you are going to be wowed at 24V. HobbyCNC has some lower impendence 425's that would be faster and a little less demanding on the voltage ~60V

[SCzEngrgGroup]

You're losing a large amount of the stepper's performance at 24v. Those 425's are 80v motors as I remember so in order to get the rated performance from them in a chopper drive you need up around 80v to drive them. Picking the motors and drivers is something where you either want to really know what are doing and understand all the theory in it or stick to the packages that are normally used for that machine.

I had those 425's and they were dogs at 50V so I doubt you are going to be wowed at 24V. HobbyCNC has some lower impendence 425's that would be faster and a little less demanding on the voltage ~60V

Higher voltage helps get higher speed, not torque. The increased voltage allows the coils to saturate faster, so they spend more of their on time running at max current. Since he doesn't seem concerned about speed, the higher voltage may not buy him anything at all.

Regards,
Ray L.

[ramkitty]

Especially without replacing my controllers which is another 300$ I will have to wait to spend. I will get it running on what I have and see where I should go from there.

The mechanicals are all installed I will start wiring for the servos/switches.

[photomankc]

I can certainly understand. I actually tried to use the Keling 425's but they would stall on me unless I crawled along and that was at 50V. However right now I'm running stock screws so I have more friction to overcome and also have to run double the RPM of most setups because of the 10 TPI pitch of the screw so you may have better luck you'll just have to see.

And yes, those TBXXXX drivers are known to blow due to the spikes that the motor coils by nature generate when switching off (back EMF). The driver chip or the circuit has to dissipate that energy and it can hit well over 100V so even though the chip can handle the voltage and current of the drive, it may not be able to handle those spikes and I've seen them with chunks missing when people tried to drive them at 30V or higher.