Back Doing Some Arcade Fun #19 - Smith's Falls, Ontario, Canada

[bradyaero]

Does anyone know how to wire the PK296A2A with the gecko 203? I have my motors and everything is ready to go, just have to get the motors connected for a test. I can't seem to find out exactly how to hook up the motors to the driver.
My PS is wired for 72vdc so I have to wire them using Bipolar Series.

My best guess is to ignore the middle lead on the coils?

Thanks, Greg

[Roadkill_321]

imageresizer.jpg
Greg,
Here is the diagram from the Oriental Motor website that I used. The PK296-A2A motor is a 6 lead motor, so you can connect the Black and Green to Phase A on the Gecko 203V, and then connect the Red and Blue to Phase B. If you need to reverse rotation of the motor, you can just reverse one pair of wires.
Hope this helps.

John

[bradyaero]

Thanks John,

That seems to work although I am only getting one motor to fire. (X). All the lights are green on the gecko's and the signals on the PMDX122 are green as well. I must be missing something basic!

[smreish]

make sure in Mach you have all the ports and pins correct. Them make sure they are enabled on. The quick set up in the Mach video tutorial will walk you thru this if you haven't done so already. Sean

[bradyaero]

It's all good, the only thing I'm missing is the actual step per value (i have 3000 by default) and the real step pulse and dir pulse (which I set to 5).

(my dir wire was before my step wire so I had to reverse the fields in mach3 and away it went!)

It sure feels good to see 4 motors moving

many thanks, Greg

[Gerald D]

Originally Posted by bradyaero

. . . My PS is wired for 72vdc so I have to wire them using Bipolar Series. . . .

I don't catch the logic, but then it is only 6.30am here . . . . Explain please?

Glad to hear the motors are all spinning now!

[Richards]

The A2A motors have an inductance rating of 6mH series and 1.4mH half-coil, so 1000 * SQRT(6mH) = 77V MAX bipolar series and 1000 * SQRT(1.4mH) = 37 V MAX half-coil.

[bradyaero]

Hi Gerald,

From what I have read because I have 72vdc I have to run the steppers in full coil mode.

I've noticed that the gecko's are running a bit warm (I can keep my hand on one but it is warm); this is just running the roadrunner program using quantum. (I am using a 22k resistor and the motors are staying cool)

Would it be a better idea to drop the transfomer down to 25vac and then run the steppers in half coil mode or am I over-reacting?

Many thanks, Greg

[domino11]

Greg,
Do you have the Geckos on a heatsink plate? If you can keep your hand on them with no heatsink, the plate will improve the situation. Just being able to keep your hand on it doesnt sound like they are getting very hot. Should be no problem. Are you able to measure case temp? Thats the best way to know if you are close to the limit on the Gecko spec. Just remember you need to keep in mind the temp in your case and temp rise during the warm months.

Good to see someone in my neck of the woods

Heath.

[bradyaero]

Hi to everyone on the forums, and many thanks for all the help and good advice. It's a great group to be a part of and I thank Gerald for the tremendous effort he has put into this community.

I'm building a mechmate for the purpose of cutting foam for molds including windmill blades and for airplane parts. My challenge with the mechmate is to get as much z as possible. I'm trying for 8 inches of cutting clearance.

For my kitchen table project I decided to use the power supply and case from an old pc. I tore apart the power supply and then bolted in my torroidal (wired at 50vac) and ran the wires to the existing power supply switch. I also wrapped 18 loops of wire around the torroidal to power up my PMDX-122 (7.6vac) using the aux connector on the PMDX.

I then put the PS back into the pc case and added my PMDX-135 ac/dc converter. I then added my terminal blocks and wired them to drive the gecko 203's. I took a CDROM apart and used the case as a mounting point for the gecko's.

Based on forum advice I chose the PK296A2A- SG7.2 steppers and will be running with 30 tooth pinions. I wired the steppers in unipolar mode (full coil) and used a 22k resistor on the gecko's.

I installed quantum and was able to get a motor turning quite by accident. With some advice I configured the parallel port pins and all of the motors now turn. I now have to work on what the correct settings are for the motors in order to get an accurate feed rate going.

My next step is to get started on the table itself. I'm enjoying this project immensely and will post updates as they happen.

Here's a few pics of what I am up to:

[Gerald D]

Greg, this thread is for you:

Understanding & Selecting gear pinions - setting the steps per mm[inch]

[bradyaero]

Hi everyone,

Wow does time fly.. it's been eleven months since I got my controller working!

Here's a quick update for my MechMate. The goal for my MechMate is to obtain 16-18" of Z-Travel, the table is 132 x 78 inches. I made a square tube fixed frame that will have a 'bed' that can be raised or lowered depending on the job at hand. This may be sprocket/screw driven or it might be pinned to the sides, or it might be both.

To attach my rails to the frame I went with aluminum angle and drilled and tapped the BWC rails to attach. I originally cut adjustment slots in the aluminum angle to pre-position the rails. This made alignment really easy; I set one side straight and then rolled the gantry along squaring the other rail as necessary.

The rail leveling went surprisingly well. There were a few spots that needed to be raised. As soon as this was done I drilled and tapped more rail positions. I used a machinist level all along the frame and everything is within one line on the level.

My gantry also worked out well. Square was pretty much dead on without shimming, Wheel contact was also close. One wheel was out by 1-1.5mm so after adjusting it's height all four wheels touch with level rails.

The Z-cart was also bang on. Motor wiring has gone very well, I'm running tests with no load at 1000 IPM. I'm anxious to get the Z-axis done.

I'm waiting for my limit switches and my z-slide to complete my MechMate. I'm going with Gerald's original design that used a linear slide vs spider plate. (I found a 1.25" rail / slide with 33 inches of travel for $120.00)

Many thanks for all the help, Greg

* shameless plug * domino11's laser cut parts were top notch, accurate and well cut.

[Gerald D]

Greg! You are still alive! Welcome back!
(Don't worry, I'm not going to kiss you)

Nice progress

[bradyaero]

whewh! I was more worried about getting yelled at

[Kobus_Joubert]

Well done...maybe you can shorten that cable chain and send it to Marius ..

[domino11]

Greg,
I think you forgot to mention that it MOVES. I know I have seen it. Glad the laser cut parts worked out good for you. Nice to see some picture of my parts in the builds. Sorta give me that fuzzy feeling.

[bradyaero]

Originally Posted by Kobus_Joubert

Well done...maybe you can shorten that cable chain and send it to Marius ..

Lol yes, but I better shorten the cable and send it to Heath! Otherwise he'll have my head!

[bradyaero]

Hi Gerald,

Finally, my linear slide showed up! On to making a working Z... Do you think I should bend a solid piece for my Z bracket or use angle iron with cross pieces like you did for your original z slide? The assembly weights about 35 lbs, with about 5 lbs for the slide, 30 lbs for the rail. I'll cut about 10" off the rail which will bring the weight down to about 20lbs for the rail which will be the moving part right? Any ideas appreciated.

Thanks, Greg

[domino11]

Originally Posted by bradyaero

Lol yes, but I better shorten the cable and send it to Heath! Otherwise he'll have my head!

My cable chain looks good on your machine. I will need it later when my garage is done though. No rush for now. Or you could just lengthen your table and the length would be ok!

[Gerald D]

If I had to do it again, I think I would prefer 4mm plate to the angle iron idea.

[bradyaero]

The 4mm plate worked fantastic for the bracket. I welded up some plate and bolted it to the Y-cart and then bolted the linear slide to it. I then took the Z motor bracket and cut it from the spider plate and mounted it to my new bracket and test fit the Z stepper. I thought gee that's great for a day's work! but my friend Todd came over and said 'lets get it cutting' so off we went.

We cut (with a skill saw) some 5" x 1/2" plate and bolted that to the linear rail, Mounted the K2 bracket for my Porter Cable Router, mounted the rack, sprung the motor, soldered the wires and turned it on!

Of course I accidentally zeroed the Z to the bottom of a test board that we clamped onto the frame. The Mechmate was able to cut 1.5" pass at about 200 IPM with some screaming. I then e-stopped the machine and restarted it, accidentally driving the bit through one of my metal beams!

I got the Z zero'ed properly and was able to run the roadrunner program at about 1/8" depth on my test board (using a 2 flute 1/2" cutter -- slightly dulled tip!). I slowed the feed rates down to something realistic and the cutting went very smoothly.

So there you go for a days work! From no Z to a working Mechmate. The linear rail is incredibly stiff, I'll measure my runout soon to see how accurate my cuts are. I have 14" of Z travel right now, I have to move my linear slide up a few inches to get the 16" that I was looking for.

My next job is to make a proper bed and get my limit switches installed. And of course, I have some painting and a MechMate logo to install!

[Gerald D]

Well done Greg & Todd!

Now we need a pic of the hole in the metal cross support

[domino11]

Greg,
Looking Good. Did you get any video of the first cuts?

[bradyaero]

Hi Gerald,

It's covered up with sticky MM blue! Althought it was suggested I stamp my initials next to it as my first beauty mark

Heath, I hope to have a base board on it tomorrow as soon as the paint dries! Will take some vid on the next cuts, is there a MM g-code file around?

Thanks, Greg

[bradyaero]

Hi Gerald.

Here it is in MM Blue! I'm still waiting for the paint to dry on the lower unit to put my spoil board on.

Thanks, Greg

[domino11]

Hey that looks like almost serial number time!

[Kobus_Joubert]

Just have to get MORE dust on it...Well done looking good and enjoy the addiction.

[Gerald D]

#19 it is! Thanks!

Tried to figure how you connected the cables to the motors and scrolled back through the thread a bit. Those 2 wires that are not used should be separately insulated - it they touch ground, or each other, either the gecko or the motor will smoke a bit.

[sailfl]

Smoking Gecko, boy I don't want to see that.....

Congratulations on #19 from #12.

[bradyaero]

Thanks #12 from #19. I'll get those wires capped right away Gerald!

I'm going to bolt my bed assembly to the bed for now and then work on the 'raise-able bed idea'... I've really got the itch to get cutting!