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MarkRH Sun 30 July 2017 18:44

Singing a Song and Working Along, MD USA
3 Attachment(s)
Hello is anyone building mechmates recently?

I started with the kitchen table project enough to get one motor spinning knowing little to nothing about how to do this, then gathered a couple boxes and went with a motor driver package 640oz , 60v/6amp power supplies and the pmdx 126.
This will be my first attempt at posting pics also. I may have to load some better pics , the wire I am going with is microphone cable, the jacket says its 16awg but its more like 18-19ga and has a nice copper braided shield, only 2 core so I'm running 2 side by side to each motor. Still not finished the wiring but am about as far as I can go without a machine to start putting things on.

Attachment 16101

Not having a nice flat steel plate, I made a quick torsion box out of scrap plywood to keep the ycar square and flat.
The y car went together very easy, easier and quicker than the skate I found.
Thanks Mike

Attachment 16099

Attachment 16100

jhiggins7 Mon 31 July 2017 05:59

Welcome, Mark

Looks like you're on your way. Getting a motor spinning is a big milestone. Congratulations! Your pictures are fine.

MarkRH Mon 31 July 2017 18:31

Thanks John, does the mechmate community have a favorite place to buy metric fasteners that you know of?

lonestaral Tue 01 August 2017 03:50

Welcome Mark.
My favorite nut and bolt shop is at the end of my road.
Probably a bit far for you.

MetalHead Tue 01 August 2017 05:26

Also beware that mic wire is probably not CNC rated. You should look at spending a few bucks now and getting CNC rated wire for any wires that will be moving in the cable chases.

The mic wire can't handle the cycles (thousands) and will break internally sooner than later and drive you nuts troubleshooting the problem.

jhiggins7 Tue 01 August 2017 06:12

I prefer to buy by the pound at Tractor Supply or Rural King. Lowes and Home Depot have begun to carry metric sizes as well. I'll use Fastenal for hard to find sizes although they generally have a shipping charge if the item is not carried in the local inventory. Also, I used SAE sizes for several "non-critical" applications like the bolts for my "bolt-together" frame and spoil board attachment. I found Harbor Freight tap and die tools to be completely adequate for most tapping needs. The use of a good tapping fluid made all the difference.

MarkRH Wed 02 August 2017 15:30

Mike, that's good to know I somehow thought .30 cents a ft was too good to be true.
(with 300ft roll of the stuff ill have to take up singing!)
John, I have a local tractor supply had forgot they sold metric and before I saw these posts I ordered some of the ycar bolts from Mcmaster carr along with the gas spring 9416k2
Still cant find the Teflon washers.

jhiggins7 Thu 03 August 2017 06:45

I got the washers at Lowes or Home Depot (don't remember which, it was 9 years ago) in the "specialty" drawers. I may have used nylon.

MarkRH Mon 13 January 2020 16:38

1 Attachment(s)
Attachment 16470

She's cutting!
The accuracy is amazing.

Thanks to Gerald for his design and instruction thru the early part of this site, cant count how many times I referred to it while getting it up and running.
Thanks to Mike for keeping this thing alive and supplying great parts.

Seems to run very true as far as squareness at rest but do push against stops when powering up.
I found the correct wire rated for cnc for a decent price and went with that.

I am having one issue maybe someone can help with. (and another I just dont understand that ill ask later)

When peck drilling 1/4" holes .5" deep at 30"ipm (2 pecks) plunge rate the Z motor will miss steps with a noticeable knock sound which resets the z height.(its not the pinion slipping) Ive tried downcut bit first then upcut bit was a little better but still doing it. My Z motor is slightly smaller than all the others at 4A nema 34 with matched power supply, it seems very slightly easier to stall than the y pushing it while powered up. It also never really gets warm to the touch. Would power supply be bad? motor undersized? or plunge too fast? The machine is direct drive.

Thanks for your help in advance.

xraydude Tue 14 January 2020 09:11

Congrats, Mark!

I had similar symptoms due to the spring force that keeps the gear and rack engaged was not quite enough and it would jump a tooth on the rack occasionally when plunging, making a knocking sound. Just bent the tab that the spring attaches to on the Y-carriage back a bit to increase the mating force and have not had it happen again.

The other time I saw similar was with my gas tube outer sleeve shoulder catching the top of the spider on the down-stroke and making a clunk and dropping some steps before it slid past the spider. Just had to make a slight adjustment to the gas strut mounting points to provide full clearance.

Good luck!


lonestaral Tue 14 January 2020 13:19

Well done Mark.

As Ted says, check the spring tension and also
the gas strut pressure

sphericos Tue 14 January 2020 15:04

I have just encountered the same issue on the Z and also to a lesser extent on the Y axis. I have doubled up springs on the Y and moved the location of the z mounting further back.
I was getting random errors and I had been round tightening the grub screws on the pinions just in case but they were all rock solid The springs were showing some movement under load though and fixing this improved things a bit.
Ultimately it turned out most of my problems were caused by the bolts I tapped into my air cooled spindle to mount it to the z slide working loose. I will have to check them more regularly. It is the first real maintenance I have done in three years so I also concur Gerald came up with a great design.

MarkRH Tue 14 January 2020 16:08

Thanks, Ted, Al , David for the directions.
I checked grubs, spring tightness, even put my finger on the end of pinion while it was peck drilling and see and feel it missing a step within the motor, so I switched out the power supply with another one and reran it, same thing.
Next I took the bit out with spindle off ran the Z down to spoil board and it didnt even have enough power to lift the Y car up at all, it stalled right out and just bounced.
I guess I will replace the motor with the matching other 3?

xraydude Tue 14 January 2020 18:41

The only other thing I can think of is if your driver has a current limiting resistor/switch setting. You said your z motor wasn't getting warm. If your driver lets you adjust current, you may be able to provide more to the motor.


Panovak Tue 14 January 2020 20:47

Mark, table looks really nice! I see you used I beams. I'm using I beams as well. What size are they? They look big. Mine are 12"x6.5". Around 30lbs/ft. I was going to put cross members on top of flange making my effective height 8"

Tom Ayres Wed 15 January 2020 04:52

Nice Job! Congratulations!

MarkRH Wed 15 January 2020 16:03

Ted, you got it! thanks
The Z has a different power supply + driver + stepper than the rest which came in a 3 pack.
I had overlooked the power dipswitch setting on Z axis, it only had half the amps it should have.

Thanks Paul, the ones I used (only because the C channel my closest supplier had wasnt anywhere near straight) are about 4.25" wide and 8" tall, id have to look up what lbs per ft they where, but when ordering I just made sure everything went to the heavier side depending on what they had in stock or could get. If I had 12" beams id still put the cross bearers under and watch the welding location, i welded mine all the way around at joint and had to heat relieve it on top to get the bow out. You can build up the spoil board for a vacuum chamber or the longer Z, its easy to raise the bed, hard to lower it.
Remember to add width for 1/2 however much your wider beam is to compensate for the plan dimensions cut size, using wider beams takes away from cut area.

Thanks Tom:)

xraydude Thu 16 January 2020 20:16

Great, Mark. Glad you got it worked out. Give us some more pics if you can!


MarkRH Sat 18 January 2020 12:26

3 Attachment(s)
Ted here are a few, I didnt take many during the build process as I should have. It was well worth the effort. All the heavier 1/4" thick material was welded with 7018 rod and the 1/8 and thinner was mig. If I build another I will make the table slightly different and use the aluminum rail option.

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