Newb in Mt Clemens, MI, USA
 

Hello All,

I'm Chuck, and I'm going to build a MechMate. There- I said it.

I run a marine canvas shop as my day job. As a hobby, I make custom kayak paddles. Said hobby is taking off, so it's time to get a bit more serious. I started carving them by hand and am currently using the ShopBot at my local TechShop. The ShopBot is OK, but I really need a CNC in my own shop if I'm going to do this seriously.

I need a machine about 24x96", so I'm planning to build something with a working area about 50x108" as long as I can shoe horn it into the space I have available... If things go well, I'll see about adding a second head later.

To make things interesting, it's going in my basement shop. I'm planning to build it in sections (small enough to fit down the stairs or window), assemble it at TechShop, then take it apart enough to get it to my shop. Non ideal, but it is what's possible.

I've been studying the plans & reading the forum. I'm getting a fairly large spreadsheet of things I need to know. This is bigger & more complex than most things I've made, so I have MUCH studying to do. I have or have access to assorted tools from a Bridgeport to a waterjet, and varying amounts of skill using them.

I'm familiar with modeling and tool pathing & have the software, as well as good dust collection, routers, and the ability to laugh at myself. I'm pretty sure I'll provide some entertainment with my build.

I bought enough steel today for the table. I'm not ready for it, but the price was too good to pass.

Welcome Chuck! :)

Well Chuck, you are on your way.

Welcome aboard !!!

With these, You are more then qualified to build a MechMate :D

Welcome to the sand box!

DO you go all the way to the tech shop in Allen Park from Mt Clemens?

Hey Chuck, welcome!

Yup, I drive (well, usually ride my sidecar) from Mt. Clemens to Allen Park. It's not that bad, my girlfriend lives in Allen Park, 2 miles from the shop. I teach a handful of classes at the shop and get a free membership as part of my compensation :D

I've been reading up on the electronics & control systems. I'm getting intimidated, but I assume that like most things, the reading about it is worse than the doing and that it will all make more sense with real parts. I've built some Arduino stepper motor thingies, so this is basically the same thing, just BIGGER and PRICIER...

As much as I want to start BUILDING, I think the smart answer is to follow the advice of the board & get the electronics working first on a table top. Now I just have to chase a few customers for some cash, then order some parts. And make a space in my shop, get my website going- OK- too much thinking here- One thing at a time!

Electrics have come a long way. Mostly plug and play if you stick to the basics.

Will you be doing belt drives? or Geared Motors?

Good to hear on the electrics- my impression is that as long as I stick with the "normal" stuff, things should be pretty much plug/play. I have visions of future tweaks, but I'll leave those until it's running, and I have a better understanding of both what I'm doing, and more importantly, how to undo it.

I'll end up with belt drives, just not sure if I'll build that way initially. My primary goal is custom kayak paddles and it's faster for me to finish them by hand than on the CNC, so I really don't need stellar resolution at this point. I'm stretching the budget a bit, but I hate building something when I know I'll be duplicating effort later. Hmmm.

I've been studying- can somebody confirm my thinking? I'm most intimidated by the electronics, so I'm starting there.

I'm planning to use:

(4) PK296A2A-SG7.2 steppers (I won't need belt drive with these, cost about $1030, vs about $900 for 4 cheaper steppers & building belt drives)

(1) G540

I'll need a power supply of about 40 to 50v, 10 amps or 500VA. This is a bit on the high side in hopes that I'll later add a second head and might need to run another stepper to power it. I'm OK if both heads are both controlled by the same Z motor, I just don't know if it will work.

I'd like the (future) ability to run 2 parts at a time in the hopes of the world beating a path to my doorway... I've not found any threads with a MM with a second head. Can somebody point me in the right direction?

The G540 will not work if I add another stepper motor for the second head Z. I'm OK with replacing it with a PDMX 126/134/Gecko 203v set up if the time comes. I'd rather save the $500 ish now. If I need to upgrade, I'll be spending income the machine is producing, which hurts less than up-front cost.

Thanks!

PS- I'm sure I'm missing things.

Are you planning and 2.5 or 3D cutting? If so I would strongly recommend belt drives.

40 to 50 for the PK296A2A-SG7.2 is not high. I run 56VDC

G540 has a 50V limit. I run mine at 48VDC. You can conceivably add one more G250X outside of the G540 for another motor, but it will use up both aux output pins. 300VA is more than enough for the first 4 motors, so 375VA ought to be enough for 5. I'd pick the next reasonable supply size above 350VA.

Or, depending on how you plan to interface to your PC (and give that some thought, parallel ports and even PCI slots are becoming rare), you could go with two G540s. That would give you an effective spare for 4 axis operation if something fails, and extra I/O with both active.

However, I agree with Pete about belt drives, which changes your motor choice, and perhaps then your driver range. I'd start with that decision, then work back to the controls.

Brad is absolutely correct about the G540 voltage.

Hmmm, I just read most of Pete's build thread. Interesting....

I'll be doing mostly 3D cutting. Kayak paddles look a lot like airplane propellers- a series of compound curves from one end to the other, but the blades are in the same plane with a paddle. I need some decent pictures.

My main use for the machine does not need great precision- it's much faster for me to finish paddles by hand than on the machine, especially since it's 2 sided machining and I'll always have a bit of hand finishing at the edges.

But- I think you have convinced me to go with belt drives. Otherwise, I'll be wanting them later for some unforeseen project or income stream.

The snowball effect has started :D

Back to the drawing board.

Ditto on the belt drives. You will not regret it.

Also you are really cutting 2.5D since the head will not rotate.

If you insist on not needing detail at the moment, I would start with straight motors since your not too worried about finish detail and this will give you an opening to add belt drives (Which I would expect to take you about a week to decide you should have to begin with :) ) !!

Welcome. .. kayak paddles. Now that's interesting. ... I drew one up in catia. Its parametric and I have cut about five from spruce. Have made wrc paddles but prefer spruce.
Good luck with your build.
Regards
Andrew

Ooops- yes, 2.5D :-)

I've read deeper into some of the build threads and see that many have converted to belt drives. It's a bit more work, a bit less cash, and looks like the way to go. Since I started mentioning to people that I'm going to build a CNC router, I've had 3 business ask me if I can do signs for their customers. I'm a good capitalist, so SURE I can do them. I'll heed the collective wisdom and build belt drives.

Andrew- cool! Us kayak builders like to argue over the best wood for everything, and which single malt Scotch is best for each stage of the build :-) Building parametric models of paddles is an interesting exercise.

I'm looking at the KL34H260-35-4B Keling/Automation Tech steppers. I'm not finding any MM's built with them, which may not be a good sign...

Thanks All!

Chuck
The motors you note are almost specifically matched for Gecko G540 or G251 Drivers with a fairly high inductance.

For the same or almost the same cost you can buy the more applicable motor.

See...Motors and drives sticky thread for help in your selection process.

Lots more studying here (and I took a week off to go to banjo building school). It looks like the G540 and KL34H260-35-4B will maybe work, but I'll be pushing the limits in about every way.

Many here seem happy with this set up (mostly copied from IMMark):
KL34H280-45-8A, Unipolar, 4.5 A, 0.71 ohms, 2.2mH
Drives; Gecko 203V
PMDX-126, and PMDX 134
Power supply around 50V, 350-600VA
3:1 belt drives

In rough numbers, 1 stepper motor rotation, run through the 3:1 belt drives and using a 1" (20T) pinion equals about 1" of movement, right...? I'm basing my calculations on cutting at about 7 ips and adding about 50% fudge factor, so my stepper will need good torque to about 600 RPM. Corner speed on the KL34H280-45-8A at 50V seems to be 776 RPM, so I should have lots of headroom if I want a faster cutting speed for some reason and jog speed should be higher.

Did you get your router up and running