Project start - Joe's R2 with servos

[gtschance]

Hello all,

Time for me to start a log of my build of Joe' R2 version. I have been a very long time lurker on this site and only registered to be able to post last month.

Pardon the long post here, I thought sharing my thoughts might inspire thought in others.

As is my standard practice, I dig into subjects very hard and read as much as I can before asking questions or illuminating my follies.

A little background on me:

Long time hobby woodworker with a fairly complete garage based woodworking setup (Table saw, band saw, drill press, jointer, planer, etc.). My real job is as a founder and CTO for a small new startup based company doing hosted software as a service. My education includes a MSEE/CS and course work done for PhD (did not have time for the dissertation - had to support my family).

My choices (my education and work experience strongly influence my choices......):

My selection of Joe's plans (and kit) was influenced by my opinion of what I see as design elegance & simplicity and the fact that I could get Joe to machine the parts so I could get into service more quickly. I wanted to start larger than JGRO without spending too much money (my wife says I already have!). While I am very confident I could have built a JGRO style unit first, especially considering the fine tools I have, I chose to save time vs. money.

I decided to go the route of servos vs. steppers. I have desires to buy and CNC mod an X2 or X3 style mill eventually. I wanted the experience with servos as I will want servos there. It certainly would have been less expensive to go the stepper route. If I did not have 35 plus years of EE/CS experience, I probably would have gone the stepper route.

I ordered kit parts from Camtronics (Dan Mauch). Power supply components, chassis, case, G320 Gecko drives and MCG ID23-005 PMDC sevo motors (400 oz in peak NEMA23). I assembled same, wire by wire, bolt by bolt, etc. with no issues. I added a simple circuit to cut power (via relays) to the servos and brake through wire-wound resistors on any ERR raised by the Gecko's. The kit route saved time - I could have easily acquired the components and built from scratch. I am really fond of the setup.

For software, I evaluated three approaches.

TurboCNC (MSDOS based). Works well, seems faster than all others - I could get my pulse counts reliably 50% faster than others due to less OS overhead. Even with the 500/2000 CPR encoders on the servos, I was able to reliably drive them to a little over 1800 RPM with TurboCNC (what would be 180 IPM) on the table when done. The specs on the ACME lead screws to be used indicate they would whip long before that. This was a simple bench test for rapids speed capability. Since I have never put a real load on the servos yet, my actual rapids speed is yet to be determined. By the way, the torque curve specs on the servos I purchased from Camtronics show much better torque at lower speeds than I am used to from my past.

EMC2. The Linux approach. Pain to setup as one must manually edit INI files and such and carefully understand how to adjust kernel thread speeds for the real-time component of the EMC setup. I remain tempted to continue the EMC path but I want to use an MPG and do not want to spend the time doing assembly from scratch (so far I have not seen kits for same that are useable without software programming and electronics breadboarding on my own - while I am capable, I do not want to spend the time!). While I love Linux I would also spend far too much time tweaking (most GUI environments [X Servers] are pigs on Linux without major tweaks - my opinion and experience!).

Mach3. I love it! I went ahead and purchased a license. Because I wanted to be able to have an MPG pendant and could get same ready to go from CandCNC, this is the route I have settled on. I purchased the Mini-IO Super Combo. Major geek factor here for me. Totally unnecessary but I want what I want when I want it! I am using a older Dell Optiplex with a 2GHz processor and can reliably get about 40KHz out of the box. That would translate to well over 1000 RPM and that would also be well beyond the capability of the ACME lead screws before whip. I should have no issues with this setup.

Now I wait for the table kit pieces to arrive from Joe....... Hard to wait!

I will be happy to answer questions.

Regards,
George

[gtschance]

Hello all,

Well, my kit arrived on November 30th. The first picture below is how it was boxed up. The box was a little rumpled but the contents were without damage (great packing job by Joe).

I was not able to start it right away afterwards (painful) as my day job was again intense for a couple weeks including weekends. I started about 2 weeks ago.

Anyway, as can be seen in the second picture attached, it is almost finished.

Torsion boxes first, wanted the gluing task done right.
Primed (parts with some strategic masking).
Painted (white as can be seen - my wife and daughter chose the color).
Assembled

I really enjoyed putting the kit together (all but the priming and painting which I hate anyway). Everything fit like a glove. Joe is really good - across many fronts.

Now need to install lead screws and motors.

Changed my mind about the servos. I recently acquired an X2 mill and it will start conversion soon - where I will use the servos.

I decided to acquire a Xylotex setup for the router. I have bench tested the lot. I have a dedicated PC, CandCNC Mini IO, Xylotex drive, power supply and motors.

Lots of family activities coming on Christmas Eve and Christmas Day so I doubt I will get to the finish until after.

Merry Christmas/Happy Holidays to all.

George

[ccsparky]

Hello George,

How's are the machines running?
I am in the process of doing research in preparation of a Gecko / Servo purchase for my Joe's kit and ran across your log. Would really be interested in seeing the progress of your Joe's kit and the X2 mod!

How is the Gecko / Servo setup working out?

Any more pics or videos?

Your build looks good from what I can see, keep um coming!

[thkoutsidthebox]

Very nice. Its been nearly 3 months since your last post. How are your finding your router?