Karbunkles 1st Gantry Machine

[karbunkle1952]

After spending my time researching, since joining in Aug. 2005, I've started construction.

Mind you I'm using the vast knowledge of this group, so I'm not going into this blind, It's more like I have been poked in one eye.
My figurative "poked eye" is the electronics hook up.

I have moved right along building the machine base x axis and z axis. I am now about to fill in the middle y axis.
I have the great fortune of working for a company that has a great deal of "stuff" at it's disposal. Anything I need for construction comes from the scraps from another job.

I am a Prototype Modelmaker and this machine will be used for both 2D and 3D work. Anything from routing Sintra signs to vacuum-form patterns.
I work for a Display Company.

I'll be posting pictures of the progress. I have a few already but, as of this writing they are on the harddrive at work.

Currently, I have this dilemma: How do I make the electronics work?
Let me tell you what I have and please give me advice and links to the information. As noted previously, I've used this forum to get this far, it is my hope that you can help finish it.

Here's what I have:
1. 3 pcs. 640oz/in Model #RHT34-640 Bipolar Steppers from www.homeshopcnc.com
2. 3 pcs. Gecko 201 Drives
3. 1 pc. Magnetek MG1 MODULAR POWER SUPPLY 48vdc 15a regulated (www2.magnetekpower.com/cps/CPS_MG_DS.pdf)

As I understand it here's what I'll need yet:
1. A parallel port interface card (to talk to the Geckos)
2. a 5vdc power source for the Geckos
3. A capacitor (10000uf?) for the feedback EMF from the steppers to the Geckos since the power supply is regulated.
4. A fuse block to protect each Gecko
5. Maybe a Safety Charge Pump (but I'm not sure how that all works)
6. Mach3

Please feel free to direct me (kick in the butt, I'm an apprentice) to the proper vendors.

The capacitor part is confusing me at present.
If I buy one large Capacitor, Can all three Geckos be connected to it?
If so, are they isolated in any way? What voltage Capacitor do I use?

I know from reading the "Stepper Basics" PDF on the Gecko page there is supposed to be at 470uf 100v Cap on each Gecko. But I've seen examples on this forum where just one large Cap is used.

[ger21]

1) www.campbelldesigns.com www.cnc4pc.com www.pmdx.com
2) I **think** you can pull this from the PC.
3) I think there is a formula in the Gecko paper on power supply design, which will give you the cap size.
4) Haven't used Geckos, but this is in the manual, right. Mariss (Gecko owner) is on vacation. Give him a call later in the week and he'll tell you everything you need to know to hook up your Geckos correctly.
5) Works with Mach3, and certain breakout boards (possibly all the above, CNC4PC is an add-on card) to keep motors from moving when Mach3 doen't have control of the system.
6) www.artofcnc.ca Also, watch all the videos at www.machsupport.com

[karbunkle1952]

Thanks Gerry,
It's the whole feedback emf issue that has me a little worried.
According to the Gecko page, if I used an unregulated power supply the feedback wouldn't be an issue since it would be absorbed by the capacitors in the power source. But since I got a deal...$35.00 on this surplus regulated "powerhouse" powersupply... I'd like to use it. (Cooling fans already part of the power supply case!)
I hope Mariss can fill in the Cap question.
-Brian

[ger21]

What I meant, was, to use the formula for the cap as if you were building a comparable size supply as shown in the Gecko white paper, and just hook that up to the output of your supply.

[karbunkle1952]

Here is the progress.
I started with whatever I could scrounge from around the plant.
The framework is made from straight pallet rack rails.
The Rails are 2 inch EMT conduit
The Rails are sitting on Unistrut
The Bearings are Skate bearings sandwiched in Machined Aluminum.
All dimensions are completely made up. I'm Drafting this thing on Cadkey98 as I go along.
That's why I started with the x axis then went to the z axis. It'll be easier to meet in the middle with the Y axis Gantry construction.

[karbunkle1952]

I laid out how the bearings would touch the rails at 60 degree angles.
Then milled the 1 inch stock so in could all be sandwiched together.

This whole works is very Bridgeport intensive.

It's been slow at work so I keep myself busy on this project. It will be used for low volume production.

[2muchstuff]

I think I'm going to like this thread. Any thread that has the word "scrounge" in it is allright by me. I like the idea of using the EMT and Unistrut, makes it simple. Not to worry you but in time the galvanized coating on the EMT will begin to flake off where the bearings ride.

[WarrenW]

I really like those bearing blocks you made! And with the pipes mounted down, they won't flex at all. Can't wait to see the rest.

Warren

[creative_mind]

How did you adjust the bearing block to fit tightly on the EMT?

[swarfmacdaddy]

How did you attach the pipe to the unistrut?

[karbunkle1952]

After I welded up the whole frame, I took a large piece of corrugated cardboard and laid out my hole placement for the unistrut mounting screws. That way I could make sure the holes at least laid out square and parallel to one another. I also laid out holes that would go through and through my welded frame rails.

Now, mind you this is a one of a kind deal. After doing this once I wouldn't build another one the same way. This machine is basically using everyone else's various techniques. I'm just building with the materials I have and adapting on the fly. Back to the story....

The unitsrut is then bolted down to the top of the frame. I drilled and tapped the conduit and installed threaded rod. I bottomed out the threaded rod in the conduit. I added a jam nut up the threaded rod against the conduit. I then dropped the conduit/threaded rod assembly onto the unistrut/frame.

Then it was a matter of using my 48" calipers and working up and down, tippy tapping the conduit left and right until the while works was parallel.

I tightened the nuts onto the threaded rod, continually checking to make sure it wasn't pulling too hard in one area making a big steel banana.

When I'm all finished I may go back and tack weld in areas so the unistrut always stays put.

Check an end view you can see the threaded rod going all the way through.

[karbunkle1952]

Great, none of the pictures I have so far show how the blocks snug up to the rail.

Here's the theory....The bearings on both sides are attached to the aluminum the same way on the same 60 degree angle. One side is actually made up of two pieces bolted together so the entire assembly can be tapped to the correct distance.

I'll get a better photo on Monday.