[Madclicker]

This is a twist on the usual "use the first machine to make parts for the second".

Background:

We went through 3 hurricanes in 5 weeks last year. I was flipping a property at the time and had an active contract that kept getting stalled because of the storm damage. Upside was the beginning of this year someone gave me a hurricane damaged doublewide. Stipulation was that I had to move it, demo a Florida room and carport and prep the lot for the new home. Ended up being a new flip project. I more than paid for the day labor for the demo from the Al i sold to the crusher and ended up keeping several very nice windows, sliding doors and some very nice structural and cage Al that I'm gonna make my second machine from.

I say second machine, because of what I've learned on this site. I want my first machine to be MDF based and smaller than the Al based table I started with. Learn on the cheap! I always intended my Al machine to be a cnc eventually, but I built it to originally be a glue-up and outfeed table for my table saw and router table. I cut all the pieces for the final design but didn't put it all together at first (see the first pic of the skeleton). It worked well for the many months I've used it, but now that I want to make torsion boxes, the old slop won't do. I had (est) .020 droop between the 4' spans for the 3/4" melamine MDF. OK for the cabinet work I was doing, but not good enough for torsion boxes.

This is my first post, so I'm gonna see how it goes....won't be my last!

Steve

[Madclicker]

Don't have the pic attach thing figured out. Help?

[spalm]

Welcome to the Zone.

Your Mom had good taste in naming children.

Show us your stuff, we can probably help. Anyone from a town called Lakeland deserves a break from all the storms.

Edit: Click on the Manage Attachments button to upload a pic. It has to be 800 X 600 or less, and less that .5meg in size.

Steve

[Madclicker]

Steve,

I don't know yet how to post the pics i have taken....oh, smaller pics only (chair)

[2muchstuff]

Are the pictures downloaded from your camera into your computer yet.

[Madclicker]

OK, trying this pic post. This is my original glue-up table. Also serves as a great outfeed table.

[Madclicker]

yahoo!

[Madclicker]

I moved the top onto the router/saw table to do this.

[2muchstuff]

See how simple that was. Now you have to keep us posted with all kinds of pictures.

[ViperTX]

Gotta commend you all.....you make some working machines from low-cost materials! CONGRATULATIONS! Just a fine example of ingenuity!

[Madclicker]

I've purchased quite a bit of materials. I'm trying to get a handle on what this first project will end up costing. I'm posting my running total as it stands so far:

3/4" MDF $42
1/4" MDF $24
VT Laminate $44
NEMA 42 1125 oz/in stepper $25
NEMA 34 450 oz/in stepper $43
Red Oak $16
T-Track $70
UHMW PE $20
2" EMT $16
3/4" flange bearings $17
ACME rods and nuts $38
4 Heavy duty castors $17
3/4" MDF $27
2 X 1 X 1/8 AL channel $10
abec-7 skate & R8 ZZ bearings $44
*10A 4 axis drive $135* (contemplating...not purchased yet)
-----------------------------------
Total $453

[2muchstuff]

Where did you find a 1125 oz/in stepper for $25. That was a steal. Also what kind of drive is it for $135, are there more.

[Madclicker]

Actually I got 3 of these 4.2" motors for $73 delivered off ebay. They were called "pulled from working mill" and very grungy. I'll clean them up, paint them and keep my fingers crossed. The shafts turn smoothly and I can feel the detents.

This is the link to the drive site:

http://dtllc.com/

p38nut uses this drive and swears by it and the guy that makes and sells them. My major reservation is that from the pics it looks like there is no optical isolation onboard. I think that if I'm careful with the wiring before I flip the switch this will not be an issue. Also, it's a unipolar drive, but I can live with that because I have these gorilla motors. The feature I like best about the drive is that it supplys 10A and my 4.2's can use 9.1A of that.

I think I'm going back to my original plan of using 2 of the 4.2's on the X, 1 on the Y and use the 3.4 on the Z. New cost sheet:

3/4" MDF $69
1/4" MDF $24
VT Laminate $44
3 NEMA 42 1125 oz/in steppers $73
NEMA 34 450 oz/in stepper $43
Red Oak $16
T-Track $70
UHMW PE $20
2" EMT $16
2 5/8" flange bearings
5/8" ACME rod and nuts
6 3/4" flange bearings $49
3/4" ACME rods and nuts $38
4 Heavy duty castors $17
2 X 1 X 1/8 AL channel $10
abec-7 skate & R8 ZZ bearings $44
*10A 4 axis drive $135* (contemplating...not purchased yet)
-----------------------------------
Total $668 (includes drive price)

I originally wanted this project to come in under $600....oh, well. Maybe $850 or less.

[2muchstuff]

I'll say this again, you stole those steppers. What luck. I checked out the drive site and I like the 10 and 15 amp ratings but I need something that is good up to about 60 volts in a bipolar chopper. It keeps looking more and more like Gecko's all the time. I know what you mean about trying to keep costs down. I must be my own government, cost over-runs are running rampid.

[jeffs555]

Using that drive may not be as economical as you think. I dont know what voltage rating your steppers have, or what power supply voltage you plan to use, but be aware that using those drives you are going to need at least 8 massive power resistors to handle 4 motors at 9 amps. For example, if your motors are rated at 3 volts and 9 amps, and you use a 12 volt power supply, the resistors will have to handle 72 watts each, probably 100watt resistors to be safe. These will cost between $7 to $12 each. In the winter you may save some money, because it will probably heat your whole shop.
Also, you will need a massive power supply. You will need 18 amps per motor, or nearly 80 amps for 4 motors.

It probably wouldn't be that much more, and might even be cheaper to get some Geko drives, which won't need power resistors, and will also have microstepping to help eliminate resonance. They will only handle 7 amps, but running bipolar series, would require only 4.5 amps to get the same torque as 9 amps unipolar. Also, using chopper drives, the power supply can be much smaller and cheaper. A resistor drive needs the power supply to handle the full motor current, but with a chopper drive and a higher voltage supply, the average current required will be much less than the rated motor current.

[2muchstuff]

Resistors are the reason for going with the chopper type of drive. I just can't see spending all that money on resistors and transformer to watch it all go up in heat. I want to build a power supply/driver not a glorified over priced shop heater.

The motors that I have are 34 frame, 2.3 volt, 5.5 amp, 450 oz/in, 4wire. I would have swore that they were 690 oz/in motors but I guess not. It had been a while since I last looked at them. Due to the size of the router that this thing has grown to be, I will more than likely have to get bigger motors. I'm guessing that both the x and y motors will have to be alike because of the circular interpolation that I will be doing. Unless software will compansate for that which I don't know. I haven't even thought about software yet, I'm still working on the mechanicals.

[Madclicker]

Jeff,

9 x 9 = 72?.... -10

I always try to approach projects from a systems (I'm a systems engineer) standpoint. Some things I have to use (the motors) and some things I have choices on. I think there are two very real design mistakes you made in your argument against this drive:

1. You seem to have arbitrarily chosen 12V PS's?

2. You have completely ignored the FET SD resistance.

Let's forget the FET resistance for now and go with your original premise. If I were to choose or build a 5V PS I would need to drop 2V across a power resistor. 18 watts. BTW, I found a 5V 150A PS today for $70.

BUT, the FET resistance matters (many blisters confirm). FET's typically have an 'on' resistance of 1 to 2 ohms in their working envelope. The resistance varies somewhat linearly with temperature. Of course, temperature increases with current. Taking the best case (1 ohm), your 12V PS would drop 9V across the FET and no additional ballast would be needed. Worst case, at 2 or so ohms, the 12V PS wouldn't power the motor to it's capacity. You would want more voltage!

I don't know what FET's are used on this driver, but Ill sure find out before I make my decision.

[mdreitzusa]

very nice looking machine.looks good enough to use as living room furniture.
as a systems engineer the controls shound be a wiz.cann't wait to see that conrtol panal that you mentioned.
keep up the good work.

[p38nut]

You are right, I really like this board for my application. I bought the 6 2 ohm 100 watt resistors for $6 bucks each from www.mouser.com. I also used 2 ATX computer power supplies, purchased from the local computer store, at $29 each. The total is 44 amps at 12v available. My steppers were 4.6 amps at 1.2v. Using the resistors has something to do with getting the best response and torque from the steppers. The on board enable relay and Mach2 shut down the PS's at the end of program. Some of this is technically beyond me. However, I do know one thing, it works, and keeps my garage warm at the same time.
Madclicker, if you have any questions, call Dave direct. He's easy to talk to, and knowledgeable about his product and the cnc craft.
Thanks. Mike

[Madclicker]

md,

Here is a link to the site that has a slick board that can be programmed to provide KB shortcut sequences with single button pushes.

I still need to find arcade style button switches.