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anoah
05-09-2003, 10:55 AM
Hi guys,

Just found this group and have read until my eyes hurt. I love it!

I worked in a woodshop that had 3 CNC Routers for a little over 5 years and now that I work at a metal fab shop I want to build my own cnc router.

I have some questions if you don't mind!

I plan to use the following software:

Generic Cadd from Corel. I love this CAD program and it can save standard DXF files.

ACE Converter: To convert the DXF files to GCode

TurboNC to drive the NC

I have already designed my frame and gantry and now I need to get on with the electronics. I plan to use threaded rod to drive the X and Y axis. Is the acceptable? (Speed is not a critical issue for me)

I am a experienced electronics builder and I want to build my own 3 Axis driver boards. Are their any reliable schematics/Board file projects/plans that are compatible with TurboNC? If so, could you please post a link.

I plan to hit a local printer repair shop to see if I can get some motors from some old HP LaserJet 3's. If I am not successful there does anyone know of a reasonably priced source for these motors?

And last but not least (for now anyway) what would the specs be for a good powersupply to drive this unit?

Thanks for all your time and I hope to share a success story with you soon. :)

Albert

cncadmin
05-09-2003, 11:09 AM
Originally posted by anoah
Hi guys,

Just found this group and have read until my eyes hurt. I love it!

Albert

I glad you love it! Just don't hurt you eye's I need you as a member. LOL :D

castguy2003
05-09-2003, 02:19 PM
If you insist on using threaded rod, make sure to get the heat treated, non plated type. Standard zinc plated threaded rod is very soft and made to low tolerances. The heat treated stuff might be harder to find but it's out there. Try a Farm & Fleet store if you have any in your area.

anoah
05-09-2003, 03:00 PM
Castguy2003:

OK, Heat treated, non plated. We do not have a Farm & Fleet but I'll see if I can find it on the net.

What size and thread ptch would you suggest or is that dependant on table size?

Thank you!

castguy2003
05-09-2003, 03:33 PM
I would go as large as feasible (1/2 is a minimum, 3/4 better). Pitch is not as important, you will most likely end up with NSF threads

castguy2003
05-09-2003, 04:07 PM
Enco www.use-enco.com has alloy steel threaded rod.

balsaman
05-09-2003, 07:20 PM
Any threaded rod will be fine for a hobby machine. Use a home made nut made from Delrin or Nylon.

Use 1/2" rod or smaller, as the bigger rod is harder to turn with stepper motors.

Here is a bipolar driver circuit. http://hans-w.com/cnc.htm

Let me know if you want a circuit for unipolar driver

Powersupply can be as easy as a surplus computer supply.

How large are you going to build? I would suggest you start with a small machine...maybe 12x24" max. Smaller would be even better.

Eric

anoah
05-09-2003, 11:41 PM
CastGuy2003: Thanks for the tips and the link!

Balsaman: Thanks for the info. Beleive it or not a lot has changed since I posted my first message!

I was discussing building a CNC Router with my boss and now he wants us to build a CNC Router for our metal shop for prototyping and such!

First, for my machine. I think I am going to build a PCB etcher/driller first. Would like your comments on what I am planning to use.

The table size will be 8" by 10"
I've changed my mind about controller software and I think I'm going to use KCam4. From what I've seen of the shareware dl it looks pretty impressive.

Since I don't think I need a lot of power with this small of a table and the fact that I am just etching PCB's and maybe some light wood ingraving do you think the following motors would be sufficient. BTW, I plan to use a Dremel as my cutter.

Size 17 T & L 33oz-in, 4V, .8A, 200 S/R, 6 wire, single shaft,
or should I go with Size 23 Vexta PH266-01, 83oz-in, 6V, 1.2A, 200 S/R, 6 wire, single shaft?

I plan to use the 3 Axis Version Kit controller at http://www.hobbycnc.com/driverboards.htm any one had any experiance with these?

Also, I know I will mount the stepper into my frame, connect to the threaded rod with a 2 set screw coupler, but what is the best way to attach it to the other side of the frame?

Now for Roger. He wants to build a machine with a 24" X 48" table. Does anyone know of a good set of plans in this range? We would like to stay in the $1000 range if possible. We already have a realy nice 4 HP router for it.

Thanks for all your time and responses. You guys are the best!

Albert

balsaman
05-10-2003, 01:17 AM
Albert,

Use size 23 steppers. Use 1/4-20 rod for a PCB mill.

That board from hobbycnc will be perfect.

Kcam works but is slower than Turbocnc. Steppers don't like Windows, unless you use Mach1. http://www.artofcnc.ca/

The other end of the rod should be supported in a ballbearing. Find a bearing that fits over the rod you will be using. Tighten a nut on each side. Mount the bearing in a nylon block. This works to keep the endplay down. The motor bearing should not take the side loads.

Here is a pic.

I know of no plans for a larger machine that cuts metal.

Eric

anoah
05-10-2003, 08:05 AM
Eric,

Thanks for the pic. That makes perfect sense and yet so simple. I won't even mention how I was thinking of doing it. :)

On the larger router I should have stated that it will be used for 99% wood and 1% plexiglass. Sorry for omitting that.

I was going to do all my programming in windows and the run TurboCNC in DOS and then I received the following message on another board:
">TurboNC to drive the NC
One quick comment before I leave the shop..... That might work for a while, but you really need "continuous contouring" on a Router ! Otherwise you will have plenty of jerks and pauses, none of which are beneficial on a Router."

That's the only reason I was thinking of using KCam4 in Windows. So will TurboCNC work pretty smootly?

I have several spare 250W computer power supplies sitting on a shelf. Would that be sufficient for those size 23 steppers? I noticed that they are 6V motors. Could I use the 5V line or do I need to half the volts on the 12?

Thanks again!

Albert

ger21
05-10-2003, 08:26 AM
Actually, you want to have as high a voltage as possible (but not more than the driver will handle). The higher the voltage, the more usable torque at higher speeds. A lot of people go with 24V power supplies for Nema 23 motors to get more speed.

Gerry

balsaman
05-10-2003, 10:15 AM
You would need the 12 volt (or more) line from the powersupply. Most people run steppers at more than the rated voltage, and use current limiting resistors to limit the current. Read about steppers here: http://209.41.165.153/stepper/Tutorials/Tutorials.htm

TurboCNC is much smoother than Kcam. Windows gets in the way and makes the output to the steppers rough. Turbo is only $20.00 USD. Version 4 will be out soon. It will include continuous contouring. I use version 3.1a and I have not had any trouble on my router.

As to your boss, I would suggest you build your PCB mill, and use what you learn to design a bigger machine. There are some plans out there for machines that are larger, but most are not setup for comercial aplications, as they are hobby machines. Probably too light for comercial work.

Eric