Hoping it works!

[Guy Smiley]

I registered in this forum last July but have lurked a few more months before that. I've seen how a CNC works and have been eyeing one of the mini-mills but after viewing the posts here and visiting the links, I have decided to try my hand on building one and hoping that the knowledge that I picked up from this forum will help me through. So here goes and it's from somebody who had "0" knowledge on the intricacies of DIY CNC but armed with knowledge picked up from reading posts from the good folks here.

I decided to use what is readily available to me. I have a 1/2" (12mm) aluminium plate that I picked up from a junk shop of which I'll use as the back-bone of the project. It's edges are perfectly square and it can give me a working area of x=30", y=12" and (I decided) z=2" but have the whole yz assembly on the gantry capable of being, repositioned manually, moved up by 4" if needed. This design decision was made because I understood from some posts here that the lesser travel on the suspended assemblies will help in the precision in faithfully reproducing the translated CAD. The repositionable feature is for later on when I decide to use a 4th axis dividing head.

The 1/2" alum. tabletop was strengthened to address the sag (0.5mm) at it's mid-point when a 100 lbs. weight is applied on the center of the table. This was achieved by bolting an aluminium sliding door track around it's perimeter. The table legs which are adjustable for leveling were also bought at the hardware store together with the sliding door tracks as well as the drawer sliders that I plan to use.

Here's the expense break-down for now.
1/2" Aluminium table-top 20.5"W x 43.3 L (from junk shop)=US$17.75
Aluminium hanging sliding door tracks 2-2mtr sections = US$20ea=US$40.00
Aluminium adjustable leveling legs x4= US$36 total
Extension drawer slides, 2 sets for x-axis, 1 each for y&z=US$26
48" Stanley brand aluminium carpenters level x2=US$20
Odds and ends= 1/2"x1"x3' scrap aluminium to make the recieving nuts to lock the sliding door rails aroung the table top and 8mm x 1.25 x 25mm allen recessed head screws x 24pcs. = US$10
Current project total= US$149.75

I bored the tabletop's perimeter for 24 recessed in allen screws to attach the sliding door rails to the bottom of the tabletop for reinforcement and made the 24 recieving nuts from the 1/2"x1" alum scrap (milled the shoulders to fit into the slide's slot the drilled and tapped for 8-1.25mm).
Total man hours so far including the shopping and plan drawing=22 hours

[Guy Smiley]

Here's the table top plans, I did this in Adobe Illustrator.
I hope you guys can help me through these uncharted waters!

[Guy Smiley]

What I'm doing right now is just reinforcing the 1/2" aluminium table top and attaching the legs to it. Just making sure that I have a strong foundation or back-bone for the structure. This is all happening whenever I get a chance to work on it while I'm doing work for my home-based business, like when the lathe is doing a run in auto-mode or waiting for adhesives or paint to dry.

In conjunction with this, I'm planning on building a smaller scale CNC dremel with the just a CNC x&y table with the z mounted on a rigid gantry with manual z control.
This I plan to build with salvaged dot-matrix printer parts and will mainly be for my education on the computer-to-servo workings of DIY CNC.

I will be using the print head assemblies (including the existing motors) of a Star 1101 for y-axis and NEC Pinwriter P6000 for the x-axis. Can someone direct me to some simple circuit plans for the parralel port to stepper motor terminal block (driver) so I can proceed with this small educational project?

I've been corresponding with Mr. Mauch of Camtronics for the electronics part of my bigger project but he's busy 'til March 2005 and I don't want to be a bother to him about this smaller project.

[Mr.Chips]

Sorry I can't help you with your electronics question, I'm in the same boat. Experimenting is good and you learn a lot as to what will work and what won't. And it sounds like you don't have a lot invested so design changes aren't too expensive.
Surf around the internet and I'm pretty sure you'll find some plans for a "driver".

Good luck and keep at it.

Hager

[da21]

here's a few electronic stepper controller links , but if electronics building is not your strong point , i am sure their are many people on this forum that can help or assist , or give me a shout .

http://www.embeddedtronics.com/ ( look at microstep)

http://www.fromorbit.com/projects/picstep/index.php ( look at picstep )

http://webpages.charter.net/pminmo/cncelectronics.htm

this list is by no means exausted , as they are many available
hope it helps , instead of total confusion !



Dave

[Guy Smiley]

Thank you Hager and Dave. What I've done so far is build the table to the point of having the x-axis rails attached. As I have mentioned, I am doing this at the same time as experimenting with printer parts. I'm not that comfortable with the electronics part so I purchased a Xylotex 4-axis box that included 4 doubleshaft motors. Aside from the above I also purchased an additional 3-axis board that will be delegated later to the printer parts router machine. Cost is starting to climb but still is low for what I've gotten to.

I've been poking around with the x-y axis of the box with the motors attached to the print head assemblies (pic in Xylotex forum of this site) of some wide carriage dot-matrix printers, that I picked up from a surplus store, and have gotten to jog from input values. I'm still trying to learn how to get .dxf files translated for use with TurboCnc, can anybody here direct me to a post about the above?

I'll post pics of my progress on the table.
EC

[da21]

try this dxf to gcode convertor

http://www.yeagerautomation.com/ace.htm


let me know , and i will try and help

dave

[da21]

as always hit the return key before brain finished !

theirs also
http://home.carolina.rr.com/gcodemcode/

i use kcam4 mostly

regards
Dave

[Guy Smiley]

Dave! Thank you. Here's a picture of how far I've gotten on Machine#1. I housed the drawer slides inside the carpenter's level to keep the 2-24" slider sections aligned and also plan to run support roller bearings, attached to the gantry uprights, on the top of the carpenter's level. I'm thinking that with roller bearings attached to the ends of the inverted "T" gantry uprights the y and z axis will be kept from swaying when the x moves. Plus the gantry will have another means of support than just the slider bearings.
EC

[Mr.Chips]

EC

Nice clean table setup. You may need some cross bracing on the legs, when your machine starts and stops you may get some flexing of the legs. But I might be getting ahead of you and you already have this planned.

Looks like a RC plane machine to me.

Hager

[Guy Smiley]

Thanks Hager. I do have cross-braces planned to go around the middle third of the legs but will attach them last to make accessibility to the x-axis drive screw assembly easier. I'm doing a combo machine with one setup having a 4th axis and x moving the yz gantry. The other set-up on the same machine is to lock the yz gantry on the middle of the disabled x-axis. Set an auxilliary table, with the top at the same level as the center of the dividing head, that will handle the shorter travel (16") x-axis for parts cutting.
EC

[Mr.Chips]

Ec,

You must have a ready need for the 4th axis, or you'r really efficient long term planner.

Anyway keep posting thoes pictures.

Hager