Building a diy cheapCNC...

[mikeschn]

Hi guys,

I want to build a cnc machine, similar to the cheapCNC machine, except I will use the Xylotex Controller to speed up the travel. I would like to use 150 oz motors or so... any suggestions? What do I use for a power supply?

I will probably stay pretty close to the size of the cheapCNC. What do you guys recommend for material. I don't really want to use MDF. I don't want to use aluminum either because I have no experience machining it. I notice that Steve Thompson is now using some kind of plastic. Is that a good choice? What is it called and where do I get this plastic?

I figure I can build this machine for under $1000. What do you think?

Motors?
Power supply?
Plastic material?

Thanks,

Mike...

[balsaman]

get the 116 oz steppers from Xylotex

Look on ebay for a powersupply. Get a 24 volt one.

What's wrong with MDF? I have no idea where to get that plastic.

Build first, buy motors and controller later.

Just my 2 cents.

Eric

[steveald]

Hi,

Bob Campbell uses a plastic called UHMW to build router clamps, maybe it would be good for the rest of the machine as well. I never would have thought you could build a functional machine out of MDF, but many of the people on this site have made some impressive machines with the stuff, so I wouldn't dismiss the possibility of using it particularly if you are on a budget. Plastic can cost more than aluminum in some cases (I don't know about UHMW)

Steve

[mikeschn]

Okay, you guys have convinced me to take another look at MDF.

Let me ask you about anti-backlash nuts. I can buy them for $19 each... But can I make my own by buying a flanged nut, and adding something to make it anti-backlash.

I'm thinking about using drill blanks for the rails, with linear recirculating bearings. On the machine that Abasir built in a weekend, did he just capture the rails in a bore in the sidewalls, or did he attach them somehow?

Mike...

[balsaman]

UHMW is expensive. It makes good budget nuts for your leadscrew. Don't use steel nuts. What were you thinking for lead screws?

I know MDF gives many people a bad taste in thier mouths, but it is quite flat, stable, sturdy, and heavy. It's better than plywood for our use.

Paint it gray and it looks like steel plate. Most people who saw my first machine IRL (in real life), thought it was made from 3/4" boiler plate.

Aluminum is better, but like you say, hard to work. Save aluminum for your next machine.

Eric

[abasir]

Mike,
>>did he just capture the rails in a bore in the sidewalls
Yes.
Take note that the machine is like 'proof of concept' thus it does not have the accuracy & rigidity like other members' homebrew.

[mikeschn]

I did some modeling this morning, trying to capture some of the basics... So using 3/4" MDF, here's what I came up with...

Using 3/4" and 1/2" drill rod, I used 36" lg for the x axis, 24" long for the y axis and 12" lg for the z axis. This is so I can buy off the shelf drill rod and not have to cut it to length.

That gives me the following allowable travel:
x = 28 1/2"
y= 16 1/2"
z= 7 1/4"

Oh yes, distance under gantry = 3"

Am I headed in the right direction? What do you guys think?

Mike...

P.S. Check out the attached picture...

[mikeschn]

Here's another picture...

I made the base lower, increased the distance under gantry to 4.5, added the stepper motors, the 1/4" thd rod and also some anti-backlash nuts.

Does anyone have the basic dims (or a solid model) of a router, like the porter cable?

Mike...

[balsaman]

Keep in mind that the router needs to reach the table. This means that the "plate" on the z axis needs to extend beyond the bottom bearing a distance equal to the distance under the gantry. Also its nice if this can be retracted to a point where the extention clears the bottom of the gantry when fully up. It's often handy to make this part from a chunk of aluminum, since it's a bit more rigid. if you use MDF, you need to make some gussets etc.

Eric

[mikeschn]

Something like this?

Mike...

[ger21]

I made mine out of baltic birch, with some gussets for extra strength.
http://www.cnczone.com/showthread.ph...r+first+router
It's a little heavy, but it's pretty stiff. Holds a Porter Cable 690 or the new 890's. I'll actually be using an 892 that I just got.

Gerry

[balsaman]

Yes, just like that. Perhaps you can get away with a little less because you only need the collet of the cutter to make it to the table.

Eric