[jstuedle]

Hi All,
I am new to this forum, looks like you all have a good healthy discussion of just about all realms of hobby CNC. A little background I believe is in order. I was retired 12 years ago from a major aerospace manufacturer after a transplant. Prior to that, I was a tool and die maker with a little CNC production time. My last 10 years were spent in Q.C. and test engineering. I have a small home machine shop consisting of a Bridgeport mill circa 1955 with a step-belt “J” head and a Clausing/Atlas 12” metal lathe. The shop has collected dust and rust more often than not in recent years due to health concerns and other projects/obligations. In 1997 I built a small point to point almost CNC machine controlled by a simple basic program to drill holes in pc boards. This was my last major shop project. It is constructed totally of aluminum with ¼”-20 lead screws and tin can steppers. I used ½” drill rod as ways and the aluminum table was the bearing. I have a pic of it if interested. Its capacity is about 6” X 8” and uses a dremel drill press for its Z axis. Its time for me to move on and I would like to build a larger, but still small router table that would fit on a tabletop. I had in mind a machine that would be from 30” X 30” to 30” X 36” in its external dimensions with a work capacity of up to 24” Sq. I have a roto-zip and a 1 HP craftsman router that I would like to drive with it. I want to do lettering, complex cutouts and 3D contour work with it.
In this long winded post, I guess my first question is, can this be built without using ball screws and expensive rails and still accomplish what I wish to do with it? I believe I can and I know I have the shop skills to get it done, but having not built one of these at this level, am I asking too much? TIA.

[ynneb]

The Shopbot is a fine example of a cheap way to build a machine that will do what you want.

Because you want to do lettering you don't need incredible tolerances. You will soon discover that people on this site have made some very good machines at very cheap prices that do great work.

You will discover that people have had success with skate bearings, nylon bushes, acme thread, and many other cheap alternatives. It all comes down to what you can afford and what you compromises you are prepared to accept with cheaper components.

I like to compare it to a car. You can have a $250,000 car, or a 2,000 car. Both will get you from A to B but one will look better and get you there in more comfort. If the only result is getting from one place to another, then pick the cheaper car.

This site is filled with ingenuity. Spend some time reading its posts.

Oh and welcome to the forum.

[Hobbiest]

I for one would enjoy seeing your photos, especially the ways. I think that you are totally reasonable in your ideas. Like Benny said, browse the DIY wood machine forum for examples of some great machinery that didn't cost any body parts! Welcome!

[chuckknigh]

Think about it this way. Your PCB drilling machine worked just fine, and used VERY low quality components. Other than loading, what's the difference between X-Y moves through air, and X-Y moves through wood?

Just make sure you beef up your components a little bit!

http://www.crankorgan.com is a site with cheap plans for "low precision" machines that are easy to build. Hardware store parts, too.

-- Chuck Knight

[jstuedle]

"I for one would enjoy seeing your photos, especially the ways. I think that you are totally reasonable in your ideas."

I made the drill rod a slip fit through a 1/2" hole on one side (each axis) and a slip fit in an elongated slot on the other. This way I could have a slight out of parallel condition between the ways and it would not bind. A concideration with these puny steppers. If you have any other questions and would like more pics, I would ot mind taking it apart for clarity. The machine is a little rusty as it has been in and out of service for 7 years now.

[jstuedle]

Maybe I'm having a brain fart, buy how do I add pics to a post?

[cncadmin]

check here- http://cnczone.com/forums/forumdispl...s=&forumid=188

[jstuedle]

Thanks Paul.

[ynneb]

Those linear bearings look like aluminium sliding on the rails? Is that right?
Is the allthread just suspended at the ends without bearings?

How well does the machine work. How much use does it get?
How well does it slide?

I have seen heaps of discussion about a cheap slide system, but that would have to be the cheapest.

Is the Z axis hand controlled?

Thanks for posting the photo.

[jstuedle]

"Those linear bearings look like aluminium sliding on the rails? Is that right?"

Yes, being dissimilar metals, there is no gallding, just keep it oiled with a couple of drops every few weeks.

"Is the allthread just suspended at the ends without bearings?"

Yes on the Y-axis, its short and not an issue. The end is sort of "cradled" by the frame on the X-axis and not allowed to sag, still is not a big issue due to its short length and slow speed.

"How well does the machine work. How much use does it get?

It is slow, the basic program and small steppers move it well, but slowly. It is used to drill component holes in printed circuit boards and only moves point-to-point. As far as service duty, it is only used when I get a wild hair and decide to build a project requiring multiple copies of the same board. I use double-sided tape to hold the board to the table.

How well does it slide?"

Quite well. Without the lead screws attached, it glides easily from side to side. There is about .005" free play in the table after all these years, but no binding. One thing you can't see, the under side of the table is milled to thin it in the central areas to reduce mass and help the small steppers. The 1/4" plate is only 1/8" thick in the majority of its area.

"I have seen heaps of discussion about a cheap slide system, but that would have to be the cheapest."

Everything but the alum. tooling plate used for the base was salvaged in the junk pile in my shop. I think at the time I spent about $60.00 U.S. on the base plate, electronic components, steppers and cabling. The home made stepped driver and power supply is all in the small gray box to the right rear.

"Is the Z axis hand controlled?"
Yes, just drills holes at each stop. Filled the need at the time.

[Hobbiest]

Cool!!! You know how to do it then, build another one. (Nothing like a good kick in the rear to get ya going!)