I am thinking about purchasing a large format (4X4 or 5X5) CNC machine engraver. I want to be able to make my own plaques, frames, 3D pieces with wood (primarily), thin aluminum, corian, etc.

Does anyone have one of these machines. I would be interested in hearing some opinions about which machine to purchase, options to get, etc....

I am looking into the CNC Router for cutting bulk supplies of plaques in thferent shapes and designs. I will then be lasering the plaques on my Epilog.

Jody,

I don't much about them, but the name ShopBot comes up from time to time.

http://www.shopbottools.com/products.htm

This is an interesting page from the site:

http://www.shopbottools.com/beforeyoubuy.htm

A sign company near here recently purchased a 5x10 powerhouse with auto Z, auto bit changing, and the works. Reportedly he paid $250,000 for the beast. Leave me really wishing I worked for him so I could play with the thing.

I've seen a couple of routers at NBM shows. Before any purchase you might want to take a look. In fact, I happen to have a flyer handy from the one in Baltimore last year.

http://www.forestscientific.com/mach.htm
Their HS Series 48" x 48" is listed at $12,999, but that may have been a show special, and even if not, that was 6 months ago.

If you have the floor space I'd recommend going at least up to a 4'x8', since that's the most common size for large sheet materials.

Sei

Large format routers do not work well as engravers , no matter what motion system etc is used.
The reason: Well the spindle assembly is by definition pretty massive and has a lot of inertia , the motion system cannot cope with very small fast movements and if you try to engrave detailed stuff fast , the engraving quality 1 s attrocious.
If engraving is your prime concern , then buy one of the cross over router/engravers (which will really do nothing 100% right) like a 1m x 500 flatbed Isel Techno/Gravograph etc.
A large format router is best served doing what it does best , profiling and routing.
We use a Tekcel that ius built like a tank.
Things to look for are rigidity , VERY robust motion systems and rails , high power high frequency spindle , vacuum hold downs etc.
Apart from anything , the system is only as good as the software , which can cost an additional left nut arm and leg.

I have to disagree with that Rodney. The place i used to work had a 24x24 inch multicam router with a colombo 3hp spindle, it had to weigh 20 pounds mabe more. It was the same set up used on the larger 4ft, 5ft and 10ft machines. i cant remember ever having inertia problems. Was it as fast as the smaller machines, no!!, but with the rigidity and bite one of these can take it turns out being faster on lots of things. There is a high school in the area thats has a 5ftx5ft machine. I helped the shop teacher early on with it. never saw any problems there either.

clay

Well, I was really talking about engraving and detailed engraving at that.
I run engravers form simple stuff like manual pantographs etc right thru to the large format 3d overhead routers and cover all the stuff between those levels
My experience has been that there is no product out there that does it all effectively otherwise we would just have a few of those.

There is an optimal feed and speed rate for any substrate. That will assure perfect cuts or routing or whatever. The problem with the big machines used as engravers of fine detail is that they cannot possibly come near these rates and you end up having to slow the machine to a point where your engraving is not optimal. Its not to say that they cant engrave , it's to say that as engravers , the generally do as well as engravers used as routers.

Roy
Thats your quality problem...PLT files. I think PLT files are 2 decimal place accuracy at best. I bet it looked jaggy with overshoots. I used to import xenetech files into alphcam, the software we used, converted it to g-code with excellent results. you might try that with enroute and see what happens.
I'll check with engineering about that m22

clay

I have seen PLt files with 5-7 significant figures.

It all depends on the size of the image and the software that is sending it out. Also the setting of plotter units. A small thing with a low plotter unit setting can give really bad results. Making it larger before exporting or upping the plotter units will increase the definition. I generally use the default plotter units of 1016, (I think). [Plotter units are, again I think, the steps per inch.] [Maybe the steps per plotter size, I am a bit confused on this one. I have not fiddled with the hpgl in about 20 years.]

Philadelphia, PA (Really Bensalem)

When you finally understand it completely... it changes.