[Havic]

Some time ago I start building a CNC table. I started with motors and drivers and the PC interface thinking that would be the hardest part of the project. I figured I would get some kit for a table. Well come to find out there is not such thing. At least nothing anywhere near the price range I can afford. I have the space for a full 4' x 8' (working area) table and I like the idea of the 80/20 material.

The question: For those of you who assembled their own tables, how much did you spend? If you have the time I'd really like to hear a break down of the component prices (rails, shafts, ball/screw, etc.).

I'm total shocked by the price of a table. I'm trying to decide whether or not to just shelve this project, I have no intentions of paying $6,000 - $10,000 for a table, especially since this is just some home workshop hobby project.

Thanks

[yukonho]

If it is a home workshop hobby project, then dont even consider making anything close to a 4 X 8 table.
I started with a 12 X 36 inch table and I am making a smaller one now because I have designed a better table, and I have never come even close to using even half of my available travel. And the smaler machine will be more rigid and more accurate.
Treat it as a hobby project and you will be astonished what you can make when you get your table running, and you will actually stand a chance of getting it running.
You already have the 3 axis board and motors, so you can honestly build a great machine for 300 or less. If you want to splurge on THK slides and Ballscrews you will push the price up closer to 800 or a thousand.
My first two machines are MDF, and I use the first one (still building the second) for production work for 4 hours every day, and it cost me 400 Canadian dollars from start to finish including buying the electronics!
Do some reading here and you will see that everyone recommends a small machine for the first one. This is for a good reason, follow the advice and you will have an operating machine in no time, not a money pit sitting idle.
co

[MATT40]

DOES ANYONE KNOW ABOUT SUPERIOR STEPPER MOTORS

[Hobbiest]

I must agree with Yukonho. Smaller is better, especially for a first build. That isn't to say though that a 4' by 8' can't be built for less than what most people pay for a used car (under $2,000). But remember that with a larger table, the motors must be stronger, as the mass of the machine is bigger. Heck...I'd build you a 4 by 8, mechanicals only for $2500, so I don't see why you couldn't do it!

[samualt]

Havic:
I'm building a 4'x8' 8020 table from scratch. Here are some prices of things. They are rough estimates including shipping.

$625 - 8020 T-slots
$900 - THK Rails (X,Y,Z Axis)
$300 - Ball screws (Y,Z Axis)
$500 - Rutex Motor Controllers (All options)
$200 - 3,1500 OzIn Servo Motors
$200 - Router, Makita RD1101
$65 - Power Supply
-----------
2790

I think you can build an outstanding large machine for under 4K. I still need miscellaneous mounting hardware, rack-n-pinion, and a few other odds and ends. But it will be under 4K. I think Machine Tool Camp has plans for a 4x8 that costs about 4K to build. CadCut has some plans that probably cost 6K or so to build, but it is a heavy duty professional type machine. That will be my next machine!
I'm certainly not saying you can't do it for cheaper than 4K. I could cut costs on mine and might have got it under 3K. But it would have been less of a machine. You get what you pay for.

Just go for it!

P.S. If it is just for a hobby, playing around, then consider a Liberty or a CheapCNC. For the price they actually look pretty cool. They arn't 4'x8', but it would be very cheap, fast, and easy to do. Just a thought.



Hobbiest:
$2500? Man, where where you when I started this monster! I would have gladly forked over the dough. LOL.

[Hobbiest]

Sam...I build out of steel, so it is a bit heavier! 7 years (I know, doesn't sound long, but I am only 24) as a fabricator have taught me how to build the frame square, and keep it square, regardless of what it is for. Machine that I refer to would be very much like the torchmate machine, www.torchmate.com,
,but using steel instead of aly. Would be rack and pinion, and acme on the z. Don't have the dough to put one together myself (that size), so haven't, but all the parts price out to a very reasonable figure to still make a decent profit (including room for "what do you mean I need another one of those"'s). Also have an idea that uses a box spring for the frame, gas pipe and bearings, and garage door tracks for the power transmission. Like I've said before...too many irons in the fire! Or maybe just not enough fire!

[ynneb]

I must say that these prices that are on display are very cheap.
I would guess that there is a lot of secondhand parts and a lot of time spend hunting around for such parts.
I too am in the process of building an 8x4 and I recon 3 to 4000 is a more acurate figure. I am hapy to be proven wrong though.

I have found an alternative for linear bearings, and this could be a huge saving. They are bearings with v's cut in them that slide on a hardened rail. I gather you sacrifice a bit of accuracy but its minimal compared with the dollars you sacrifice.

From all the picture I have seen on the shopbot tables they use these sorts of v bearings too. The question must be asked how does shop bot make thier machines that cheap and still make a profit? I guess that proves that there are inexpensive ways to do it.

[Patrick2by4]

where do you guys pick up the rack and pinion railing? I can't seem to find it anywhere

[Patrick2by4]

never mind, I found a place www.qtcgears.com
I thought it was called a rack and pinion rack, its actually called a rack rail.:

[Havic]

What is the cost to benefit comparison of using just round shafts vs. linear rails. I see a lot of designs that have a couple of shafts that keep an axis square to another. Does it not work? It only works up to a certain length or width.

What about ball/screw vs. rack/pinion? My research shows that ball/screw is better but if I want an 8 foot x axis I don't see any ball/screw 8 foot long. If I want to have the y-axis span 5 foot (4 foot work area) do I need to drive both end of the x-axis to keep it square?

[samualt]

Havic:
I'm a newbie also, keep that in mind, but:

1. From what I've read the linear rails are more accurate, move smoother, and are much more expensive. I'm using THK rails.
2. Ball/screw vs. rack/pinion - Ball screws are fine till you get over 5 feet (better be 1" thick). But then you must go to rack-n-pinion. The rack-n-pinion setups I have seen, and are using, use a shaft with gears on each end. So, you will be driving from both sides but just using one motor. Ball screws over 5 feet whip around too much, which is why rack-n-pinion are better for longer lengths.
3. I'm building a 4'x8' machine and plan on using a ball screw for the Y axis. But it will be 1" thick with 3/4" milled ends for mounting. At least that's the current plan. You usually have to gear-down a rack-n-pinion system so it doesn't turn so fast. Each has its own set of problems.