Vertical Travel Machine Design?

[bri-guyCMFGT]

Greetings All,

I have been looking all over and have not found anyone who has designed or built a router machine in a vertical configuration. Anyone have any pictures?

I am considering building a machine in my garage but space is limited. It seems crazy to layout a machine horizontally in the traditional manner. Why not have the machine in a vertical orientation or tilted back at an angle?

I don't mean a long Z-axis travel. What I am referring to would be to have the spindle mounted horizontally with the Y-axis extending vertically and the X-axis for left to right.

Any Thoughts?

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[ger21]

Like this?
http://www.camtech.ca/images/machine...ker_zoomed.jpg

[jsheerin]

I see two issues to consider in your design. One is the obvious one of having to lift the entire Z axis. You'll need a beefier y axis drive to do this than normally required. I know my z axis antibacklash nut takes a beating in my router and it's only having to lift the router - not the router plus linear rails, support structure, lead screw, stepper motor, dust collector hood, etc.

The second issue I see is fixturing your parts. What happens when you cut out a part? I use small tabs on my horizontal router to keep things in place, but the size tabs I use readily break (which is the idea - it's easy to pull parts out and sand off the tabs). If you use vacuum that's fine, but you'd have to have pods or custom boards for all the different parts you made. For production that might be workable, but I know I use my machine to make lots of unique parts in addition to more mass produced pieces.

[tpworks]

http://www.otocoup.com/index_e.htm

[FandZ]

I see two issues to consider in your design. One is the obvious one of having to lift the entire Z axis.

You can use counter weights to offset any weight issues. Also, whatever method you use to secure your work on a horizontal table should work equally as well on a vertical plane.

There are definitely some benefits to going vertical. Space is one, of course, but also you rails could stay cleaner too. I keep coming back to designing a vertical cnc at some point. I'm building a small mill type cnc now, hopefully to work metal, but at some point I'd really like a 4x4 or bigger machine. With my lack of space, I may just join the small crazy vertical cnc group.

[jsheerin]

Yes, you can use a counter weight, but the disadvantage is that now you have more mass to accelerate. It just requires the same force to go in both directions.

I'd disagree that the tabs I use could support the pieces I'm cutting in a vertical arrangement. I've picked up my cut pieces and the tabs immediately break. They are only strong enough to prevent the pieces from shifting and getting eaten by the spinning cutter as the cut is finishing. Also, if you use vacuum, while that might be strong enough to hold pieces, going vertically will impose an additional load across the piece in the vertical direction. The vacuum force would have to increase enough to increase the friction force that holds the part to compensate for this.

So I'm not saying it can't be done - just that there are a lot of additional factors to design around.

[NEATman]

How about just mounting it on hinges at the bottom and allowing it to tilt up against the wall when not in use?
NEATman

[FandZ]

Yes, you can use a counter weight, but the disadvantage is that now you have more mass to accelerate. It just requires the same force to go in both directions.

I'd disagree that the tabs I use could support the pieces I'm cutting in a vertical arrangement. I've picked up my cut pieces and the tabs immediately break. They are only strong enough to prevent the pieces from shifting and getting eaten by the spinning cutter as the cut is finishing. Also, if you use vacuum, while that might be strong enough to hold pieces, going vertically will impose an additional load across the piece in the vertical direction. The vacuum force would have to increase enough to increase the friction force that holds the part to compensate for this.

So I'm not saying it can't be done - just that there are a lot of additional factors to design around.

I'm not sure about having more mass to accelerate. As you lift, gravity will be pulling the counterweight down. I don't think one would be accelerating something faster than the pull of gravity, 9.8 meters a second squared, on a cnc. There could be an issue with mass when quick stopping on rapids but even then gravity would help out.

I've only used hot glue so far, so I haven't had to deal with tabs but I've had work pieces come undone after being hot glued while cncing. Nothing like seeing a block of .75 MDF flying off your machine to get your heart going. That's such a horrible noise when a piece comes undone and your machine is just grinding into itself. Makes me feel like I just stepped on my wifes toes by accedent with boots on...lol

[jsheerin]

Thanks, you're right - it will always require less force from your linear motion hardware to accelerate with a counterweight as long as you are accelerating below 1g. I guess I was thinking of above 1g for some reason. I think there are cnc's that do that, but probably not very common around here. But if you go over 1g, then losing the counterweight will require less force. Basically F=2ma at all times for the counterweighted case while F=ma-mg for the non-counterweight. So the force required for the counterweight increases twice as fast with increasing acceleration as without a counterweight, and the break even point is when a=g.

[X-29]

But when accelerating in the horisontal direction you have to take the added mass from the counter weight(s) in consideration.
But with a skillful design, I think there is a lot of weight to save on the moving parts.

[H.O]

The counter balance adds inertia to the balanced axis (as well as to the axis carrying it as X-29 says). So, even though the linear force to actually move the axis will be smaller by balancing it, once you get it going it'll be harder to stop. Think of it kind of like a flywheel. With that said, many large VMC's have their heads counter balanced.

Gas-struts is another way to offset or balance the mass of an axis without adding much inertia, the drawback is that the force generated by the struts goes up as compress them, like normal coil springs.

[jsheerin]

Actually that is not correct for the a<1g case - the force required to accelerate (or decelerate) is lower with the counterweight. Regardless of higher momentum, F=ma accounts for that.

Example: The moving assembly is going down at a constant velocity while the counterweight is rising with no net force on the system (hence constant velocity). There is a force = mg downwards on the moving assembly and mg downwards on the counterweight which are connected via a cable over a pulley. Now there is a force Fs (from a screw) upwards on the moving assembly to decelerate the system. The sum of the forces on the moving assembly is Fs-mg+mg, so the net force is Fs. Fs=2ma due to having the counterweight.

For the same situation without counterweight, the sum of the forces is Fs-mg. In this case Fs=ma due to no counter weight. So ma+mg, or m(a+g). Ie, more force is required to decelerate if a < g.

[corwes]

To counter act the weight of the z axis use a rodless pneumatic cylinder on the y axis. The type that has a magnet on the inside. Have a large pressure tank on the side of the machine and adjust the pressure for the tank until the y axis is weightless. These cylinders can be expensive , but Ebay is our friend.

[dagger987]

Did you ever find a solution for an upright CNC machine? AXYZ International who purchased Camtech has updated the original design and now manufactures an Upright Panel CNC machine.

Please check out this page

http://www.axyz.com/sys/router/panelrouter/


Larry

[jsheerin]

Looks cool, but I still wonder what they do for fixturing - use high flow rate vacuum through a sacrificial spoilboard? I guess that would be possible but out of reach for a lot of us diyer's.