Okay, check this idea

[Jan]

Okay,
here's the idea, and keep in mind, this is just another idea.
Being the everlasting cheapsakte I am, what do you think about modding a radial arm saw for the basic traversing arm, using the height crank with a stepper motor, for height control, adding a acme screw rod for back,forth and a moving table for the left/right motion.
What say you?

[pminmo]

The old Roybi R200 actually becomes an overarm router by removing the blade and rotating the motor 90 degrees, and I have one: http://webpages.charter.net/pminmo/i...ment%20007.jpg

But depending on tolerances, I don't believe it would hold on side loading without being beefed up. Interesting thought.

[sol]

I converted a Craftsman arm saw into a panel cutter and in the process found that, as pminmo stated above, the side loading tolerances just are not there...also the arm is heavy and would require a substantial motor to lift it. For the time and trouble involved in overcoming these limitations I would place my energies at a different starting point.
Neat idea though; it is on the right track....after a while anything that slides will look like it has potential. Gee! Wonder if I could turn an Arby's meat slicer into a CNC machine....

[Jan]

Thanks for the thoughts.
Just a little confused about the side load comments. Can you explain further?
The height adjustment doesn't seem that difficult to operate, but there is about a half turn of back lash present, any way to remove that without disassembly?
Thanks
jerry

[pminmo]

A RAS is designed for the force/resistance to be in line with the arm, i.e. when you pull the saw thru lumber. With the saw not on, push it from the side, i.e. perpendicular to the blade when crosscutting. That's side load. I think the problem would be accuracy in that axis.

Phil

[sol]

The cutter will be experiencing loads not only in the standard arm saw front and back (Y) direction but from side to side (X) as well. Arm saw's bearings are made to handle Y well enough, but the X is frequently loose. Hold the arm saw's blade and push it from side to side, you'll probably find quite a bit of slop there.
The lift back-lash is probably in the nut and the end bearing, if there even is a bearing at the shaft's end, and some saws use two bevel gears in the mechanism for even more play...disassembly required.
Sorry ‘bout the redundancy... Phil posted while I was writing this

[Jan]

Okay gotcha on the side load.
I've checked the side load deflection and on this 20 year old (get yer mind out of the gutter) machine, it's minimal, also that play is adjustable, the carriage mounts are mounted with eccentric bolts, loosening the nuts and turning the bolts results in increasing or decreasing the amount of play or friction present along the length of the arm.
On another note, the motor is a 110 volt, prolly 1750 or 3750 rpm, I seem to recall somewhere someone made a spindle that was driven by an external motor. This rpm is to low for router performance, my thinking at this point is to use a cog belt to increase the speed. And now, finally the question,what is a good speed to shoot for for routing operation?
and I'm not sure about my math, so any help here would be appreciated, but seems to me if this is 3750 rpm motor and we need high rpm for routing, 6 inch pully on the motor and 1 inch on the driven end would produce 22500 rpm, is that too much to expect?
Thanks
jerry