I was wondering if anyone has thought about or tried replacing the pen with a Dremel. The tool itself would probably be much too heavy, but using a flex shaft might work.

An intriguing idea, indeed, especially the flex shaft thought.

My concern is that the bot relies on gravity to keep the drawing tool in contact with the surface of whatever it's drawing/engraving on if the surface is irregular. It may be difficult to control the depth of the dremel in that case, and if the surface is irregular enough (mini-pumpkin, for example), the increased drag might burn out the motors.

It would probably depend a LOT on the object being carved and the bit being used in the dremel.

You definitely wouldn't want to try it with eggs.

I've tried a Dremel tool with flex shaft. It worked, but poorly. I didn't spend a whole lot of time trying to counterbalance the (relatively) enormous mass of the flex shaft (plus its intrinsic springiness). I switched to a Turbo Carver (cheap high speed air turbine). This worked very well. But is expensive. I'm sure the Dremel rig could work pretty well, but if you really want to do high precision engraving, air tools, with they're incredibly low mass, are the clear choice.

b

We've been developing a low-weight alternative using a vibrated (not rotated) diamond point tool as well. It's effective at etching glass, but can't do the sort of carving that a dremel tool can.

Any word on when this might come out ?

Also, I need to do some marking on 4" rock spheres,
They weigh about 1.5 lbs. Do you thing the springs might hold this ?

If the scribe will make the rock great, if not then I can used
pen markings to control some masking before I sand etch the
sphere.

Thanks
Lewis

Any word on when this might come out ?

Target is sometime this spring, so between now and June.

Also, I need to do some marking on 4" rock spheres,
They weigh about 1.5 lbs. Do you thing the springs might hold this ?

If the spheres have relatively smooth surfaces, then yes, you should be able to mark them. We can, for example, engrave glass spheres. If the surface is rough, the "pen" will have trouble moving over it, and the shallow engraving will also not be visible. Don't expect deep engraving-- just marking, like etched glass --unless you really want to put some effort and/or patience into it.

As far as weight goes, you may well have trouble without planning. It should be quite possible if you (1) use the precision pen coupler and (2) compress the spring almost all the way and (3) stand the Eggbot upright, with the "egg motor" facing down. That way all of the weight of the stone "egg" will be down onto the motor, helping to achieve good coupling to the motor, rather than pulling sideways, trying to dislodge the sphere from the 'bot. As the mass is high, you may also need to adjust the motor current up slightly (using the built-in trimmer) and/or use slightly slower turning speeds to avoid slippage and overshoots from inertia.

Since the engraver is just an add-on, you might consider getting the Eggbot now to learn the process with a pen or pencil.

Standing it on end,

SWEET, thanks

About what is your target price for the engraver ? I would hate to spend $200 on the
eggbot and then have to tell my wife I need to spend another $200 for the engraver,
before I can use it for what I want. She's funny that way.

About what is your target price for the engraver ? I would hate to spend $200 on the
eggbot and then have to tell my wife I need to spend another $200 for the engraver,
before I can use it for what I want.

Current estimate is $(55 +/- 15). Replacement diamond points will be under $15.