I have an idea for a mini engaver. See the attached JPG. It will use two Vexta motors (PK264-01B, 1.8 deg., 1A/Phase) and one EAD motor with hollow threaded shaft for a 1/4-40 tpi lead screw. Has anyone seen or used one like this before? The travel will be about 2"x, 2"y, and 1"z. Programming will be interesting, because the x and y will not be linear but rotary (an A and B axis expressed in degrees.) I could manage this by generating the NC code in Esprit, but I want to find a way, if possible, to control it with x and y linear co-ordinates (but that is a different forum!)

I expect that rigidity wouldn't be a problem. The engraving bit goes to a point and would cut at max. 0.015". The natural braking torque of the steppers would be strong enough for that kind of cut.

I'll include a photo of another mini-mill I started building. I designed it with steppers, but haven't finished attaching them. Not sure I ever will. Travel of 4.5"x and 1.75"y.

The spindle with be parts from a cordless Dremel (12v DC motor with attached collet.)

Built my first Desktop mill two years ago. Xylotex driver, all EAD linear motors (same 1/40-40 lead). X and y travel of 6" and 8". Gantry style. Used a 24v DC motor and an old Flex-shaft handpiece for a spindle. About a max. feed of 5"/min. Not bad, but a bit slow for engraving. Used TurboCNC to control.

I would love to hear what anyone has to say about the mini-engraver. Or field questions.

oopps. Mini-Engraver image didn't upload on first try. Here it is.

very cool. reminds me of this older site I saw which is very similar, http://freeandeasy.sourceforge.net/rotproto.php.

so, the 'side to side' movement is on an arc? this seems like quite a bit of programming hassle compared with just a straight axial movement?

otherwise, i like the ideal of a tiny machine.. i totally want to build one one day... something with a work area of ~2x2x.5" and high resolution... could be lots of fun.

my plan would be to use all high-quality positioning stuff off ebay..slides with these small travels are cheap... $15 each or less... and highly accurate.. would be a neat machine to make tiny circuit boards, and other percision parts.. i could be wrong, but it seems 'easy' top calibrate such a little guy.

Robert

Neat mini mill, have plans to make one myself, after I get my router going of course, I planned to use it at work (electrician) to engrave light switches, power points, data outlets etc. Might be handy to use on site via laptop when needed. Has the added advantage of being cheap to get the parts, electronics will prob be the most expensive part.

Russell.

you could control this machine by implementing the equations feature in Mach3, see:

www.indoor.flyer.co.uk/kinematics.htm

look at the pdf file, I show how to use the equation for a different sort of machine but the same rules apply. This keeps your g-code simple but you do have to do a little maths to get the equations. Happy to help with that.

Graham

This page has some equations to use for a rotational "xy" table. They link to the "free and easy cnc" rotational table design.

http://www.sxlist.com/techref/pcbmill.htm

I'm definately going to be building one of these just for the coolness factor. A standard cnc gantry machine is mezmerizing but this would be absolutely spellbinding.