Hi,

I've spent the last couple of months learning CNC methodology with the help of a small (14"x14") router and an ok CAD/CAM package (V-Carve Pro). The application i am working towards is performing repeatable inlay on stringed musical instruments. I am at the point where i am about to purchase the CNC machine that i will actually use for production. The benchtop machine i am using is a good little router, it is perfect for carving,cuts really smoothly, but is a tad too "sloppy" for highly detailed inlay, I can only hold about .007" over a foot, my X and Y axis are belt driven off stepper motors and i suspect the belts may be the culprit.

An example of my art is creating "tree of life" type inlays on fretboards, personalized head plates as well as the standard embellishments found on stringed instruments.

My dilemma is this: i do not know which type of machine is best for my application, a better built CNC router with all three axis using "ball screws" or a full blown milling machine with a CNC conversion applied?

I like the bang for the buck one gets with a router with regard to addressable size, but also am impressed with the much higher degree of accuracy obtained with a milling machine equipped with a high-speed spindle.

Any opinions about this would be greatly appreciated. I've pasted a couple links below to the machines. I am also welcome for other suggestions, perhaps you have a good used machine or know of one? I am looking to purchase within about the next week.

I am considering the "Vortech" router, the "CNC masters" Jr. and the Microkenitics Mills
http://microkinetics.com/express/
http://www.vortechrouters.com/shortcut-203.html
http://www.cncmasters.com/index.php?page=cnc-jr-table-top-mill

Thanks in advance for taking the time to add you two cents,
Jen
 

HI JEN,
        NOT SURE IF YOU ARE INTERESTED OR HAVE SEEN THE FIREBALL COMET BUT IT SEEMS NICE. IM USING A V90 I BUILT FOR PRODUCTION.
I HAVE A 30,000 RPM AIR SPINDLE MOUNTED. HOLDS 1/8 IN SOLID CARBIDE BITS. SEEMS PRETTY ACCURATE... CUTS NICE. IM DOING VERY CLOSE WORK.

http://www.probotix.com/FireBall_Comet_cnc_router/


DAVE

One concern I would have with a mill is the sawdust will get in the ways and clog up the oiling. I refuse to turn wood for the boatyard on my lathes as about 10yrs ago I agreed to make a plug for a boats tube so they could put it down the slipway whilst waiting on the parts arriving.  Anyway I did it and was constantly trying to clean the sawdust out and after about 5 yrs I had to strip the whole thing down as the oil ways were totally clogged, still was loads of sawdust under the saddle.

Hood

Hi Jen,

My 2 cents.....

Routers for wood and plastic, Miling machine for metals (and some plastics).
Ballscrews are best and if the router has a table larger than about 600mm x 600mm then servos are best. Three phase high speed spindle with VFD is best and good dust / fume extraction is essential.
Exact model and where to buy - that's another story.

Tweakie.

Dave,

I took a look at the probotics offring and do not think it will be enough of an improvment over what i have now to justify the cost. I do like the larger 25x25 cutting area.

The table appears to be made of some kind of composite, that worries me. if the table is out by more than about .005" or so i could wind up with "pockets" that are too deep. That could prove costly with regards to material. The same goes for the male part of the inlay, the abalone.

A 5" x 9"x .050" piece of material (Ablam) costs me about $300. A grade AAA Ebony Fretboard can go for close to $100. So the stiffness of the machine,repeatability, and having a stable "plane"working surface is very important.

I like the idea of an air spindle, 40k rpm is a good increase out of the 25k i am getting now, i could kick up the feed by a good 35%. But i would have to add the complexity and noise of a air supply and the noise of a screamimn turbine. I have found some high speed electrical spindles that run on 220v single phase, that are rated about 2hp and turn 40k as well, but they tend to be bulky.

so, the search continues....
thanks for the feedback

Forgot,

with regard to material, what i am doing is cutting very fine inlays out of a material called "Ablam" it is basically abaline shell that has be delaminated and re laminated with a plastic compound as a binder. many thin layers of shell. the size i use if .050" thick. it is basically limestone. the amount of wood carvig is equally small. "pockets" that are like very thin vines ("tree of life" designs) about .040" in depth. in very hard woods like ebony, ironwood, rosewood & etc...

thanks for the feedback guys!
Jen

JEN,
     IF YOU ARE INTERESTED I COULD BUILD ONE AND DESIGN IT IN 3D SOLIDWORKS. OUR COMPANY IS A FULL METAL FAB & DESIGN SHOP... ALL CNC
WE HAVE LASERS BRAKE PRESSES, VMC'S LATHES AND A FULL STOCK OF FLAT SHEET, RND STOCK, TUBING AND EVERYTHING YOU COULD THINK OF...
I BOUGHT THE V90 SO I COULD LEARN STEPPERS AND CONTROLLERS BETTER AND THEN TAKE THAT KNOWLEDGE AN PUT TO BUILDING OUR OWN PLASMA CUTTER...
NEMA 34 SCALE...  THIS LITTLE AIR SPINDLE I AM USING IS SWEET.. I GOT IT FROM NSK AND BUILT AN ATTACHMENT FOR OUR MACHINING CENTER (VMC) NOW ITS TOO BUSY
SO I PUT IT ON THIS V90.. PERFECT SCALE.   THE MATERIALS YOU ARE CUTTING I CUT ON OUR 6-AXIS 1500 WATT LASER. IT CUTS THE PEARL AND SHELL GREAT.
IT ONLY TAKES ABOUT 450 WATTS. YOU CAN BUY OFF THE NET A 450WATT LASER AND A FOCAL LENS.  YOUR CUT WIDTH WOULD BE ABOUT .005 DIAMETER....
YOU CAN ALSO BUY FOR THE COMET AN ALUMINUM TABLE...

DAVE

Dave,

that is not a bad idea. i could replace the belt drives with ball screw feeds on the X & Y on the table i have. there is room to bring the travel up to 18 X 32 on the table i have. the Z axis is already a very precise set up. built with ball screws and dovetail rails of hard steel. no slop at all.

i have a budget of 8k for this machine, aren't laser heads much more expensive? could it be made switchable so i could use the spindle i have for wood, and the laser for shell?

Jen

YES YOU CAN MAKE A UNIVERSAL MOUNT ON YOUR Z AND JUST MAKE INDIVIDUAL LASER MNT AND SPINDLE MNT. ( QUICK CHANGE )
 WE CAN BUILD ANYTHING HERE.  WE HAVE EVERY MACHINE IN HOUSE TO BUILD MOST ANYTHING.

Hi Dave,

could you please e-mail me your contact information, so we can take this discussion off line? my address is: jedwards@hanger.com.

Thanks,
Jen