4th axis design

[mocnc]

I was wondering if anyone has made a 4th axis design or concept for these diy wood cnc? I am in the process in building the jgro cnc, but I want to incorperate a 4th axis. My goal is to be able to do inlaying or carving on items such as pool cues, gun stocks and well anything really. I was also hoping to one day....way way into the future in trying to build my very own pool cue using the 4th axis method. I do know that building a pool cue is more then just slapping a piece of wood on the cnc router and letting it go. But I like to plan just a bit for the future as well. So......is there any diy 4th axis out there??

[chuckknigh]

Harbor Freight (and similar) has a rotary table that they sell for ~$100. It's a worm driven chuck which is easily converted.

Let me see if I can find the number for you...
http://www.harborfreight.com/cpi/cta...emnumber=47052

It also comes in other sizes. I've no idea how you deal with backlash...but it can't be too hard, since more than a few people have done it.

Several have also built a similar device from off-the-shelf worm wheels, etc.

-- Chuck Knight

P.S. I had the idea, too, that if I could attach a toothed pulley to a MT2 taper, and maybe under a 4-jaw machinist's chuck, I could use my wood lathe as a 4th axis. Seems easy enough...and wouldn't require a complete reworking of the lathe.

[buscht]

I bought a cheap wood lathe from Menards and just replaced the motor with a stepper motor.
That way I could control the rotation. It works fine if you keep these things in mind.
1. There isn't much holding power. Keep the router centered over the top of the Rotational axis. If you need Y moves, then rotate the axis.
2. Any off center routing will cause the rotational axis to miss steps.

I would think that for pool cues, this setup might work just fine. I ended up changing this out to a rotary table for my application. I bought the one from littlemachineshop.com. It cost more than the harbor freight, but I'm happy with it.

Look in the gallery section of this forum. There are several pictures of machines with a 4th axis. Marvinstov has an excellent example.
http://www.cnczone.com/gallery/showp...500/ppuser/223

[Switcher]

mocnc, You should talk to "whiteriver" here on the forum. He does 4-axis milling, (And his work looks Great!) check out some of his work.

http://www.cnczone.com/gallery/data/...and_column.jpg

http://www.cnczone.com/gallery/data/...foam_bust8.jpg

http://www.cnczone.com/gallery/data/..._knight8sm.jpg