Hello from NJ
 

Hello there,

I've been lurking here for a while and reading on and off with interest.
By day I build software systems for TV, and at night I fix my old house.
My woodworking skills and electronics skills are very decent, and my mechanical skill are basic.

I have three main reasons for my interest in mechmate:

• Longer term (5 years), I'm interested in building a ocean-going boat (it's good to dream, right?)
• In the next year or so, I'm planning to construct a lot of custom cabinets, and would use a X-Y CNC panel cutter for this (that project alone would justify the cost for me).
• Short term, I'm planning to fabricate many identical 3" x 40" spindles for my house restoration.

..and who knows what else might follow..

With that in mind, I'm thinking about building the Y car and gantry first.
My plan is to mount that to my wood lathe, and use it as a CNC machine for making dozens of identical spindles (the lathe would free turn at low speed, and the router would cut the rough profile -anything except sharp recesses really- under control of MACH3).

The table and X-axes control would be added later when I'm ready to starting building cabinets (and ultimately, to cut the parts for the boat), and I would then use the Y-car and gantry for that setup, and have a full three-axis CNC machine.

What do you think, is this a crazy idea?
Has anybody here used the Y and Z controls for a CNC lathe?

Looking forward to hearing your opinions!

Erik

While the frame and x-axis are physically the biggest part of the project, it is at most 20 percent of the time and cost. If you are willing to do the 80%, you might as well do the last 20% and have a fully functional machine.

Would be so cool to see a lathe with the Y&Z alone.

I think with a lathe, you would still want 3 axis capability.
Some bits and operations would best be performed with the bit off the centerline of the workpiece, essentially using the workpiece rotation to feed the material into the edge of the cutter
IE, on my old Legacy machine the cutting edge of a flatbottom bit was aligned with material center when rounding, This offsets the cutter 1/2 of bit diameter.
Fluting obviously would be done with bit centered on material.

And some fluting is best done on the side of the job with the cutter following the profile shape and cutting with the wings of the cutter...

Initially, I was going to disagree Alan, because a CNC can follow a varied z height along a workpiece.
Upon reflection, I'll agree that a winged cutter from the side will work better than a cove bit from the top, especially at the ends where burning would occur.
Soooo, very good point, sir.

Each aproach has its advantages and disadvantages. The wing cutter will blow-out at the end of the cut but leave a relatively clean cut on the rest, while the other will create a small line right down the middle of the flute (which is a pain in the arse to sand out) with bidirectional tearout at both ends. I guess it depends on what you can live with.

.... and you all are assuming the entire length of the spindle will be turned... often balusters are left square at one or both ends.

No, that's not assumed, quite the opposite. I've turned hundreds of ballusters by hand and with a legacy decorative lathe, unless it's outside of the norm just about 99% have that block at least one end. Generally a lot of stops and starts in the middle are expected.