[RomanLini]

I put the various parts on the scale today and ...holy moly... it adds up.

The entire machine is now about 584 pounds

That reminds me of that quote from the original "Jurassic Park" movie; the kid is playing with the nightvision goggles and the lawyer says "What's that you got? Is it heavy? Then it must be EXPENSIVE! Put it down..."

[JerryBurks]

That reminds me of that quote from the original "Jurassic Park" movie; the kid is playing with the nightvision goggles and the lawyer says "What's that you got? Is it heavy? Then it must be EXPENSIVE! Put it down..."

Interesting way of looking at it. My new machine is then about $6.90 per pound. Maybe I should have made it from steel

But WAY cheaper by the pound than rib eye steak or the SharkPro+ tabletop CNC that I have been using.

[RomanLini]

Interesting way of looking at it. My new machine is then about $6.90 per pound. Maybe I should have made it from steel

But WAY cheaper by the pound than rib eye steak or the SharkPro+ tabletop CNC that I have been using.

It should keep better than the rib eye.

Interesting to see the cost per pound, thanks! I recently bought a heap of marine grade aluminium 5083 plate in 12mm and 16mm thick to build my next machine. The aluminium cost me $7 AUD per kg, which works out at about $3.05 USD per pound. But I have no idea of the relative stiffness per pound of a comparable structure built from aluminium vs the bamboo ply. Since my machine is quite small I think the aluminium works out better but on a large machine like yours the bamboo is likely stiffer (and more damped) for the same poundage in plate materials.

I assume too your cost includes heavy stuff like motors and linear rails, did you do a costing of just the bamboo ply per pound?

[JerryBurks]

I assume too your cost includes heavy stuff like motors and linear rails, did you do a costing of just the bamboo ply per pound?

Yes that includes everything: tabletop extrusions, rails, step motors, lead screws and spindle. The relative stiffness by weight of the bamboo (or high quality baltic plywood) is about the same as typical aluminum, 5 times less rigid but also 5 times less weight. That means for the same stiffness you got to build a bigger structure. The major reason for me to use wood was however the machinability and easier joining (glue and screws).

The bamboo plywood by itself is about US$1.52 per pound or $200 retail for a 4'x8' sheet (20mm thick). A commercial outfit can probably get it much cheaper. For wood the stuff is pretty heavy, you definitely need 2 people to handle a sheet.

Actually, your earlier post with the "all bamboo" joke has triggered an intriguing project idea (when I am done with this one)....to design a smaller working CNC machine (maybe 2'x2') entirely in wood, including rack/pinion, reduction gears, linear guides, and structure. No so much because it makes any practical sense or for promising performance but as a woodworking showpiece and for fun like a wood clock. Oh well, maybe next year.

Unfortunately nobody makes stepper motors or small ball bearings from wood so there will be some compromise

[bobsch]

Unfortunately nobody makes stepper motors or small ball bearings from wood so there will be some compromise

Have to use hand cranks since wooden drivers and computers aren't exactly thick on the ground, either.

[JerryBurks]

Have to use hand cranks since wooden drivers and computers aren't exactly thick on the ground, either.

I think I solved the motor, drive and computer problem May need a little training to get the 3 axis to move as needed.

[zool]

JerryBurks stated: The bamboo plywood by itself is about US$1.52 per pound or $200 retail for a 4'x8' sheet (20mm thick). A commercial outfit can probably get it much cheaper. For wood the stuff is pretty heavy, you definitely need 2 people to handle a sheet.

Did kitchen and bathroom cabinets with a friend this spring, client wanted bamboo plywood [PlyBoo]. His cost was $185 per sheet for 25 sheets. He buys many units of sheet goods from this distributor a year, and the $185 per sheet was a "good" price.

PlyBoo [as it is called] is still a low production item, and it costs lot to make, so it will probably always be expensive.