Motorized lazy susan

[Mark Gibney]

I want to shape a chunk of wood into something resembling a sphere, and I have an idea that I could do this using a motorized lazy susan and a carbide toothed shaping wheel.

I roughed out the shape of the chunk maybe five or six years ago with a chainsaw and then it lay in the corner since, until this week when I got a shaping disc and went at it. It looks more like a large pumpkin than a round thing.

So I had an idea that if I secured it to a rotating base I could control the disc shaping better, and I knocked around an idea with a machinist friend on how to make this, but I wondered if there is something out there already suited to this, or adaptable. The rpms should be pretty low, I'm thinking maybe 30 rpm, but that's based on zero experience, so if any of you have other ideas I'm open to them.

The wood pumpkin is about 20" in diameter, and is easily liftable, so it's not too heavy.

Mods - feel free to move the thread if it's more suited to another forum.

[Jerry Miner]

An old record player? (33 1/3 RPM)

Have you seen Izzy Swan's (https://www.youtube.com/watch?v=dhaTNIm_uhg) method for making a wood sphere?

[Wayne Lomman]

Use a lathe and turn it on 2 axes. Cheers

[Paul K. Johnson]

A potter's wheel?

[John K Jordan]

Woodturners use several method to make wood spheres. If you are not a woodturner but know a friendly person with a lathe large enough perhaps you could use it to hold the wood but shape with your carbide wheel, rotating by hand or very slowly under power. It seems to me that supporting the wood horizontally would give better access than setting it on a lazy susan.

The biggest issue is holding the wood while rotating it. On the lathe the wood is often held tight between centers on a horizontal axis and make round. Then it is removed and reinstalled at 90-deg to the first axis and made round in that direction. Repeating this will give you a perfect sphere.

The sphere is often held by friction between cupped blocks. A lathe is perfect for this since it is designed to hold things, the tailstock makes a big clamp, and both ends have bearings to let it rotate easily. However, I can imagine rigging up something from wood or metal that would let you do the same thing - think of a giant C-clamp. You would not need precision bearings since the piece would be turned by hand - just something that would allow it to be turned.

To get it perfectly round turners use several techniques. One is to make a curved template with the desired radius from cardboard or something. Another is to mount a small but bright lamp high above the work and project a shadow onto a big piece of white paper or something with the radius drawn. Another is to simply repeat rotating around different axes, removing less material each time.

Some time back David Marks turned a big sphere and wrote about it. It was done on a lathe and actually hollowed inside. He wrote about it but I can't find it now - maybe a google search for 'david marks redwood sphere'. This thread tells a little:
http://www.sawmillcreek.org/showthread.php?18296-Couple-of-days-with-David-Marks

http://www.sawmillcreek.org/attachment.php?attachmentid=17512&d=1111592882

JKJ

[Mark Gibney]

Is that you holding up that sphere? - beautiful work! What's the diameter? And what wood is it?

I found this a vimeo video of this guy Keith Holaman who makes big spheres with a custom rig. He sold the farm to fund this rig, committed fellow.

[John K Jordan]

[QUOTE=Mark Gibney;2673062]Is that you holding up that sphere? - beautiful work! What's the diameter? And what wood is it?

Not me. If the link worked you can read who went to visit David. I never saw the sphere, only pictures. David told me it was redwood.

JKJ

[Grant Wilkinson]

You could try mounting a BBQ rotisserie motor vertically. They turn very slowly.

[Mark Gibney]

BBQ rotisserie - fantastic idea, I'll chase this one down. I love the idea of standing in the corner of the garden with an apron on, making wooden spheres on Sunday afternoon.

Less imaginatively, how about this idea - I attach three pieces of 4x4 lumber to a plywood square, clamp this to the top of my tablesaw, and place my approximate sphere on the 4x4s, raise the blade thru the plywood until it's just shy of kissing the sphere at it's lowest point, turn on the saw, raise the blade a hair and rotate the sphere by hand. I would need to remove plywood all around the blade so I can move the plywood base to get the blade as centered as I can between the 4x4 contact points.

As the sphere becomes rounder it will lower itself towards the blade so I'll have to be mindful of retracting the blade as I progress.

The wood is heavy enough to be stable on the rig-up, so I think it's fairly safe.

Here's a sketch of the set-up I'm thinking of.

356763

Would it work?

[John K Jordan]

...three pieces of 4x4 lumber to a plywood square, clamp this to the top of my tablesaw, ...
Would it work?

I suspect the uneven, not-yet-rounded portions of the wood would raise up the wood but it might eventually take off the high (low) spots and move towards a sphere. Sitting on large ball casters might let you roll it easier Make sure your insurance is up to date. :) I wonder if a router would be safer than the table saw.

If the sphere is heavy it might overload a typical BBQ mechanism.

JKJ

[Mike Henderson]

Use a lathe. The lathe people have been turning spheres for a long time and have the techniques to do it.

Mike

[Mark Gibney]

Mike, yes they have, but I don't have a lathe that'll take a piece of wood that big, and I don't have access to one.

[Bill Dufour]

look up "rotary table" and "welding positoner" for ideas from the metal working trades.
Bill
small ones often cost more then the bigger ones. power it with a cordless drill.
http://www.ebay.com/itm/15-Troyke-Index-Rotary-Table-/272588247410?hash=item3f77869172:g:ymsAAOSwubRXIAO u

http://www.ebay.com/itm/Nonworking-Atlas-Model-200-Welding-Positioner-200-Lb-Capacity-w-Foot-Pedal-/222448850836?hash=item33cafc1794:g:0wUAAOSw4CFY0xv c (http://www.ebay.com/itm/15-Troyke-Index-Rotary-Table-/272588247410?hash=item3f77869172:g:ymsAAOSwubRXIAO u)

[Mark Gibney]

Bill, interesting idea, I'll ask my machinist friend about these, I've never seen one before.

Between Izzy Swan, potter's wheels, record players and BBQ rotisseries I don't lack for creative suggestions. Thanks everyone.

[Keith Weber]

Just thinking out loud: If a manually-turned, rotating table is called a Lazy Susan, would a motorized Lazy Susan be called an Extremely Lazy Susan?

[John K Jordan]

Just thinking out loud: If a manually-turned, rotating table is called a Lazy Susan, would a motorized Lazy Susan be called an Extremely Lazy Susan?

That's funny! In my shop it would be a Slothful Susan.

Mark, about not having access to a big enough lathe - I suspect there is a woodturning club in your area and someone with a 20" lathe and a willingness to assist. Our club sends out emails to the membership if someone contacts them looking for help. I know I'd gladly to invite you to my shop.

JKJ

[Bill ThompsonNM]

Since its a one time thing you could probably adapt a dmaller lathe by mounting the head and tailstock Then just hand turn the sphere without a motor using your grinder