Wednesday, January 12, 2011

Building a lathe workstation

So, I've had this lathe for a few months, but haven't set it up yet:

http://www.woodstockint.com/SHOP-FOX-Shop-Fox-Mini-Wood-Lathe/W1752/

And the extension bed for it:

http://www.woodstockint.com/Extended-Bed-for-W1752-Shop-Fox-Mini-Wood-Lathe/W1753/

The extension bed stretches the distance center to center up to 38" (so I can turn full spindles and table legs, canes, and other long items, in addition to the 15" and under tool handles, pens etc...); and extends the overall length of the lathe to 60".

The manufacturer makes a stand for the lathe without the extension bed, but not for the lathe with it. There are a few sets of lathe legs that can bolt to the lathe bed; but I don't like leaving the bed extender join unsupported.

There are some generic stands out there that are large enough, but they're all sized for much large lathes. Besides, they're really quite expensive (much more than the lathe itself cost), and I don't think any of them are quite what I want. Frankly, I don't think any of the commercial lathe stands are heavy enough, and they're all made of the "wrong" material.

The lathe itself only weighs 140lbs (with the extension. 102lbs without). The commercial lathe stands for smaller lathes are all stamped and bent sheetmetal, with bolted together construction; and most of them on their own weigh less than 60lbs. For a lathe of this size, I'd like to see at least 300lbs weight overall for stability and to damp out vibration. Not only that, but sheetmetal is a poor material for damping, especially when bolted together. Wood or cast Iron are much better choices, being both heavy, and naturally vibration damping. If you have to have sheetmetal, you want it fully boxed out, with welded construction (and if you want to improve it, fill the boxed tubes with foam, sand, or concrete, for more damping).

Since I don't have the capability of making a cast iron stand, and boxing out and welding up a sheetmetal stand is a hell of a lot of trouble and expense; I'm going to go for wood.

Frankly, just about every serious woodturner I know has either a huge, heavy, and expensive cast iron or welded steel stand made specifically for their lathes (usually by the manufacturer of the lathe); or they build their own wood stand. Most guys using smaller lathes (and yes, this is a very small lathe by "serious" standards) build their own.

...plus, I've already GOT a bunch of 4x4s and plywood, in the right sizes, plus all the hardware I need, as leftovers from other projects; cost being a not insignificant factor here.

So, what I'm thinking of, is milling four 6 foot lengths of 4x4 down to 3" wide, flat and true, gluing and lag screwing three of them together across the top and one more as a stringer down the middle creating a T. That will give me a very stable structure to bolt legs and a top into.

Then I'll glue and screw a 3/4" plywood top down over the T, and glue a tempered hardboard surface down over that. Then I'll reinforce the edges of the top with drywall corner bead.

For legs, I'm thinking an A frame style (like a sawhorse only bigger), with three uprights rafter cut at the top to notch into the T truss. I'm thinking about a shelf at the bottom of the a frame gussets (call it 12" below the worktop), and a floor shelf at the bottom of the legs; with heavy duty locking casters on one end, and height adjusting feet at the other, with non-slip pads.

Oh and there is one other major problem I have with most commercial stands: they are all WAY too low.

I'm 6'2", and I like my tool rest to be at 44-48"; which is where my forearms arms are 90 degrees from the elbows out, when standing up straight with my feet shoulder width apart. Most lathe tables, or lathe leg sets, put the tool rest at 38"-44"

The top is going to be 9" wide, and I'm thinking a 28" wide base should be wide enough to be stable, without forcing me to lean too much... but I'm not sure. I may need to dogbone the base shelf, making the end frames 32" wide, and make the center uprights perpendicular members, cutting the center shelf in along the working length of the bed so I can stand closer to the toolrest.

I think I'll put a bracket/upright/holddown for a dust and chip collection system on the backside, and some chisel racks, and layout tool racks; on the front side, in the upper shelf area.

Finally, some hinged or sliding covers over the shelves, to keep out the dust and chips. 

So any ideas? criticisms? experience? suggestions? Anything I'm missing? Think I've got the dimensions right? Any cool features I should be thinking of?

UPDATE:

So, I got some comments about my lathe workstation idea, saying that people couldn't visualize what I was thinking of.

Well, thanks to the wonderful people at Google, that's easy enough to resolve.

Someone asked for a threeview; but I think reciprocal isometric views, and a face on view (rather than two faces and an isometric) would be more illustrative.

So here's a couple of shots of a quickie sketchup model I did...

first the left iso:


Then the right iso:


And the end face:


Not sure exactly why sketchup added and/or subtracted 1/64th inch to the measurements, because I know they were accurate when I drew them up.

The lighter wood is 4x4 dimensional lumber, milled to 3". The mid tone wood is 3/4" plywood, and the dark wood is tempered hardboard.

I'm not sure whether the center uprights are necessary or not. I'm thinking with the T-Beam for the top, it's probably strong and rigid enough without them. Also, I wouldn't be doing any silly through joinery on the middle shelf. Just a gap around the legs with some edging.... if I even put the legs in at all.

What the drawing doesn't show is the metal top coaming (done with drywall corner probably), shelf edging (probably some premade molding trim strips), bottom framing, or the casters and height adjusting feet.

I left them off for clarity; and because I haven't found exactly what I want to use yet. Same thing for whatever dust and chip collection system I end up rigging (probably one of those big ABS chutes into my shop dust collector).

Also,  I need to reduce the height of the legs based on whatever heavy duty locking casters I find, so that the worktop ends up at 40 inches.

Now that I've clarified with a drawing, let's confuse things again.

I'd probably put in another 3" frame member across the bottom center of the upper shelf (between the center legs), and a triangulating crossmember between the leg uprights, crossbolted into the legs and the shelf member, and screwed into the bottom of the plywood end plates.

The end plate is a full structural gusset, glued and screwed into each individual member, for rigidity.

For the drawing, basically because I didn't feel like taking the time to do it, I just show a simple miter and butt join from the top of the outboard legs, to the bottom of the T-Beam. For the real thing, I haven't decided whether I'll rafter cut it, to give a two face join; or cut a corner block and pocket screw through it (thank god for Kreg jigs).

I'll probably put 3" longmembers and crossmembers across the bottom of the outside legs, and from leg to leg, both on the bottom and the top of the base shelf. Then I'll do inside corner bracing on the bottom frame, with a 3" brace, and a 3/4" ply gusset glued and screwed over it; to bolt the casters and feet to. Finally, I'll run two more 3" longmembers,  from one the inside edge of the corner brace, across the entire bottom to the other inside edge of the corner brace, on each side... or if I decide to keep the center legs, I'll just run the two long members underneath the legs and screw up through them..

All that will edge the base shelf, keep the center of the base rock solid, add mass, AND make for a seriously rigid frame structure.

If I end up dogboning the bottom shelf, I'll leave the end crossmembers, but move the outer long members inboard to say... an 18" wide center section; then triangulate the frame with outside corner bracing (making a 7" right triangle with diagonal members on all four corners, from the end of the outboard legs, to the long members).

However, I don't think I need to dogbone it. Looking at it drawn up, and given the mass of the thing; possibly including a few bags of lead shot, or sand... I think I can reduce the width of the bottom shelf/splay of the legs, down to 28". Given the lathe is 8" wide (the benchtop it's on is 9" wide) and the toolrest is right on the outside edge of that width, that would only leave 9.5" sticking out further than the tool rest, which should let me work just fine without leaning in...

...and frankly, even at 32" wide that's still only an 11.5" reach; and I've personally got a 14" reach from 90 degrees, elbows straight down from the midline of my body to the center of my fist (add another 5" from the center of my fist to the tips of my fingers). In a normal working stance, I don't think the full width bottom shelf would restrict my movement or force a reach at all, especially with 4" or 6" casters on the thing, so I can get my toes under the frame (somehow, I'm not worried about the frame collapsing and falling on my feet).

Of course, I'm taller than most, with longer arms than most.

Oh and yes, I know this is a ridiculously heavy, and overbuilt design.

That's the point.  All up, that's about 96 linear feet of 3" milled 4x4 and most of a sheet of plywood. It should weigh in around 280-300lbs, depending on the total weight of the hardware and fasteners used.

I WANT it to be very heavy to absorb vibration. I want lots of doubled up structure to improve rigidity; but I also want it to be of very slightly elastic elastic wood construction, to better damp out that vibration.

Oh and incidentally, the total cost, including fasteners, would run about $180 if bought from a home despot in my area.

One might also note, that if you took the 32" wide dogbone base I talk about above, graft it to the top T-Beam instead of just the 9" wide benchtop, and run a couple of legs down the outside corners into the base frame; one could make one hell of a rigid, heavy, solid, and ambidextrous shooting bench.