I am building my first crosscut sled from the David J Mark's plans.
For the rear fence, which I consider the most important part, I am considering maple. The trouble is that a 4' piece of 8/4 maple, 7" high will cost me $68 in New York from a lumberyard. They will mill the faces parallel for that price and joint the edges.
If I did this by buying 2 pieces of 3/4" maple and gluing the faces together to make a 1-1/2 inch thick piece, would that be as stable? It would certainly cost less. I do NOT have a jointer-planer so I have to rely on my supplier to mill the faces parallel.
Also which is more dimensionally stable, Oak or Maple?
I am also considering 2 pieces of MDF face-glued, OR two pieces of Baltic Birch ply face-glued. With either, driving screws into the edge of these seems problematic to me.
You're getting hung up on details...it's only a sled. The fence bottom and inside face need to be straight and perpendicular to each other. The top edge and back face don't need to be straight or flat.
Face-glued solid wood or ply would work just fine, as long as you don't make it go wavy when face-gluing. Even MDF would be fine unless you're making a sled with an adjustable fence, in which case I'd suggest using threaded inserts so that the threads of the screws don't strip out. For regular screws into MDF, always predrill and don't over-tighten.
No matter what the material, assuming that you have one good face, cut one edge in your tablesaw (good face down) to get a good edge, and fasten it to the sled with the good face inward.
I've built sleds using whatever solid wood was laying around, as well as built-up ply or mdf box girders as fences. As long as the flat & square basics are covered, you're good to go.
Some of my sleds are built on the spot to solve a specific problem. Once you build one, you'll see where you might like a smaller version, huge version, taper ripping version...
Metal fasteners are fine, as long as they can't hit the blade. Pre-drill for screws and add glue to back things up. In a hurry? Use 5 minute epoxy. Spot-built sleds and jigs go together instantly with staples, screws and brads. It's pretty easy to know ahead of time where the blade will be, so plan on no metal there.
Sounds like you already have some replies about the fence itself, so I won't add to that. But...
$68?!? That's more than $14.50/bdft for maple? Sounds like you need a new lumberyard. If you need maple for this or any other project, you should be able to find it much cheaper than that, even if you have to mail order it. At my favorite dealer (Lakeshore Hardwoods, Pulaski, NY) it would cost about $27 for a 4' board, S3S, of 8/4 hard maple. ($5.50/bdft, -$.20/bdft discount for 4' and under, +$.50/bdft for S3S). I don't know if Lakeshore typically ships small orders. If they don't, you should be able to find someone with competitive pricing who does ship, and shipping should cost less than $20 (from somewhere in the northeast US to anywhere in NY).
Mon, Feb 4, 2008, 8:25am (EST-3) snipped-for-privacy@verizon.net (Alan) doth sayeth: I am also considering 2 pieces of MDF face-glued, OR two pieces of Baltic Birch ply face-glued. With either, driving screws into the edge of these seems problematic to me. Opinions?
My opinion is that you don't need screws. My last saw glued together with no problem. The back fence was, I believe, 3 chunks of
2X4, stacked and blued. Very stable, worked well for a long time, but then my needs changed, and I scrapped it. Haven't made a new one yet, because I got a miter saw and have been making a custom setup for it. The next saw sled will probably be all ply, laminated as required, with the at least one chunk of 2X4. All glued. The chunk of 2X4 will run from fron to back, a couple of inches high, with two screws holding a caulking gun that's been modified into a hold-down, that was salvaged from the other sled. It's all good.
JOAT - who does not welcome thread question e-mails..
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Another time-saving plan is to make your runners long enough to poke out front and back, rather than cutting them to size before you attach them. Then you can see where they are when you screw them on.
- mill the runners to fit snugly, but slightly less in thickness than the slot depth, slightly over length
- retract the blade and wax the table and slots
- add strips of masking tape to the bottoms of the runners until they stand ~ 1/32" proud when inserted in the slots.
- stick the runners in the slots and run a bead of glue down them
- put the sled bottom on the glue, add a few brad nails
- drill and countersink screws through the base into the runners
- screw the front and rear fences on, using not more than (2) screws on the rear fence, one at each end. Use 4-6 on the front, avoiding the kerf area
- take the sled off the table and remove the tape from the runner bottoms
- raise the blade and slide the sled across the saw, when the kerf gets to the rear fence, STOP. Shut off the saw and hold things until the blade stops.
- remove ONE of the rear fence screws and adjust the fence to 90 degrees to the kerf.
- clamp the fence in place, and drill / countersink / install a screw in a _different_ location, near the one removed.
- Double check the kerf to fence angle and install more screws
- Wax the runners and bottom of the sled, and optionally cut the extra material off
I don't apply finishes or wax to the inside of the sled, as I like the work to have some wood-on-wood "traction" helping to hold it in place, and I have a habit of writing and making pencil marks all over my tools.
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