another Panel Sled question

With all the talk of panel sleds recently, I thought I'd ask:
How does one get the sled fences REALLY square to the line of travel/blade?
I've made a couple of small sleds, but they were never EXACTLY square. What's the secret technique?
I have an Incra miter guage and love it, but it's only a left-of-blade affair. It would be great to have a nice large sled, but if it isn't EXACTLY square, I wouldn't be able to sleep at night.
Any advice?
Joe
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wrote:

Glue / screw the runners to the sheet.
Raise the spinning blade through the sled (HOLD ON TO THE SLED!!<G>). All you need is about a 10" kerf, leave good amounts of plywood at both the front and the back.
Screw one end of the rear fence, which has one face jointed flat, and one edge jointed straight and 90 degrees to the face, to the plywood.
Use a big drafting triangle to square the face of the fence to the kerf.
Clamp tightly.
Check squareness again.
Screw fence all along the length.
I don't bother with the front fence. In fact, I've been know to use rough lumber for the front fence.
Barry
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Joe wrote: >How does one get the sled fences REALLY square to the line of travel/blade?
Trial and error. >I've made a couple of small sleds, but they were never EXACTLY square.

First make sure your blade is parallel to the mitre slot. Place one fastener at one end of the sled fence as a pivot point. Square the fence to the blade as closely as possible using a carpenter's square, not touching any teeth on the blade with the square. Mark the position of the fence on the sled. Secure the fence to the sled with a couple more screws, and make a small trimming cut using a 2 foot board with freshly jointed, planed faces and edges along the fence. Mark the edge that will be against the fence. Then take about a 5-inch wide crosscut. Keeping the same edge against the fence, flip the 5 incher over, butt it up against the other piece and check for space. The wider the board, the more apparent any out-of-squareness will be. Then remove the two screws (not the pivoting one), and go figure which way to move the fence to square it up. Use new holes for the new screw placements. It may take five or more efforts to get it close enough so you can sleep at night. Tom >
Someday, it'll all be over....
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The easiest solution is to screw the fence on to the edge of the sled and shim it on one side or the other until square.

travel/blade?
What's
affair.
square, I

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BTY, test cut piece of plywood to test you squareness. About 10" square. Adjust you sled fence by the results of the cut not by squaring the sled to a square.
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Check the the Fine Woodworking "methods of work" collection - the tablesaw book. There's a method in there that works really well :
- Use double sided tape to stick a square bit of sacrificial material in the middle of the sled, straddling the section where the kerf will end up. - Raise the sawblade and push the sled into the blade, cutting only halfway through the sled, but enough to have a kerf line completely through the sacrificial piece. - Your one sacrificial piece is now two pieces, stuck down on the sled by double sided tabe. - Lever off one of the pieces, and use an accurate square against the cut edge of the remaining piece to provide a 90 degree reference that you can set your sled fence/s to. - When your fence/s are done, lever off the remaining sacrificial piece, and you've got yourself an accurate sled.
Cheers,
Justin.

travel/blade?
What's
affair.
square, I

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Here's my method:
1. Attach runner(s)
2. Cut the saw kerf. For a straddling 2-runner sled, cut most of the saw kerf :-) This can be done by raising the blade into the sled like a zero-clearance insert, and then sliding the sled until there is an inch or two of material to hold it together.
3. Square the fence to the kerf using a known good 90 degree "something"..

travel/blade?
What's
affair.
square, I

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