How to square a cut off sled

[Lee Schierer]

After struggling to get two wide end panels cut to length and square on my TS last night, I feel the need to make a cut off sled. I've seen lots of designs, but one thing that isn't clear is how do you get the backer guide exactly 90 degrees to the blade??

[Stan Mitchell]

I believe that the common procedure is that after you've built the sled and guides - run the blade up through a portion of the sled - then you have a zero clearance slot to square your front and rear fence to.

[Dan Friedrichs]

I've tried doing it many times and failed. I have a good square, and can set the sled so that the square can rest between the TS fence and the sled's fence, then I can tack the fence in place with some brads, then screw it tight. The screws tend to move the fence ever so slightly, though, so that's difficult.

I can get something that looks square, but doing the 5-cut method, I find that it's always off by a little (or at least off by MUCH more than I will tolerate with my miter gauge). This problem is compounded because you'll be using the sled with large panels, so the error is more obvious than with short pieces, so I feel that it really does need to be dead square.

I think what I need to do is fix one end of the fence, then put some sort of adjustment mechanism on the other side (a bolt that can be turned to precisely pivot the fence a small amount, for example). Then 5-cut can be done while adjusting the fence until it's square. Some may think that's overkill (and maybe they're right - if I need to get out feeler gauges to tell how out-of-square my sled is, maybe that's "square enough"), but I don't think it is. A well-adjusted rip fence should allow you to cut a board that is the same width (within a few thou's) end-to-end, so why shouldn't we expect the same precision from a miter sled?

[Jeff Bratt]

Just remember that the critical squareness measurement is between the fence and the miter slot runners.

I've had success with fastening the fence to the sled with two screws - one at either end - then checking for squareness. If one end of the fence needs adjusting, replacing one of these end screws and repeat as required. After I'm satisfied the fence is square, then I put in more screws along the center to really hold the fence in place.

[Glen Blanchard]

The method I use is to place 3 or 4 bolts through the fence to secure it. Create the holes larger than the diameter of the bolts so that the fence can be moved. Using the 5 cut method, determine how much you are off and using a dial indicator temporarily clamped to the sled, move the fence as needed, tighten the bolts and retest with the 5 cut method.

I just completed this process last week and it is much easier than any other method I know of and is very precise (although it took many attempts to dial it in just right). According to the last 5 cut test I made, I was off by .00075" over a 14" distance.

[Craig McDaniel]

This may not be the best way, but it worked for me...

Secure one end of the fence with a bolt/screw and that will be the pivot point.

At the other end of the fence, screw a block to the sled that, when the fence is clamped to it, will create an angle that's just a little more than 90 degrees. This block can be left on the sled or removed after you're squared up.

Use playing cards/paper to shim the space between the clamp block and the fence until you find 90 degrees (or as close to it as you're happy with). Each time you shim the gap, use clamps to hold everything snug. This will let you make your test cuts to check for square and not worry about your angles changing on you.

When you've got your angle, put screws into fence from underneath to hold your setting. Remove the clamp block if you'd like.

Good luck with it.

Craig

[John Coloccia]

Is your fence square to the miter slot? Have your local mill cut your sled plywood on their slider. You'll end up with a piece of wood with nice, square corners. Put double sided tape on the runner, stick the runner in the miter slot, and bring your fence over maybe an inch to the left of the blade. Square the sled plywood with the fence, push down on tape, and now everything is square with everything else. Then it's just a matter of making the cross piece flush to the back of the sled. Run it through the saw to trim it, and done. No reason to remove the tape on the runner, by the way. If you use thin double sided tape (like turner's double sided) it's so thin it won't interfere with anything. Just screw right through it. Use a couple of dimes under the runner so that it's just proud of the table saw top and the tape will contact the wood.

If the sled is on both sides of the blade, you can do it the same way if you have room to the right of the saw for the sled and the fence. There's always a little wiggle room when you screw down the cross piece so you can adjust if you have to, but as long as all the wood is flat and square, I've never had to adjust it.

That's just how I do it, but I've never seen anyone else do it like this so maybe there's something wrong with this technique and I'm just getting lucky.

[Vince Shriver]

Craig, I really like your idea. It got me thinking that if you made the fence adjustable for other than 90 degee angles, that block - if left in place - would be a quick index to return the fence to the 90 degree mark.

[Craig McDaniel]

Vince,

If you do the adjustable fence and the fence goes on both sides of the blade, you'll end up with a big gap where the kerf changes with the angles.

If you want to change the angle of the fence, the pivot point and the rest of the fence need to be on the same side of the blade.

Craig

[glenn bradley]

My rear fences have been adjustable since my first unsuccessful sled. I use 1/4" t-bolts with 1/4" holes in the fence so that the bolt shafts are tight. The heads ride in oblong recesses on the underside of the bed and the shafts feed through 3/4" holes. This allows much more adjustment capability than I have ever required. To align the fence (and my miter gauges) I use the 5 cut method.

[Nissim Avrahami]

Hi Lee

Do it like on this post....I made 2 "Full sleds" and 2 "Half sleds" with this method...I'm so confident that I just Super-glue the fence even without scres (on the half sleds) without doing any 2, 3, or 5 cut test...
http://www.sawmillcreek.org/showthread.php?t=64448

And, if you'll roll-up, you'll see how I made the "Home-made triangles"

Regards
niki

[Stephen Edwards]

My rear fences have been adjustable since my first unsuccessful sled. I use 1/4" t-bolts with 1/4" holes in the fence so that the bolt shafts are tight. The heads ride in oblong recesses on the underside of the bed and the shafts feed through 3/4" holes. This allows much more adjustment capability than I have ever required. To align the fence (and my miter gauges) I use the 5 cut method.

Glen's adjustable fence method has worked for me. The nice thing about is that when you retune your saw in the future, as surely you will, it takes just a few minutes to make any necessary adjustments on the sled fence.

I forgot to mention: John Nixon, a fellow creeker, has made an excellent video on his website for building a sled. He shows in detail in the video his method of squaring the fence. You can find the video by doing a google search using the phrase, "super sled".

[John Schroeder]

I've built two different sleds and can't imagine crosscuting without one. Both are based off of an article at highland woodworking:

http://www.highlandwoodworking.com/l...able%20Kit.pdf

I did not get the kit and just cut two hickory runners and planed down to size. For the second table, I added t-tracks for hold downs and stops that were loosely based on John Nixon's Super Sled here:

http://www.eaglelakewoodworking.com/...iter-Sled.aspx

The first article at highland woodworking (which I think was originally at fine woodworking?) documents what I've found to be a very, very precise way to fit the back fence at exactly 90 degrees to the saw kerf (which should be dead parallel to the mitre tracks).

A quick summary: attach the runners, then raise the saw and cut most of the kerf through the middle of the sled. You do not want to cut through either end until the back and front fences are permanently attached, so leave several inches (I left 4 to 6) on either end. Then take a pair of trammels or a beam compass and stick the point in one end of the kerf cut and then scribe an arc on each outside edge approximately equi-distant from the front and back. Now put the point in the opposite end of the kerf cut and scribe two more arcs on the outside edges, each of which intersects with one of the first two lines. Now take a straight edge and draw a line across the sled through both intersections. This line is precisely 90 degrees to the kerf and the runners. Transfer it to the front and the back edges and use it to align your fences.

I used this method twice, along with the intructions to clamp the back fence in place and then attach with a couple of screws to make a test cut. Now take a perfectly square, long, wide piece and cross cut it.Flip one side and if both sides are still straight you're in good shape. If not, loosen, adjust the fence, and repeat. When alignment is perfect, clamp two blocks against the front of the back fence, remove, apply glue, and reseat the fence against the blocks. Clamp and screw it in and you're done. The whole process is illustrated and explained much better in the link.

I did this twice and the line was dead on both times, and I did not need to adjust the fence either time. This method uses the entire width and length of the sled as a reference and is as accurate a method as I've run across. Good luck, I hope you get as much use, precision, and enjoyment out of yours as I have with mine.

[Ken Shoemaker]

I only make sleds using the tutorial shown in Nissim's post. They are dead on EVERY time!!!! Try it.

[Cary Falk]

I made a sled once and also had a hard time adjusting to get it dead on. Every time I would go to screw the fence down it would move ever so slightly. I was going to make an adjustable one but I found a good deal on the Incra sled. I attached my 1000SE to it and cannot be happier. It is much easier to store and much lighter.