Table saw Sled question

[Marc Jeske]

I have a general use sled, based on miter slot.

Looking to upgrade to a larger one, and build a new medium general use one.

I have looked at hundreds of images.. but I have a nagging question...

Why are virtually all based on the miter slot(s), and virtually none running against the fence?

Marc

[Cary Falk]

I would guess it would be harder to control. You not only have to hold the piece you are cutting to the sled but you have to keep the sled against the fence. The other reason is a lot of the time the piece you are cutting extends past the sled. You can't do that if the fence is in the way.

[Marc Jeske]

Well I understand that, but I'm talking if the size/w-h ratio of the piece is suitable, why not along the fence?

In my case I will be production crosscutting a 30" x 6' panel in half, so 3' to right of blade, 3' to left.

If it was a flat sheet, no sled would be needed.

But, the panel is not flat, it has moldings attached and is 5" high around the perimeter.

Picture a casket lid that is cut near the midpoint.

So cause it has this 5" deep lip, I need to use a sled to fully support it.

So I need to make a 2 1/2"+ high cut, flip it over, and cut the other side.

Only reason I see is as you said.. w the miter slot you just push one way, but if against fence, one needs to keep eye on that also.

Any further reasons why like no sleds ride along fences that I may have missed?

Marc

[Ken Fitzgerald]

It could be that the alignment between the blade and miter slot is more consistent and stable than keeping an alignment between the fence and the blade.

[Matt Day]

These are the reasons I can think of off the too of my head:

It’s more stable and predictable to have the sled locked into the x and y axis with the miter slots.

Miter slots don’t move so your kerf stays in the same place.

And your fence blocks the allowable width of cut to the right side. So, a fence guided sled limits the size you can cut to the size of your fence rail.

If you are cutting a 6’ wide piece like in your case, the sled can be as small as say 2’ wide with 2’ overhanging the end on both sides.

[Travis Porter]

For me, at the time, my fence only had 24” to the right of the blade and using a sled that used the fence would have limited how long of a piece I could crosscut.

[Doug Hepler]

Mark

You have seen that almost all crosscut sled designs run in the miter slots. Cary and Ken have answered your question about why. I agree. Now you have three opinions. Yet you seem to minimize the importance of using the miter slots instead of the fence. Apparently you don't feel that is enough of an advantage? That makes me think that maybe there is another aspect to your question that isn't clear yet. Maybe it would help if you would state your objection to making a sled that runs in the miter slots.

Doug

[Alan Schwabacher]

If your sled rides in the miter slot, the kerf will always be in the same spot in the sled. This is advantageous both for measuring to set up the cut, and as a zero clearance edge to keep the cut clean. A sled that rode against the fence would not allow the blade to ride in a single kerf unless the fence were carefully adjusted. Without that feature, I would not call it a sled. Such things exist but are called something like a straight edge jig.

[Art Mann]

I make crosscuts with my table saw sled that are quite long occasionally. A sled that depends on the presence of the fence would drastically limit that capacity.

[Dave Diaman]

Marc, another reason I have not seen mentioned is a big safety issue. Typically when you use a sled you push it across the blade and then pull it back. If you are counting on the fence as a guide sooner or later you will get your cross cut sled thrown into your face when you are not holding it against the fence tight enough and it rides up onto the top of the blade as you pull it back. Think kick back only with your crosscut sled as the projectile. Would you rip a piece on the saw and then pull it back between the blade and fence? Using the fence as a guide is doing exactly that. With the miter slots the sled is locked into position and this is not a concern. Using the fence any little bump of the sled will lead to a ruined part, sled or worse, a kick back injury.

[Jim Becker]

The simple, succint answer is...stability and accuracy. There is no possible way for anything that runs along a table saw fence by human power to provide the same level of accuracy as a sled that's guided by miter slots with a properly fitted rail (or two). That method simulates the benefits of a true sliding table saw when it comes to accuracy. Take the time to get it right and your new sleds will kick things up a notch for your work!

[glenn bradley]

I think you have your answer here. The idea is that you don't have to consider control of the sled at all other than forward motion. This leaves you free to deal with whatever you are cutting. For the ultimate in safety on smaller blanks I clamp the blank and the expected cutoff to the sled and just slide it through the blade. No possibility of me misguiding anything and getting kickback or a small off-cut getting launched.

[Rick Potter]

What happens if you sneeze, and involuntarily jerk the work a bit. Kickback?

[Warren Lake]

dont pull stuff back, everyone does it I dont know why, I was taught you dont pull stuff back its machined remove it. its easier I suppose to pull it back and take it off where im standing on larger parts. Everyone running a shaper tennon sled seems to run the part then drag it back. I realize its clamped, the part is run it doesnt need to be run back over the head again.

[Dave Diaman]

dont pull stuff back, everyone does it I dont know why, I was taught you dont pull stuff back its machined remove it. its easier I suppose to pull it back and take it off where im standing on larger parts. Everyone running a shaper tennon sled seems to run the part then drag it back. I realize its clamped, the part is run it doesnt need to be run back over the head again.

So how do you get the sled back to the start position? Do you walk around the saw and remove it or just pick it up and lift it over the blade?

[Warren Lake]

if you are cutting solid stuff for doors etc then just lift it off after the cut. On big stuff I must have walked around. Its over thirty years since i used a wood sled. I had a long fence on the cross cut saw that could do up to 90 plus inches and the sled itself could take a 4 x 8 it was made from half inch baltic birch on the base so a 4 x 8 could fit in.

[Art Moore]

Being rather advanced in age (read that as o-l-d) I make the cut, turn the saw off, and when the blade stops turning, pull the sled back and remove the piece.

[Warren Lake]

that wont happen if you are cutting solid that would slow you down way too much. Probably had some cuts where i needed two hands on the material in that case the knee turned the saw off after the cut

[Dave Diaman]

Warren, I’m not talking about the material being cut. I’m talking about the sled itself. I push the sled across, pull the material being cut off and then pull the sled back, repeat. If you are using the fence as a guide not only do you risk pushing the sled into the blade when you remove the material but you also risk the sled coming away from the fence when you move it back to the start position to make the next cut since there is nothing keeping the sled from racking except your hand pressure against the fence.

[Warren Lake]

my sled ran in the table slots. For smaller one off parts i stapled up jigs to cross cut angles whatever that ran from the fence and once through the cut were not pulled back along the fence. Ive got enough time om saws that I probably did pull back more times than I would admit. But bulk of the time did it the safer way. If your jig that ran on the fence was long rather than wide it would be safer but either way and time on the saw I go through take the part off the other side then start again with the jig. There are variables as well like if there is a splitter there or not. Most of the time i had no splitter or sometimes a nail in a wood table insert. my newer saw not set up yet has a metal splitter.

[Dave Diaman]

Warren, I’m addressing the original posters question about why to not just use the fence instead of using the miter slots for guiding the sled. My point is along with all the other issues with using the fence as a guide that other members have pointed out there is also a major safety reason for not using the fence. It is an accident waiting to happen.