[OP]
Member
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
Contributor
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.
[OP]
Member
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
Contributor
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.
Ken
So much to learn, so little time.....
Contributor
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.
Contributor
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.
Contributor
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
Member
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.
Member
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.
Member
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.
Diamanwoodcrafters
Moderator
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!
--
The most expensive tool is the one you buy "cheaply" and often...
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.
"A hen is only an egg's way of making another egg".
– Samuel Butler
Contributor
What happens if you sneeze, and involuntarily jerk the work a bit. Kickback?
Rick Potter
DIY journeyman,
FWW wannabe.
AKA Village Idiot.
Contributor
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.
Member
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?Originally Posted by Warren Lake
Diamanwoodcrafters
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