All you need to build this sled is:
1) A bar clamp long enough to handle the wood you will be cutting;
2) Two pieces of 3/4" plywood about 3" wide and about the length of the clamp;
3) Two wood screws about 1-1/2" long
There are a lot of band saw sled plans on the net. Here are some of the characteristics of ones I found:
1) Every log sled relied on the miter slot to make straight cuts. Since most saws have the miter slot to the right of the blade, the log is, of course, cut to the right of the blade. This puts the weight of the log out near the end of the table on an already top heavy band saw.
2) Most sleds require a lot of material to construct. Either you must, initially, build a sled big enough for all logs you cut, or build a new one, when you deal with bigger logs. For example, when I made my first sled, I was working with logs small enough to be milled in a stock, fourteen inch band saw. The logs were less than six inches in diameter and no more than fourteen to sixteen inches long.
After adding a riser block, which allows me to cut logs up to twelve inches in diameter, I needed a sled with the capacity to handle the larger logs.
3) Log sleds take up a lot of room to store.
For the foregoing reasons, I set out to come up with a jig or sled that both allowed me to cut on the left side of the fence, use scraps or a minimal amount of materials, and end up with an easy to store sled. This is what I came up with, and it works. I used a bar clamp sold by Harbor Freight.
Like other log sleds, this one attaches to the log and stabilizes it. For the most part, that is where the similarity between my sled, or jig, and others ends.
Rather than follow the miter slot, this jig follows the fence.
The clamp is only needed to stabilize the log, so it doesn't roll. If the log is allowed to roll, it will destroy your blade and could be dangerous, if your hand were anywhere near the blade and pulled right (cutting on the right of the log) or left (cutting on the left of the log) into it.
When using this jig, if you make your initial cut using the fence and cut to the left of the blade, on the side where the clamp secures the log, the blade will push the fence down, against the table. So the log cannot roll, if the clamp is secured adequately. Of course, you must make sure the blade will clear the clamp.
NOTE: If it will clear the front of the clamp, it will, also, clear the back of the clamp.
If you make your first cut on the right side of the blade, the blade will want to pull the log down on the right, thus trying to lift the jig.
In both instances, like feeding wood through any saw, you should maintain control of the log and jig.
I make most my initial cuts on the right side of the log. Merely holding the jig, at the fence, has been adequate. If more pressure was needed, it's time to sharpen or replace the blade, or adjust the saw set up.
When using my log stabilizer / log sled / log jig, I make my first cut, then flip the log, so the flat side rests on the table. After that, , then reconnect the jig to allow me to get another straight line cut off the fence, ninety degrees off the first. After that, the sled is no longer needed.
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To build this jig, or sled, you need:
1) A bar clamp long enough to clamp both ends of the logs you are going to mill into boards (this doesn't ruin the bar clamp and it can be removed and used for other things).
Keep in mind, equipped with a three foot clamp, this jig can be closed down to hold a log only a few inches long. As such, you can use a four foot bar clamp, if you don't mind the excess.
If desired, the sled could be modified to use heavier duty half or three quarter inch pipe clamps. Since your pipe clamp jaws do not reach out as far as the bar clamp jaws, it would be easier to cut some logs on the left. However that would add weight and be more difficult to handle.
2) Two pieces of 3/4" plywood a couple inches longer than the clamp you choose.
For mine, the piece of 3/4" plywood the clamp mounts on is two inches wide. The second piece, which rides against the fence, is two and three quarters (2-3/4") wide and the same length as the other, give or take an inch or so.
3) Two 1-1/2" (1-1/2") screws to mount the clamp to the two inch (2") pieces of plywood.
4) Depending on how you want to join the two pieces of plywood together, you'll need about four 1-1/4" screws or nails. I also glued mine, but, with screws, that shouldn't be necessary.
Regarding the two pieces of plywood used to build this log cutting jig, the clamp will rest on the first pieces and the second is only to keep the clamp away from the fence, so it doesn't catch. More specifically, the second piece of plywood provides the smooth surface needed to move the log along the fence.
The bar portion of the clamp will lay on the edge of the plywood and will be secured to it at both ends. Because the clamping parts of the clamp stick out from the bar, a notch will have to be cut out of both pieces of plywood, at the non-moving edge, sufficient to allow the bar to sit flat on the plywood and so that the shim piece of plywood can mount flush to the pieces supporting the clamp.
Similarly, a long notch must be cut for the moving part of the clamp, so that it can move up and down the length of the bar. Leave at least an inch and a half (1-12") at the end, for the end of the bar to rest on.
For my clamp, I only had to cut down one half inch (1/2") to allow the two pieces of plywood to join and to allow the clamp to move for different sized logs.
If desired, you could just mimic your first piece of plywood by using it as a pattern.
Once you've assembled your log cutting jig, you merely need to:
1) Mount your fence to the table.
2) Lay your log on the table and roll it to a position for your first cut.
3) Clamp the log, tightly.
4) Turn on the band saw and dust collection, then start cutting, while holding the clamp against the fence and down to the table.
5) After the first cut, loosen the clamp, turn the log so the flat side is down, re-secure the log, then re-position the fence and make your next cut.
6) With two square sides, ninety degrees to each other, you can finish cutting the log into boards just using the fence or other re-saw guide.