I see a lot of comments about 3/4" and 1/2" thick bases out there, but I happen to have a good size piece 3/8" baltic birch ply sitting around and need a bigger sled for an upcoming project. Any reason not to use the 3/8"? It sits on the saw table so doesn't seem like flex is an issue, and I don't plan to add holddowns or anything else to the base, so just wondered if there's something I'm missing before I cut this one up. I'll still use 8/4 material for the front fence, and probably for the back too since I have some scrap that's been sitting around a long time.
The question is whether it is dead flat and will remain dead flat.
(11-21-2020, 12:49 PM)MsNomer Wrote: [ -> ]The question is whether it is dead flat and will remain dead flat.
That's what I think, too. The leading and trailing edge hardwood "spanners" ( I don't know what you call them), combined with the hardwood runners will be key to keeping it all flat and square.
My big sled is 1/2" MDF. I made another, smaller sled last week for cutting box joints. That sled uses 3/4" particle board because that's the scrap I had hanging around.
Good points. I was thinking the front and back fence, along with runners, would keep it flat.
Go for it. The front and rear fences are the only thing that keep it flat anyway. Whether it is 3/8 or 3/4, it is actually 0 inches thick where the saw kerf so, so the fences keep in flat. I have gone as thin as 1/4, no problems
You could make the front and back fence higher to have more assurance it will stay flat side to side. When I made mine, I actually used MDF since I had some. I milled some 2x4s for the fences. So far, so good.
(11-21-2020, 12:59 PM)WxMan Wrote: [ -> ]That's what I think, too. The leading and trailing edge hardwood "spanners" ( I don't know what you call them), combined with the hardwood runners will be key to keeping it all flat and square.
My big sled is 1/2" MDF. I made another, smaller sled last week for cutting box joints. That sled uses 3/4" particle board because that's the scrap I had hanging around.
I used 3/4" melamine covered particle board. It was (and remains) perfectly flat and it has a good deal of lubricity so it slides more easily than other options. I had it in my scrap bin, so it was what I used. A good choice.
Thin plywood flexes enough to if it isn't flat, you can make it flat.
That said, if there is a cup, you want it so the fences flatten it, runners aren't going to do much.
FWIW I use 1/2" MDF for most all my sleds.
(11-23-2020, 08:58 AM)Cooler Wrote: [ -> ]I used 3/4" melamine covered particle board. It was (and remains) perfectly flat and it has a good deal of lubricity so it slides more easily than other options. I had it in my scrap bin, so it was what I used. A good choice.
+1
(11-23-2020, 08:58 AM)Cooler Wrote: [ -> ]I used 3/4" melamine covered particle board. It was (and remains) perfectly flat and it has a good deal of lubricity so it slides more easily than other options. I had it in my scrap bin, so it was what I used. A good choice.
Lubricity is an awesome word.