Crosscut Sled Base Thickness

[jcredding]

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.

[MsNomer]

The question is whether it is dead flat and will remain dead flat.

[R Clark]

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.

[Cooler]

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.

[rwe2156]

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.

[Stwood_]

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

[Mike67]

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.

[jcredding]

Good points. I was thinking the front and back fence, along with runners, would keep it flat.

[barryvabeach]

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

[lincmercguy]

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.