Making a crosscut sled

[Brogan]

I'm planning to make a large(r) crosscut sled so I can cut 24" pieces (the size of the hinged lids for my drop zone).

The first thing I realised is that without an existing large crosscut sled, it's difficult to get a perfectly square piece of plywood for the base for the new one.
I had to use a combination of the table saw and circular saw, coupled with a large square and straight edge (which I first had to make on the table saw ... :icon_scra).

Anyway, the base is done and then I moved on to the fences.

I'm using 3/4" plywood - two pieces laminated together.
I can't use hardwood as I don't have a jointer and planer to ensure a perfectly flat face.

Unfortunately, the plywood is bowed and although I put the two bowed sections together opposite (to cancel out the bow), it's still not perfectly flat.

So, what are my options considering my limited tools?

I even considered some sort of aluminium straight edge as the rear fence but there are obvious issues with that with regards to cutting the slot, possibly catching the blade with it, etc.

 

[MarkE]

Perfect and woodworking don't really go together in the real world.

I know that is not much help in your current situation. Just a woodworking philosophy for me.

If you are willing to accept pretty close, or close enough, I would be happy to help you get your plywood squared up and your hardwoods really close to flat.

 

[Bill Clemmons]

If you're using plywood for jigs & fixtures, like a crosscut sled, it's probably worth a little extra to use baltic birch plywood. It is more stable and flat. I've also used 1/2" MDF for some TS sleds.

 

[Jeremy Scuteri]

Ditch what you have and start over with a flat piece of plywood or MDF. A crosscut sled should make your life easier, not introduce more frustration. Take the extra time, build it right and it will pay off every time you use it. There is no need for the base of the sled to actually be square, as long as the fence is 90 degrees to the runners, you will get a square cut. Most carbide blades will cut aluminum without any issues. The wood whisperer had an aluminum fence on a crosscut sled for a while.

 

[Melinapex]

If you have a router just google "flatten a board with a router " and that should get you some methods to try. I was trying to think of a way to use the tablesaw - but too many ways for that to go wrong....
i made the one William Ng did on YouTube. Plus he has a great method for checking squareness.

 

[junquecol]

Instead of a cross cut sled, why not build a panel cutter, and drop off table? The panel cutter only uses one of the miter slots for a guide, with a fence located at the back (near operator). The drop off table is a piece of same material as panel cutter, keyed to fit in other miter slot. The fence on the panel cutter extends past the blade to push cut offs all the way thru blade. Measure your miter using calipers slots to see what width they are. A lot of Sears saws used slots that were 0.740", instead of the standard 0.750". I use a piece of melamine for my panel cutter.

 

[Brogan]

It sucks not having a planer/jointer.

I just removed the clamps from the front fence and that's more than acceptable as it doesn't have to be true.
Most, if not all, of the bow has gone.

The rear fence is glueing up overnight so I'll check in the morning to see how it is.

I have some baltic birch plywood so I may try that next if this doesn't work.

 

[Hmerkle]

Paul,
If this one doesn't work for you or you intend to make another - have a look at this

https://www.youtube.com/watch?v=ZtwK9X8o1Gw

That is Nick Ferry's take on a sled and I REALLY like that one - I haven't made it, yet but that is the design I intend to use.

Also Mel mentioned William Ng's version and I think that was really good too, but I think all the plexiglass was a little over killl...
Ah, I found it - https://www.youtube.com/watch?v=UbG-n--LFgQ

 

[Brogan]

Thanks for the input all.

A panel cutter jig is a good idea for my use case so I may also have a go at one of those.

It's much easier to get a true straight edge when using the end of a board, as it has been ripped on the table saw, and there won't be any bow.

 

[Bear Republic]

Lots of input helps me figure out things, both of those videos are good the Wood Whisperer does one also here:http://www.youtube.com/watch?v=uE9f4bp_wm8

[video] http://www.youtube.com/watch?v=uE9f4bp_wm8[/video]

I take the best from all of them.

 

[Brogan]

He has perfectly flat stock thanks to his jointer/planer, etc.

I know how to make one, it's trying to make an accurate one with limited tools which is the challenge.

Having thought about it, I do have some thoughts as to how to remove any bow from the fence so I'll try that tomorrow.

I used the table saw to remove the bow from a piece of pine earlier today by screwing it to a piece of ripped ply and using that as the reference against the fence.
Where there's a will, there's a way ...

 

[Wyatt Co.]

Didn't you just purchase a jointer?

 

[KenOfCary]

Not having a planer / jointer might be a good excuse to spend some money on premium wood at the borg. My experience is that the short pieces of poplar that Lowes sells are very straight and very stable. They aren't as cheap as doing it yourself, but I sometimes just buy some to use for a fence or bench hook straight edge when I'm being lazy.

 

[Brogan]

Didn't you just purchase a jointer?

I did but it's not really good enough to achieve what I want.
It may need some setting up to get it a bit better but it doesn't have an adjustable bed so there's snipe, and the knives are damaged in places.

Agree on the poplar from Lowes, Ken.
It's far superior to that sold by HD.

That's a good alternative and one I may consider.

 

[mpholway]

Paul,
I have some of that laminated MDF from some table tops that is as flat and square as it comes. I have found that it is perfect for this sort of jig work: for the sled and for the fence. I will be glad to drop one off in the next few days.
Regards,
Matt

 

[Wyatt Co.]

I did but it's not really good enough to achieve what I want.
It may need some setting up to get it a bit better but it doesn't have an adjustable bed so there's snipe, and the knives are damaged in places.

Agree on the poplar from Lowes, Ken.
It's far superior to that sold by HD.

That's a good alternative and one I may consider.

Both beds are adjustable. Isn't it a Craftsman 113.20xxx?