An Evening in the Shop #3: Flattening Boards part II

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Blog entry by ChunkyC posted 10-15-2011 10:13 PM 2825 reads 4 times favorited 2 comments Add to Favorites Watch
« Part 2: Flattening Boards Part 3 of An Evening in the Shop series Part 4: Flattening Boards - Mods and lessons learned »

Now that I have proven to myself that using a router is a viable way to flatten large boards, it’s time to scale things up a bit.

I found a 1-1/4 straight bit on sale at Peachtree that I thought that I would give a try. Turns out that it works very well. Unfortunately it would work with my original sled. The original sled was made to use a 3/4” bushing. 3/4” bushing and an 1-1/4” bit just didn’t cut it. So I just made two rails that the router base would slide back and forth on. Worked great.

So on to the monster…

The base is nothing more than 5/8 OSB with two rails running the entire length. I slopped on two coats of 50:50 poly to seal the OSB and make the hot melt glue release a little easier. I don’t reference off of the rails, I reference off of the bottom, or top as it were, of the OSB. My sled actually sits just proud of the rails. I use the rails to keep the base from flexing and to keep the sled contained.

The first sled I made just didn’t work. The router tossed chips and dust EVERYWHERE! It was a real mess. It was so bad I had to change the air filter after just two passes on the first board that I flattened. So I pulled from the original design and came up with this:

It’s nothing more than a piece of Melamine for the 1/4 ply router base to slide on and an MDF rail to keep it all contained. I marked some reference marks on the one edge at 1/2” increments. Man is that the ticket! It makes it a lot easier to know how far I moved the router each pass. I’m not sure that Melamine was the best thing to use though. It’s too slick and it takes more effort to hold the router in place during each pass. May need to add some grip.

I attached some rubber to the sides like I did in the original sled and added a dust “control” port. I hesitate to call it dust collection as a lot of the chips don’t get collected, but they get contained. A HUGE improvement over what I had on Sled Rev1. The 4” dust control hose is a bit of pain to work with. It flops around, pulls and fights me every step of the way. I need to find a way to get it up in the air so that it hangs down verses having to drag it across the work bench.

And a couple more shots:

You can see in this shot how the chips collect on the sides of the board. There’s still a few chips that get loose as you can see on the work bench behind the sled. It may seem like a lot chips get loose, but this is after flattening two boards. I wish I would have snapped a shot of what it looked like before.

I can flatten an 8 footer up to about 20” wide and about 3” thick. I have one board that is 4-1/2” thick that I need to flatten. All I have to do is add some runners under the sled to raise it up and I can do almost any thickness I need to with this setup.

-- Chunk's Workshop pictures:

2 comments so far

View gfadvm's profile


14940 posts in 2652 days

#1 posted 10-16-2011 03:24 AM

That is a very cool jig. I think fencing in the debris was genius on your part. I may have to copy this as I hate having to split and then glue up boards that are too wide for my planer. Thanks for posting this. I just tied a string to my 4” hose and hung it from a hook on the ceiling when I have it hooked to my ROS. Simple, but much better than dragging it back and forth across the bench as I sand.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View ChunkyC's profile


856 posts in 3217 days

#2 posted 10-16-2011 09:06 PM

I made a couple of slight mods to the setup, one being using a shorter length of hose and tying it up! It works pretty darn slick now. I still have the problem of the base sliding too easily on the melamine though. I tried adding a clamp to add a little downward pressure. It worked ok but I need something better.

I wish that my DC was 4” all the way, I think it would a lot better if it was. As of now, I have to go down to 2” to fit the triangle DC fitting that I’m using.

-- Chunk's Workshop pictures:

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