How Make a Flattening Jig for a Router





Introduction: How Make a Flattening Jig for a Router

About: I'm a woodworker/maker on YouTube

For this project you'll need a piece of melamine and a couple 2x4s. I'll also assume that you have a router with some kind of base, it can be either a plunge base or a fixed base.

Watch the sled in action:

Step 1: Cut a Slot Into the Melamine

The length of the melamine is determined by the width of the wood you want to flatten. In my case I used a 1200mm strip of melamine in anticipation of any wide slabs in the future.

Find the centre of the melamine, lengthways, and draw a line down the centre. This will be the reference point from now on.

Come in from the ends around 100mm-150mm. This will give you a space to attach stops later. Now drill a through the melamine on each end. This how should be bigger than the router bit that you plan on using. In my case, I was using a 19mm router bit so the hole was 25mm wide.

To cut the majority of the hole I used a circular saw, "dropping" it into the cut. Start the cut away from the drilled holes then come back and finish the off with either a jigsaw or a hand saw.

Step 2: Attach the 2x4s

Use two 2x4s on the top side of the sled. These do 2 things; they stop the router from running into the sides of the slot in the melamine, and brace the melamine, kind of like a spine.

With that said make sure the 2x4s are as straight as possible. If they are curved that will transfer into the melamine.

To attach the 2x4s use screws.

Step 3: Set Up the Rails

Place 2 rails on a flat surface. The height of the rails need to be slightly more than the height of the slab you're flattening, but not so high that the router bit can't reach the wood. In my case I could use more 2x4s.

Join the rails on either end with some scrap wood. This will stop them moving apart as you work.

Now chuck your router into the slot and get milling! This is done by moving the router from left to right taking off around 5mm of material. Take a pass, then move the sled forward up the slab. Take another pass, then repeat. This might take a while but be patient. On my 1 meter long slab it took about 15 minutes per pass.



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    top video will have to enquire from local tree trimmers for material

    I enjoyed watching that thoroughly. Great job!

    1 reply

    Hi. I enjoyed your video. Can you post a link to the pad you are using at the end with 50/50 mineral spirits and polyurethane? Also, do you have a variable speed oscillating tool? Was it rotating very slow?

    1 reply

    Thanks very much.
    I was using a random orbit sander around half speed. Thinking back going faster might've been better, but it worked fine for me. Here's a link to the pad in Australia, but it should be the same name/description everywhere.

    If you used plywood ripped into strips instead of 2X4s for the strongbacks, you wouldn't have to worry about finding perfectly straight ones. I live in a humid climate, and have brought home wood I thought was straight, only to find it very warped a couple of weeks later. Or maybe it was those shots of tequila that I did to calm my nerves... :) My workbench is getting pretty crufty and dinged up, looks to be a good way to get it true again.

    Great video. I'm in North Central Vic, and I love Silky Oak too. I planted 15 on my 2 acres 10 years ago, and they're 45 CM circ now. I'll chop one down soon, put it in a solar kiln for 6 months and use your flattening jig to make slabs. Love your work.


    2 replies

    Thanks very much. I didn't realise they grew so quick, that's great!

    Did you mean the trees were 45 cm diameter or 45 cm circumference? I only ask since a tree that diameter would be a really fast growing tree!

    Nice one Robin

    Only puzzle is the final finish

    is the PolyU water base type, and not sure what spirits that you mix it is?

    I make tables from logs in Indonesia and I like your finish


    1 reply

    Thank you very much! The polyurethane is oil based and I mixed it with mineral turpentine (also called mineral spirits) at a 50:50 ratio

    I meant circ. 45cm Diameter wb a very big tree for 10 years. Anyway, I doesn't snow here.. and we only get -2 in July and very wet winters and hot Summers. Silkys aclimatise.

    Very nice instructable and easily made jig . Your jig could be used to scarf plywood (to edge gluing plywood to make larger sheets).

    Great project and instructable. Will be trying the polyurethane and spirits finish on my next project.