This instructable gives an overview of how to plane your wood slabs flat using a router and a Planing sled.
Step 1: Start With Your Wood Slabs.
Here are the two wood slabs that I want to plane flat
Step 2: Measure Your Wood Slabs Maximum Width and Length.
These wood slabs are on the smallish side. So I wanted to plane them together and match up the thicknesses. I figured I would make a planing sled that accommodates one large slab.
Measure the maximum width of the slab and the maximum length of the two slabs together.
I came up with 19" x 65"
Step 3: Figure Out the Maximum Thickness of the Slab
Now find the maximum thickness of the slab.
You can now design your sled to accommodate for this.
(I noticed after making this Instructable that most slabs are 4" or less in thickness.)
Step 4: Measure Your Router and Router Bit.
Measure the diameter of your routers base, and the diameter of the router bit that you will be using.
This determines the inside dimensions of your router sled and the hole that the router bit fits into.
My router base was 5 3/4" and the router bit was 1 1/4 ".
Step 5: Construct Your Sled
Take your dimensions of your router and bit and apply it to your sleds dimensions. The router base was 5 3/4" so I made the inside width of the sled 5 7/8" The router will fit into this with an offset of 1/8". I also made the hole for the router bit 1 1/2" wide.
Step 6: The Sled Assembled
Here is a photo of the sled. The first photo is the sled upright and the second photo is the sled flipped over. The sled has a flat base except for the two overhangs. This keeps the sled aligned on the rails while you slide it laterally.
Step 7: Build the Box With Rails.
Take your maximum width and length of your wood slabs and basically build a box for it. The rails must be parallel and square. this is the reference for the sled. Also make the rails tall enough to accommodate the maximum thickness of the wood, in this case 4 inches, plus the thickness of the sled which is 3/4 inches, plus another 3/4 inches of "air" for your safety plane.
Step 8: The Sled Base, Sled and Router.
here are photos of the sled base, which you will drop your wood slab into, the sled atop the rails, and the router placed into the sled.
Step 9: Place Your Slabs Into the Sled Base
this is what it looks like after I place the slabs of wood into the sled base.
If the bottom of your wood slabs do not lay flat in your sled base, you can use shims and wedges so that they don't rock.
the final step is adjust the router bits dept so that i barely touches the highest point of the slab. You want to take off about 1/16" of wood at a time.
Step 10: A Little at a Time
you can see how much wood I take off for each pass.
Step 11: Start Planing
Start planing on one side and work you way to the other side. back and forth, right to left or vice versa.
and always wear your Personal Protective Equipment! PPE's
Preserve your eyes, ears and lungs!
Step 12: Heres the Planed Surface
And here is a photo of the planed surface. its now perfectly flat and now needs a sanding in the direction of the grain.