Thread: Flattening large boards... How?

One problem that could occur is that the cupping could start all over again once flattened out, the joys of slabs.
Saw a similar situation with a redgum kitchen bench, this bloke bolted it to the floor and it pulled up the slab.
Sorry to be negative but it is worth considering.
You could consider ripping the slab into strips and reglueing in reverse order to help prevent this ifit occurs.
Apart from that a jig to hold a router above, oh sod it, go to this link, it's easier than trying to describe it:
http://www.popularmechanics.com/home...1/router_jigs/

WD

There are two ways to do this at home.

(1) The first is with your router. You will need to build a level platform around each slab (use MDF, or steel square sections). Set your router into a sled (a piece of MDF reinforced at the edges so that it will not sag). This will run along the top of the platform, sliding it back-and-forth. Using your widest straight bit in the router, slowly skim off the high points until everything is level.

I have done this very successfully in the past.

(2) These days I am more likely to use a pair of "winding sticks" and handplanes. I'd begin with a scrub plane, move to a jack, then the longest jointer I have (in my case a #7 Stanley). The winding sticks can be used in (1) as well to determine where the twist acually lies. And keep in mind that you need to do both sides of the slabs.

What are winding sticks? Just long (3'/1m) straight and even pieces of timber (or aluminium section). Place at each end of the slab parallel to each other. When you stand back and look over the front stick at the rear stick, you will be able to quickly tell if there is twist. Move the front stick back and forth to assess various sections of the slab.

Regards from Perth

Derek

See Fine Woodworking #173 for an article on just this problem.

Shane, I responded to a similar question some time ago, suggest you do a search on slabber. Dereck has the right idea with the router, instead of a straight bit I used a dish cutter bit (page 124 Carba-Tec cattledog).Hope this helps.
Cheers
Barry

All of the above sounds great to plane the slab back to flat. What about preventing it to cup again?

I suggest a series of cuts along the board on the underside, cutting half way through the timber, in the area that cannot be seen.

Wild Dingo,

I had a similar problem with a slab of camphor laurel a while back. I used a jig I made from plans on the net - similar to what Derek described and used an 1 1/4" end cutting bit in the Triton. Got a good result and the winding sticks are showing that everything is still OK.

I wasn't sure how well the 3" slab was seasoned :confused:

I used threaded stair tread ties so that I could use the jig on anything upto 1200mm wide so it's had a workout. If you want it and can't find it on the web, let me know and I'll email you with it

Jamie

Originally Posted by Iain

Apart from that a jig to hold a router above, oh sod it, go to this link, it's easier than trying to describe it:
http://www.popularmechanics.com/home...1/router_jigs/

That popular mechanics has a number of good woodworking ideas.
I am interested in using an overarm router with an X-Y axis table to act like a small vertical mill.
Someone on the USA routerforum replied to my query with a link for that site showing how to make a mount to hold a router on a pillar drill column.
http://popularmechanics.com/home_imp...er/index.phtml
This will be a great help to me.

Shane, I agree with the others recommending using the router.

Refer the following thread http://www.woodworkforums.ubeaut.com...ad.php?t=12712

Just ask if you're interested in more detail.........cheers.......Sean

Seems Iain gave you the URL anyway.

This was the one I made. It's at the followingsite

As I said by using the threaded rods you get a bit of flexibility in the width department

Jamie