How to level your router flattening jig

[Violaplayer]

There are many plans available on building a jig to flatten slabs, boards etc.  The key to any of them is to get the long rails parallel and coplanar with the place you rest your work on.  I have a lot of cherry I got inexpensively because many of the boards have about a 1/2” of twist over 4 feet.  Building the jig is straightforward, but how do I ensure things are lined up over the 8-12 feet the boards are long?

Thanks

Ray

[gee-dub]

I level all of my machines with mother earth.  I also level my non-mobile work surfaces.  This allows me to use a spirit level for difficult references.  I would level your supporting surface, then level your guides while setting your depth. If the table and the guides are both level, you should be lined up for surfacing.

BTW, are you really a viola player?  I played in Jr. High and again in college.  I was never much good but enjoyed it immensely.

[Dave H]

I level my rails with 2 levels, I set one at one end of the rails and, one at the other end I get down low close one eye and sight where the 2 levels line up with each other and shim the rails until I have them coplanar. I set my rails on my shop saw horses when doing the leveling operation once I get every thing coplanar I screw the rails to the saw horses through the shims, for the shims I use door shims that I make out of 2x4 off cuts with a jig i made for my band saw I always have some shims on hand as they are handy for lots of thing around the shop. Instead of using 2 levels You could use 2 straight parallel boards as winding sticks. I'm a retired carpenter so I have an assortment of levels.

[wtnhighlander]

First, don't flatten 8 to 12 ft boards, unless you are buildind with the full length. That wastes too much stock. Cut to near final length first, and you'll find that a lot less effort is required to get them flat.

[Ronn W]

I think that Marc had a video on level ing the rails and making a sled or carriage for the router.

[Chestnut]

2 Stings going diagonal across corner to corner. Put a piece of string under each end of one diagonal. Bump the boards up and down until the strings touch. At this point the boards are coplaner, or parallel to one another.

This video shows how to do it for flattening a bench. If you are using this for flattening boards just add additional heignt to the boards you clamp to your bench.