Need help with glue on riser

[sleek]

So, here is my deal. I have two spliced billets that I need to glue a riser on at the splice. I have the riser material in board form so its surface is flat. The problem is, no matter how I try, I can not get the section on the bow handle flat enough to get a good glue line. It looks flat on one end, but has a dip or some other gap causing defect on the other. I have a board and 80 grit to sand with, and am running out of material to sand away. How to yall get flat surfaces to glue against?

[bubby]

sleek use multiple lams in the riser, sand the first one down so its a good  fit and you should be set,I've done belly lams like this then steamed them and clamped to get a good fit,shorter pcs if you wrap them in a wet towel you can nuke'em in the microwave for 90-120 secs and they bend like a noddle

[DarkSoul]

Yup, try gluing up four to six lams of only 1/8" thick. This will easily follow any curvature of that handle area.

[Pappy]

I use a belt sander.
   Pappy

[PatM]

I buy a roll of that 60 grit anti-slip material for icy surfaces and stick a large piece to a perfectly flat board. Then you can place your glue surface that you want flattened on it and work the piece across it at a diagonal to flatten the surface. As long as you don't "rock" the bow the surface will be perfectly flat.
 Basically this is a stationary belt sander. It also works great for flattening  bamboo backing strips etc.

[Tom Leemans]

The laminated riser solution will work fine, but it still needs to mate up nice. One other trick of the trade is that when you have two mating surfaces to glue together and one of them is a little off from the other, use the opposing piece as your sanding block. In other other words, hold a piece of sandpaper on the bottom of your riser "block" and use it to knock down high spots (using short strokes) on the billet handle area, then take that sandpaper off your riser block and use a piece on the billet handle area with the grit "up", facing your riser block, and repeat. Don't bear down too much. Alternate back and forth and eventually they mate up pretty darn close. Use a good gap filling, catalyzed 2 part glue like URAC 182 if you have some, otherwise Unibond 800 (also from Nelson Paints) or Resoucinol if you can find it.