Stone Grinding?

Great site! My question relates to stone grinding. I have built about 6 pairs of skis and always end up going to the local ski shop to get the bases truly flat and to get a good "structrure" in the base. Unfortunately this is quite expensive and violates the principle of doing the entire job myself.

Any thoughts about suitable (inexpensive) alternatives?

I use a large file to flat the edges at the same level as the base, then I use some sandpaper (80), to clean the base and make the structure.

They does not look like racing skis, but they glide.

See here: http://www.skibuilders.com/phpBB2/viewtopic.php?t=247