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Dovetail Lapping or Scraping
The mills and lathes that come from overseas most times don't have the best fitting gibs.
A lot of them, especially Sieg products, suffer from dovetails that are sloppily machined
which leads to binding at one end of travel or both with table slop in the middle. The G0704
has better tapered gibs versus the flat gibs on most other machines.They can still suffer from
some of the same problems, ususally because of a warped gib strip. All these troubles can be lessened or eliminated by lapping, scraping or both. Which to do, which to do. You'll find many arguments for/against both such as in this long thread on Cnczone. It's my thought that if the amount of material to be removed is small, then lapping should be good enough.
Basically, Lapping invloves loosening the gibs, pulling the table for example off, applying a gritting paste to the dovetails, reassembling, and pushing the table back and forth by hand many times
until you feel the binding areas no more, apply more grit paste and adjust the gibs a little tighter, and repeat. Generally starting with a coarse grit (240 or 320 if severe) and then with a couple finer grits, 600 and 1200 for example. that's what I used on my X2 years ago. Follow up with a thorough cleaning and reassembly. Scraping can be more involved and requires more skill, basically you apply a layout fluid such as Dykem to the mating part, assemble them and push them back and forth against each other. This will show you the high spots that you can then scrape down with a flat tool. Repeat the process until you have a uniform transfer of dykem over the entire length.
You'll find some links below for more details, some are for lathes but the process is very similar.
Lapping
Lapping with Wet/Dry Sandpaper - from mini-lathe.com
Lapping the Dovetails - Mike Taglieri's Procedure
Scraping
Basic Hand Scraping books and videos - machinerepair.com
Video - Scraping in a dovetail - detailed
Video - Scraping in a lathe's top slide with tapered gib
Lapping Compounds
American Lap Company
Newman Tools Timesaver
MscDirect Clover Lapping Compound
Scraping Tools
MscDirect - Machinists Scrapers
