Grinding a Warped Cast-Iron Table Saw Top Flat
Last night I put a straight edge on the cast iron top, and to my surprise it is crowned up in the middle 1/16"! I tried two other straight edges, and they all read the same. I don't remember this saw having a crown in it like this, and I don't know if it could have happened somehow in storage, but it is a problem.
Is there any way to get this crown out? I imagine that if it was brought to a machine shop, somehow they could resurface it flat, I just don't know that it is worth the cost or the time for this. I was possibly planning to remove the saw from the shop to save space, but I also wouldn't mind keeping it for dados if it were flat.
From contributor H:
Remove the top and take it to a machine shop and have it milled. It's safer than you trying to hammer it out.
From contributor R:
You would want it ground, not milled. I've had many jointers ground. In my area, Blanchard grinding is more common for bigger tables. The table must be supported correctly or the magnet will pull it out of shape and be in worse condition after grinding. Blanchard grinding gives a circular pattern to the finish as opposed to linear from a precision grind.
From contributor O:
Contributor R is the man to listen to here. I have every shaper top Blanchard ground, and every two-piece adjustable fence belt ground. Brand doesn't matter – they're all junk when you first get them. They claim that cast iron must season, and that it was correct when manufactured - yeah right! GM doesn't season a 350 engine block, and that's one hell of a magnet. I've watched it in use - they must shim the underside before grinding. And if your top holds up any amount of weight, it needs a little crown. Then when the motor and spindle or trunion is bolted to it, it will pull down. I have a super 27 with 40'' top within .002. Nice to see a woodworker that knows machinery. It takes good woodworking machinery to do good work fast. Get your machinery right and anyone can do good work without a 100k CNC.
Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?
Have you reviewed the related Knowledge Base areas below?