Refurbushing a iron TS top

[LarryG]

I'd rather have a stained top than an uneven one.

Even a belt sander won't remove enough cast iron to make the top uneven. Well, maybe on a microscopic level; and maybe if the rust was more than just surface rust; and maybe if you stood there for days on end running a 40 grit belt over the thing with heavy pressure. As Ken says, you just place the sander on the surface and let the tool's weight do the work. After removing all the rust from my mortiser's table, I checked it with a straightedge. It's perfectly flat, no discernable variation anywhere (and it was rusted pretty badly, in a couple spots).

My variable-speed Ryobi belt sander has a little chart on the top with the recommended speed settings and grits for various jobs. One of them is "Rust Removal."

[WayneJ]

An ROS with 220 and WD40 works best for me. I have found that covering the top with a sheet of cardboard helps greatly to keep surface rust from comming back.During the summer months in N.J. the humidity is real high and I have yet to clean any rust from my T.S. this season. When I get done using the saw I spray the top with WD40 and wipe it down, then cover it with the cardboard.It works for me.
Wayne

[cgallery]

Even a belt sander won't remove enough cast iron to make the top uneven. Well, maybe on a microscopic level; and maybe if the rust was more than just surface rust; and maybe if you stood there for days on end running a 40 grit belt over the thing with heavy pressure.

I'm going to disagree but I'll leave open the possibility that I'm wrong.

[LCHIEN]

I'm going to disagree but I'll leave open the possibility that I'm wrong.

Light sanding pressure with a modest150-220 grit, even with a power sander, you can't remove enough cast iron material to make a significant height change relative to the .001 - .003 flatness of a good TS.

now a grinder is a different animal...
but bear in mind even a gouge here and a gouge there won't affect the height of flat material slid on the remaining surface.

[cgallery]

Light sanding pressure with a modest150-220 grit, even with a power sander, you can't remove enough cast iron material to make a significant height change relative to the .001 - .003 flatness of a good TS.

now a grinder is a different animal...
but bear in mind even a gouge here and a gouge there won't affect the height of flat material slid on the remaining surface.

Someone had suggested using a 40 to 80-grit belt sander in an earlier message, though, and I think that would actually cut .001" of CI far faster than most people think. Try it on the bottom of an old skillet.

And I agree that the TS doesn't have to be perfectly flat to make good cuts, but there is no reason to make it any less flat than it already is.

[kwgeorge]

Well I will have to disagree on the sanding. Cast-iron is relatively soft and deformed pretty easily with abrasives. I keep my Cast-iron tool rest on my lathes sanded down and free of imperfections. Hand planes are another thing as it does not take me very long with 220 grit to sand flat the sole and sides of a plane. If you are sanding your saw table top on regular bases you are increasing the deformities more and more every time you do it. When the table was originally ground it was done so with a large grinding wheel normally running horizontal. This is not unlike the methods used to flatten cylinder heads for engines at your local Auto Machine Shop. This process normally makes the top pretty flat. One of the reasons I bought the Ridgid 3650 was due to the flatness of the table. I often will use mine to dry assemble components and for checking flatness of different things. I spent a lot of time in this tables assembly make sure the full cast-iron wings were level and parallel to the rest of the table which is yet Another reason why I bought the 3650.

I agree that this Table saw is a substantial investment Ken and I also would like to keep mine as long as possible after all I had well over 10 years in the BT3K. With this desire in mind I would like to keep the top as flat as possible for as long as possible.

You are probably right Loring, it really won’t make a great deal of difference when done once but consider what will happen on a rather regimented routine of sanding ones cast-iron table top. I would challenge you to attempt this with your digital calipers, a ROS, 220 Grit sandpaper and many repeated sessions on a board and see just how flat and even that board stays. Granted this is more to the extreme but does serve to illustrate the point. I also wonder how many people that are using their saw for a living run through this process. Most I have seen are not rusty but rather discolored.

I am not trying to sway anyone from their ways of doing things but rather putting forth my thoughts on why I do not. I am also trying to understand what the problem is that needs repairing other that a discoloration. If it works for you that is what you should do but I myself will refrain.

Ken

[messmaker]

A cup-style wire brush on an angle grinder works really well and is probably quicker and a bit more gentle than a belt sander.