I have been given a cast iron router table top,it is the same model of router table that Peter Parfitt reviewed not that long ago,the problem is that it is not flat,almost 1 mm high in the centre, around the edge of the plate rebate and some other high's and low's elsewhere,i would like to flatten it as much as possible and as I have the BS75 (3")belt sander with sanding frame I wonder if its possible to flatten cast iron with that,has anyone tried to flatten cast iron machine beds or tops before? as its usable as is(but far from ideal) I wouldn't want to ruin it completely,i worry that I could render it unusable if it all go's horribly wrong
possible or advisable to flatten cast iron top with BS75 belt sander?
- Thread starter skinee
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My opinion is 'no'.
I wouldn't touch it with a belt sander even if I could. There's no way to hold the precision, and it's gonna get hot and potentially warp if you do manage to get into the metal.
Check for 'surface grinding services' around you. They can make it like new and perfectly flat.
I wouldn't touch it with a belt sander even if I could. There's no way to hold the precision, and it's gonna get hot and potentially warp if you do manage to get into the metal.
Check for 'surface grinding services' around you. They can make it like new and perfectly flat.
Stephen B
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[size=10pt]
WOW, he has a sanding frame for this sander which is another NAINA. This frame assists in overcoming many of the errors common in using belt sanders.
However, (and because he does not have the wider 105) I would agree that a professional grinding service should obtain an excellent result.
http://www.festool.com.au/epages/tooltechnic.sf/en_AU/?ObjectPath=/Shops/tooltechnic/Categories/Sanders/belt-sanders
WOW, he has a sanding frame for this sander which is another NAINA. This frame assists in overcoming many of the errors common in using belt sanders.
However, (and because he does not have the wider 105) I would agree that a professional grinding service should obtain an excellent result.
http://www.festool.com.au/epages/tooltechnic.sf/en_AU/?ObjectPath=/Shops/tooltechnic/Categories/Sanders/belt-sanders
If you have a reference you can " scrape" the cast iron to extraordinary levels of "flatness". This process is used for precision machinery. You can control the area of bearing very well. If you do. to have a reference you can do your spotting with float glass and your scraping with an old file.
shed9
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A good trick for flattening machined surfaces is to use a sharpening stone.
Simply put a bit of oil on the surface and rub a flat sharpening stone over the entire surface in a figure eight pattern. keep wiping and replenishing with oil as needed. It is a laborious process but it's cheap and will give you an incredibly flat surface.
That said, 1mm is quite significant so I would also consider the previous two options as well.
Simply put a bit of oil on the surface and rub a flat sharpening stone over the entire surface in a figure eight pattern. keep wiping and replenishing with oil as needed. It is a laborious process but it's cheap and will give you an incredibly flat surface.
That said, 1mm is quite significant so I would also consider the previous two options as well.
Michael Kellough
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If the table was 1 mm low in the middle I'd give it a go with the belt sander and frame.
Since it is high in the middle you should try to find a way to pull it down to "close enough". Or, just learn to use it as is. High in the middle is much less problem than low in the middle. You really only need full contact with the router plate in the area around the bit and with a crown there you're pretty much assured of that.
Grinding it down that much by any means will leave you with a router plate that is proud of the surface and then you have to try to remedy that too. It might also make the dado slots too shallow.
A few years ago I bought a Bench Dog cast iron router table. It was severely concave in the middle. That is much worse than if it was high in the middle. I did figure out that I could flatten it most of the way with clamps and I thought I could replace the clamps with threaded rod but the vender (Rockler bought Bench Dog) replaced the thing. (They said I could keep the warped one. Still haven't found a use for it. I do get a lot of use out of an old table saw top as a clamping and fixture assembly surface but the table saw top is flat...) The replacement top isn't flat either but it is better than the first, just good enough. I really like using magnetic feather boards etc. but based on my experience I don't recommend cast iron router table tops.
Since it is high in the middle you should try to find a way to pull it down to "close enough". Or, just learn to use it as is. High in the middle is much less problem than low in the middle. You really only need full contact with the router plate in the area around the bit and with a crown there you're pretty much assured of that.
Grinding it down that much by any means will leave you with a router plate that is proud of the surface and then you have to try to remedy that too. It might also make the dado slots too shallow.
A few years ago I bought a Bench Dog cast iron router table. It was severely concave in the middle. That is much worse than if it was high in the middle. I did figure out that I could flatten it most of the way with clamps and I thought I could replace the clamps with threaded rod but the vender (Rockler bought Bench Dog) replaced the thing. (They said I could keep the warped one. Still haven't found a use for it. I do get a lot of use out of an old table saw top as a clamping and fixture assembly surface but the table saw top is flat...) The replacement top isn't flat either but it is better than the first, just good enough. I really like using magnetic feather boards etc. but based on my experience I don't recommend cast iron router table tops.
