Slab leveling

[Winegrower]

Today I finished and tried out a platform to hold my router and keep it a constant height above a rough slab, so I could get a plane surface. Awhile ago I saw on eBay some precision rails and recirculating ball guides for a surprisingly low price, around $100 for 4 1000mm rails and 8 ball guides. I finally got around to making some supporting parts that give it a range of about zero to 12” high. I used a 1.5” straight flute carbide cutter. I was concerned that there would be too much vertical play, but it was really rock solid, with a surface finish that looked just like it had run through a planer. It slides in XY very easily, is quite controllable but reminds you about conventional vs. climb milling. Similarly the horizontal stability was fine, even just supported on a sheet of 1/2” plywood on sawhorses.

i have some nice redwood, walnut and oak slabs that I’m anxious to run through this. Only downside is it sure makes some chips!

 

[Nutfarmer]

That's a great way to finish off a slab that's too large for a planer. I have tried to finish some natural edge slabs with a belt sander with less than optimum results. Thanks for the idea. It will work well with some of the walnuts we are removing after they come off the saw mill. If you have a link for the rails it would be appreciated. Thanks again. It is always a pleasant surprise what the members of this group come up with.

 

[matthewsx]

That's kinda like a metal working project for your woodworking project. The only thing left is to make it CNC

John

 

[Aukai]

Reminds ME of what a mess cast iron makes looking at that.

 

[Al 1]

Thats a nice set up. Have a not so fancy setup I threw together from some old aluminum stock that was scrapped off an old sliding glass door.
It was set up to refinish and flatten out an old butcher block table. Yours looks nice. Al

 

[SLK001]

How are you securing the slabs? Using only gravity?

 

[Winegrower]

Thanks for the feedback. It was long enough ago that the prices were lower, but this is about what I got:
Two sets of : 2Pcs SBR16 300-2000mm Linear Slide Rail Guide with 4 SBR16UU Bearing Block
(for some reason the link doesn't work correctly. Search eBay for the above)
At the time, 1000mm was the biggest, but maybe now I should order the 2000mm. Oh, I think I will!

Yes, I positioned the slab with scrap wood blocks and wedges, but it was not otherwise held down. Seemed to work fine for 1/4" deep passes cutting not quite half the diameter of the cutter. These are pretty big and heavy slabs, and it goes fast!

The slab, both sides, came out much smoother than it looks in the picture, and the parallelism of the sides was excellent.

 

[Winegrower]

I just received two 2200mm rails with guides, that’s over 7’. This will let me finish some king size slabs.

Get the SBR20 rails, that’s a 20mm rod diameter, the 16mm seems a little less stiff than optimal.

 

[Winegrower]

Here’s a shot of the longer rails, set up on a 4x8 plywood base, so you can get an idea of the size capability. The slab is just sitting there for the photo, to get the idea. It has two very parallel sides, just needs another pass or two to thin it down and complete this project. The next slab coming up is so big and heavy I will need to use the engine hoist.

And like always, i see some mods coming up to improve ease of use. For example, i can adjust the rail heights in one inch intervals, but the plunge router has only a bit more travel than that. If the slab is pretty irregular, i.e., a big elevation change from lowest to highest points it takes a number of rail movements to cover that range. It doesn’t take long, but it is not optimal.

 

[SLK001]

Is that some bow in your plywood base that I'm seeing? What does the plywood base look like underneath?