Slab Flattening Router Bit - Which one?

[ron kanter]

Planning to build a slab flattening jig. Might get the Lee Valley kit or build a jig from scratch similar to the one suggested by Infinity Tools.
I'm wondering what router bit folks have used successfully. Infinity has their Mega Dado & Planer Bit that looks like it would be an excellent choice, but I am concerned that it might be too much for my Triton 2 1/4 HP router unless I took very shallow passes.
Would love to hear from anyone who has put together a successful slab flattening setup.

[jteneyck]

I build my own sleds for the task at hand. There's no need to buy anything.  They are nothing more than two straight pieces along the sides of your slab, tied together at the ends, or even just clamped to your workbench, and a simple sled riding on top.  I screw them together from scrap and take it apart when done.  I use my Bosch 1617 router with a 1/2" straight bit or a 3/4" bowl bottoming bit, although Amana and others offer bits specifically designed for this task.  You definitely need to take shallow passes, less than 1/8", but it still doesn't take all that long to flatten a slab; maybe 45 minutes per side on a 2' x 6' slab.  

If you plan to do this indoors you'll want to add some sort of dust collection to your set up because dust and chips go everywhere.  A brush system encircling the bit, like you see on CNC machines, has given me the best results; still not perfect but much better than nothing.  

John

[rwe2156]

Yes, that can be asking a lot for a 2HP router.

Depending on the size of the slab, this can be an extreme task for any router.  I flattened a 40x80" top and I took 1/16" deep passes, and still had to go slow and let it cool down (both the machine and the bit).  I was using a 1 1/2" planer bit and a Hitachi M12V 3 1/4HP router.

So yes, its doable with a smaller one, I think the key is match the diameter & depth of cut to the router and monitor for overheating.  With a job of this type you have to rein yourself in a little to keep from going to fast.

[Stwood_]

I use a Whiteside flat bottom/surfacing bit. 1-1/4" wide

[shoottmx]

I used one of these in a Bosch 1617 to flatten a 2 1/2 x 6' RO workbench top (single pass with about 3/32" max cut) and an epoxy/cherry 1 1/2' x2 1/2' table top with multiple shallow pases. So far there's no noticeable loss of sharpness. I bought it because of the replaceable cutters but doubt I'll ever wear out the 4 edges on the originals.

Here's a link CNC Spoilboard Surfacing Router Bit, 1/2" Shank 2" Cutting Diameter, Insert Carbide Slab Flattening Router Bit

$78.77 & FREE Shipping.





g

[ron kanter]

Thanks for the feedback folks.
I see many "spoilboard" flattening bits.
They are often listed for flattening CNC spoilboards. Is there any difference between these bits and those designed for flat bottom flattening?

[briman87]

Thanks for the feedback folks.
I see many "spoilboard" flattening bits.
They are often listed for flattening CNC spoilboards. Is there any difference between these bits and those designed for flat bottom flattening?

I don't believe so. A spoil board is just a slab of mdf.