Spoilboard surfacing bit

Can anyone recommend a surfacing bit for my LR3 (makita701c router). The spoilboard is MDF. I’m concerned about going too big for the machine. The cutting area is 2ftX6ft

Recently (so not used extensively…) ordered CNC Spoilboard Surfacing Router Bit, 1/4" Shank 1-1/2" Cutting Diameter, Carbide Insert Slab Flattening Router Bits Planing Bit was recommended on this forum, using on my LR3, same router.

Found reco, was from Cutting board for thanksgiving - #4 by jallen

While digging around for the reco post, I stumbled onto bunch of interesting surfacing bit threads Search results for 'surfacing bit' - V1 Engineering Forum with ideas on ensuring setup is perpendicular.

Am using jamiek’s surfacing gcode generator script, see Spoilboard leveling with estlcam - #2 by aaronse

Cheers!

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Aaron, thank you very much for the info. I hope to be surfacing soon.

For the surfacing code I just generate a square that is larger than my piece to insure that it runs the entire surface and I normally generate the square large enough that it runs off the edge of the piece about an inch or two. I have also noticed that with this large of a bit, it doesn’t like cuttend grain near as much as side grain. You have to slow the feed rate way down.

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Idk how well the makita will swing that 1.5” bit but I’m running the Dewalt 660.

A larger bit will also reveal any tramming issues your machine may have. Even a slight tilt in the router will reveal itself if you are doing linear passes. Easy enough to fix but try a piece of scrap first.

The makita should handle the bit for mdf fine just don’t expect similar results surfacing a hardwood with knots.

I was using the Makita on my LR3, and it did well with the same bit size.
The 660 should perform the same way.

That is correct, I trim my router before surface the spoil board, little pieces of E-tape and a 3D printed jig, will go a long ways.

Thank you all for the insight. I have ordered a 1 1/4” to stay a little on the conservative side.

GP, I’m not sure what E tape is but I assume you use it for a shim? I would like to check my router for tram. Where do you put the shims, between the core and router mount clamps? Where might I find this jig file and how is it used?

E-Tape= Electrical Tape

Yes, both are correct.

The Jig looks like this.

You just press fit into the collet nut.
I just copied @vicious1 design for the Dewalt 660 that is on Printables with the size for the Makita collet nut.

So once the jig is in place you rotate the router shaft by hand looking for the low spot and high spot?

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Yep, that is right, and you add the tape to the mount and do it again and again until it is tram.
If you have a 1/8” collet, you can also try using a coat hanger, just cut it and bend to form Z about 100 mm long

I like the coat hanger idea. When Shimming the router top mount or the bottom mount the router is adjusted perpendicular to the X axis. How do you make the adjustment parallel to the X axis. The only way I can think of is if the clamps have enough play in the mounting holes.

Nope. I’ve been doing the same way for all the machines I built, Burly, Primo, LR2(a little different) and LR3.
Add tape top and bottom, opposite sides for parallel. Also, don’t forget that you can use M666 to compensate for any Z height difference on the X axis from X0 Y0 and (lets say) X900 Y0
Here is a Thread that @jeffeb3 give a good explanation on how to use it

Personally, I would start with M666 then follow with the Jig or the coat hanger…

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GP, thanks again for the additional shim info and the Z offset tip. I did the Z offset once before prior to cutting my strut plates. Just finished installing my strut plates so I will recheck square, including the Z offset then tram.

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