I have a rough bit of oak. I noticed an old surfacing article where William’s pocket toolpath was set to use #251
But #201 is flat at the end.
Anyone know which is better (which leaves less marks)?
What’s a #251? A flat end mill will leave a flat surface. There may be cutter marks that need to be sanded out. A very sharp cutter on a well trammed machine should be pretty smooth.
The #251 is a 2-flute downcut, the #201 is a 3-flute upcut — I prefer the #251 in wood, but of cours use the #201 in metal and plastic.
Toolpath and stepover are a bigger influence on surface finish — best strategy if you have Pro is to inset by a bit more than tool radius and use a Facing toolpath at the bottom of a pocket aligned w/ the grain direction. If you don’t have Pro, see:
which shows how to manually draw up a toolpath for this sort of thing.
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I broke a (1/8") bit today. It was a downcut bit. I was cutting some baltic birch and the cutter went outside the material and on the way back in it broke. That was on me. The previous cutouts were very good. I had to look for another bit and found an upcut 1/8" bit. The upcut bit left a very rough top surface where the downcut bit left a clean top surface. These were all contour cuts that cut all the way through .5" plywood.
For surfacing material a larger bit works better. I have a 1" Whiteside bit that works quite well. C3D sells the McFly which is a carbide insert cutter.
It depends on your shop. If you only have a CNC then surfacing on the Shapeoko will work but there are better ways to surface rough cut lumber. A planner will work if you shim the piece on a carrier board like a piece of plywood. You can hot glue the shims and board to the carrier and run it through a planner until it is smooth on the top side. Then remove the board from the carrier and run it back through the planner until it is flat and you have two parallel sides.
If you have a drum sander you can use the carrier method like on a planner but it is much slower.
They have slab flattening jigs for sale and you can build one very cheaply if you have a good size router to use. I have a 5’ x 10’ slabbing jig with a Porter Cable 7518 3HP router and I use an Infinity 2" Mega Planner router bit. But a 2HP router will work with a .75" bit. There are plans all over the internet for making a slabbing jig on the cheap. After making the jig you can use it over and over.
The Shapeoko can flatten a piece of rough lumber but it is not the fastest or maybe easiest way to flatten rough lumber. But as they say any port in a storm.
My point is if a carpenter only has a hammer then everything looks like a nail. If you only have a CNC then you try to use that tool for everything. Do not get tunnel vision on tackling shop projects. Expand your thoughts to other methods.
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Thanks for the heads up. Just briefly, my project is a butchers block table. I have glued it up so I now have two large and very heavy halves. One side is approximately flat but not quite enough. The other side is very rough and in a jagged way. Each half fits in my XXL. The surface is end grain.
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