Surfacing Bit

What would be a good surfacing bit to use with the 660? I know that it cant handle a bit 2" router bit but my little 3.05mm endmills are really not suited for surfacing at all.

I use a 3/4" flat router bit with 1/4" shank. It was part of a set that I got at Lowes.

I used a 1/4" endmill, take your time surfacing and the results will show.

A larger bit doesn’t always mean better results, you can move a 1/4" bit faster than a 1/2" bit since it’s cutting less wood.
More importantly, if the router isn’t perpendicular to the surface a 1/2" (or larger) bit can end up leaving lines between passes, this is less noticeable on a smaller bit being off.

I’d highly suggest using a perpendicularity tester as well.

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Yep, I have a 3/4" I think, bogged down my 660 doing 1mm passes.

Well if you are doing metal, a flycutter would be optimal. Although you have to keep in mind that when doing surfacing cuts like what you talking about, your DOC should be waaaaay shallower to allow for the massive difference in surface feet per minute that a larger cutter creates. But really, you’re getting into feeds and speeds territory.

If you want a larger diameter cutter for surface finishing metal or wood, use shallower depth of cuts and slow your feed rate down.

What are you cutting?

right now I am just doing wood and potentially other soft material as needed. Eventually I will do some aluminum but I think that my footprint is a little to large for it at the moment. I have some plans to stiffen things up a big with my current foot print but They are future plans.

My spoil board (mdf) also needs some surfacing but I am going to use my wood router with a jig for that.

It’s very doable. There is kind of a law of conservation of cutting ability. After considering material to be cut, any time you increase a cutting variable, bit/ mill size, DOC, RPM, or feed speed, you need to decrease the others accordingly (that’s the simple explanation anyway). The trade offs depend on what you’re trying to accomplish with your cutting operation. Going with a wider cutter? Need to make shallower cuts and lower RPM.

IF you do decide to go up in bit size, just remember that you’ll need to keep your depth of cut much shallower and adjust your RPMs accordingly.

Using the CNC to surface has the advantage of including any errors. So if it dips in the middle, your spoil board will too. You could try surfacing a few small circles in different areas, and either use that to reference your jig, or use it to confirm your jig is going to match. Sort of splitting hairs, but if you’re surfacing your spoil board, you must care.