Cutting 3/4" material with 1/8" Endmill

#1

So I need to cut some 3/4" plywood. I have tried a few test cuts with a 2 flute 1/4" end mill with ok results. I was wondering if I could get cleaner cuts with a 1/8" cutter. Has anyone done 3/4" deep cuts with an 1/8" cutter? (Obviously in multiple passes.)

Does anyone have a link to a 1/8" cutter that can cut that deep? In a little bit of searching it looks like 1/2" is the typical flute length. I have found some cutters with 1.25" flute length, but I would be concerned with deflection on those.

Would it be bad to cut 3/4" deep with a cutter that only has a flute length of .5"?

Thanks for any input.

#2

Yes, cut 1" thick Ipê w/ a 1/8" endmill:

https://www.shapeoko.com/wiki/index.php/Endmills#Long_endmills

Cutting material which is thicker than the flutes can lead to rubbing which generates heat through friction which is a bad idea.

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#3

What are your thoughts on using a Rotozip bit? They’re designed to run that fast and are much longer.

#4

ISTR someone tried one over on the Shapeoko forums and it didn’t work out well.

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#5

I have not found root zip bits to work so well.

Larger bits typically offer better finishes.

I sometimes use a 3/16 bit because I need bolt holes that are smaller than 1/4".

#6

I have been using a 3/4" plunge router bit to hog out lots of material. It is MDF, so lots of dust too, which is why I use a dust mask and a vacuum to minimize exposure. It is not so bad with plywood, just start off slow and shallow, about 1/4"-3/8" deep cuts. At least, it is working for me. You might to go slower IPM and lower RPM.
Sorry, I don’t have the RPM, IPM and all that available atm.

#7

So far in my learning curve,I have been having good luck overall with solid carbide down cut router bits.

#8

What @WillAdams said about rubbing is very important to keep in mind. The way to deal with it is to do the cut with a slight taper. Maybe 0.1mm or 0.2mm over the 19mm depth. For slotting, you want this on both walls, so you double the path length. For pocketing and profiling, there is no additional time involved.

Then again, slotting is hard on the tools and machine to begin with, and a good finish will often require a clean up pass. You can do the fine cut on the finish side to handle this and not get a penalty, if you want clean surface finish. This small of a taper doesn’t require fine depth grades, as the steps on the finish surface are insignificant (a few 0.01mm) if you do, say, 5mm depth of cut.

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#9

I use these: ((I definitely recommend a spring cut (or 2) to eliminate any deflection or a quick sand with a sanding block to smooth out the edges))

NOTE: THe OAL length is the same, they just ground a longer flute, so there isn’t much to hold.

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