Hey, Folks. Relatively new user here with a question about how deep I can actually expect to cut with my Shapeoko XXL. The specs say that the max is 3". I suspect that captures the vertical distance that the cutter is capable of. I’m looking at how deep a pocket I could cut and it seems that the answer for that is roughly 1.5" if I’m using a #201 bit which is 2.5" Overall Length and assuming roughly an inch in the collet, leaving 1.5" before the cut will hit the collet. Does this sound correct?
Another option, I would guess, is a longer CNC bit from another vendor. I see I can get a 4" flat bottom bit for around $100 from another site, which might give me the full 3" of pocket before hitting the collet.
I may also be failing to take into account the thickness of my wasteboard, so perhaps that shaves an additional 3/4" from my vertical travel as well?
Does that sound reasonable or am I missing any other considerations? Thanks!
What Shapeoko do you have? The Shapeoko 4 / Pro have an advertised cutting area of 4" for the Z-axis. On my Shapeoko Pro from the spoilboard to bottom of the gantry there’s actually closer to 5" clearance and I upgraded to the HDZ for my Z-axis which has 140mm travel which is 5.5" of travel. The Z-plus is less and if I remember correctly it was something like 110mm which is closer to 4.3" so definately less than the HDZ upgrade.
That said what it will come down to is how high/low your router/spindle in mounted and you’ll certainly need a longer endmill to cut deep pockets. Keep in mind the longer your endmill the more deflection you’ll get so you’ll need to compensate for that in your toolpaths. Also the thicker your stock is + using longer endmills you’ll be pushing the limits of the Z-axis range/travel so each retract you’ll likely be very close to crashing on the Z-axis so watch out for that (retract height, safe height, …) and make sure your clearing your work holding/clamping.
A #201 has a maximum cutting depth of .75". If you cut deeper with a #201 you will be rubbing the bit around the sides of the pocket and possibly burning the material. I use a Melin 4" OAL bit with a 1.5" cutting depth and have cut slightly deeper than the 1.5" However bits like the #102 1/8" has a cutting depth of .5" and is a relatively short bit so if you cut deeper you may hit the material with the collet. The bit should always be put into the collet the distance that the collet is long. So measure your collet and insert the bit at least in that deep to get the best grip on your bit. The Melin bit is quite long and if you are not careful you can get a lot of run out. So if you use a longer bit then you should make sure it is seated correctly in the collet and start the router before cutting to see and feel if the router has excessive vibration and visually you can see the router bit running crooked. Even longer bits are available but they are quite problematic on 1.25 HP routers. To use really long bits you may need to upgrade to a spindle to get better grip and power to handle long bits. A 3" cut on a Shapeoko is a tall order. It can be done but it also has to be carefully done to avoid run out and burning of your material.
Here is the Melin AMG-808-E bit that I have used for up to 1.7" cut depth.
He has several videos showing how he carves larger sculptures on the Shapeoko. He uses a clever combination of lowering the base of the table (with a big hole) and splitting the models up into multiple pieces.
He also gets into the complications of dealing with tool paths and making sure the bits don’t crash into things, especially on the deeper cuts with long bits.
