I’m a new CNC’er, starting out with a Shapeoko 4 XL machine. I bought the Shapeoko getting started end mill kit, but I want to cut guitar bodies. So I bought a 1/4", 4" overall length square end mill. But I find that with wood blanks of 1.75" inches, I need a fraction of a bit more clearance, as the 4" long bit is too long.
It seems like there might be a few solutions here:
Take the aluminum base slats / MDF off
Cutting the endmill down somehow
Raise the spindle up in its clamp
Taking the hybrid table off doesn’t seem like a great idea, and trying to modify an expensive carbide end mill by cutting into the shank seems dangerous/ill-advised. Which leaves 3…will it be unstable if I move the spindle up slightly, then tighten it down? It’s all the way down now, so that gravity keeps it as low as it will go in the clamp.
It will be very easy to get large vibrations, chatter and endmill failure on a cutter that long, especially at high RPM, did the vendor give a max RPM for the bit?
you can move the spindle up some no problem… just make sure it’s clamped tight.
you could try to find (roughly) the center of gravity of the spindle/router along the Z direction… clamping all the way to that point should be fine (above that the top heavy part might start to create some wobble)
as Will said, if you then later want to use a short end mill, you might need to move it down again obviously.
Hi, I have had this problem many times. My solution has always been to raise/lower the router in the mount. As long as is clamped firmly, you will be fine.
Yeah, that list of endmills shows 4" long end mills working, which is effectively my question. I probably should’ve just sent the pictures and asked how to make it work instead of specifying 3 scenarios
The end mill I chose was from Bits and Bits, 4" long vs. the Carbide one at 2.5" long. My blank was 1.89", and we’re talking that I needed just a fraction shorter blank to make it work. But it didn’t work, and having the 4" bit in ran the spindle into the blank from the side. And using the 2.5" one is uncomfortably close (for me at least) to not having enough shank in the collet, and I still hit the spindle into the work from the top.
But you along with @fenrus and @Tlytle999 have confirmed my suspicion, that just slightly moving the spindle upwards is the first thing to try. In my imagined use cases, I’m not going to be trying to go through more than 2" blanks, and with the exception of the final contour cut, pockets will always be less than that (pockets usually 5/8" to 1 1/4" or so).
Some of the promotional pics on c3d show router 3 inches above router mount. So nothing wrong with raising router. Several made points about long bits and they have a point.
I recently cut out several outdoor chairs that were 1.5 inches thick. I used a 4 inch oal with 1.5 inch cutting length. Everything went fine with the long bit.
Make some test cuts in scrap project material to see how it works. You dont need to cut the first body out of expensive hardwood. Glue up pine and cut the whole guitar body to make sure all your toolpaths are correct, then hang it on the wall. If mistakes are made you can correct in the pine model before turning expensive hw into firewood.
