Chatter when cutting 1.75" thick guitar body

One of the reasons I bought an X-carve was to built guitar bodies and necks. Well, I don’t really think the 611 is up to the task. I have a long enough bit, but it chatters when I cut the outside of the body. Has anyone installed a larger router? Or will the new upgrades to the xcarve that stiffen the rails help?

Are you cutting it in steps? What diameter hit are you using? 1 3/4 is a big cut for anything other than a finish pass of maybe .010 - .020. That’s what I do, and I’m using a full machining center. Also depends on the wood you are cutting. Maple will chatter like crazy, mahogany, ash and alder, not so much.

It’s a 1/4" shaft and 1/4" cutting bit, 1.5" cut length, overall length 4". Dewalt 611, 75 inches per minute, .125 depth per pass on mdf (figured I would learn on the mdf before I sacrificed any actual guitar blanks.) one option I’ve seen is to cut only say 1/2" deep and then use a jigsaw to cut the rest and sand the edges. I’m just trying to use the xcarve as much as possible.

IMHO 75 IPM AND .125" pass is a lot of material to remove at once.
Reduce one of those variables and try again…

Ditch the sanding, and use a flush trim bit in a router and save yourself some pain.
See David Picciuto’s make a guitar video:

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Also, if you’re cutting 1.75 with a 1.5 length of cut bit, make sure that the area after the cutting edge of the bit is relieved, or you will rub and burn.

I also had a problem with chatter cutting guitar bodies. What I did to eliminate the issue was to stiffen both the X and Y axis. I also check the belt tension periodically with a digital luggage scale and check to make sure the V-wheels are adjusted properly before each cut. Instead of cutting through a full 1.75 thick blank, I cut a 1.5" blank for the body and a separate .25" thick top. The bodies are usually Alder, Mahogany, Limba, Swamp Ash or similar. The tops are usually much harder woods like Maple, Rosewood, Walnut or similar. I use a .25" solid carbide 2 flute spiral upcut bit for the body and a .125" solid carbide 2 flute spiral upcut bit for the top. The body is cut at 125 IPM with a DOC of .04" while the top is cut at 80 IPM with a DOC of .03." To cut the shape of a body takes about 25 minutes and the top about 8 minutes. So far I haven’t had any chatter like I used to experience. Eventually, I would like to upgrade my z axis since I believe the lack of an anti backlash bearing on the lead screw could be a major cause of chatter when the DOC is increased beyond what I’m currently using.