I have a G0704 clone (Weiss VM25L) with a CNC ballscrew/Clearpath Servo conversion on it. It has an 1100w motor that I have Hoss' timing belt drive conversion and it currently hits just a hair under 5000rpm. When I bored the pulleys my gibs were too tight so the radial concentricity isn't great, which I believe creates vibrations. (Just another reason to buy a lathe, right?) I'm redoing this as soon as soon as the new pulleys arrive since the XY is much more accurate now. I'll probably end up upgrading to a more powerful motor and changing to a 1:1 pulley ratio in the future so I can have the spindle automated also.
I have mostly cut aluminum so far and have had pretty good luck using NYC CNC's speeds and feeds video (youtu.be/uw8uL2jjEBs) for that. I still have some adjusting/upgrading to do because using 100% tool diameter DOC and 20% WOC I can hear the motor working a little too hard. Kind of surprising for an 1100w motor, I thought it'd handle it a big better.
For steel, I don't plan on cutting it as often as aluminum, but I'd like to have an idea of speeds and feeds for that as well. I have a piece of 1215 steel 1"x1"x12" to test feeds and speeds on. I tried following along to this NYC CNC video: (youtu.be/SzBFJ7oRo8c), but haven't really had any luck. I know that's for a Tormach 770, but I would think the baseline numbers should be working for me.
My justification for that is John cutting 4140 at much more aggressive F/S setup on a 440 in this video (https://youtu.be/YNNFjNyeOYM). The cut in that video sounds great. I believe these G0704's should be pretty dang close to 440's as far as rigidity goes, mostly lacking in the spindle. The problem I have is that even with conservative feedrates, I'm having chatter problems. I'll add some pictures and a video below to show how I have this part setup. On the back and side of the cut is where I'm getting chatter. The front sounds good and like it could be pushed further. I moved the part all the way into the vise and it helped slightly, but if you listen carefully in the video (over the air) you can hear the kind of squealing sound going on. On the finished cut I can also just tell by the surface finish it's chattering. I'll post the different cut recipes I used at the bottom also.
I'm not sure why this is. Could it be the way I have the gibs adjusted? I adjusted the XY gibs to be as tight as I could get them before I started noticing lost motion, then backed them off slightly. There doesn't seem to be any visible play in the table. The Z gib I adjusted from a starting point where I believed it was too tight. I noticed drills wouldn't really follow the spot drill and I read that other people had this problem because the gib was too tight. So I loosened it until the drill didn't visibly walk. I also checked the lost motion on this and it seemed to be really good also. I also have the mill trammed pretty well too. My only other thought is that the spindle pulley vibration is causing the issue, but I would think that it would chatter on all sides, so I'm not sure.
Any suggestions would be great, recipes, pictures, and video below. Thanks! (Sorry for the vertical video, and the poor formatting, I couldn't get it just right for some reason.)
5FL Altin Coated CEM
100SFM (1550RPM/7.5IPM), .25DOC, .02WOC
100SFM (1550RPM/7.5IPM), .1875DOC, .02WOC
200SFM (3050RPM/15IPM), .25DOC, .02WOC
200SFM (3050RPM/15IPM), .1875DOC, .02WOC
https://drive.google.com/open?id=1to...PBPFYsQI7k1bgN