Hey all!
I'm struggling for a very long time now with my homemade wooden CNC machine.
In short: when contour cutting sheets of plywood or hardboard (4-6mm) it will always leave some rough chattered side surface. This only happens to certain side of the stock.
The issue: Cutting straight, single axis, lines leaves a perfect smooth finish. The issue is when cutting diagonal/arcs.
When cutting a circle for example, where the grains are going from left to right (nr 1&3 on first image), the chatter accurs from 12 to 3 on a clock and from 6 to 9. *Rotating the plywood 90 deg mirrors the chatter in de opposite sides.
I made about 40 circles with different speeds, feed, RPM and different tools.
Things i tried:
- Checking for backlash: basically no backlash
- Using 3mm to 6mm 4f carbide flat end mill
- Using 3mm 1f straight flute
- Using 3mm 2f spiral downcut end mill
- Screwing + double sided tape the stock
- Using tool with minimum stickout *(10mm)
- Conventional or climb milling with 0,5-1 mm stock to leave and then climb or conv. milling the meat + finishing pass climb and/or conv. I tried every combination possible.
- Spoilboard is flattend
- Cutting full depth*
- Cutting 1mm per pass
- Beefing up the arms that hold the y carrier
- Tramming
I've been looking on a lot of forums discussing schatter issues. My issue lies only on certain edges, the opposite side of de grain seems clean. This is the part that really confuses me and i really have no idea what to try next.
I recently tried some lettering in MDF. even this gave me poor results when carving diagonal.
I have really no where else to look. I’ve already spend 30+ hours to track this issue down without any significant improvement. Any help would be much appreciated!
HGR20 linear rails
SFU1605 ballscrew with BK BF
1/32 microstepping
Makita rt0700c router
Rough cut 1500 mm/m
Finishing cut 200 or 500 mm/m
Fusion360 for modeling and generating gcode*
Using ramp to enter stock*
Router is for about 98% square to the spoilboard