Shapeoke 5 Pro with Makita router. Like most beginners, I started out using the defaults and realized fairly quickly I could up those but was chicken to go overboard.
I finally decided to start pushing a little to see if I could find the envelope. I had a project using 18 mm baltic birch cutting out some parts using contours.
I used a 251 end mill with a .125 depth of cut, 18000 rpm, 150 in/m feed rate and 75 in/mm plunge rate. The router never seemed stressed. The chips were still more sawdust than chips but I thought this might be attributed to cutting plywood.
After running for about 20+ minutes, I checked the bit and it was too hot to hold. Does this tell me I still need to bump up feed rates even more?
Yes, if the tool is moving so slowly/spinning so fast that the chips are not able to carry away the heat of cutting then you need to increase feed rate or slow the speed.
That speed/feed should be giving you 0.004" chips.
I suspect the trapped heat is due to the downcut tool and slotting (cutting a slot the same width as the tool). And the dust you’re seeing is the chips getting recut after being jammed down in the slot.
Downcut tools are meant for side-cutting and through cutting thinner materials with a gap below the cut to allow the chips to disperse.
You could use the downcut for the first pass, then switch to an upcut for the remaining 5 passes.
Or you could widen the slot & cut it as a narrow pocket to avoid binding the tool.
Yeah, if it were me I would try again with an upcut and on a scrap board and see if it changes and doesnt leave too much of a rough top edge for his liking if he didnt want to build in a tool change
I needed to do some more cutouts on some Baltic birch. I set my feed at 150, plunge rate at 75 and speed at 16500 (about halfway between 2 and 3 on router) used a 201 end mill.
Zipped through job in about 16 minutes. I’d just finished a thorough cleaning of my machine and didn’t feel like making another mess so I attached the dust collection and I don’t know about chip size but after the job finished, I checked the bit and not only was it not hot, it was barely warm,
Faster is better. At least faster feed, slower speed.