This is a curious questions for me. I was strolling through the home depot today, and as usual I detoured through the tool section. I stopped to look at the dremel bits, and I noticed that they look VERY different from the end mills we use.
I understand that using different numbers of flutes helps us to manipulate the spindle and feed speeds so they are acceptable for the DeWalt’s super high RPMs. But I saw that the Dremel bits have LOADS of flutes, if I can even call them that, and they are rated/designed for 30k RPM tools.
So why are they not preferred? Is it the geometry of the tools, or are they generally crappier metal? I ask because the only time I ever did much with cutters on my old Dremel was wear some out porting a cylinder head (yes, one). Everything else was wearing out grinding stones and sanding tools. No intentions of buying any, mind you, just trying to get less stupid.
I am sure there are a few that might work, but for the price I don’t think it would be worth experimenting with. Most of them are hand carving bits. All sorts of reasons, some are not meant to plunge, some are just meant for drywall (plain steel?), lots of flutes means no room for chip evacuation (=fire).
Then the short answer is that they aren’t meant for machines that chug out a steady, not-insignificant flow of material. More like bump bump, look, bump bump some more, look again, etc.
I suspected it would come down to that, and might explain why I wrecked mine so regularly.
I have tried Dremel bits on soft pine (on my Chinese “3020” engraver). I did not properly understand feeds and speeds (and likely still don’t) but they don’t operate like real endmills. While they look like they have cutting edges, they behave more like sandpaper. I suppose flutes allow faster removal like coarse sandpaper, while not leaving an awful surface that coarse sandpaper would leave. I found with moderate feed rates the bit would seize, and with slower feed rates it left burn marks in the wood and then would seize (presumably after dulling the bit from heat).
I may try again, but if I do I will most likely flood with coolant or maybe try post-processing to “peck” along the toolpath and dwell between cuts to let everything cool, basically like the cutter is intended to be used. If there is one thing I’ve learned about feeds and speeds, it’s that you can’t just reduce feed rate or depth of cut and expect any old tool to work.
I’ve looked at a pretty good assortment of mills since I started on this path, and literally NONE of them look like Dremel tools. It’s pretty obvious that they aren’t a great choice, or I’d be able to find at least one actual mill that resembles a Dremel tool. I just didn’t want to chuck one in to find out what happened.
Thanks for sharing your experience, since you actually tried it. I don’t think I’d waste any more money on them either. You’re probably right about the surface finish. That makes intuitive sense to me.