Hi! The material removal rate is definetely very low, but anyway it's cutting and at the same time also rolling. Similar to negative inserts on milling machine, they also provide better surface due the rolling effect. At that time I did't have a real tool and cutter grinder and also those angles are definetely too negative, but anyway those work fine (anyway rare use)

That's true, especially with straight reamers that could just be pulled back. Anyway originally those reamers did not work at all using those factory angles, mainly due the sloppy blade grooves. But a while ago I needed to increase a hole by

Hi! Yeah the finish looks terrible when the blades keeps diggin in... You could try to make a little bit sharper edge (i.e. rake angle) than mine, but still keeping the negative cutting edge. And despite the negative edges aren't able to cut much material at a time, it's a joy to use them 👌

Yeah, fixed reamers work fine with positive angles. But my adjustable reamers just didn't work smoothly on steel. And the one seen on the video was a cheap factory ground reamer and it was digging badly, probably due the blade sloppiness.

i am assuming the sloppiness is a good thing, the blades have no where to go, they are between the collars and against the shaft, mine was too tight to adjust, it made it a pain to adjust, i also want to note that i did not like the grinding setup u did, perhaps u can explain, u r resting on the shaft ends of the reamer, these are typically not straight enough, u cant really depend on them, as a result the blades wont be parallel and only some will do the cutting i am assuming, i dont know what would be the right method for a used (bent) reamer, because the shaft grooved of the reamer has to be involved, so doing the blades away from their slots is not also ideal

@@GraphicManInnovations I didn't have the Tool And Cutter grinder at that time so I had to use the surface grinder. I think that shanks must assumed to be pretty straight, e.g. when grinding longer reamers, you would anyway need a center support for the shank end.

Yeah, that seems a lot. But I think you can do decent reaming without each blade even touching the work.

Hi! As I just ground those in the surface grinder, I didn't measure the actual angle, but I believe that the included angle is like 130-140 degrees. But the main point is that with these kind of loose fitting adjustable reamers, the positive rake angle seemed to dig in way too easily, and this my attempt to do it totally opposite, and it worked. But for fixed reamers, you should be able to use the positive angles.