Today I toured a production shop that makes architectural turnings. The vast majority of their work is on duplicator "Lathes" that follow a pattern. One of the lathes rotated the part at about 100 rpm but removed material using a roughly 12" carbide saw blade running at a high rpm.

Another one used a unique (at least to me) cutter that kind of shear cut. The part was spinning at around 3000 rpm. The surface finish was still a bit rough but better than I would have expected from scraping.

I took a look at the cutter. It was shaped a little bit like a Vee-shaped bowl gouge on very end but the vee flute only went in a short ways. It was introduced to the wood on the tangent. So it was actually shear cutting rather than scraping. They shaped the turning in two steps. First they used a more rounded cutter and follower that made the piece to within about 1/4 inch of the final shape. Then they changed to a more pointed vee and cut the final form. The feed rate was pretty slow, so even though they were taking off 1/4 in in depth, they were advancing perhaps 5 - 10 inches a minute. In this machine the cutter was pointed upwards and the wood was rotated into it. I snapped a couple of pictures of the cutter for those who may be interested.


IMG_0003 (1024x768).jpgIMG_0001 (1024x768).jpg