Andrew J. Coholic
10-20-2016, 10:05 PM
Two days ago I received a bit that I had Royce/Ayr Cutting tools make up for me. I do these carved top cutting boards (quite a few yearly) and have been trying to get my time down on the machining - and also a better machined surface as to cut down on sanding time.
I was using a box stock "bowl and tray bit", 1 1/4" diameter with a 1/4" radius bottom edge. Running about 240 inches per minute and 13,500 rpm, with a 31% step over. Cut pretty good, with a decently smooth surface.
The bit I had made is 2" in diameter, with two carbide inserts, also with the same radius. The inserts are set to up-shear cut. Also, with a 3/4" shank (the maximum I can run in my spindle). Its a fair bit larger than the other one!
Today I finally got a chance to test it out. I did a test cut in a scrap of hard maple, then put one of my cutting board blanks on the machine a did a test cut at the same feed speed, 13,000 rpm and same step-over.
Cut the machine time from about 7 and a half minutes, to just under 5. I need to play with the cutting speed and step over to see if I can shave it down to 4 minutes (I was hoping to cut the machine time in half.
I would say the cut quality is better than the bowl bit, especially around the perimeter. I hit the cut section with a ROS and 120 grit for 30 seconds or so and removed all the visible machine marks, so they were very minimal, with no chips or tearing out.
I wish I had more time to spend trying to push the bit, but that will have to wait a bit longer. But if I can get to my target time, I can possibly save nearly an hour every time I do a run of a dozen of these.
The bits
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/FullSizeRender2_zpsopjwnnp4.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/FullSizeRender2_zpsopjwnnp4.jpg.html)
Off the CNC router
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/IMG_2108_zpsf1gj8yqp.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/IMG_2108_zpsf1gj8yqp.jpg.html)
After a bit of sanding
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/IMG_2109_zpsqurqunt3.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/IMG_2109_zpsqurqunt3.jpg.html)
Here is a video of the cut..
https://www.youtube.com/watch?v=1JKJq-Zmm4M&feature=em-upload_owner
I was using a box stock "bowl and tray bit", 1 1/4" diameter with a 1/4" radius bottom edge. Running about 240 inches per minute and 13,500 rpm, with a 31% step over. Cut pretty good, with a decently smooth surface.
The bit I had made is 2" in diameter, with two carbide inserts, also with the same radius. The inserts are set to up-shear cut. Also, with a 3/4" shank (the maximum I can run in my spindle). Its a fair bit larger than the other one!
Today I finally got a chance to test it out. I did a test cut in a scrap of hard maple, then put one of my cutting board blanks on the machine a did a test cut at the same feed speed, 13,000 rpm and same step-over.
Cut the machine time from about 7 and a half minutes, to just under 5. I need to play with the cutting speed and step over to see if I can shave it down to 4 minutes (I was hoping to cut the machine time in half.
I would say the cut quality is better than the bowl bit, especially around the perimeter. I hit the cut section with a ROS and 120 grit for 30 seconds or so and removed all the visible machine marks, so they were very minimal, with no chips or tearing out.
I wish I had more time to spend trying to push the bit, but that will have to wait a bit longer. But if I can get to my target time, I can possibly save nearly an hour every time I do a run of a dozen of these.
The bits
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/FullSizeRender2_zpsopjwnnp4.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/FullSizeRender2_zpsopjwnnp4.jpg.html)
Off the CNC router
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/IMG_2108_zpsf1gj8yqp.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/IMG_2108_zpsf1gj8yqp.jpg.html)
After a bit of sanding
http://i83.photobucket.com/albums/j307/ajcoholic/ajcoholic047/IMG_2109_zpsqurqunt3.jpg (http://s83.photobucket.com/user/ajcoholic/media/ajcoholic047/IMG_2109_zpsqurqunt3.jpg.html)
Here is a video of the cut..
https://www.youtube.com/watch?v=1JKJq-Zmm4M&feature=em-upload_owner