To date, I’ve been cutting pine and plywood. For my latest project I wanted to give Tasmanian Oak a try.
Cuts are smooth along and across the grain, but where I have curves, I get a very rough finish, the photo shows a couple of examples.
No luck with searches so far, has anyone run across this problem before?
I have an original 500mm Shapeoko 2 upgraded to X-Carve configuration (still using the original double x axis), with a 400W Quiet Cut spindle.
The settings I have used are:
Bit - 1/8 inch 2 flute upcut
Roughing pass - 0.5mm DOC, 1000 mm/min, spiral ramp lead in, with 0.1mm roughing clearance, conventional milling.
Finishing pass - 3mm DOC, 1000 mm/min, spiral lead in, conventional milling direction
Quick tests on Tasmanian Oak have shown that conventional milling gives smoother results than climb milling.
Thanks in advance for any input.
I would suggest you try climb cutting for profiles. That looks to be tear-out.
The problem is that on those curves, you are going against the grain, which is causing tearout. Imagine petting a dog front to back versus back to front.
This can be alleviated to an extent by change the direction of cut, as was suggested. The problem is that you cant change the direction in easel. I believe you can in Vcarve, but I haven’t bought it yet (next purchase).
Tear out like others said, but I’m betting due to a dull bit. A sharp bit will leave no tear out going against the grain. When I start to get the slightest hint of it, I toss the bit or just save it for test pieces and use a new one for the cuts I want to be perfect.
I am not used to metric feed rates and now looking back and converting what you stated I have to ask why your roughing pass is so shallow DOC?
Your finishing pass is quite agressive for 1/8 bit.
Typically roughing is aggressive and finishing less so.
Rule of thumb is 1/2 bit diameter for DOC and I usually use a little less that that.
Brian does have a valid suggestion regarding dull bit as a possibility. An up cut or down cut bit has a shear action that often reduces tear out. However I still prefer climb cutting for profiles but it can introduce chatter if machine is not solid and tight.
I use CamBam & bCNC, so climb rather than conventional cutting is an option. When I tested climb cutting before it was on straight profiles, so this could be worth a shot.
Now that you mention it, that bit could be getting a bit dull, its left fuzzies cutting across the grain. Thanks for the tip.
I started with an original Shapeoko 2 and it still has the original dual x-axis, along with one the Inventables Quiet Cut spindles. I found when cutting pine that if I went much over 1mm DOC (on a 3.2mm bit) I’d get chatter. The photo shows my second attempt at cutting this, the original was worse, so I thought of trying an even shallower DOC for oak. Didn’t cure the problem as you can see.
The roughing pass left 0.1mm and the plan was to see if a finishing pass could clean up any roughness. I’d read elsewhere that a full depth finishing pass gives a nice finish, but I wasn’t game to go the whole hog on DOC. Didn’t work as you can see.
Sounds like I’m going to be spending money on a new bit and giving climb cutting a go.