For reference here is the amana feeds and sellers charts for straight end mills.
I use fusion so I have imported their tool list. And these are what the default tool settings are. I do some test cuts at 50% speed using a 1xD Doc and a 1/2 D step over. I work up to 100% with test cuts and having had an issue yet.
My biggest concerns is the belts on the machine. That chart lists but limitation (and conservative ones at that) not machine limitations.
I have been on the fence about buying a 1/2” bit ($$$) to reduce roughing times in Baltic birch. But I’m unsure of the belts can handle the load required. Especially for a 3 flute.
In a cheaper plywood (not as heavy as baltic birch) I ran Adaptive Clearing at:
24,000RPM
1920mm/min
5mm optimal engagement (WoC)
10mm stepdown (DoC)
And it was perfectly happy, I was even able to push the feed override up as it threw chips around the room.
Thanks for the feedback, interesting, so that’s a 0.0015 chipload and 80%D for DOC in plywood.
Did you capture a video of your 1/2" cutter butchering the stock ?
at that amount of violence I’ll start worrying about work holding
(sadly I only have an ER11 collet so limited to 3/8"… but I want to add a 1/2" bit to the tool library at https://fenrus75.github.io/FenrusCNCtools/stl2nc/stl2nc.html in addition to a 3/8" and 5/16"… and figured that one I know what a 1/2" can do I’ll run the 3/8" at that same F&S)
Not sure exactly what feed rates I grabbed phone video at, once I sped the feeds up I was a bit more focussed on the machine.
Here it is clearing out a side pocket in the ply, that’s a 204mm long side pocket it’s clearing out at 10mm depth and 5 engagement, seems like about 4.5 Seconds to cover 204mm based on the video
And yes, the dust extraction is running, it’s just the chips are being thrown straight past it.
Here’s the first go at a full pocket with Adaptive Clear, again. After watching it do the first pocket like this I hit the feed override to see how much faster it would go. The big cutter clears chips out of pockets with no problem and didn’t tear up the surface even on this poor quality ply.
I suspect the large spinning mass of the cutter along with the rigidity back to the spindle of 1/2 inch of tool steel works as some kind of giant gyrostabilising wobble preventer.
This was quite a soft plywood, I’d be a lot more careful in a proper baltic birch.
Workholding wasn’t much of a problem as the cutter is straight flute so not pulling up on the workpiece. When I used the cutter to do some joinery on a 2x4 however, the workholding was definitely on the “step away from the machine” side of happy. Not sure what feed rate this is but I’m getting chips not dust
Amana makes “Carbide Tipped Straight Plunge” bits for wood with 1/4" shanks and cutting diameters up to 1". So, you should be able to significantly increase your MRR by using more of your spindle power without increasing cutting forces. But, beware that the glue in light weight Baltic Birch will chew up HSS cutters. It will also likely require more cutting power.
They do not plunge well. With an hdz it’s not an issue. But a belt drive z will loose steps undoes you ramp slowly.
I actually stopped using them to rough out material because I can run a 1/“4 bit sooo much faster that it doesn’t really save me any time especially when I have to do a bit change to get into smaller areas.
I’ll have to see what the 1/2" one can do… it looks very different from my 1" surfacing bit i the pictures (my surfacing bit plunges like a brick so yeah not too useful)
I’m Camping for the night. I’ll look up my speeds when I get home tomorrow and post them.
They call them A plunge bit but the cutters do not come together in the tip. There is a ledge ground into the steel that can be plowed through wood but takes some force.
I have an XXL with a Chinese 2.2KW water-cooled spindle with ER20 collets. I have built a new Z-axis for it because the stock one was woefully inadequate. (nursed the stock Z-axis along so I could cut the parts for the new Z.)
The new Z-axis if fantastic! I no-longer worry about tool paths that need to raise and lower the bit repeatedly. I upgraded the steppers on Z and X to ones with more torque. Definitely recommended… I ordered linear rails for the X-axis too. Should be another big step forward in reliability like the Z-axis has been. (after I ordered them I saw Shapeoko have gone down this path for the pro model too.) I find the ER20 very useful. A lot of my tooling is half inch. It just feels more solid to me. I recently printed a drag-knife for cutting cardboard using my Shapeoko; the 1/2" shaft butting against the shoulder of the ER20 collet is study enough for cutting even quite thick cardboard. It would not have been remotely possible with a smaller collet.
The other upgrade I heartily recommend is a small 3d printed fan attached to the spindle. It blasts a hurricane of air down the cutter into the trench the cutter has just made. It blows the swarf out so well. It’s made my machine much more reliable, especially when I use down-cut or compression bits.
I totally thought it would, but it’s been going strong for months now. It was a careful tight press fit over the collet nut. I used a vice to squeeze it on. So it’s not flopping around. Also, the ring around the outside helps keep it in one piece (and direct the airflow like winglets on airplane wings) It’s also a safety measure. I figured something would one-day catch on exposed fan blades. I suspect also stops it from whirring badly. I should drop a copy up on thingiverse in case anyone is interested. I used petG plastic at 100% infill.
That’s awesome, I’m more and more amazed at 3d printing. I just got my printer a few months ago and it’s been a blast learning just how much it can really do.
I imagine with a dust sucker of some sort it must really work well. Almost like ram air into the vacuum. Would love the STL.
I was facing an end grain board i’d glued up from birch ply strips today using a 22.3mm 2 flute cutter. I had a 1.5mm depth but was driving it at 5000mm/min (197 ipm) I heard no drop in rotational speed in the 2.2kw spindle… I think the torque of the 2.2kw spindle means that something else is always the limiting factor in your speeds and feeds. For me, after doing a slightly over the top upgrade for my Z axis, the weakest link is the v-wheels on the X axis and the torque of the X stepper. Things go wrong on that axis if i push too hard. So that’s why I bought linear rails and a high-torque stepper… have to wait till the lull after the holidays to install them. Too busy at the moment!
I reckon you can push your feedrate higher. For a facing cut you might as well keep going faster until you get missed steps and then back off your feed rate about 30%. That should give you a calibration. It works flexibly too. If you double the depth of cut you half the feed rate. Lessening tool engagement is the other option. (as with adaptive clearing strategies - I use fusion 360 for my toolpaths.
I keep finding uses for it.
I just uploaded the fan to thingiverse. The fusion 360 file is there so you can modify it directly (if you have f360) Also an STL.
Mine fit snugly over my er20 large collet nut.
The fan is thin enough that it doesn’t get in the way of the spanner flats on the nut.
