Hoping to get some advice on my setup, as I think I am doing something wrong. I recently purchased a OneFinity Woodworker, running a Makita Router. I am cutting letters all the way through half inch Birch Plywood, using a 1/4 shank to 1/8 downcut Whiteside endmill. I have the router sitting at 16,500 rpm, and climb 150 feed rate and 30inch per minute plunge rate. I have been getting a pretty significant amount of fuzzy on some of the layers. I have been having to take a rotary tool with a thin bit and run all along the inside of the letters, to smooth them out, but it takes SO long. I have tried other bits, including a SpeTool 1/8th Compression bit, and another new 1/8 downcut endmill, all with similar results. The Compression bit actually made it worse. I tried using conventional instead of climb, and ended up getting some bad chip out. I have wasted so much plywood at this point, and with the price of Baltic Birch right now, I figured I would give up and ask the pros. Any guidance is extremely appreciated.
I was having a problem with tear out, but finally got the compression bit working. I’ll need to check my speeds, but pretty sure they were much slower than what you’re trying. 18k on the router though.
Are you cutting all the way through in a single pass? If you’re doing one pass @ full depth, it sounds like you’re going way too fast. I usually base my speeds off the Amana charts.
For plywood with a 1/8" Spiral with 1/4" shank, 2-flute (not compression):
1/8" Depth of Cut, 18,000 RPM, 145 IPM Feed, Chip Load .0040" per tooth, Ramp Down 72.5 IPM
1/4" Depth of Cut, decrease feed rate by 25% to 108.75 IPM
3/8" Depth of Cut, decrease feed rate by 50% to 72.5 IPM
The Spectra 1/8" 2-flute compression bit with 1/4" shank:
1/8" DOC, 18,000 RPM, 40 IPM, Chip Load .0011" per tooth, Ramp Down 20 IPM.
1/4" DOC, decrease by 25%
3/8" DOC, decrease by 50%
It seems to happen mostly on the lower layers of the plywood. I have also included an example of regular Birch Plywood as well. I understand using a downcut bit, the back will always be very frayed, and have no issues with that, it is just the middle layers I am concerned with.
It takes 3-4 passes to cut through the plywood, but I do get a lot of what I can only describe as “hhhrrrrrrrnnnkkkkkkkkkkkkkkkk” as it makes long straight or curved passes. Maybe that is a symptom? I was previously using 100 IPM Feed with a 24,000 RPM, but understand that was much too high. Here are settings here using CarveCo.
I don’t have my CNC yet but wondering if this is not a problem with the bit or your feed or speed, but maybe a mechanical problem, namely is your spindle and machine all squared up. If the rails are twisted (not in the same plane) then the bit will rotate slightly as it moves. If the spindle (or router) is not perpendicular to the work surface then it could be dragging the bit as it moves through the wood.
It’s like a table saw with the blade and fence not parallel. You make a rip cut and the back of the blade is dragging on the wood as it exits the blade. The teeth at the back of the blade are not directly in line behind the front of the blade so they drag on the edge of the cut. Same condition can occur on other tools.
So if you haven’t maybe go over the machine from start to finish and check everything for square. You have to start at the beginning, not half way through the procedure. One adjustment can affect all the following adjustments. They build on each other. You can’t set the spindle to be perpendicular to the worksurface if the rails at twisted. Well you can but it would only apply to that one location (X,Y). If you move from that point the bit will drift out of perpendicularity and the farther you move the worse it will get.
Can you see any difference in the amount of fuzz from one section to another, or is it consistent across the whole piece. That could help diagnose the problem.
I use a 1/8 compression bit no tabs 1/2 birch plywood, ramp .75 inch 5 degrees @ 70 IPM single pass Makita router 1600rpm or I believe no.2 or 3 setting but I’ve never had to with either setting and I cut a lot of birch 1/2 ply with no sanding after.
I agree with everyone above about doing a finish pass. also Use a down cut bit since your just cutting out letters. it will leave a smooth top surface and side surface and only have to cleanup the back edge of plywood.