I've had my Lead 1010 CNC for a few months now, and I have to say, I'm rather frustrated with the rate that I burn through bits. I've tried finding tutorials and calculations for what Feeds/Speeds/Depth of Cut to use, and I am still burning up bits, even on stuff like Pine. I've tried using the Shapeoko feeds & speeds chart, and even that hasn't been great. As I understand it, Depth of Cut is "machine dependent" meaning if you have a theoretically strong enough machine, you can use a 1" depth of cut. I've been using simple 1/4" 2-flute downcuts, and I am lucky if I get a couple hours out of the bit before it is clearly dull. I have a 1/16" DoC, running at 100in/min +/- 30% (this can be adjusted on the fly), and somewhere in the 18k-21k RPM speed for my DeWalt DWP611 (2.5 to 3.5 on the dial). Here's what I get for "results": Increase feed rate? The bit chatters, leaving visible chatter marks in the cut. Lots of vibration, poor quality of cut. Decrease feed rate? Cuts down on the chatter, but I am still burning up bits. I was going somewhere in 50in/min at one point. Increase Speed? The bit starts to "scream". This is a high-pitched whine much louder than normal cutting sounds. I can back off the speed but then... Decrease Speed? Once again, I am burning up bits. Increase DoC? I get a really poor quality cut, and lots of cutter deflection, you can clearly see deflection in the system based on load, tends to make places near start and end have extra material removed or left behind in little divots. Decrease DoC? I'm already at 1/16", I have tried slightly less than that, but at some point, I have to be removing material. I started with the recommended 0.4" DoC (1/2 bit diameter), 75in/min, and 21k RPM, and it sounded awful, left terrible quality of cut, and looked like the machine was going to fly apart. I kept reducing the feed rate until I hit about 30in/min as well as 1/16" DoC, and burned up my bit without ever really hitting good cut quality. Did some research, left DoC at 1/16" and feed rate at 75in/min, tried lowering the router speed until it just stopped screaming. Still burned up the bit. Still sometimes have to slow the speed when cutting in -Y to keep the machine from chattering. Everything is about as tight as I can get it, and I am still at a loss as to how to keep from going through bits. What am I missing? Is there a specific process I can follow, or a recommended DoC for Openbuilds machines I can at least start with? I can't afford to keep having to replace bits.
Depth of cut is generally half the bit diameter or slightly lower. Your settings of 1/16" DOC @17k and 100" should work fine although the cut could be a little deeper so there has to be something else amiss. Where did you source the bits from? Do you have the same problem with upcut bits?
I haven't tried upcut bits. I started with a Sharkbits when I bought my machine, but switched to Freud through Home Depot locally when I started burning bits.
I have absolutely no issues cutting 2500mm/min (100 IPM) at 1/2 the endmill diameter, so 1/8" for a 1/4" endmill. I keep my rpms in the 10000 to 14000 range with my Makita router. Basically using position 1 to 2 on the dial. If the machine sounds like it is struggling, I will speed it up until it sounds "right." If possible, I always do a roughing cut leaving about 0.3mm. Then I do a full depth finishing pass removing that material. This cleans up any lines and gives a better finish.
I appreciate the response. I'll give that a shot, sounds like I'm just running too high a speed. The DeWalt only goes down to 16k. Is there something you can describe about sounding "right"?
It is hard to describe. My dad used me as slave labor as a youngster in his cabinet shop so I just kind of learned to tell by ear on some tools. If it sounds like it is struggling, or bogging down, bump the router rpms up a bit. If you are making really fine dust (you want chips not dust) slow the rpms down. The router should have no problem removing material. For Large 3D carves, I will use an 8mm round nose endmill and cut 4mm deep at 3500mm/min but I am using a 40% stepover. The very first pass when it is removing a full 8mm wide of material, I will speed the router up quite a bit.
Can you open "Device manager" on your computer and scroll to "Ports" and locate the device your PC is connected to on your controller (for example "arduino uno") - double click on it and choose the "port settings" tab on the properties page. Check the 'bits per second" is set to 115200 and NOT the default 9600. I seem to remember the Z axis not raising to safe height enough during travel moves resulting in cuts too deep occurring. May be a red herring but the port should still not be set to 9600
My CNC is not connected to a computer. It is set up solely on a Openbuilds Interface and Openbuilds Blackbox, reading gcode files from a flash drive. I'm not even sure I can change the baudrate.
Its not baud rate related... Never need to set that in port settings anyway Christian, applications specify baud when they open the port, on the fly
downcut bits push the chips INTO the slot you are cutting. if they get stuck in there and get RECUT this will dull the bits really quickly. to prevent this you need to make sure you are cutting at a combination of RPM and feedrate that creates real chips (not powder) that can be thrown clear. I use a handheld vacuum to clear everything out of the groove before the next pass. Also, for pine, if it has more than just fine lines of hard grain you need to set feedrates etc for hardwood because that is what the grain lines are.
Good to know on Downcut bits. I do have a Dust Collection set up to vacuum as it cuts. I've cut a few hardwoods as well with similar results, so its not just pine. I think I just have my Speed higher than I should. That's interesting about pine, I have noticed a lot of auditory difference and even some cutting difference between the types of grain in the wood. I'll be sure to treat it more as hardwood.
