2mm Al. + Artcam + newbie = horror

[MGPL]

Hey, I'm new, I work in metric, and would appreciate the help. Some terminology might be wrong.

I have a TS-3040C-H80 cnc machine with a spindle that goes up to 20000rpm. it's one of those machines whereas the cutter moves across the surface, the bottom part doesn't move (yes, i don't know the term)

So machining wood was fine but aluminum wasn't so fine..
Here's my setup and the parameters i used to achieve breaking the bit and making the chuck fall out.

Task
make a 9mm diameter hole all the way through 2mm of aluminum (seems simple)

material: 2mm thick Aluminum, probably 6061
drill bit: 3.175mm diameter, 37mm entire length, 18mm length for cutting area, flat at the end, 2 flutes, and supposedly made for metal (can't read the description, it's in chinese, probably HSS, (hope that's enough), feed per tooth not provided.

Settings in program
2D Area Clearance
Start Depth: 0
Finish Depth: 2.05
Allowance: 0
Final Tool Allowance: 0
Tolerance: 0.02
Tool: Stepover: 1.27mm; Stepdown: 3mm; Feed Rate: 17mm; Plunge Rate:4mm; Spindle:15000rpm
Tool clearance strategy: Offset / cut direction: Conventional / start point: inside
Independent Finish Depth: not used
Add Ramping Moves: not used
material: 2.05mm

i calculated the toolpath, saved it, and ran it in Mach3
the initial plunge went straight down into 2mm, lots of noise, lots of small bits of metal debris, and the chuck fell off, the bit got stuck and broke.

I got the basics of Artcam down, but the parameters are off I think.
I don't really understand stepover in contrast to feed rate nor, plunge rate in comparison to stepdown, allowance, tollerance. help me out, thanks.

[zeed]

Originally Posted by MGPL Task make a 9mm diameter hole all the way through 2mm of aluminum (seems simple) material: 2mm thick Aluminum, probably 6061 drill bit: 3.175mm diameter, 37mm entire length, 18mm length for cutting area, flat at the end, 2 flutes, and supposedly made for metal (can't read the description, it's in chinese, probably HSS, (hope that's enough), feed per tooth not provided. Settings in program 2D Area Clearance Start Depth: 0 Finish Depth: 2.05 Allowance: 0 Final Tool Allowance: 0 Tolerance: 0.02 Tool: Stepover: 1.27mm; Stepdown: 3mm; Feed Rate: 17mm; Plunge Rate:4mm; Spindle:15000rpm Tool clearance strategy: Offset / cut direction: Conventional / start point: inside Independent Finish Depth: not used Add Ramping Moves: not used material: 2.05mm i calculated the toolpath, saved it, and ran it in Mach3 the initial plunge went straight down into 2mm, lots of noise, lots of small bits of metal debris, and the chuck fell off, the bit got stuck and broke. I got the basics of Artcam down, but the parameters are off I think. I don't really understand stepover in contrast to feed rate nor, plunge rate in comparison to stepdown, allowance, tollerance. help me out, thanks.

I gues that 3mm stepdown is too much for your machine...i usualy take 0.1mm stepdown but I have DIY cnc and not very sturdy.
And I always take ramping moves when cutting Al to save my tools...

Here are some definitions:
http://www.toolingu.com/definition-3...step-over.html

[ViperTX]

I believe your stepdown is your maximum depth, so what is under the 2mm sheet of aluminum because you're driving 1 mm below the underside of the aluminum.

Paul

[thackman]

Can you post an image or a link so we can see the machine? Your description of the chuck falling off was shocking. A true milling chuck shouldn't fall off even with a crash that damages the rest of the machine. Bending a cutter, breaking a cutter, throwing a part across the room. Those can happen but a collet chuck ripping of the machine is unusual. Now if your using a drill chuck that's a different story. End mills are not drill bits and behave differently. I wasn't sure from your post which you were using. End mill can plunge into material but that's usually for fairly large manual machines. Plunging is slow, hard on the cutter, and hard on the machine. Straight ramping or helical ramping is much more common. It sounds like you are cutting some form a sheet which poses it's own set of issues because it starts to chatter and bounce unless the clamping method was selected based on the specific cutting operation that you were attempting. A picture of the mill and your setup would help a lot.

[MGPL]

thanks Zeed for your definitions and suggestions , I tried a 0.5mm and 0.2mm stepdown and those worked much better. I also slowed the feed down, and stepover to 0.2mm too. I will also experiment with the ramping moves too to see what it does.

Thackman, ViperTX, my setup is sturdy, no worries there. What happened is that the cutter got stuck in the metal because of too large of a stepover, the machine thought it went back up and then it went down another 2mm even more and got stuck in some metal screw hole i had under the material (don't ask) which is what seized the cutter and made the chuck fall out.

here's the machine I use, does this type of cnc machine have a special name other than cnc engraving machine?
if the images don't work, look for TONSEN 东达数控钻铣雕刻机（桌面型）TS3040C in www.taobao.com


The top part is similar to what i'm machining, without the pockets on top.

the one in the middle is similar to what i use, except it has two flutes.

I also have these conical and parallel engraving cutters, but I'm not sure if I can use these in aluminum or not because the tool name was written in Chinese and the translation of these technical terms from Chinese to English aren't so easy to find.

[dewme5]

That's a gantry style machine.

Careful on "the machine thought it went back up" That machine is just doing what you told it. With a new machine, and learning, it's always a good idea to do a dry run. Offset your Z height, so you care just cutting air, but somewhat close to the material so you can tell it's going where you think it should.

Use charts to look up your feeds and speeds. Running at things full bore will get expensive quick. Aluminum will clog up if you move to slow, and that will cause you to break tools. They'll break moving to fast as well.

It's an extrusion, so I'm going to assume Aluminum 5053.

[MGPL]

Thanks for the suggestions, the mental notes are stacking, I assure you.

"
Aluminum will clog up if you move to slow, and that will cause you to break tools. They'll break moving to fast as well.

It's an extrusion, so I'm going to assume Aluminum 5053.
"

So taking in consideration that's it's 5053 and the the tool bit I'm using (3.175mm diameter HSS end mill) what is too slow and too fast (feed, spindle)?

[dewme5]

using inch measurements.

I'd start at 10,000 or 15,000 RPM. Move about 6 inches per minute, taking cut depths of about .005" Step over would be half the distance of the end mill.

Run a short sample. you need your chips to look like clean little chips. consistent size, straight edges. Check your end mill, the flutes should be clean, not filled with melted aluminum.

Watch the end mill. there will be a little deflection as soon as it touches material. but once into a cut, that deflection should stay constant. if it starts to bend more while you are cutting, stop.

Coolant is always nice. I don't know if your machine will handle coolant. You can easily add just a few drops at a time.

[MGPL]

any idea how to start a run from a specific line in mach3, with the right X,Y,and Z?
last time i tried that button i quickly figured out it didn't turn on the spindle or use the machine coord. and broke the drill bit while driving it into the material.

is there some kind of way to skip to a specific line while keeping in consideration all the past moves until that point?

ex.: i have 3 z passes for remove the surface of something large. I did 2 of them, but then something went wrong on the 3rd and i don't want to rewind the program and sit through the first 2 passes.

[dewme5]

I believe F5 key will turn on the spindle.

skipping forward when using absolute mode. Just start a few lines before where you need to be. I usually find a spot prior to the last Z retract. highlight that line. start the spindle manually, then "run from here".

Doing this will start milling air. It will move from spot to spot cutting nothing. Then the Z retract will move the height of the tool to the safe distance (which may be up or down from where you are). Then, it will move to XY, and bring Z down to cut depth as the program moves on.

There are several things that can alter this, but for my G-code, I only output Z commands when necessary. Your post processor may have them on every line.

[MGPL]

got it all figured out, thanks. Proceeding to my next newb questions

Working the aluminum is becoming better, I got comfortable with a 2mm end mill at 15000RPM,
feed of 2mm/sec, stepdown: 0.2mm i believe. (with a little 220Vmotor)

This works fine for a big piece of aluminum but for a little plate of 1.2mm thick, 3cm width, and
114mm length, it gets really warm and melts the aluminum. I did tons of test and the best result
i got is still unsatisfying at 0.75mm stepdown, 10000RPM, 4mm/sec feed rate with a rough outside contour.

please send me a link for working aluminum settings if you know of one. My chip per tooth is also unknown

much appreciated, thanks

[awerby]

flexshaft (or a Chinese copy of same). A Jacobs chuck (which it has) is fine for drilling, but isn't recommended for milling operations. It doesn't grip firmly enough, and it's not concentric enough. I'm not sure how it's mounted, but if it fell off, that's not a good sign. If you upgrade your spindle to something more substantial, with a collet chuck, things will probably improve...

Andrew Werby
www.computersculpture.com