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View Full Version : Well that didn't end well...



Dangle_kt
12-12-2016, 11:16 AM
super excited I had found a bit of old aluminium to try my new novamill on.

ordered some t nuts and clamps (clamp was WAY too big...), some er16 collets (bought a whole set of 10...stupid, most I'll never use) and a few smallish 3 flute end mills for alu. I don't have a C spanner, so couldn't swap them out so I was running the old small end mill that it came with, maybe 3mm...so nothing massive.

It all arrived and I set about jogging the machine about a bit, stopping and starting the spindle etc.

I had a simple program that I ran with no tool in. just a simple square.

I then tried to zero the machine, using a piece of paper I could figure out Z (tool offset i think the button was called) but couldn't figure out how to zero X and Y... (if anyone knows how to do this on VR milling I'd be grateful), I also don't think the toopl was set up properly in the tool library - I need to look at this more.

Set the speed to 1000rpm, and feed to 300 - no idea i this is any good or not, but seemed a sensible start rate as thats what the seller I bought it off was using.

anyway, I shifted the work piece so I could run the the program without crashing, set it to run at z10 above and it went fine.

so then I tried to jog down manually, and did a first tiny side mill into the material, I was jogging at 0.05mm so I was hardly blowing chips everywhere, but was really pleased to have made my first tiny mark on the world of milling.

next I jogged to the middle and then tried a little plunge, same idea, tiny steps into the material, then jogged sideways a couple of mm - all worked ok...

So I figured I'd re run the program but just touching the surface.

so changed the program to run at z1, worked great. (which I think means it runs 1mm above the zero - stock top)

So feeling bold, I reset it to run at z-1. The idea was it would plunge in 1mm, then do a simple square. (so should be 1mm into the stock?)

Well, 1mm plunge was either too much, or my speeds/feeds was way off. so it bit into the alu for half a second then broke the end mill.

Really not 100% sure what I did wrong, though I probably should have tried to run the program at z-.1 or something first...

I'm used to watching youtube videos with insert tools hogging out at huge speeds/feeds.

So now I have a broken end mill stuck in my easy change holder, and no C spanner to swap it out. I gave up at that point.

Looking forward to having another go, but will probably use a bigger end mill next time, calculate proper speeds and feeds, maybe alter the program to just nibble at the side of the material rather than plunge - though I'll need to figure out how to zero X and Y first.

On wards!

Boyan Silyavski
12-12-2016, 12:18 PM
What is the exact tool you used? The stick out in mm from collet? What is the max spindle speed and feedrate of your machine?

Chaz
12-12-2016, 12:27 PM
super excited I had found a bit of old aluminium to try my new novamill on.

ordered some t nuts and clamps (clamp was WAY too big...), some er16 collets (bought a whole set of 10...stupid, most I'll never use) and a few smallish 3 flute end mills for alu. I don't have a C spanner, so couldn't swap them out so I was running the old small end mill that it came with, maybe 3mm...so nothing massive.

It all arrived and I set about jogging the machine about a bit, stopping and starting the spindle etc.

I had a simple program that I ran with no tool in. just a simple square.

I then tried to zero the machine, using a piece of paper I could figure out Z (tool offset i think the button was called) but couldn't figure out how to zero X and Y... (if anyone knows how to do this on VR milling I'd be grateful), I also don't think the toopl was set up properly in the tool library - I need to look at this more.

Set the speed to 1000rpm, and feed to 300 - no idea i this is any good or not, but seemed a sensible start rate as thats what the seller I bought it off was using.

anyway, I shifted the work piece so I could run the the program without crashing, set it to run at z10 above and it went fine.

so then I tried to jog down manually, and did a first tiny side mill into the material, I was jogging at 0.05mm so I was hardly blowing chips everywhere, but was really pleased to have made my first tiny mark on the world of milling.

next I jogged to the middle and then tried a little plunge, same idea, tiny steps into the material, then jogged sideways a couple of mm - all worked ok...

So I figured I'd re run the program but just touching the surface.

so changed the program to run at z1, worked great. (which I think means it runs 1mm above the zero - stock top)

So feeling bold, I reset it to run at z-1. The idea was it would plunge in 1mm, then do a simple square. (so should be 1mm into the stock?)

Well, 1mm plunge was either too much, or my speeds/feeds was way off. so it bit into the alu for half a second then broke the end mill.

Really not 100% sure what I did wrong, though I probably should have tried to run the program at z-.1 or something first...

I'm used to watching youtube videos with insert tools hogging out at huge speeds/feeds.

So now I have a broken end mill stuck in my easy change holder, and no C spanner to swap it out. I gave up at that point.

Looking forward to having another go, but will probably use a bigger end mill next time, calculate proper speeds and feeds, maybe alter the program to just nibble at the side of the material rather than plunge - though I'll need to figure out how to zero X and Y first.

On wards!

It sounds like you are trying to 'jimmy' the outcome.

You start at Z = 0, always. Its from this point that your G Code tells your machine to go 'down', how quickly, or what technique (plunge, spiral, helix etc).

This vid (and others like it) may help.

https://www.youtube.com/watch?v=o-GBpUZ3piY

Dangle_kt
12-12-2016, 12:45 PM
the small sample program was what I edited, it was set to run above the work peice to demo the machine to me when I bought it. I just set it to run the same path but 1mm into the material. stupid mistake to have not thought it through more. I have since learned that plunge rate needs to be a lot slower than feed rate.

My max spindle speed is 5000, and I'm not sure what it can rapid at

Chaz
12-12-2016, 12:49 PM
the small sample program was what I edited, it was set to run above the work peice to demo the machine to me when I bought it. I just set it to run the same path but 1mm into the material. stupid mistake to have not thought it through more. I have since learned that plunge rate needs to be a lot slower than feed rate.

My max spindle speed is 5000, and I'm not sure what it can rapid at

Yep, a lot slower plunge. Keep in mind, some end mills cannot mill straight down if they are not cutting in the centre. Its better to helix or profile in at an angle anyways.

What is the HP rating of the spindle?

Dangle_kt
12-12-2016, 01:22 PM
its a novamill so it only has 0.5hp I think

JAZZCNC
12-12-2016, 08:03 PM
If at all possible avoid Plunging into material. Or like mentioned helical into it. Or at very least peck into it using peck drill cycle.

However the most likely reason your tool broke was too low feedrate and too low Spindle RPM for aluminium. 1000rpm isn't anywhere near fast enough unless was using really large cutter.
Can't really give you any figures to use because we don't have enough info regards cutter used but I'm pretty sure you'll need nearly all your 5000rpm if trying to cut aluminium.