Chatter on climb milling but not conventional

[durableoreo]

16000rpm and your getting sparks?

Why so fast?

If I was using my G0755, I would drill the corners, drill the center stepping up to 5/8, then cut out the remaining material using a 1/4" carbide endmill at 2,000 RPM. That's 130 SFM and it's as fast as the spindle goes, so there's no option.

With a faster spindle, you can have any speed but there is a minimum speed where you have enough torque to cut. I haven't personally found it and it's a Chinese spindle so the documentation is somewhat lacking. Breaking Taps (YouTube) did a bunch of test cuts in steel and found that 8,000 RPM was as low as he could go. That's 525 SFM with a 1/4" endmill.

 

[RaisedByWolves]

If I was using my G0755, I would drill the corners, drill the center stepping up to 5/8, then cut out the remaining material using a 1/4" carbide endmill at 2,000 RPM. That's 130 SFM and it's as fast as the spindle goes, so there's no option.

With a faster spindle, you can have any speed but there is a minimum speed where you have enough torque to cut. I haven't personally found it and it's a Chinese spindle so the documentation is somewhat lacking. Breaking Taps (YouTube) did a bunch of test cuts in steel and found that 8,000 RPM was as low as he could go. That's 525 SFM with a 1/4" endmill.

I can understand machine limitations, but IMO you’re 75% too fast with your spindle speeds.

I’m guessing you’re looking at machining charts or YouTube stars and I’ll advise to throw all of that out the window.

Your machine and tooling is not capable and there’s really no need to max out your equipment.

Unless you have too much money.

 

[wrmiller]

I would only do climb milling on a finish pass of a couple thousands on a manual machine. IMHO

I do climb milling on my little PM25 for finish passes of a few thou. Did the same on my 935. When side-milling it leaves a really nice finish. Those little slivers like to get stuck in my hands though.

 

[Iceberg86300]

Harvey is a reliable source but the 200 SFM figure seems wrong. I found a post on PM where people where talking 4140 finish and they liked 450-650 SFM.
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The 3/4 square hole was cut with 10% step over, 0.125 step down, 0.000,7 per rev on the ramp down. I used a 1/8" 4-flute carbide endmill with 1/2" of flutes and necked down so I could get down to the bottom of the pocket, 3/4" deep.
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The machine has only 1 nut per axis, so there is probably some backlash. I haven't measured it yet.

Wait, is this a nut or a ball screw machine? Actually, do you have a pic of the machine as well?

Coolant?

Coated carbide or plain?

Shank dia? Is it a full step down?

And now that you've really grabbed my attention regarding your machine, with the questionable tool in the questionable machine I'm now envisioning, 550sfm, .063, 16k, still seems heavy handed. (Although the pocketing numbers seem more reasonable as far as high speed machining goes, what RPM were you running on that? How was it cutting?)

But I've been outta the machine design game for awhile so who knows.

Anyway, I've got a much more comprehensive calculator if you give me the full end mill details. Especially the coating.

Steve

Sent from my SM-N975U using Tapatalk

 

[Iceberg86300]

Those little slivers like to get stuck in my hands though.

Man those really suck!

But damn that snow storm of needles in a fast machine looks good!!

Sent from my SM-N975U using Tapatalk

 

[durableoreo]

Wait, is this a nut or a ball screw machine? Actually, do you have a pic of the machine as well?

Coolant?

Coated carbide or plain?

Shank dia? Is it a full step down?

And now that you've really grabbed my attention regarding your machine, with the questionable tool in the questionable machine I'm now envisioning, 550sfm, .063, 16k, still seems heavy handed. (Although the pocketing numbers seem more reasonable as far as high speed machining goes, what RPM were you running on that? How was it cutting?)

But I've been outta the machine design game for awhile so who knows.

Anyway, I've got a much more comprehensive calculator if you give me the full end mill details. Especially the coating.

Steve

Sent from my SM-N975U using Tapatalk

Rolled no-name ball screws, single nut. X and Y linear rails have 4 trucks but Z has only 2. The Y axis (toward and away) has its rails bolted to a heavy C-section. Fairly stiff but it's only supported on the ends, which leads to a certain amount of beam bending. I blocked it up on 1-2-3 blocks for testing purposes. The table support is limited so I'm only mounting work in the center of the table. The Z axis is the weakest part of the system. I had purchased a separate Z axis (also from China) but it might be too big and this experiment is already on the verge of ridiculous.

To answer your questions: No coolant. Manual air blast. Carbide 1/8" generic 4-flute endmill, 1/8 shank, 1/2 LOC, relieved above the flutes. I don't think there was a coating. The step down was 0.125.

The consensus is that the cuts are too aggressive, and they're probably right.