Can I cut at 600 ipm? Video added!

[difalkner]

Yes, definitely!! Did I mean to do that? Absolutely not!!

I have made several changes to the toolpath profile for cutting the Longworth chucks and all for the better. When I started cutting them 100 chucks and almost a year ago the feed was 125 ipm, 18k rpm, 0.125" depth of cut, with a 1/4" downcut spiral bit. These chucks are 1/2" Baltic Birch and I knew this was conservative but I tend to stay on that side. I have slowly crept the speed up to where I am now cutting chucks at 250 ipm and all the other specs are the same except depth of cut is now 0.2".

When I opened the file for the 16" chuck I realized it was still at 200 ipm for the outer profile, with tabs, so I changed it to 250 ipm. Or so I thought... What I actually did was replace the '2' with '250' and didn't delete the extra '00'. My new feed rate was now 25000 but since I thought I had overwritten the 200 all I did was hit Ok and went out to the shop.

Everything cut just fine until it got to the outer profile. The ramp was at 250 ipm but when the cut reached the 0.2" depth it jumped up to 600 ipm, which is the max setting I have on the X & Y steppers. I was in a mild state of shock for a second trying to figure out what had happened but it cut around that 16" circumference so quickly that all I basically did was watch it cut. And it cut perfectly! The 3kW (4HP) spindle didn't blink at what I had inadvertently thrown at it, the bit was cool when it finished, and the edge was just as clean as it could be.

I don't plan to move any future cuts to 600 ipm but I have to say, now that it's over and nothing broke, it was fascinating watching it cut that fast! This Saturn frame is one stout and rigid CNC setup!





I have a camera in the shop but the output is proprietary and requires its own player. If I can figure out how to export that to something I can upload to YouTube I'll show y'all.

David

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[wmgeorge]

Wow, that had to be kind of a shock!! My Fast speed is either at 500 or 600 ipm but most of the time I run at about 150.

[he1957]

Scary huh? :-)

[difalkner]

You have no idea!! LOL! In the video I can see me whipping around to look at Mach4 to see what the speed was and it showed 600, which is about what it looked like when it was making the circle.

Rapids are set at 600 ipm and I see that all the time but it's in a straight line and not cutting anything. 600 ipm cutting in a 16" circle is really fast!

David

[mactec54]

You have no idea!! LOL! In the video I can see me whipping around to look at Mach4 to see what the speed was and it showed 600, which is about what it looked like when it was making the circle.

Rapids are set at 600 ipm and I see that all the time but it's in a straight line and not cutting anything. 600 ipm cutting in a 16" circle is really fast!

David

It was not a deep cut and a big diameter which is just over 50" around it, so should not be a problem for your rigid machine with good tooling, Mach4 must be working really well too

[difalkner]

It seems to be working well, Mac. But having never used anything else I don't have a benchmark for comparison. And I guess it's just my conservative nature but the faster I go the more uneasy I get even though I KNOW I am nowhere near approaching the limits of this machine. Maybe one day I'll get over that...

I think one of the things that gives me an uneasy feeling is that a lot of what I cut is small, like the slots on a 12" Longworth chuck. It seems like the faster I cut those the more the machine seems to jerk in the direction change because it gets up to speed quick enough and then it's time to reverse direction in just 6 or 7 inches. I have acceleration set to 40 but did have it at 50 and that seems to be a bit smoother. If I was cutting more along a longer path where there may be some turns it might feel different, like the outer profile. That's a smooth cut regardless of the feed rate.

Still learning, I guess.

David

[mactec54]

It seems to be working well, Mac. But having never used anything else I don't have a benchmark for comparison. And I guess it's just my conservative nature but the faster I go the more uneasy I get even though I KNOW I am nowhere near approaching the limits of this machine. Maybe one day I'll get over that...

I think one of the things that gives me an uneasy feeling is that a lot of what I cut is small, like the slots on a 12" Longworth chuck. It seems like the faster I cut those the more the machine seems to jerk in the direction change because it gets up to speed quick enough and then it's time to reverse direction in just 6 or 7 inches. I have acceleration set to 40 but did have it at 50 and that seems to be a bit smoother. If I was cutting more along a longer path where there may be some turns it might feel different, like the outer profile. That's a smooth cut regardless of the feed rate.

Still learning, I guess.

David

With speed comes wear and tear, so if you don't need to go fast then run at the speed you are comfortable with, the machine will last much longer before needing new parts

[difalkner]

With speed comes wear and tear, so if you don't need to go fast then run at the speed you are comfortable with, the machine will last much longer before needing new parts

Good. Then I'm comfortable with 250! Ok, I might try 300 or even 350...

Here's the video of my little 600 ipm 'incident' -



David

[mactec54]

Good. Then I'm comfortable with 250! Ok, I might try 300 or even 350...

Here's the video of my little 600 ipm 'incident' -



David

Especially on the large diameters that is where you can make up time

[difalkner]

Especially on the large diameters that is where you can make up time

I agree, Mac. I may move those to 350 ipm and see how it does. In reality, while I've cut a hundred or more of these, I rarely have to cut more than one or two sets at a time and saving 30 seconds just isn't critical or necessary. But it would be cool to see it run at a programmed 350 ipm.

David