Can't seem to make it through a "deep" cut.

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tbeaulieu
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Can't seem to make it through a "deep" cut.

Post by tbeaulieu »

I'm new to CNC. I have a BobsEvo 4 and w/o facebook for their forum, this is the only forum that I know of. Aspire latest. Using gSender.

So, I have a fairly straightforward charcuterie board that I designed and have cut out several so far with 3/4" edge grain glue-ups, with excellent results. I decided to make some chunkier ones out of some good quality white oak, again edge grain, but this time it's 1 1/16" thick.

I'm having a really hard time trying to get through the deeper cuts. It's getting almost entirely through each time, only to go off the rails in one of the last few passes. I've slowed this thing down quite a bit, over the thinner boards and it looks and sounds great until it goes haywire.

I've read a recent similar thread here and will move my laptop and controller to use the same outlet. The thread also recommended a USB isolator, but I've read conflicting reviews about not being able to reach the device with the isolator present?

Good quality 1/4" down-cut extended bit.
The step over is 30%.
The speed is 60 inches.

I've managed to downsize the board three times, while increasing the hand hold hole, but I'm nearly out of room for another pass!

I will say that I get a lot of Alarm 1 codes in general that abort my cuts, complaining about a hard limit hit, which is false. I've been forced to disable hard limits to get through jobs reliably. Tried finding solutions to that, but so far, nothing straight-forward.

Does anyone have any insight into "deep" cuts? Or is that just a coincidence? Does anything else come to mind when looking at the photo? You can see each attempt and what happened at nearly the end. There are at least five explosions in this pictures and virtually all are on a corner.

I've also attached the aspire file, slimmed down.
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PXL_20221201_203830739.jpg
PXL_20221201_203833147.jpg
PXL_20221201_203836083.jpg
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Rcnewcomb
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Re: Can't seem to make it through a "deep" cut.

Post by Rcnewcomb »

What is your actual spindle RPM? The tool database shows 4 RPM. :shock:
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- Randall Newcomb
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rscrawford
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Re: Can't seem to make it through a "deep" cut.

Post by rscrawford »

I'm assuming its a combination of the extended downcut bit which starts to vibrate when cutting deeper in a narrow kerf (no where for the chips to go with a downcut), and a lack of rigidity in your cnc, which leads to the bit cutting wider than it should at the deeper passes and your stepper motors are under powered and begin losing steps.

You need the shortest tooling that will get the job done, maybe an upcut bit, and very light passes. Or buy a rigid machine with servo motors :D
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Rcnewcomb
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Re: Can't seem to make it through a "deep" cut.

Post by Rcnewcomb »

Good quality 1/4" down-cut extended bit.
But the tool database says it is an upcut. Which is it?
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adze_cnc
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Re: Can't seem to make it through a "deep" cut.

Post by adze_cnc »

...different step over value too...

tbeaulieu
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Re: Can't seem to make it through a "deep" cut.

Post by tbeaulieu »

I just decreased the step over to 20%. The speed to 50 in. The depth to .03. The speed in the file is simply the Makita setting, so 4, but I had it at 5 because I experienced no burn and wanted to be overkill. I do that because I have the bit descriptor including the speed to make it easy in the shop. So much for that.

So, once again ... it was FINE ... amazingly tame ... until 65%. Destroyed. Ripped the

And, FYI - I had a regular 1/4" down cut on for the first three attempts, switch to extended to see if that was the issue because the cutter stopped super close to the height of the stock.

I am soooooo frustrated. 55 minutes for a single pocket and it still blows up? Again, on the end. One thing that I've noticed about aspire is that it adds this "j" hook to each level of a pocket that is quite violent. On each level it starts forward, backs up, does a violent reverse hook to "finish" the level and then proceeds. Very odd, IMO.
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Adrian
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Re: Can't seem to make it through a "deep" cut.

Post by Adrian »

tbeaulieu wrote:
Fri Dec 02, 2022 2:03 am

I am soooooo frustrated. 55 minutes for a single pocket and it still blows up? Again, on the end. One thing that I've noticed about aspire is that it adds this "j" hook to each level of a pocket that is quite violent. On each level it starts forward, backs up, does a violent reverse hook to "finish" the level and then proceeds. Very odd, IMO.
If you're seeing "violent" movement then that would be a warning sign to me that the acceleration/deceleration settings in your control software aren't correct for what you're cutting.

I've never seen that movement when doing a pocket in Aspire and there is nothing in the 2D wireframe previews in your file that would seem to show it either.

How good is your dust extraction? A down cut bit will pack more and more dust and chips into cuts which can cause a lot of issues on a profile cut with some machines. Shouldn't be an issue with a large pocket though.

tbeaulieu
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Re: Can't seem to make it through a "deep" cut.

Post by tbeaulieu »

Remember, this pocket is already open! I'm just trying to enlarge it each attempt by the bare minimum to save the board. Which is now too late. So, there was zero chips there. I have a CV1900, so lots of suckage. It occured to me last night that the move I described is probably the ramp of 1 inch. I will do more testing after I repair the machine. Thank you.

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adze_cnc
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Re: Can't seem to make it through a "deep" cut.

Post by adze_cnc »

Also remember that bits inherently want to pull themselves into the work when climb cutting which in a raster pattern will be half the time. The deeper you go the more of the cutting edge length is available to grab. Have you tried the offset method with a conventional direction of cut?

tbeaulieu
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Re: Can't seem to make it through a "deep" cut.

Post by tbeaulieu »

I hadn't even thought of that. Should I be switching to an upcut? Or would that be a similar problem with deep cuts, only trying to rip the stock up? I can try changing the direction. I just assumed with such small nibbles and slow speed there would be no way to fail!

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Leo
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Re: Can't seem to make it through a "deep" cut.

Post by Leo »

The cuts you are taking are so light and so slow I am surprised that there is a problem at all.

I want to look at it from a different angle. Not a sortware issue. Vectric is pretty ROCK SOLID as a CAM software.

I wouls liik at the machine. Especially when the machine is located with the cutter in the area where the failure occurs.

Binding
Loosness
rough travel in the ways or drive screws
gantry bumping on something
Collet hitting something
Clamping of the workpiece
Anything at all that might be interferring with the motion of the machine
Grit on the guide ways

Nuts, Bolts, screws tight
Belts slipping
Screws on the stepper motors thight
Stepper motor shaft screws tight
Imagine the Possibilities of a Creative mind, combined with the functionality of CNC

tbeaulieu
Posts: 21
Joined: Tue Aug 09, 2022 9:11 pm
Model of CNC Machine: Bobs Evolution 4

Re: Can't seem to make it through a "deep" cut.

Post by tbeaulieu »

Well, you've narrowed it down to just a dozen possibilities! ;)

I agree that's it's environmental. I have my sites on a higher end machine. This one seems to be just fine for signs, but I'm more interested in bowls, trays, boxes, etc. The OneFinity X-50 looks sweet.

I spent two hours getting that thing back together today and trammed it, only for it to explode again on the next job. In all fairness, I suspect it was because the board vibrated loose. There was chatter on the endgrain as it came around. I'm going to experiment with just screwing down the material.

Thanks all.

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