Problems with 3D Carving

[hardidon]

Have started (or tried starting) to cut some 3D images with some limited success. Started off with a Coat of Arms for a friend where i imported a 3D image in from the ones Vectric provided with Desktop, and made two of them for him, but last two i have tried, during the roughing pass, the machine tries to drill down to China. I bought a model of a couple of horses across three panels for my granddaughter and first two panels went fine, but on the third as the finishing pass completed, the machine went back to 0:0 but didn't raise the Z to clear the work, so a gouge across the piece. Ran the third panel again, no problem. Have had a request for another set of the 3 panels, and now three times on the roughing pass of the first panel, machine is drilling through. Normal 2D V-carves not a problem. Vectric says not a problem with the software, must be hardware. Nextwave says that they see nothing wrong, and yet i have 5 pieces of firewood now.

Any thoughts?

[tonydude]

Need to see the file to figure it out

Tony

[hardidon]

Not sure which files you want to look at, so am attaching the .crv and .tap files for this.

This last time that the machine took the nose dive, i was recording a video of it, and then took a picture of the pendant showing the last line to be 805.

24Left 3D Roughing 1.tap

(758.82 KiB) Downloaded 52 times

LeftPanel_24.crv

(5.34 MiB) Downloaded 60 times

Thanks for taking a look at this.
don

[tonydude]

I haven't found anything wrong with the file. Do you have a dust collector hooked up to it? Might be static electric that's causing it. Let me give you a tip, when using ball nose bits on 3D work, your feed rate will only go as fast as your slowest axis. Example: Say your feed rate is at 100ipm on your x and y but your plunge rate on your bit is 30, it will go 30ipm. I have mine set at 150 feed rate and 150 on the plunge.

Tony

[hardidon]

Thanks for looking at this Tony... You have come up with the same answer as everyone else.

And no, i do not have a dustcollector attached to the CNC (just use my shop vac when the chips get too deep). And for the roughing i am not using the ball nose but rather straight end mill, and i am running the speed and plunge at the same ipm.

Can there be something to do with the model??? I am running Desktop, so the model was purchased off of the internet, and i am not sure of the “quality” of the files. I have only cut a couple 3D objects, in fact just last night i did a small 5” x 5” x 1/2” without a hiccup. Could there be something like an open vector (whatever the 3D equivalent would be)?

Again, thanks for looking.

don

[tonydude]

Don't see no vectors at all. It's only a 3d model u gave me. There are no vector lines in it.

Tony

[jeb2cav]

This kind of condition is almost never the result of the tap file. In my experience and observation, it is either: 1) mechanical or 2) electrical.

1. Mechanical - check the lead screw for the z axis (in this case) to ensure it is tight. There is a 'flat' part to the lead screw that the set screw should be setting against. I use wood glue to hold this in place (vice red or blue paste). If this is not seated correctly, you can run into the condition - runs for a while, then off track, then runs for a while after that (but now is foobar). Check to ensure the router is clamped correctly and not moving. You can use a marker to draw a line to help gauge any movement while carving. Check to ensure the bit is tight and not moving during the carving.

2. Electrical - in my case, I ran into this condition as a result of poor electrical service. Sometimes it happened more often - like 1-2 times per 8 hours or run time - sometimes not for days. In my area, the power fluctuates some in voltage/amps, and I have the added bonus of momentary on/off of the power. I purchased an UPS for the primary purpose of conditioning the power, and plugged the shark into this. It also provides power during the momentary on/off conditions, and 5-10 minutes to gracefully stop the job if the power is 'out'. Since I've done this, I've never had a dive like this, and the one time I did it was mechanical (loose lead screw) (almost 8 years now). I also purchased a heavy duty usb cable - but that may not be an issue depending on the machine you have. Make sure your cables are attached well to the controller. If this was reasonably repeatable - like you could get the dive within an hour of operation every time - you could try switching axis cables and air cutting this. If the z axis cable is the culprit, or if the z axis output from the controller is the culprit, you could narrow it down and then contact NWA for resolution.

If 1 and 2 are addressed, and you still run into this, then you have an intermittent failure with your control box, or there is an intermittent break in the z axis cable and you'll need to work out repair/replacement with NWA.

[hardidon]

Hey Joe, thanks for taking a look at this. Problem that kicks my logic, is that it is not random/intermittent... Things happen in the same place, repeatedly. First instance was on a project that i had carved 4 times, now the next three times i have tried it, nose dive in the same exact place (same hole). More recently i have tried carving another 3d project that i have done successfully prior, with the only change i grew it from 12" height to 24", and three times now, at the same point in the roughing, a nose dive. I can and have done 2d signs and the like, before and after the nose dives with no issues.

Mechanical, i still have to confirm that everything is tight, though a quick visual shows nothing amiss, and i have made two signs and a small 3d since my last nose dive.
Electrical, is solid. We are on the same grid as the hospital in back of us and in the 17 years we have lived here, i could count the number of power bumps / losses on one hand and have fingers left over.

I have made a video of the last nose dive, but mp4 nor mov are not allowed as attachments. So everyone has to take my word for it that the spindle isn't falling out and causing the holes in the carvings.

[jeb2cav]

So, if I understand your description correctly - 2 different projects (tap files), and nose dive at the same spot on the table - correct?

If that is the case - did you capture/jot down the x,y location? And if you did, or even if you didn't - what happens when you jog around that location - do you get the dive?

If you swap the z cable with x (don't attach the x to the z as you won't have enough gantry run) - and air run the job - no bit, do you get an excessive movement in x at that point in the job?

If repeatable, and nothing wrong with the tap file - my guess would be a bad cable. And it is exposed based on tension at that point - or near that point in movement.

[hardidon]

Yes it has happened to me on two different projects... and it happened/happens at the same place on the PROJECT... not the same place on the table. Just went out to make sure but the holes in my spoil board are in different spots.

A local friend and CNC'er suggested that it has happened to him and he guessed/determined/stumbled across that the control box was getting hot, and so set up a fan blowing across the controller. This has started happening to me just this summer and my garage/shop is not air-conditioned, and i am in Texas. And it happens to me when i am doing the rough out for a 3d carving, which has the machine running for a longer stretch than when i do my 2d plaques and signs... Maybe something to it. I am setting up a fan to blow on/at the controller, and our 100+ degree days have seemed to have broken... Se shall see.

Cables show now wear, there is no tension on any of them and they have no other cables laying across any of them to induce any RFI.

Thanks for the suggestions, I keep looking.
don