Do you folks watch your projects run?

CNC Machines Shapeoko
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Although I’ve been in woodworking for a long time, I’m a relative newcomer to the CNC game (< 1yr) and am just getting to the point now where I’m getting reasonable at it. One thing I’m not yet used to is the length of time it takes to do some of these jobs. I can accept the trade off for the accuracy and cleanliness of the cuts, even for jobs that I used to do in minutes with a jig and a handheld router, that might take 20-30 minutes to cut on the CNC…and I readily admit that I don’t have the dexterity to control a handheld router with enough accuracy to provide these kinds of results. However, the thing that drives me crazy is the amount of “Do nothing” time I’m facing.

Everything I’ve read tells you to watch the job as it runs…and be on the ready to hit the kill switch if something goes south. And…being new…I’ve had a number of things go wrong, including having my bit “stick” on retraction out of a pocket that was cut too deep for the cutter - causing my Z to skip and then re-plunge into the work and go straight into the spoilboard. I’ve broken a bit by pushing the speeds and feeds faster than I should have, and I’ve had jobs start in the wrong place because I forgot whether I was referenced lower left or dead center. All my own fault and never to be repeated…but it does leave me with a respect for what can go wrong…and fast. And so, I watch.

Given the combination of my nature and a desire to maximize my time in the shop, I can’t sit and watch something run for 30 minutes, 60 minutes, an hour and half…it drives me stir-crazy - especially when I know I have other things waiting for me in the shop.

What do you do? Do you watch your jobs run? Are you ever-ready at the kill switch? I’m sure confidence will come when I begin to have more and more jobs run without issue (and many do now), but is that a false sense of security? What really is the best practice?

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You’ve answered your own question! :smiley: Seriously, You don’t walk away from your table / band saw, do you?

Just because CNC is in your tool’s name doesn’t mean it is really in “control”, now does it? :smiley:

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That’s different…it needs me to operate. I don’t watch my dust collector…it runs at all times in my shop and does what it does while I do other things. The only purpose for me to watch a CNC is to shut it down if there’s a problem. I have no other analogous tool in the shop.

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Me, I usually try and work on CAD/CAM for the next project, sitting at the computer right next to my enclosure, and I keep an ear open. As long as the cut sounds right I’ll let it run, and if I hear anything suspicious I’ll check, and hit the feedhold button if there is anything worth pausing the cut. As long as you stay nearby within ear and smell range, you can multitask. The machine is solid and worst case scenario you crash it, no biggie. I personally choose to not go do something else outside the shop for more than a minute or two when the machine is running. It also depends on the toolpath: for a finishing pass on a 3d carving, with virtually zero load on the machine and the stock, the risk of mishap is very low. Having a 3D printer also keeps you busy, I like starting a job on either machine and work on the other in the meantime.

EDIT: I also spend more time than I care to admit just watching the live feed from the dust shoe now, it’s just mesmerizing :slight_smile:

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Perhaps you missed my point. :smiley:

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This is a really difficult question to answer, because it is very situational.

There are times where I watch closely, with a finger at the hold button, such as with a new setup, a new tool, finish-to-fit tasks, things where I anticipate potential problems.

I would say that I never leave the area when the machine is running (close to true, at least. The coffee pot isn’t in the room), but that I am often doing other things. Most of the time, I just keep an ear open, an eye open, and check status, rather than stare at the machine. When things go bad, there isn’t usually time to stop the machine before the damage is done at the speeds these move, other than right at the beginning of a job during the initial moves.

When you are first starting, it is a good idea to keep a focus on the machine. Any machine. You need to learn it. You get to recognize the behaviours, the sounds, the little regularities and irregularities. What it looks and sounds like during a proper clearing pass, or during a fine finish. The sound and look that indicates chip evacuation issues and in about five seconds, there will be a problem.

But as time goes on, you learn when you need the deep focus, such as when the job starts, or a tool was changed, and when a general attentiveness is sufficient.

Typical for me on a repetitive job might be: fixture a part and load the first tool. Start the machine. Once the first roughing pass is making chips, which tells me the tool is correct, the zero is correct, and the part is secure, Start prep on the next part so it is ready when the first is done. Recent job involved cutting and facing rounds on the lathe before they went into the CNC. After the initial part, all f that was done while the CNC was running, in the same space, in clear view, close enough for me to get to it. When all stock was prepped, I was sitting back at the CAD machine while the rest of the parts finished.

The key thing is: Don’t stare at the machine waiting for something to go wrong all of the time, but recognize key points where hard focus is needed, and ALWAYS be aware that things CAN go wrong and what they might be…

No matter what you are doing, it is preferable to have dust control that is as quiet as possible (so you don’t go nuts, and so you can hear the machine doing its job) and guarding to the extent possible, so when something DOES go wrong, you don’t get pelted by barely-subsonic shards of razor sharp carbide. Keep in mind that it is just a machine. It can be repaired or replaced. You can’t. There is little that can happen where the difference between 1 second and ten to hit the kill switch is worth getting hurt. Most problems are going to damage the work or break a tool in either case. That’s ok. It will happen. YOUR safety needs to be the first concern. Always.

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I watched the machine carefully during my first couple of weeks. Now after checking that the bit and stock is set tight and the zeroing done right, I usually leave the room if I don’t have anything else to do there. I’ll then check every 10-15 minutes and I’m always in hearing range.

First thing is, I don’t wanna be around when things really go flying.
Second, it’s a compromise for me: If I can use the time the CNC is working for any other stuff, I think that’s well worth the risk of destroying a bit, clamp or even the router (assuming this doesn’t happen on a regular basis and gladly none of this happened so far).

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For short jobs I watch a machine. For long jobs I stay close but in the same room. On long jobs I will leave for a few mins to get a drink or a use the restroom but I return asap. The Shapeoko can start a fire that could go from smoke to blaze quickly. You never know when something will come loose or otherwise malfunction.

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I usually stay in the same room with the CNC and do other work or clean up. Sometimes I’ll step out for no more than a minute or two to grab a snack or drink. A good habit to get into is to never ignore a failure, even if it’s minor. Immediately figure out why it happened and how to solve it. Iterate until you eliminate that source of error. Very soon, you’ll discover that nearly every job runs perfectly.

Poor workholding can lead to the most catastrophic of CNC failures - friction fires. It’s a good idea to put a smoke detector above your CNC - they are cheap. And have a fire extinguisher close at hand, but not too close. The extinguisher does no good if you can’t reach it due to the fire.

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I’m pretty new at this myself, but for short jobs (< 10 minutes) I typically watch the whole job. For longer jobs I am always near the machine, but often not watching (using the routing table to finish pieces, cleaning up the never ending mess from working too many things at once, playing on the computer, etc). I do watch it for the first couple of minutes to make sure the clamps are holding the piece. My “long” jobs are short though, I don’t think I have run a job that is over an hour (I mostly do cut outs, not carving). I tend to split longer jobs into multiple steps, and run each separately. Makes it easy to recover if something can go wrong. If I need to step away I just pause the job, CNCing is great for not being timing sensitive. I have had pieces break free from clamps before, I have had a bit get pulled down from the router (collet not tightened enough), and I have had tabs break on small pieces. The tabs breaking was really close to being a fire (it was scorched and smoking in seconds as the piece was being pushed around by the router bit). Fire is definitely what I worry about the most with the CNC. There is a good video on youtube that shows just how quick things can ignite when things go bad:

https://www.youtube.com/watch?v=D2xoxPlDnW4

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Yep.
at least 20 characters

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I’ve had two failures that make me want to watch…unfortunately:

  1. While cutting out a pocket in a cardioid, the bit plunged down and through the bottom of the piece. I was “Nearby” and heard the commotion, came over and stopped it all. Reran the job and watched. At the same point, about an inch down in the pocket, I saw that the bit hesitated when trying to come up out of the pocket to recenter and start the next pass…Z slipped (belt)…the bit recentered and plunged down into the piece and through to the spoilboard (thank goodness for spoilboards). I learned not to pocket deeper than the cutter length, even if the bit is long enough to clear…at least not on curved surfaces. By the way, does anyone know if the Zplus or HDZ would avoid that problem because it wouldn’t slip the Z?
    Anyway, I watch because I know I’ll see that hesitation - and WILL have time to get to the pause button before it plunges into the center of the earth. I wish I never saw it.
  1. I was cutting another large pocket and I noticed that as the bit changed directions, the Z plate was shifting. I paused the job and discovered that one of my eccentric nuts holding the Z to the rail had worked itself loose. I was able to tighten it up and resume the job and got lucky that it had not yet caused any noticeable damage.
    So again, I’m motivated to watch.

It’s a train wreck…I don’t want to watch, but I feel compelled to do so!

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I always watch when trying something a bit new. Or a new bit. But most of my projects require very small bits and very long times. If I’m reasonably sure the files are correct, usually on repeat use, I may leave the shop once an initial pass is done. The worst thing that happens, with micro bits, is that they break and the Nomad has been cutting air for the last hour. If I’m pushing the envelope with a delicate cut, I will closely monitor to see where bit breakage might occur, on the plunge for example. The main reason I return to the machine during these safe, long cuts is to check the spindle for overheating.

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I’m pretty new to this myself but I agree with bpedit that when using a small bit for long cuts the risk of catastrophe is low. I mounted a cheap IP camera over the CNC so I can watch and hear from my desk in the house and be there in a few seconds if something goes wrong

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Yes. I do. And you should too.

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I’d say that owner was pretty lucky there was no dust extraction system running, or to give it it’s proper name “fire oxygen supply, propagation and flammable dust reservoir system”.

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I watch my stuff run. As luck would have it, I haven’t yet had an issue. I mostly watch because the material is valuable, and often enough, its my only piece. I live on an island, a specialty supplier is not down the street. I am rather stupid, and entirely capable of mistakes. I don’t cut wood, and my shop being what it is, if something is going to catch on fire, I doubt its the Shapeoko. I like watching the machine work, and when I make my tool paths, I try to make interesting ones.

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I use to keep an eye on my S3 while running, after getting comfortable with the results and being more confident in my work, now, I keep an eye for a few minutes, then let the S3 do its job. But after the incident that happened to me a few days ago where I lost a project that was 89% done, I think I will record all projects from now on so I can try to figure out any issues that might happens in the future.

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I’ve got a two and a half hour carve to run tomorrow… I plan to clean my shop - and keep a close eye. I’ll be sure to bring coffee with me - and use the bathroom before I start! :wink:

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My 2 cents - I’m in the space with the machine when it’s running.

I may not be in front of it but I can hear it hiccup, belch and occasionally, scream and emit clunks and groans. Never more then 20 feet from the e-stop.

If I need to leave the room I pause the job. If I need to sleep, I pause the job and shut down the spindle. Been doing this for years now, no problem.

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