Newbie Preflight Checks - XXL

Relatively new guy here. Getting better though. Quick question regarding maintenance checks. When you are doing a “pre-flight” check before running projects, what are you checking, and how often? I’ve already learned my lesson on making sure the V-wheels are tight, and recently realized my router was 1 freakin degree off plumb, which sucks when trying to do an inlay for the first time.

So any lists, or videos you know of that will help me, would be greatly appreciated. Learning on the fly with expensive wood just sucks.

I want to thank everyone who has helped me in the past. I’ve been on a lot of forums for musicians, recording, etc. But I’ve never seen more helpful people in my life.

Well, there’s:

My big thing is if using expensive/difficulty to replace materials is to make a test cut in a piece or scrap or MDF or something similarly painless to toss.

Thank you for responding. I 100% agree. When I was cutting some stars out for a flag I was making, I ran 2 tests on some scrap wood and they were perfect. But I didn’t realize with every cut, things loosen up, like the V-wheels. So when I ran the production cut on maple, the machine got out of sync and it wasn’t pretty. A couple of guys here taught me about checking the V-wheels, so that is a religious practice now. Then last week, while I was cutting my first inlay, I noticed my cuts were not perfectly square. That is when I checked my level again on the router mount and found it was 1 degree off. So I’m just wondering what else I don’t know to check.

Thanks again for your advice.


My experience (which admittedly is that of a casual/hobby user, I’m not doing any kind of production) is that after initially spending time to get the machine mechanically sound (wheels just tight enough, machine squared, belts just tight enough, router squared, wasteboard surfaced), I usually don’t bother re-checking the vwheels/belts or anything else at the machine level really, except “once in a while” (every 10 jobs or so? I don’t even do it that often). BUT, what I do on every single job is double-checking what I just did (in the spirit of “measure twice, cut once”), because 99.9% of the mishaps I had were totally on me.

So for example, I’ll double check zeroes, and I will most definitely do a 3D preview the Gcode I’m about the run (too bad CM does not have that feature yet), every-single-time. I can’t count the number of times I have realized “wait, that’s not the toolpath I thought I had loaded” by just looking at the preview (in CNCjs, for example, or in an online G-code viewer, it takes 30 seconds tops), and it turned out that I picked the wrong file by mistake, OR that I had messed up the CAM. You can instantly spot a zero reference mistakenly set to stock bottom instead of stock top by just looking at that preview, for example

So I guess I’m following a “Machine Operator checklist” rather than a machine operating checklist.

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I am also a hobbyist. I agree with everything you said, and have caught myself on some of the things that you mentioned. I actually have a written checklist now to do everything you mentioned, as well as verifying I have the right bit in the router. In this case, and a few other runs, everything was running perfectly. It was cutting simple 90 degree v-bit stars into a piece of maple. Then, without any rhyme or reason, the machine makes a strange noise, like it was caught up on something (nothing in the way) and then the stars were being cut roughly 1/2 in to the right from where it should be. The only thing I notices was one wheel was a little bit loose, but not to where I could move the mechanism up and down.

My problem now is that I don’t trust the machine to do what it is supposed to do, but in reality, I think that I must be be the one missing something. If this CnC was not quality, then I wouldn’t be seeing such unbelievably beautiful projects posted on this forum. I don’t know what I don’t know, and I appreciate the forum member’s advice, as always.

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As we note on the wiki:

The great thing about CNC is that given a properly prepared file, a machine set up which matches the file, and nothing going wrong in the cutting, a part will be made correctly.

The awful thing about CNC is that a part will only be made correctly if the file is prepared properly, the machine setup to match the file, and nothing goes wrong in the cutting.

Just keep track of the machine’s progress w/ each cut — hopefully you can kill the power before anything goes horribly wrong and salvage the piece — if not, hopefully it will be a learning experience which will help one to not have the same difficulty in the future.

It’s a learning process and the machine isn’t smart, it relies on you for smarts and common sense.

I keep a bottle of loctite 242 handy and any bolt that comes loose twice gets a single tiny drip of loctite on the threads to stop it vibrating loose. I also twang my belts at least once a week, you can use your phone to check pitch but after a while you get the hang of twanging all three and listening for the pitch changes.

I have also got in the habit of, when I first rapid the machine to the front to insert the first cutter, holding the spindle by the collet (when it’s not rotating…) and giving it a gentle waggle left / right and front / back. If I feel anything knocking or loose then I go through the whole preload check on V wheels, set screws on pulleys etc. to find out what’s loose. After a few tries you get a feel for what the flex should be, just don’t gorrila it, you only need a few Newtons (or pounds) to feel if something is loose.