CNC Router Discussion

Woodshop
#1

I wanted to start a thread, aimed at CNC Router users, to discuss a few issues related to the machine and it’s use. We still routinely have problems, damage, and cutting issues, and I think many of them can be readily addressed. But this thread is about defining and looking for solutions to problems. So, I’ll list a few, and some possible solutiions, to start things off.

Compression bits - These are proving to be difficult for users running the machine at the basic training level. Using a compression bit requires an understanding of how to manipulate the chip size the bit produces, and that just isn’t widely known info, and isn’t covered in the Basic CNC class. After talking about this a bit with Alex, I think these bits need to be moved to the advanced bit category, or dropped from inventory, and let advanced users bring their own bits (which many do anyway).

Dropped Pendant - The pendant is hitting the concrete floor and getting damaged. At minimum, the cradle bracket on the wall needs to be replaced, but I think we need to do something more to greatly reduce the damage being done. One idea I had, was to attach a largish eyelet to the back of the pendant, and a locking cable reel to the ceiling with a small carabiner-type clip on it. You’d use the pendant by clipping it to the reel, and making sure if it is dropped, it won’t hit the floor. We could also try rubber mats.

Maintenance - The machine needs more regular maintenance, done on a routine basis. Class? CNC Users Group?

Training - I think its time to update the syllabus for the Basic CNC class. Currently, the knowledge can be loosely grouped into four areas: Operating the machine, configuring cutpaths, using VcarvePro. The class also includes a demonstration, and a test as well. It’s my observation, that users completing the class, are still very uncertain when it comes time to operate the machine, and lack understanding of important concepts like chipload, manipulating cutting at runtimes, and recovering from problems. The class is already long, but more is clearly needed (and reflected in our high repair costs). Perhaps divide the class into two nights, with the second focusing on operating the machine and cutpath configuration?

I believe we need to increase the emphasis on operating the machine and provide more detail on building cutpaths, bit selection, chipload, and recovering from jams and cutting problems, to address the most frequent problems we are seeing at the router.

Lastly, it would be nice if we started a users group, and started sharing what we learn, techniques, etc with each other.

And Rodney should teach vCarve more often.

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#2

So this doesn’t solve the root problem in any way, but since we can print ninjaflex can we make what is in effect a giant phone case for the pendant? That would at least provide it some cushion for bumps.

#3

That sounds like a fine idea. How about putting a “stop ball”, like a hose reel has, so that the pendant always retracts to about eye-level when hanging freely, and then make the attachment to the cable permanent?

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#4

Good idea, I guess having it retract to the ceiling might be problematic. We’d have to modify the rfid lockbox to make it permanent, but that might be a better way.

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#5

Please keep in mind that some eyes are a bit lower than others… There are a few of us who are not able to use the fancy new power cables in the workshop because they were hung out of our reach…

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#6

Keep in mind that I have not seen the lock-box, but how about putting a “slot” in the top of the box where the cable can slide into when the pendant is put back in the box.

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#7

Hey Tapper,
I’ve already offered to design a case for the pendant, and @themitch22 had offered to print it in ninja flex. The only thing holding us up was having someone figure out what to mount it to so if it is hit it won’t hit the ground. If you or someone else can figure that part out, I’ll get the other 2 parts done. I’ll also make a new holding clip for the pendant in the box.

Yeah, I’ve noticed those bits looking ultra burned up at times. I’m not sure you need an advanced class to solve the issue. I think a poster with general tips might work, like how to adjust chip load while cutting, the command for running your tool path without cutting, the XY layout of the table, ect. If we can get a few of these listed some where, I’d be willing to make and laminate a poster in CA and hang it on the wall.

I hope this is helpful.

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#8

Other thoughts? Feedback helps…

#9

I agree with you on both the compression bits and the Training issues.

Putting on my Capt. Obvious hat: Someone would need to change the Basics curriculum to take the compression bits out, and presumably also change the default tools to be used for cutting plywood/MDF in VCarve.

Limiting the availability of compression bits only to members who have taken the Advanced CNC class puts a higher premium on a class that does not currently get offered very often. But, given that there are other tools available to do the same work on the Multicam, this probably won’t create a significant problem. And, if the demand is great enough, hopefully we could offer more Advanced classes.

I recently had a problem using compression bits, using the default feed/speeds set by VCarve. This is all that we’re really equipped to do by the current CNC Basics class. This reinforces your training point. I feel like I SHOULD know how to manipulate cuts while running the machine, by adjusting chip load, etc.

I think the complexity of the machine merits a two-night Basics class, so long as we can continue to get volunteers willing to offer it just as frequently. Perhaps the teaching responsibilities could be split for the two nights?

if we add this to the CNC Basics curriculum, then we should also encourage existing users, who have not already taken the Advanced class, to take the second night of the new Basics course. You could even require that these users take the updated portion of the new Basics course within a certain time period, or their CNC user privileges will be suspended. I don’t know if the current maintenance problems merit this, but it seems like they might.

I love the users group idea.

Those are my current thoughts.

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#10

We’ve basically been offering it according to demand, but it is no where near as popular as the basic class.

I’m hearing that from a lot of users. Most trainees have never laid a hand on the machine prior to taking their key test - and we provide a step by step cheat sheet to make that easy to pass without really knowing much at all about running the machine.

Your comments are thoughtful, and appreciated.

#11

I’d like to make another suggestion for the issue with the compression bit.

In the CNC Basics class, we go over the basics of end mills, including down cut, up cut, v bit and compression bits. When testing out of the class, the requirements are making pocket, profile, and vbit cuts.

Would it make more sense to not only require the 3 cut types, but also require using each end mill type as well? I think this would solve a few problems.

Firstly, it would allow the student out multiple opportunities to change end mills, and set the surface and depth for each tool change. Additionally, this could help reinforce what’s taught in the class about why some end mills are better than others for certain cuts. I.e. using and up cut end mill on a plywood pocket will likely cause tearout. And most importantly, it gives the student hands on experience setting up and running their files for each type of end mill.

The first time I used the compression bit, I honestly thought something was broken due to the speed and noise. After using it a few times, I now have a better idea of what to expect when making a cut with the compression bit.

If this is not possible due to the time constraints of testing out, then at the very least, I think it would be valuable to see a demonstration of all cut types and end mill types in the class demo.

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#12

We won’t be able to make changes for the class tonight too much. But I will try and incorporate more about feeds and speeds, calculations and such for future classes. I have my own personal feelings on compression bits and whether they are worth the cost for our type of environment.

#13

Definitely not for tonight, but I think we’ve reached a point where significant changes need to be made to address known shortcomings, especially the basic table operations, bit selection, F&S adjustment at runtime, stopping and restarting jobs, etc.