OMIO CNC Tips, Tricks and Questions

The interesting thing to note about wiring switches in series is that both switches must be closed in order to complete the circuit. A great example of switches wired in series is in the typical nuclear-war movie, where two people must flip a switch in order to launch the missiles. Switches wired in series means that Denzel Washington and Gene Hackman must both agree to launch the missiles.
When switches are wired in parallel, closing either switch will complete the circuit. Thus, parallel switches are often used when you want the convenience of controlling a circuit from two different locations. If the nuclear missile switches were wired in parallel, either Denzel Washington or Gene Hackman could fire the missiles.

Source: https://www.dummies.com/programming/electronics/diy-projects/electronics-projects-how-to-build-series-and-parallel-switched-circuits/

It’s a normally closed signal. You want to be able to break any one point in order to Open the signal path and stop the machine.

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My bad, I was thinking normally open signal :sweat:

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That was along the lines of what I was thinking too. I like the performance characteristics of the OMIO, but the safety side of things leaves some to be desired. Especially when you have new students operating it (albeit, with training) and a board that would have everything wrapped in bubble wrap if they could because it’s “more safe”.

Maybe I’m being a little harsh with the board there, but some of the stuff does get a little ridiculous at times. :roll_eyes:

There are a couple of differences in design between the OMIO and something like the SharkHD4. I don’t have experience directly with that machine, but I have used machines which use similar construction. If you look closely, you will see that the X,Y and Z axis all use unsupported hardened round rails. This construction style is very popular as only the surface of the rail is hardened, this allows them to be drilled and end tapped for cheap construction. As you cut the endmill is essentially acting as a lever trying to twist these rods apart, so you are substantially limited in cutting speeds.

The HDPE plastic construction of that machine really isn’t going to be doing it any favors either.

The proper spindle that the OMIO has is also an advantage but putting a heavy spindle on a machine with unsupported round rails and HDPE construction would probably just cause additional deflection. The main benefit of proper spindle in your circumstance would probably be a reduction in noise.

If you are trying to get this machine to work well in aluminium you need to use endmills that are as small as possible, 4mm or smaller is probably ideal. By removing less material when you are cutting out your parts you will be significantly reducing the amount of load on the machine.

I would suggest to use around 40-60ipm as your base feed rate, and start with a super low depth of cut, maybe around 0.25mm test cut a few parts and then increase it slightly until you find the max depth that you can do at once. When doing very low depths of cut you will find your endmills will wear out faster because all the load is on a small portion of the tool so you might want to check what brand your endmills are and try use cheaper ones if possible.

You can probably getting that machine working well for you, but you are always going to be limited on cutting speeds. Perhaps trying to use more plastic and less aluminium would help you.

When we bought our machine, we bought a similar 1.5” surfacing bit. However, we have never used it because I have no idea how to determine feeds and speeds for such a bit. Everything else we run has been based on specific recommendations from people who have used the same material+bit combination.

So I have three questions: how do you determine a good starting speed and feed rate for a new bit, and for this specific case (surfacing MDF with a 1.5” bit), what feeds and speeds would you recommend? Also, for generating CAM for the surfacing op: do you just make a box shape the size of the bed and run an adaptive clear on it?

We just winged it and it turned out great. It was something like 15000 RPM and we just had one student doing it manually with the rapids in Mach3 and another student with a vacuum. I’m not sure what the default rapid is set at, maybe about 30 ipm taking off 0.06". Doing it manually with the arrow keys are like a IRL version of this old flash game. The reason why we didn’t make a program is that we have the edges of the waste board very close to the limits of the machine. If I was to generate code I would just pocket it.

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Seems to me that this thread is worth getting Pinned for easy reference…

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E-Stop switches are wired normally-closed so that if anything happens to the signal, its a fail-safe. This also allows you to wire them in series.

In most cases, industrial switches have contacts for both NC and NO

Dang, that’s really fast. Do you have any tolerance issues at that speed? We’ve been running our x6 at only around 40ipm.

No not at all really. I do parts with bearing holes etc at speed and experience no issues. You will want to account for tool deflection though, so you will want the tool to be as short as possible with the flute pretty much touching the collet. I also run a low load full DOC contouring run around the bearing hole to take off the last 0.25-0.5mm of material around the edge.

At what point do you decide you need a cooling system rather than dry cutting?

im no expert by any means, but I believe part of coolant mist an air spray is chip clearing and surface finish. Also cutting tool longevity. It is there to avoid having chips welding to the cutting tool and to prevent any work hardening of the material.

You can get away with very low speed and conservative DOCs without coolant, but once you get up to the speeds and feeds that OP is at you would want to add some coolant mist and air spray.

So, we have an x6. We’ve been running 40ish IPM, I’d be hard pressed to remember what DOC and stepover (we haven’t run it since probably March.) We’ve been using a 2 flute 3mm endmills from McMaster (https://www.mcmaster.com/8866a252). No fogbuster set up, but we do own one (we’ve been trapped in the back of a classroom for a while…), but we’ve been manually putting cutting oil in the path and shopvac-ing chips away. Would the fogbuster + switching to 4mm really give us that huge of a jump in cutting speed?

The coolant serves quite a few purposes and is pretty much necessary if you don’t want your experience with the router to be terrible. Camren above hit pretty much all the reasons why its needed.

The air component is both for getting the coolant to the cutter and to blow the chips out of the area. Most of the time when someone is using a router they are doing a slotting operation which is not ideal at all and can very easily result in chip welding in the slotted channel or on the cutter itself. This is bad for a couple of reasons. The material sticking to the cutter does many bad things such as change the diameter of cutter such that the welded chips are now the outermost radius, it off balances the cutter, and it can even render the cutter a write off if the chips manage to stick hard enough. All of these are bad, but the first two can easily ruin the part you’re cutting. The expanded radius both screws the finish and can make the actual part dimensions off from what it is in the cad. This is also the same with the off balanced cutter though not as bad. Similar stuff can happen chips get welded into the channel that was cut as well. If it was a finishing pass now you have to deal with getting welded chips off of the nice surface you hoped for. If its not the finishing pass then the cutter has to go back through that mess and will have an extremely uneven chip load which can cause the cutter to flex making both your part gouged and dimensionally off. This can also break the cutter and is actually the most common reason I saw for us to break cutters initially.

The coolant part has a few important functions as well. It acts to both cool the tool/cut area down and to lubricate the cutter. When you cool the cutter and cutting area down you pretty much negate the threat of any chip welding. The air mentioned above will do most of the job but without coolant you can still get chip welding just not as bad. Cool chips (relative at least) can’t weld back on the surface. The coolant also acts as a lubricant between the cutter and the material its cutting. This makes it so that tool rubbing, which is a big cause for heat buildup, is lessened with there now being a layer of coolant between the cutter and the material, minus the cutting edge. This also makes our tool last longer as its both not scraping the entire time and its not going through nearly as intense heat cycle every time you use it.

Doing both of these will not only extend the life of the tool and make your parts better but it will extend the life of the router itself. Obviously over time the router will wear down but the constant shock loads from a cutter getting an extremely uneven chip load will lead to faster wear both in the axis and in the router internals itself though it will manifest itself in the actual router long before anything is even noticeable in the axis. A cutter getting really hot can also subject the router itself to lots of heat which again over time can degrade it faster. Both the heat and shock loads mentioned above can also wear out collets much faster. In general use coolant, it might make the parts a bit slimy but it saves so much time and money both in the short run and in the long run.

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Does anyone have the 2200 user manual? Looks like omio forgot to send ours.

There isn’t exactly a user manual. Check the email of whoever placed the order, they should have sent info to that email address. If not, PM me and I can forward the email.

Something that I have been wanting to look more into is what kind of coolant is good for this machine. I have been using a ton of WD-40 manually sprayed for the cause. The spray system that is being suggested seems like a great solution. But I have been interested in potentially a more permanent system involving coolant flooding that is done normally in other machines. The only reason why I haven’t gone for that as an idea is I don’t think the stepper motors are built for it. But I must admit I doubt WD-40 is a good idea either.

What is suggested?

Koolmist is good, and their commonly available stuff is very human safe compared to most alternatives. Highly recommended. Also a gallon of the concentrate lasts forever.

We run that through a Fogbuster and it’s a very nice setup.

Would you mind sharing a picture of your setup? I like the Fogbuster, and seeing other’s setups is extremely helpful!