vigilante398
Authorized Vendor
Looks like he hasn't even logged in for over two years, safe bet that the answer is no.
STICKMAN'S LETS LEARN CNC THREAD
- Thread starter Stickman393
- Start date
Stickman393
Well-known member
IM BACK BITCHES!!!!!
The new setup is something I picked up recently. I've funneled a lot of time Into a 750mmX500mm machine, but that one is gonna take a bit more time to finish up.
I needed something usable and solid for the short term, so I bought an AnoleX 3030. Good little unit. I've got gripes though:
The PSU brick sucks. It wasnt even able to keep up with inrush on the spindle completely unloaded. Would lead to disconnects immediately after starting.
The way this thing handles probing is wonky too. I gotta figure out exactly what's happening, but since the whole machine is conductive I have to electrically isolate the body of the spindle from the rest of the machine. Otherwise, the probe connection closes as soon as I place my leads on the machine.
This little thing is decently solid though. The NEMA 17 motors do an OK job, moreso after I tuned the stepper drivers to run 'em at their full 1.5A rating.
Linear rails on each axis, very little slop. I'm thinking about maybe filling the extrusions with a few carbon fiber bars and resin, plus bolting on a piece of cold rolled steel to the back of the x axis. Would help stiffen this thing up a bit more.
I binned the original spindle too, pulled out my 600 watt model from my previous build. It can competently do 0.1mm passes with a 1/8" bit at 600mm/min.
Workholding is a struggle, though. Enclosures like to vibrate.
Best fucking advice I ever got though? Painters tape and super glue. Holy shit. Wow. Put painters tape on the bed and on your workpiece, spread super glue across the painters tape on the bed, squish it all together. Sold as a goddamned rock.
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Stickman393
Well-known member
Also: I've only used this thing to cut through some 1/2" plywood so far, but I recently picked up a laser engraver as well.
These things have gotten pretty cheap recently. The entire setup including the honeycomb board and air pump cost about 300 dollars. It's got a 10 watt output diode laser.
This gets around a lot of the difficulty with engraving and carving aluminum enclosures. The machine does not need to be nearly as rigid.
Important things to point out about laser engravers:
You're never going to engrave bare aluminum with a commercially available blue diode laser. Not gonna happen.
You can certainly *mark* aluminum. But you're going to need specialty laser marking paint or some dry moly lube to facilitate the process. Aluminum is reflective: it's not going to absorb the energy you're directing at it.
Also: ventilation. Super important. We're burning shit here. Nasty, poisonous fumes.
Lasers should be *perfect* for pre-painted enclosures, as they will burn off the powdercoat quite easily.
I'm currently struggling a little bit with mine: workpiece locating is a PITA. One of the primary advantages with lasers, though, is Lightburn. Seriously. I hear the developers of lightburn are making something for CNC routers, and I cannot wait.
Lightburn allows for webcam integration with accuracy within 1mm. That means you can stream a view of the workbench to your desktop and design directly on the surface of the enclosure. Pretty nifty.
I've got mine setup in the garage right now with a mini PC that I remote into. It's been going...eh...not great. That's primarily because of my wifi connection in the garage though. I've got a new adapter for the PC with a pair of high gain antennas to help with my connectivity issues.
In learning about lasers, there are three commercially available types:
Diode lasers. Cheapest. Typically on a gantry style syste. Anywhere from 5-80watt output. Big jump in cost between 10 to 20 watt. Typically operate in the visible spectrum, cannot directly engrave metals without a coating.
--sub category: infrared 1064nm diode lasers. Top out at 2 watts. About 2.5-3x as expensive as a 10watt laser, but can actually engrave bare aluminum. Slowly. *Very* slowly. So slowly that they're typically marketed for jewelry engraving. Not commercially viable, but certainly doable for DIY on 125b enclosures if you're OK with waiting.
CO2 lasers: dunno much about these. Typically gantry-based as far as I can tell. More expensive, and typically more powerful than diode lasers. Visible spectrum lasers, cannot typically engrave metal without a coating.
Fiber lasers: most expensive. Tend to be stationary with a "galvo" head (uses automated movable mirrors to direct the laser beam into the workpiece). *EXTREMELY* fast working. Tend to work in the 1064nm IR range and be more powerful than diode IR lasers. Some work in the visible range, some cheaper models are quite weak. The galvo head is both a blessing and a curse, as these tend to have the smallest workspace area of the bunch, and larger areas come with an increase in cost. There are some cheaper models that come with a trolley for extending one axis, but this slows down the operation considerably. Still, it might be the only way to pick one up that can do a bunch of different enclosures for under 3K.
--sub category: I've seen split fiber lasers with a gantry module connected to a power supply/laser generator via some cabling. These tend to be much more affordable (some under 1K) and far more powerful than the 2w IR diode laser modules. This seems ideal for DIY, as they pack about 10x the punch of the IR diode. Not as fast as a galvo model, but far more workspace area is opened up. Need to read more.
These things have gotten pretty cheap recently. The entire setup including the honeycomb board and air pump cost about 300 dollars. It's got a 10 watt output diode laser.
This gets around a lot of the difficulty with engraving and carving aluminum enclosures. The machine does not need to be nearly as rigid.
Important things to point out about laser engravers:
You're never going to engrave bare aluminum with a commercially available blue diode laser. Not gonna happen.
You can certainly *mark* aluminum. But you're going to need specialty laser marking paint or some dry moly lube to facilitate the process. Aluminum is reflective: it's not going to absorb the energy you're directing at it.
Also: ventilation. Super important. We're burning shit here. Nasty, poisonous fumes.
Lasers should be *perfect* for pre-painted enclosures, as they will burn off the powdercoat quite easily.
I'm currently struggling a little bit with mine: workpiece locating is a PITA. One of the primary advantages with lasers, though, is Lightburn. Seriously. I hear the developers of lightburn are making something for CNC routers, and I cannot wait.
Lightburn allows for webcam integration with accuracy within 1mm. That means you can stream a view of the workbench to your desktop and design directly on the surface of the enclosure. Pretty nifty.
I've got mine setup in the garage right now with a mini PC that I remote into. It's been going...eh...not great. That's primarily because of my wifi connection in the garage though. I've got a new adapter for the PC with a pair of high gain antennas to help with my connectivity issues.
In learning about lasers, there are three commercially available types:
Diode lasers. Cheapest. Typically on a gantry style syste. Anywhere from 5-80watt output. Big jump in cost between 10 to 20 watt. Typically operate in the visible spectrum, cannot directly engrave metals without a coating.
--sub category: infrared 1064nm diode lasers. Top out at 2 watts. About 2.5-3x as expensive as a 10watt laser, but can actually engrave bare aluminum. Slowly. *Very* slowly. So slowly that they're typically marketed for jewelry engraving. Not commercially viable, but certainly doable for DIY on 125b enclosures if you're OK with waiting.
CO2 lasers: dunno much about these. Typically gantry-based as far as I can tell. More expensive, and typically more powerful than diode lasers. Visible spectrum lasers, cannot typically engrave metal without a coating.
Fiber lasers: most expensive. Tend to be stationary with a "galvo" head (uses automated movable mirrors to direct the laser beam into the workpiece). *EXTREMELY* fast working. Tend to work in the 1064nm IR range and be more powerful than diode IR lasers. Some work in the visible range, some cheaper models are quite weak. The galvo head is both a blessing and a curse, as these tend to have the smallest workspace area of the bunch, and larger areas come with an increase in cost. There are some cheaper models that come with a trolley for extending one axis, but this slows down the operation considerably. Still, it might be the only way to pick one up that can do a bunch of different enclosures for under 3K.
--sub category: I've seen split fiber lasers with a gantry module connected to a power supply/laser generator via some cabling. These tend to be much more affordable (some under 1K) and far more powerful than the 2w IR diode laser modules. This seems ideal for DIY, as they pack about 10x the punch of the IR diode. Not as fast as a galvo model, but far more workspace area is opened up. Need to read more.
vigilante398
Authorized Vendor
Just a couple notes:
I typically deal with workpiece locating on a laser the same way I do with the CNC: jigs. These don't have to be super intricate, but if you're going to do something approximately the same size over and over again (like enclosures) you can mount/tape/glue a right angle piece to designate the corner so it goes in the same place every time. It doesn't have to be as secure as the CNC because nothing is going to touch the enclosure, just needs to land in the same spot , then you can keep a file as a template for that location.
I started with a 5W diode laser then moved to a 40W CO2 laser, and now I'm back to a 30W diode laser. CO2 is neat and can do some things that diodes can't (most notably cutting transparent materials like acrylic; the wavelength of a diode laser will typically pass right through it), but it comes with extra housekeeping like water cooling for the laser tube or, the worst part, mirror alignment. With a CO2 laser you will constantly be adjusting the mirrors to make sure they're aligned. Move the machine to a new room? Mirrors will come out of alignment. Move it a few inches on the bench? Mirrors will come out of alignment. Sneeze too hard next to it? Mirrors will come out of alignment. Proper mirror alignment makes it work the best, but poor alignment can stop it from working at all if your laser beam is hitting somewhere it isn't supposed to.
Anyway, that's all I've got. Welcome back, excited to see more of your adventures with neat machines.
Stickman393
Well-known member
Little preview of what I've got coming up.
I've found my workflow works best like this:
Start with CNCJS. Use my spark concepts hole probe to locate XYZ zero. CNCJS is neat, because it uses its own sort of modified gcode language that allows for the computer to automatically perform certain calculations on the fly. What that means is that you can use a single command to do a whole lotta stuff.
The problem? Well, it's development has slowed to a crawl in recent years, and it never implemented height mapping. Which, for the kind of engraving I do, is absolutely necessary.
So, I manually move the machine back to 0,0,0, and exit CNCJS. Then I open open CNC pilot.
From there, I heightmap, apply to gcode, and let er rip.
I've found my workflow works best like this:
Start with CNCJS. Use my spark concepts hole probe to locate XYZ zero. CNCJS is neat, because it uses its own sort of modified gcode language that allows for the computer to automatically perform certain calculations on the fly. What that means is that you can use a single command to do a whole lotta stuff.
The problem? Well, it's development has slowed to a crawl in recent years, and it never implemented height mapping. Which, for the kind of engraving I do, is absolutely necessary.
So, I manually move the machine back to 0,0,0, and exit CNCJS. Then I open open CNC pilot.
From there, I heightmap, apply to gcode, and let er rip.
Stickman393
Well-known member
Another new update:
I'm ditching my 600 watt BLDC spindle.
Why? Cause it's garbage. Holy crap.
I ended up throwing my mikita palm router onto a clamp that's made for it, and wowza. Jesus man. Game over. My o-flute bits are just tearing through material at 1500mm/minute.
Granted, it's "1.25hp", which is a hair less than a thousand watts. So some improvement is to be expected. Also, 30k RPM vs 9k RPM.
Which is why I was hesitant to swap em. Power is divisible by speed and torque: and increase in one at the same HP requires a proportional reduction in the other. I was concerned that, even with the increase in wattage, the math works out to a decrease in torque.
No need to worry it seems. Should have done this a long time ago.
Gripes? Fuck yeah. I got em.
My biggest gripe is the collet on the Makita router. These things aren't quite as precise as spindles. I would kill for an ER11 collet on this thing. As it stands I have to use a 1/4" collet with a 1/8" adapter that fits fairly loose and makes installing bits a PITA.
There are alternatives online. Unfortunately it looks like the genmitsu version with the ER11 collet is only around 1HP. Pricks.
Also: it doesn't interface with my controller. Gotta adjust speed and do on/off manually. Oh well.
I'm ditching my 600 watt BLDC spindle.
Why? Cause it's garbage. Holy crap.
I ended up throwing my mikita palm router onto a clamp that's made for it, and wowza. Jesus man. Game over. My o-flute bits are just tearing through material at 1500mm/minute.
Granted, it's "1.25hp", which is a hair less than a thousand watts. So some improvement is to be expected. Also, 30k RPM vs 9k RPM.
Which is why I was hesitant to swap em. Power is divisible by speed and torque: and increase in one at the same HP requires a proportional reduction in the other. I was concerned that, even with the increase in wattage, the math works out to a decrease in torque.
No need to worry it seems. Should have done this a long time ago.
Gripes? Fuck yeah. I got em.
My biggest gripe is the collet on the Makita router. These things aren't quite as precise as spindles. I would kill for an ER11 collet on this thing. As it stands I have to use a 1/4" collet with a 1/8" adapter that fits fairly loose and makes installing bits a PITA.
There are alternatives online. Unfortunately it looks like the genmitsu version with the ER11 collet is only around 1HP. Pricks.
Also: it doesn't interface with my controller. Gotta adjust speed and do on/off manually. Oh well.
Stickman393
Well-known member
Five wah tread plates. Total of 15 minutes of CNC time.
I grabbed an "er-11 extension" with an 8mm shaft off Amazon. It was way too long, but my portaband made short work of the extra length. That's plugged into the 8mm collet on my Makita, and viola. Now I have access to far more options in terms of bit sizes.
Now, I can hit 1500+ mm a minute at 1.25mm depth of cut. That's with an O flute 1/8" end mill. Wow. My previous spindle couldn't even handle 0.1mm depth of cut at 500mm a minute.
And not only does it cut faster...it leaves a cleaner finish. Jeeeze.
Weird, weird, weird. Not sure why. Something tells me that the spindle wasn't really getting the full 600 watts from my PSU. I wanted to put an ammeter on the enclosure for the longest time...now I don't ever wanna go back to the old spindle.
Edit: photo with my ER11 extension:
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Stickman393
Well-known member
Well...balls.
Things were going well. A little too well.
First thing: my Makita router developed a loose speed wheel. Drifts from 6 to 5 on its own. Not a big deal, easy to tighten up with some sticky backed foam...but...
That also led me to realize that, ah fuck, my bearings are shot. Them fuckers be making all kinds of noise and rattling the shit out of the router.
Guess I was going too deep on each cut. The extra leverage from the ER11 extension collet probably sealed the deal.
Got replacement bearings on the way now. Got my eyes drifting to those snazzy 1.5-2.2KW vfd spindles though...
Things were going well. A little too well.
First thing: my Makita router developed a loose speed wheel. Drifts from 6 to 5 on its own. Not a big deal, easy to tighten up with some sticky backed foam...but...
That also led me to realize that, ah fuck, my bearings are shot. Them fuckers be making all kinds of noise and rattling the shit out of the router.
Guess I was going too deep on each cut. The extra leverage from the ER11 extension collet probably sealed the deal.
Got replacement bearings on the way now. Got my eyes drifting to those snazzy 1.5-2.2KW vfd spindles though...
Nostradoomus
Well-known member
I'm kinda glad someone else went thru the trouble of doing this all. I had this thought a few years ago before I bought a laser.
Still following though and I know you'll find something that works eventually
Still following though and I know you'll find something that works eventually
Or just get really quick at swapping bearingsI'm kinda glad someone else went thru the trouble of doing this all. I had this thought a few years ago before I bought a laser.
Still following though and I know you'll find something that works eventually
Nostradoomus
Well-known member
vigilante398
Authorized Vendor
My 2.2kW vfd spindle is pretty neat. I don't do anything super crazy with it though, and I'm always super conservative with speeds and feeds to reduce wear and tear on the spindle motor and on the my bits.
Stickman393
Well-known member
I'm kinda glad someone else went thru the trouble of doing this all. I had this thought a few years ago before I bought a laser.
Still following though and I know you'll find something that works eventually
A good fiber laser is on my list once I get this thing tuned a bit better.
I'm just too lazy to go about this business of hole drilling. Like...I kinda want to set up a means to automatically position my enclosures on an XY table on my drill press for top-mounted jacks.
Because I ams a laziness chasers.
Man, I'll tell you what. I do a 15HP three phase motor bearing change lickity split. I'll even throw in a pump seal replacement. No leaks.
Granted...my bearing pullers are...ah...considerably larger than these. I'll probably just have to make a jig.
For sure! Right now I'm just gonna swap the bearings as I need to focus on paying down some ah...bills that have gotten out of control because I've been purposefully avoiding confronting them due to my recent underemployment.
I'm leaning towards a 2HP/1.5KW...simply because with the 115v that I have readily available in my garage that's *about* what I can safety run on the circuit. There's a freezer in there as well: taking power factor into account, I'm liable to pop a breaker if that thing starts and pulls LRA while I'm in the middle of a heavy cut with a 3Hp/2.2kw spindle.
Though I'm more than capable of running a new, dedicated 240V 20 amp circuit into the garage. Which would unlock a whole bunch of possibilities. Hmmm...
For pedals: 1.5kw seems like it would be sufficient. I'd like to eventually do some work with cold rolled steel too: some DIY single-string bridges that I can use premade steel/brass/graphite saddles with. Wilkinson-style saddles only require a flat plate to mount on, after all.
steviejr92
Authorized Vendor
I went with a 1.5kw spindle for those same reasons. No matter what spindle you go with (1.5kw or 2.2kw) you’re going to have to baby the jobs. It’s the high speed operation of these spindles that don’t have the torque needed to make proper cuts in metal. If you look at the Mr1 it has a 2.5kw spindle but it tops out at 8000rpm and can hog through material like butter.
What I’m trying to say is at 1.5kw it can certainly be done but don’t expect a fast job when cutting metals.
Reading your earlier posts. You’re way too aggressive with your depth of cuts. Limit it to .25mm max and a smaller dia end mill. Remember horse power is directly related to depth of cut and dia of end mill. 3mm end mill is perfect for most jobs even contouring. Stick to single flute end mills and you won’t have a problem. If you want to do a perfect pass and clean up any material slow the feed rate and use 2 or more flute end mill cutters.
It’s cool seeing your progress keep it up!
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Stickman393
Well-known member
Appreciate the input!
I was definitely getting a bit too aggressive with my cuts. I'm it's odd, though: I had grown accustomed to hearing some very, very loud screeching and awful vibrations when making cuts with my old 600 watt spindle. That was with an O flute, 9k RPM, a little under 500mm/a and 0.1mm DOC. I had been listening for some kind of indication that the spindle itself was getting bogged down, but i can only presume that I was mistaking or missing the signs.
The Makita did not seem to have any issues at all while I was cutting at 0.75mm DOC, 30KRPM, 1520MM/S. Cuts were clean, no strange noises, chips flying like confetti.
BUT: the bearings. Looking at the parts breakdown: This is a two bearing device, which is clearly a bit underbuilt for what I was asking it to do.
Makes sense. Trim routers are meant to be portable, relatively light duty devices that get pulled out, round over a corner, flush up a countertop edge, and set down. I imagine they aren't designed for the kind of duty cycle that folks subject them to in a CNC setup: since I started using it, I've seen some horror stories about these things lighting themselves on fire while using a surfacing bit.
I'm a bit surprised to hear that the 2.2KW spindle can only handle a 0.25mm cut, honestly. It's entirely possible that I was simply running mine far beyond it's long term capabilities, and I'm just lucky the bearings went out before the coils.
I caught sight of a square-mount 1.5kw spindle on AliExpress that tops out around 6krpm. Would be a killer with a triple flute end mill, even with my low end 0.002" chip load. 3 bills, though. Pretty much for any decent four-bearing spindle + VFD.
Gonna have to try to squeeze a little more life out of this trim router.
steviejr92
Authorized Vendor
A lot of that comes down to technique as well. You can drive the end mill all the way through the material but you would have to go incredibly slow to allow the cutter to do its job. I prefer shallow depth of cuts and high feed rates.
For instance for aluminum cutting I go 1600mm/min but only .15mm depth of cut. I get very nice cuts this way. Something to consider as well is the actual tool. Make sure to use nothing but the best tooling. I shop at Datron and have only used their tooling and have never had a problem other than anything that has to do with user error. They’re expensive but again the best IMO.
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Stickman393
Well-known member
^ great info. Many thanks!
This has got me thinking a little bit: I wonder what the design of these motors is like.
Knowing what I know about 3 phase motors: a two pole AC induction motor is rated at 3600RPM, but that is of course an idealized number. Since induction motors are asynchronous (always chasing the next pole) two pole motors tend to run around 3.4kRPM or so
So: a little math is in order methinks. Many spindles I've seen have been rated up to 400hz, which is roughly 6.66 times 60hz and fucking br00tal.
Thus a two pole AC induction motor running at 400hz has a theoretical idea speed of 24,000RPM. This is pretty well in line with the published specs of many manufacturers.
So...anything with those specs, it seems, is likely a three phase two pole AC induction motor. Or some kind of permanent magnet motor. It is also likely not representative of the actual speed achieved, due to the asynchronous nature of the motor.
The thing about two pole motors is that each shift of the magnetic field is responsible for close to 1/2 of a rotation. Four pole motors are incredibly common (1800 RPM nominal). One of those should be about 12k RPM at 400hz. I wonder why we don't see those as often.
This has got me thinking a little bit: I wonder what the design of these motors is like.
Knowing what I know about 3 phase motors: a two pole AC induction motor is rated at 3600RPM, but that is of course an idealized number. Since induction motors are asynchronous (always chasing the next pole) two pole motors tend to run around 3.4kRPM or so
So: a little math is in order methinks. Many spindles I've seen have been rated up to 400hz, which is roughly 6.66 times 60hz and fucking br00tal.
Thus a two pole AC induction motor running at 400hz has a theoretical idea speed of 24,000RPM. This is pretty well in line with the published specs of many manufacturers.
So...anything with those specs, it seems, is likely a three phase two pole AC induction motor. Or some kind of permanent magnet motor. It is also likely not representative of the actual speed achieved, due to the asynchronous nature of the motor.
The thing about two pole motors is that each shift of the magnetic field is responsible for close to 1/2 of a rotation. Four pole motors are incredibly common (1800 RPM nominal). One of those should be about 12k RPM at 400hz. I wonder why we don't see those as often.
Stickman393
Well-known member
Another wah pedal base.
I've decided that if I'm going to be going through the process of changing bearings on a router, I should have a backup on hand.
Thus: the genmitsu. It appears on paper to be less powerful than the Makita, but it's certainly using more modern tech. Permanent magnets. It's only rated up to 1hp vs the Makita's 1.25hp. But! It also has the ER-11 collet.
First pass, 1526mm/s, 0.1mm depth of cut, 0.05mm chip load per revolution, 30,000rpm, 3.175mm 0 flute end mill. Not even breaking a sweat. Finishes are quite good, only needs a light deburring of the edges.
I'm gonna stick a power meter on this thing and see how deep I can get before I top out around 1HP, then I'm gonna roll it back a bit.
The dust collection is woefully underpowered. That's gonna be my next upgrade. I figure...swap spindles if I kill em. If the bearings go out, replace the bearings. I should be able to make em last a bit longer if I monitor their current draw.
Eventually I'll get a more powerful spindle. For now, this'll do.
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Stickman393
Well-known member
So, AliExpress has some interesting options for low-speed spindles that are reasonably priced.
Getting anything in the US that does under 24,000RPM at or above 2hp is near impossible, unless one is willing to spend over a kilobuck. Which I am in no position to do on anything at the moment.
As @steviejr92 said, torque and speed are inversely proportional. They are both expressions of energy (which, as we know from the first law of thermodynamics: energy cannot be created or destroyed, but it can be transformed).
Electrical energy (power, defined as KW or HP) applied to an electric motor an be converted into speed (RPMS), rotational force (torque), and heat (generated by the friction).
Generally, we want that last bit to be as small of a piece or the pie as possible, but some of the input will always be "lost" to heat.
VFD driven CNC spindles, in their simplest form, are 3 phase, two pole motors. This means that they are driven by three separate conductors that transfer three different voltage and amperage sine waves to the motor. Each sine wave is about 120⁰ out of phase with each other.
What does that mean? Well, simply that about a third of the way through one sine wave's cycle, a second one "starts". Two thirds of the way through the first sine wave's cycle, the third sine wave "starts".
A picture will help here:
These waves are generated by passing massive magnets over iron cores wrapped in copper. Not entirely dissimilar from how guitar pickups work.
As I've looked into spindles more and more here, Im willing to venture a guess that the reason we don't see more 4 pole spindles is because they're a bit more difficult to fit into a small form factor needed for hobby CNC. Here's a photo of the inner workings:
This also serves as a great illustration as to *why* a four pole motor provides more torque than a 2 pole motor. As I had said before, every complete shift from "North" to "South" of the poles accounts for one half of one rotation. This is represented by one of the sine waves above going from "minimum" to "maximum". Another complete shift, going from "maximum" to "minimum" completes the rotation.
Thus, speed can be controlled on these motors by adjusting the *frequency* of pole shifts. For a long time we were stuck with whatever the local utility provided for our base motor speed: 60hz applied to a two pole motor would yeild a "nominal" 3600RPM motor (60 cycles per second X 60 seconds in a minute = 3600). For folks with 50hz distribution that would be 3Krpm.
We used pulleys and gears to achieve different shaft speeds in the past, but VFDs have allowed us to rectify that 60hz power and re-assemble a sine wave using pulse width modulation.
The sine waves generated are generally not perfect. But they have gotten much better in recent years. This is a very rudimentary version of how this ends up working:
The upshot here is that by pulsing voltage at variable widths to the motor, the current waveform is re-assembled and can drive the movie at a lower *or* higher frequency. (Above, red equals voltage. Black equals current)
I work extensively with VFDs during my day job as a commercial HVAC mechanic. They're great bits of tech. They enable all kinds of control strategies for saving energy, and have enabled newer strategies for delivering large volumes of air to buildings (like fan walls).
There is an issue, though: a motor can only dissipate so much power. If we run over that amount, the motor begins to heat up and will eventually fail. You can typically squeeze a bit more power out of a motor running at a higher HZ, but that is entirely dependent on the motor design, bearings, and torque applied.
This, I come back to this photo:
As you see, four pole motors are divided into quadrants. Every shift of the sine wave from low to high translates to one *quarter* of a rotation. Two full sine wave cycles are required for a single rotation, which means that the following equation is used to determine the motor speed:
(Hz X [# of poles/2]) X 60=nominal RPM.
Say you have two motors, both rated for the same HP. But, one is a two pole, and one is a four pole.
The four pole motor is only traveling half the distance per sine wave cycle, it is rotating at a lower speed, but *at a higher torque*. A higher torque because the rotor is *closer* to the magnetic field of it's destination, and magnetism is a highly distance-dependent force.
Why are there so few four pole spindles out there? Probably size constraints. As one can see in the photo above, the 4 pole motor has more windings crammed into the same space. There are options, though, even down to 6K rpm @ 400hz available on AliExpress, but it seems all those options are for 220v.
Anywho, hopefully this has been an educational post. And hopefully I didn't get too much of that wrong. Hey, I'm just an HVAC mechanic.
Getting anything in the US that does under 24,000RPM at or above 2hp is near impossible, unless one is willing to spend over a kilobuck. Which I am in no position to do on anything at the moment.
As @steviejr92 said, torque and speed are inversely proportional. They are both expressions of energy (which, as we know from the first law of thermodynamics: energy cannot be created or destroyed, but it can be transformed).
Electrical energy (power, defined as KW or HP) applied to an electric motor an be converted into speed (RPMS), rotational force (torque), and heat (generated by the friction).
Generally, we want that last bit to be as small of a piece or the pie as possible, but some of the input will always be "lost" to heat.
VFD driven CNC spindles, in their simplest form, are 3 phase, two pole motors. This means that they are driven by three separate conductors that transfer three different voltage and amperage sine waves to the motor. Each sine wave is about 120⁰ out of phase with each other.
What does that mean? Well, simply that about a third of the way through one sine wave's cycle, a second one "starts". Two thirds of the way through the first sine wave's cycle, the third sine wave "starts".
A picture will help here:
These waves are generated by passing massive magnets over iron cores wrapped in copper. Not entirely dissimilar from how guitar pickups work.
As I've looked into spindles more and more here, Im willing to venture a guess that the reason we don't see more 4 pole spindles is because they're a bit more difficult to fit into a small form factor needed for hobby CNC. Here's a photo of the inner workings:
This also serves as a great illustration as to *why* a four pole motor provides more torque than a 2 pole motor. As I had said before, every complete shift from "North" to "South" of the poles accounts for one half of one rotation. This is represented by one of the sine waves above going from "minimum" to "maximum". Another complete shift, going from "maximum" to "minimum" completes the rotation.
Thus, speed can be controlled on these motors by adjusting the *frequency* of pole shifts. For a long time we were stuck with whatever the local utility provided for our base motor speed: 60hz applied to a two pole motor would yeild a "nominal" 3600RPM motor (60 cycles per second X 60 seconds in a minute = 3600). For folks with 50hz distribution that would be 3Krpm.
We used pulleys and gears to achieve different shaft speeds in the past, but VFDs have allowed us to rectify that 60hz power and re-assemble a sine wave using pulse width modulation.
The sine waves generated are generally not perfect. But they have gotten much better in recent years. This is a very rudimentary version of how this ends up working:
The upshot here is that by pulsing voltage at variable widths to the motor, the current waveform is re-assembled and can drive the movie at a lower *or* higher frequency. (Above, red equals voltage. Black equals current)
I work extensively with VFDs during my day job as a commercial HVAC mechanic. They're great bits of tech. They enable all kinds of control strategies for saving energy, and have enabled newer strategies for delivering large volumes of air to buildings (like fan walls).
There is an issue, though: a motor can only dissipate so much power. If we run over that amount, the motor begins to heat up and will eventually fail. You can typically squeeze a bit more power out of a motor running at a higher HZ, but that is entirely dependent on the motor design, bearings, and torque applied.
This, I come back to this photo:
As you see, four pole motors are divided into quadrants. Every shift of the sine wave from low to high translates to one *quarter* of a rotation. Two full sine wave cycles are required for a single rotation, which means that the following equation is used to determine the motor speed:
(Hz X [# of poles/2]) X 60=nominal RPM.
Say you have two motors, both rated for the same HP. But, one is a two pole, and one is a four pole.
The four pole motor is only traveling half the distance per sine wave cycle, it is rotating at a lower speed, but *at a higher torque*. A higher torque because the rotor is *closer* to the magnetic field of it's destination, and magnetism is a highly distance-dependent force.
Why are there so few four pole spindles out there? Probably size constraints. As one can see in the photo above, the 4 pole motor has more windings crammed into the same space. There are options, though, even down to 6K rpm @ 400hz available on AliExpress, but it seems all those options are for 220v.
Anywho, hopefully this has been an educational post. And hopefully I didn't get too much of that wrong. Hey, I'm just an HVAC mechanic.
@Stickman393
Came across these when googling a week ago after your router failure.
They have a handful of decently priced 110V but it seems water cooling is needed for any decent power.
Do you have a hot water heater you could branch off? Just turn it off when milling...
As long as it's not shower time, no one will notice.
Came across these when googling a week ago after your router failure.
They have a handful of decently priced 110V but it seems water cooling is needed for any decent power.
Do you have a hot water heater you could branch off? Just turn it off when milling...
As long as it's not shower time, no one will notice.
