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Are any of you knowledgeable about brushless DC motors? This site has some interesting motors that look like they might be a good physical fit on an X2 mill as an upgraded spindle motor.
http://goldenmotor.com//
Look under "brushless motors". It seems that the 500 to 1000 watt motors might work great if an appropriate controller/power source could be sourced. Or, would the OEM power controller work?
Please share your thoughts.
Bill
A gentleman over on RCGroups has done just that, although he used a large RC airplane motor ( and I believe he uses a rc brushless motor controller to run it.
I'll try and find a link to it
found it, using it on his taig
http://www.rcgroups.com/forums/showt...highlight=mill
another guy mentions using the bike motor on his taig, seems to be good way to go.
Most people think I'm nuts, but I have been a fan of taking this tack for a while now. Motors are cheap, controllers are also cheap and easy. Controllers aren't your problem - the only real difficulty is a power supply.
Finding a 24v - 36v power supply that will deliver the 25, 30, or even 50 amps or more needed to drive a decently sized motor can be prohibitively expensive unless you scrounge for a surplus find. They are physically larger than the ones you might be used to, and you may need to put them on their own breaker if they are large enough, especially into the 1500w range. They do appear regularly though, and cheaply, just not in large numbers. Keep your eyes open and be patient and deals do appear though.
For cheap controllers you can check out Ebay under "scooter controller" or the like, and you will find a great number of cheap chinese BLDC controllers for electric scooters and wheelchairs and golf carts and such. Most are really self-explanatory to hook up, too - two power leads, three "throttle" (speed control pot. or hall effect sensor) leads, and leads that output to your motor. Sometimes they will have will have extra leads like "brake" or "kill switch" (e-stop if you like!) wires, and sometimes extra superfluous turn signal and brake light leads that can just be ignored.
Don't know how they will do for long-term durability yet, as they are obviously of really low-grade manufacture even for Chinese electronics, but they are really dirt cheap and I haven't had one fail yet in my time messing with them as spindle controllers.
Something like this is just one of dozens of options - http://www.tncscooters.com/YK42-3.php - its a 36v BLDC controller that will drive a 1HP spindle motor for under 30 bucks. This one uses a hall-effect sensor for a speed control, which means that Mach can be used to control speed pretty easily through a Digispeed or similar common methods that vary voltage (0-5v).
Also, in my experience stay away from R/C controllers. Tried it. Not only do they use a complex and really strange protocol of signal pulses that makes them essentially unusable in practice for what we need, they are usually kind of frail and not designed for any real heat dissipation. In R/C use they just don't see severe peak current draws for long periods of high torque loads, and they are designed to be as light as possible for obvious reasons. Just not the droids you're looking for.
Last edited by Stepper Monkey; 04-21-2008 at 10:15 PM.
Could a 36/48 volt golf cart battery charger be used? they are usually 20 amps or more.
The link you showed appeared to indicate that the motors over 500w were the high voltage kind, 300v+. Which is more practical.Originally Posted by bilinghm
I have used both AC and DC servo motors for spindle motors and tend to use 120dc~230vdc types, this way it is relatively easier to find/build a DC power supply from a standard isolation transformer, but for 1 to 2kw motor they are still large.
For drives, I use Advanced Motion.
Other than that, a 220v 3 phase motor can be used with a VFD off 220 1ph.
Al.
CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
So what do you guys think of this motor? It is a brushless 24 volt DC described as either 300 or 400 watt depending on where you look. It is manufactured by Kolmorgen for use on electric bikes and scooters. The size is 5" in diameter and 3.5 " thick and about 5 pounds weight. It seems that this motor paired with a 24 volt 25 amp power supply would do a good job running an X2 spindle. See any problems before I buy?
They make both 300 and 400 watt versions, and versions for both fixed rotation directions. Luckily the rotation direction we want are the cheap ones, as they go on the wrong side for bicycle conversions. The other direction is more than twice the cost for that reason alone, if you are wondering why different part numbers sell for such different prices. They have the PWM controller built right in, just add power.
You just discovered one of my secrets. I buy the 400 watt motors by the case for spindle drives from a guy that is sitting on a warehouse of them from a canceled order. They have no nameplates, but are Kollmorgen motors, and the cases have Danaher Motion labels and seals on them. They are made in India, but I wouldn't have guessed it by the rather nice build quality. They work great - light and quiet. Being designed to directly drive a scooter they have plenty of torque and sturdy bearings. Add power supply and a 5k pot and go, and/or wire it up to Mach for speed control that way.
Only major hangup is that the drive stub is very short, and stepped. It's two different diameters, and both in metric. That and it really is a stub - it only projects about a half an inch. Impossible to put much on it that way, I have to use specially built shaft extender/adapters that are turned out to match the stepped shaft and bring it up to a standard shaft size for pulleys. You could make one yourself if you have a lathe and a lot of patience, it is pretty straightforward but they are kind of a distinct pain in the butt to get right the first time as you have so little space to work with, and have to cross-drill it for a roll or taper pin to secure it properly. Otherwise, PM me and I will send you one of my adapters or just a sell you a whole motor with the shaft extension already pinned on and ready to go if you want to try one. I only have about 6 or 8 extras in stock right now, I usually don't keep more than I need for myself. I guess if people are really interested I could make up a batch of them for the folks on here if there is much interest, or send samples out of the shaft adapter mod if someone else wants to make them for sale - I really don't have the time or interest.
Biggest problem I see is the lack of 25 amp supplies, that might be the biggest damp to interest. However, they are designed to tolerate being driven from batteries that vary in voltage radically in scooter usage, so they are tolerant of power supplies much less stable than required for our CNC drives. Maybe one of the power supply gurus on here could come up with a really cheap and not-so-stable supply that fits this bill. If they can, I have a feeling all of us will be using these things in a year. They kick ass.
Last edited by Stepper Monkey; 04-24-2008 at 11:08 AM.
400 watts equals (.54) roughly half of a horsepower
Walking is highly over-rated
I would think you may run into disappointment, if you are replacing a 3/4hp ~(550w) spindle motor, generally the tendency is to go slightly larger.
If someone has already tried it and it worked out OK, go for it.
The down side to the cheap low voltage motors is the fact it is offset by high P.S. price, i.e. transformers with low voltage/high current secondaries.
If the right VA toroidal transformer can be obtained, and the secondary removed, a low voltage large gauge secondary could be wound on, for 24v you would only need around 32 turns but around 6awg circular or square section copper conductor.
But also the Large value electrolytics are expensive.
Al.
CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Everything that I have seen says that the OEM X2 motor is only 350 watts. They say 4/5 HP, but I don't understand their rating. I figure that 400 watts from a quality brushless motor (one that is capable of powering a bike and rider to 15-18 MPH), will have more torque and power than the stocker. Am I missing something?
Their site shows 4/5hp which is 596w by my estimation. Which is more than 3/4hp!
It depends on how accurate their HP assessment of the original motor is?
When powering a bike, I assume there is gearing involved?
To do an accurate comparison, the drive train system would have to be known. No?
Al.
CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Al, Good point on the gearing issue, but about watts, see the compairison chart on the little machine shop site:
http://littlemachineshop.com/Info/minimill_compare.php
They list all the variations of the X2 style machines, each has the same wattage rating on the motor: 350, but the stated HP goes from 4/5 HP for Harbor Freight, to 3/4HP for Grizzly, and .47 HP for Micro Mark. Little Machine Shop sells the replacement motor that fits them all, and it is rated 350 watts. Is there a 550 watt replacement motor out there for the X2?
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