Glad to see you back at it. So the shoulder has healed somewhat?
The motor baseplate is steel that you've fab'd up? I'm always more surprised I can weld to old mystery metal than not. So the idea is the motor goes in between the 4 angles and then you're going to use like a hose clamp around them to clamp the motor in place? Should work, might even act like cooling fins if you can somehow get some airflow in there.
thanks for the concern, my shoulder is more tolerable now. I am trying to just use my left arm rather than the injured right.Originally Posted by C-Bag
the base plates are steel where there once was the old motors cast iron. exactly right about the angle and motor fitment. the motor slides in between the angle but instead of a hose clamp I am thinking about using 4 long bolts. tacking an unthreaded sleeve and a nut to each piece of angle then threading the bolts through to apply tension to the ends of the angle. i am going to add two sections of plate between the angle to use the treadmills mounting bolt holes. it's not what I was thinking during planning but hopefully this will do the trick.
for cooling I found a small rounded caged metal fan. it is about 4 inches around and looks sort of like the one below
I am thinking about cutting a round hole on the underside of the old motors housing and fitting the above fan inside. then facing the fan so it blows cool air in. or maybe it would be better to have it pull air out?
The treadmill motors I have, have fans on both ends that slip onto the shaft. I have more than enough shaft on either end to have the gear on one end and maybe enough to stick out of the old housing on the other end to mount the little fan to blow through the casting. Of course you'd need to do like you talked about to hole saw a hole or two in the side of the old case so the air could flow. BTW lots of these mill motors are totally sealed so there would be no worry about dust getting inside. The other bigger nicer motor has some perforations in the rear cover and vents at both end for air circulation. But when I think about the stuff my grinders pick up and blow through them and still keep on chuggin', makes you go hmmm?
I know what you mean about the grinders. the 7 inch ones I had cut every thing from concrete to stripped rust/paint/bondo, even wood. I think the only thing that was wrong with it was the bearings wore down.
the motor I am using is the later of the two you described (I have one of each). it is the one with slots for air in the castings. length wise the mill motor is almost the same as the one it replaces just much narrower in diameter. with the motor I am using being the better style I want to prolong its life if possible. it was free from craigslist with the rest of the mill so if it doesn't last its not a huge disaster. I would rather have as much power as I can get with the bandsaw. they are considered underpowered with 1/2 hp motors the saws came with.
There is so much to learn here. I have no idea what "treadmill rating" means in the real world. So it will be interesting to see if the new motor you have has more hp as the old one. And how being stuck with the gear ratio you have is going to work out. I'm so busy/ lazy and slow at my projects I tend to only go for the sure thing. And if an experiment doesn't work it seems more a major problem for me than the other folks on here.
The next great frontier is going to be the motor controller and how you adapt it.
The "black box" I got works, but I've not got it and the motor installed yet. I need to figure out if it's really spinning my motor to it's full potential. I don't think it is, but I need figure out a tach and maybe hook a ammeter to it. The voltage is within the motor's spec, but I think my motor can draw more amps than this controller is able to. The other major concern for me is a subject we've hit on. This mill was really dirty and I don't know if it was left outside or just used in a really dusty place.
I wonder if anybody has any insight into using spray electrical cleaner to clean off the boards on my old controller that was working when I bought my mill?
I hope I'm not hyjacking your thread jere, I'm hoping to see if we can add some more experience with mill controllers and motors.
jere (Sep 4, 2015)
C-Bag: I've always used CRC products for board and contacts. Amazon and even HFT has them now...environmentally safe too.I wonder if anybody has any insight into using spray electrical cleaner to clean off the boards on my old controller that was working when I bought my mill?
Jere: Glad your RC is doing better! Takes a while (done both of mine a couple of times now) and was taught by a rehab guy to use 5lb dumbbells and raise them slowly from the sides to horizontal then down again, then up at about 45º in front, down, then up straight out then down again...rinse repeat for about 10 or more reps...as much as you can stand...then rest them at least 2-3 hrs. Couple of times a day and works for me in a week or so to be back to the grind or bandsaw...in your case.
Looks good so far on your build but still recommend going to Lithium White Grease on the gears...then the seal isn't as critical and less likely to seep into the motor.
Have you bench run your new motor with the controller? Thinking I might leave that transformer/coil in there to clean the pulses. Power is Power (1hp=~750W), AC or DC...to me it's the torque associated for all the drive mechanisms and what's available in Amps from the controller that's available to windings/frame size of the motor. The controller quality/match to the motor is Key for your application. Theoretically based on what you've shown here it should be better than the original 1/2HP motor by a good margin. Look forward to your progress!! ~PJI would rather have as much power as I can get with the bandsaw. they are considered underpowered with 1/2 hp motors the saws came with.
‘‘Always do right. This will gratify some people and astonish the rest.’’
Mark Twain
jere (Sep 4, 2015)
Ahh, Master Wizard, much thanks! The local hardware store does indeed have CNC contact cleaner so next time I'm down there I'll pick up a can.
Glad you've rejoined us. My expertise was long ago exhausted. I think I more than Jere could use someone more qualified in the mystic arts of the electron.
I thought that I would comment on the phrase "treadmill rating". The horsepower rating on a treadmill motor is the hp at a certain rpm. If the treadmill motor is rated at 3 hp at 7000 rpm, than any lesser rpm would produce a lesser hp. Some of the treadmill motors state on the placard that 100% duty cycle is only valid with a fan. Most are rated without the fan at 60% full power without a fan. Most have a thermal switch, so if it exceeds the heat, it shuts down. I don't think, on a bandsaw, one would have to worry about the rating. To get the most power available, I have found that using the stock small pulley that comes with the treadmill motor will give you the most power, in any given configuration. Bob.
So there's the crux of the biscuit. Both my motors say nothing about fans but one says its 100% duty cycle is lower than its max hp rating and lists its rpm at 2500. The other is different. This all reminds me of what we had to go through trying to interpret stereo amplifier specs back in the day. One outfit would use peak and others would use rms. The peak was meant to catch those that were not looking close or didn't know what peak vs rms meant.
So it would seem these mill motors derive their hp from high rpm, which in the case of Jere's bandsaw might end up no bueno. The drive gear looks pretty big and there's no messing around ratios with that like you can with a belt. And the motor has to spin higher than original motor to get its hp. Good thing there's a speed control
Well said Bob! HP and torque curves are just that, based on RPM and other factors...the key is they are curves! The controller PWM or otherwise will try to compensate for the changes in load and speed with current and voltage via frequency/duty cycle. DC motors also must compensate for the hysteresis of the magnetic field, which will also affect the torque at lower rpm than rated.
This all brings up another point I missed about what the original motor speed was (?) for the gear ratio it has, to achieve an optimum SFM. Over all I still think this motor/controller will serve fine as Bob does...but might take a hard look at that gear ratio to old motor spec, as to whether you continue with the gears or move to a pulley system. For instance if the old motor was 1725RPM and a 10:1 gear ratio puts the SMF at ~3k for wood, then operating your DC motor/controller around that 1725RPM value if its rated at 7k RPM, will put it at the lower end (lower duty cycle) of the rated output which will put more pressure on the controller/motor and result in more heat dissipation and likely less power. Not sure what kind of ratio the treadmill had originally but likely to have been a hi ratio to spin the belt so as to not flip people into the ditch. Maybe this is a mountain out of mole hill but thought it worth consideration from the armchair. ~PJ
‘‘Always do right. This will gratify some people and astonish the rest.’’
Mark Twain
jere (Sep 4, 2015)
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