Big Score today almost a knife maker

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Ryan J

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Jul 14, 2014
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Wanted to post this here where people will understand my excitement. I also have one question Ill put at the end. Today I got a free weslo dl40!treadmill! 2hp continuos, 6100 rpm. Ill get a belt speed of 3149 fpm with a 2" drive pulley. Which should be perfect because I'm using abec 11 skateboard wheels for idlers so Ill use one for a drive pulley and wont need to buy one. Ill figure out a way to make it work. Thread the motor shaft maybe. I've done a ton of research on building 2x72 grinders. This forum has been invaluable for finding info. The treadmill has almost everything I need already. A half sheet of 3/4 particle board to build a box to keep the electronics clean and free of metal shavings, and the whole thing is steel. There's enough tube steel to build two grinders. Got it all torn apart tonight and ready for when the wheels get here. I'm just going to have a flat platen for now. The treadmill had detachable legs of 1 1/2 tube steel and end was crimped to fit inside the other perfectly and threaded for a set screw. It will make a perfect platen holder and since there are two I can use the other to have an interchangeable contact wheel later on when I can afford one. I also wanted to say I know the motor is open frame and needs to be protected. I'm building a box for it to with two filtered holes with dc computer fans blowing through it.
Anyway thats enough rambling. I'm so happy it'll be hard to sleep tonight. So to the question. I know that some people who have taken this approach hit a snag. The flywheel has a tach monitor that tells the computer how fast its spinning. Most just leave the flywheel. On mine the sensor is on the tread belt pulley. From what I understand it wont function without this sensor. Anybody think of a workaround for this? If I had to I could mount the pulley by the motor. But that means having a useless wheel spinning with no usable function. I wonder if putting the magnet that the sensor reads on one of my idlers or the flywheel would work? If I mounted it the same distance from the center of the shaft as it is currently. Seems logical to me but I wanted to see if anyone had ideas or experience with this. Thanks guys.
 
Should be an interesting build. The bearings in the skateboard wheels must be rated for that kind of speed but is the wheel designed to withstand those kind of rpms? Is the wheel adhered to an axle or dose the axle bear on the bearing and the bearing live in a bearing pocket? Be Safe.
 
PT Doc said:
Should be an interesting build. The bearings in the skateboard wheels must be rated for that kind of speed but is the wheel designed to withstand those kind of rpms? Is the wheel adhered to an axle or dose the axle bear on the bearing and the bearing live in a bearing pocket? Be Safe.
Click to expand...

Wheels should be fine at those speeds, 4000fpm is about 45 mph which isn't considered terribly fast in the downhill skateboarding community. Abec 11 is a quality brand too: they have holes in the wheel hub that the urethane flows through to create a mechanical lock.
 
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Thanks for the replies and the video link. There was a big debate in the skateboard wheels in here before. One guy said he needed to replace a bearing in a sunray contact wheel and when they ran the numbers at a hardware store they turned out to be skateboard bearings. Lots of people use them. Id watched that youtube video before. Think Ive watched them all lol. Hes the one that left the flywheel on to solve the problem. I've been thinking about though. I wondering if the tach sensor is just a safety feature to stop the motor if the tread belt isn't moving. It would explain why they say without it the motor runs for a few seconds and stops. Motor speed is controlled by a simple potentiometer so I doubt the sensor has anything to do with controlling motor speed. If thats the case then as long as the magnet for the sensor was turning rpm wouldnt matter. Just so the controller knows the belt is moving. I'll stick the magnet to the flywheel and try it out to see what happens.
 
Just had another thought. People say a spring isn't the best way to tension the belt as its inconsistent. They say to use gas pistons. Gas pistons are expensive. The treadmill has a motor for power incline. Its a motor that pushes and hold a shaft in and out. Why not power belt tension. It will hold it solid. This thing is gonna be sweet
 
Could be more to it then that. A pot is often used as a digital input and the controller maps the output accordingly.
If using the potentiometer in analog circuit you don't get any energy savings at lower speeds, just a lot of wasted energy in the form of heat.
 
Boogaloo said:
Could be more to it then that. A pot is often used as a digital input and the controller maps the output accordingly.
If using the potentiometer in analog circuit you don't get any energy savings at lower speeds, just a lot of wasted energy in the form of heat.
Click to expand...

Okay. Thank you. Is there an advantage to keeping the flywheel? Thought maybe the inertia would help the motor from bogging down but i dont know. If I could eliminate the flywheel i could mount the pulley with the magnet for the sensor on the drive shaft. If this thing helps control speed then the ratio of the two pulleys would come into play. The drive pulley on the motor is bigger then the shaft. In this case i dont think mounting the pulley on the drive shaft so that its the same distance from center as it was originally would work. Because the two shafts would if turned at different rpms. Anyone? Math isn't my strong suit

Edit: thanks for helping. I did a little more research and it turns out your right. The sensor is a speed sensor and does tell the controller what voltage to send. It maintains the tread speed. I simple problem that should be easy to fix.
 
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Good luck on the project. I find building and collecting tools almost as fun as using them.LOL
FYI If you find the right spring you will have just as good or better results as a gas strut. I will say most grinders do not come with a strong enough spring for heavy grinding. The springs that I have made work very well. Not sure if one of mine would fit your design but let me know if need one.

Brett Mathews
Esteem grinders
 
Thanks for the offer Brett. A quick update. I have to admit the speed controller thing worried me. Was up most of the night researching. Tested it out today for the first time since it was out of the treadmill. I dont think my sensor had anything to do with speed control because I didnt experience any of the problems others did when it was unplugged. Maybe because its an older model. It has four leds that light up for diagnostic purposes and according to them everything was functioning nominally. I think the sensor was only used to calculate distance ran. My only concern was that the 130 v motor was only seeing 87 volts at max setting. But the motor controller circuit is simple and has only one trim pot that adjusts the voltage the motor sees. I turned it up a little and the motor tried to take off from my hand so I'll wait till its bolted into the machine for further testing. Ill see how it works right now before adjusting it.
 
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