Thank you so much for all your videos on treadmills. Very well made, full of informations and very clear. It is nice to find people that are willing to share the knowledge they have. I will start to hunt for cheap treadmills today!
Well done sir, another subject covered professionally. I have the treadmill motor set up on my Lathe and was trying to figure out how to set this up when I complete my Electric Leadscrew. Thanks again for the idea’s and explanation. I have some 50 Amp resistors left over from fixing flasher error with LED turn signals, a perfect use for them.
my only question would be, for what voltage are those resistors raited at 50 amps? Amps X volts equals watts and you will need to be in the 1000 watt range.
@@dazecars of course I can’t find the product listing that said 50 amp, most are saying 50W 6Ohm and 12 volt. I looked at a write up on adding a brake resistor to a DC motor, and a resistor like these was pictured, but I had no idea how it worked until your explanation
@@Richard-gh1gv I don't think that will be big enough for a treadmill motor. This is what I went through to determine that I needed 1000 watt resistor for my project. Watts is calculated by multiplying amps times volts. Most treadmill motors are 15-20 amps. Max RPM is usually around 90v so the motor is 1800 watts at max. As a generator output would be somewhere less than 1800 due to efficiency. Before I ordered a resistor I used my DPST switch to test the voltage being generated while free spinning. I hooked the meter up in place of the direct short/resistor and brought the motor up to max RPM. When I flipped the switch the motor was generating about 50v and dropped quickly. Using the same calculations, at max I was looking at 1000w (50V X 20 amps) I don't like having things like this at the limits of their capability but If for some reason the free spinning motor produced a little more voltage than 50 creating more watts a braking resistor can handle a quick burst of way more than it is rated at and the wattage drops so quickly that it is more than enough. Also my lathe is almost never at max it’s 2/3 or less so we’ll below the 1000w. Then when I considered the motor is going from max watts production to 0 watts In 1 second or less it is even less likely to damage the resistor I chose. But in your case you are way under that wattage, by a lot. The resistor you have must be for a smaller motor. Also at 6Ω it will not be fast enough IMHO
@@dazecars did some digging on this and many only use about 50W as it’s not taking much of a load and the load exponentially decreases as it runs. As long as it’s not used more than every 40 secs, it should stand up. One of the recommended items to use is a water heater element. High wattage and made for heat. I also have a few used block heaters here, and they average 600-1000w in a compact size.
@@Richard-gh1gv I burned up some 50 watt resistors I had on hand before I "did the math" if it works for you fantastic, but the volts and amps of these motors are high even as a generator so you will likely need something bigger.
I need to stop a reversible AC motor quickly. Two wires under the cover plate are reversed to change the motor direction. This motor is a brushless 1/4 hp motor. (I believe it's brushless. The motor has a gray rolled sheet steel case, cast aluminum ends and no caps covering brush springs and no internal sparks when running)
Hello. Firstly, thank you for your videos. They are helping me tremendously. However, I do have a question. I see you are using two resisters to achieve 2 ohms. Why did you decide 2 ohms? I've seen resisters on the market @ 1 Ohm 5% 1000W. Can you tell me the calculation you used to determine what is right for a given motor. My motor says 16 AMP / 140 VDC @ 3500 RPM 3HP. Any response would be appreciated.
Not being an electrical engineer I do not have any calculations other than watts. I ball parked watts by multiplying amps and volts which is how watts is calculated BUT that doesn't take into account the rapid voltage drop as the motor brakes. To get the correct ohms I guesses and picked up the two 4ohm resistors knowing I could put them in parallel if 4 ohms was too high. The guessing /trial and error worked well as you can see the results in the video but I knew that my results were not accurate enough because of the rapid decrease in watts and I wanted to find the minimum ohms that would still protect the motor while maximizing braking. To answer all this I devised an experiment and made a video on it. th-cam.com/video/2p3-sUZ4VPE/w-d-xo.html It should answer all your questions. Please let me know if you have any further questions.
I was thinking that perhaps this is the generated force acting in opposing force to the magnets? This would (I theorized?) make a almost “reverse” force relative this the speed of the motor (generator)? Also, I wonder if an incandescent light bulb would work in place of resistor?
I am not exactly sure what you are trying to convey. Putting the motor in reverse from forward is a BAD idea. Drawing on the current produced from the motor is what makes the braking action. It is kind of like using a gas generator for 110 when you plug something in and turn it on the gas motor will bog until the generator adjusts RPMs to compensate. producing electricity creates resistance.
I meant that shorting the windings actually causes the motor to resist itself. The motion of the windings (relative to the magnets) builds a magnetic field that opposes the rotation. That’s why it’s more of a break than just turning it off.
@@davidkask510 Thanks for the explanation of what you were trying to say, Thats an interesting way to look at it and makes a lot of sense. I am no electrical engineer but it is my understanding that the action of one magnetic field being forced against another magnetic field that creates the current and I do know any generator is harder to turn when there is a load. With that in mind your explanation seams to be spot on as I found one description online of what is happening is that "as electricity is produced in the coil the coil creates its own magnetic field and that field is what causes the braking action." That field would have to be in the opposit rotation of the motor or the motor would spin longer not shorter when you short it out so I think you are right on.
A lot of lathes don't have a screw on chuck, and it was my understanding that the ones that do also have some sort of lock so you can run them in reverse but not having messed with one I do not know that for sure.
Thanks for the great video! I would like to understand how you calculate that you need 1000 watt resistor. Also, do you think you could use an electric stove heating element as a braking resistor?
First you need to know that I am not an electrical engineer. I do know enough to do basic calculations but not the more complicated things. With that in mind I do the simple calculations and then err on the side of caution. In other words I overbuild to compensate for my lack of complete understanding. With that said the basic calculation for watts is watts = amps times volts. If you look at most treadmill motors they are 90V and 10-25 amps, so there power draw is 900-2250 watts. For the purpose of this explanation we will assume they are all 90V and 25A. When the treadmill motor goes from being a motor to a generator that same wattage should be produced, BUT that would be at 100% efficiency which will never be the case. I was not sure how efficient these motors were as a generator so before I ordered a resistor I used my DPDT switch to test the voltage being generated while free spinning. I hooked the meter up in place of the direct short/resistor and brought the motor up to full speed. Then when I flipped the switch and the motor began free spinning it was generating about 50v and dropped quickly. 50V X 25 amps would be 1250w which is more then my resistor but a braking resistor can handle a quick burst of way more than it is rated at and the wattage drops so quickly that the 1000W I went with is actually more than enough. Then when you consider It’s going from max watts to no watts In a few seconds or less it is even less likely to damage the resistor. With that info in mind I chose 1000 watts because I knew it would be enough at max. Because the wattage output drops so quickly I probably could have used a smaller resistor, say 500 watts but again I wanted to err on the side of caution. As to using a heating element I would think that would handle the wattage no problem but you would need to measure the resistance. There was a huge difference in braking speed between 4Ω and 2Ω resistor and if the heating element was more than 2Ω it would not be effective as a brake
@@dazecars Thanks so much for the lengthy detailed explanation, you made it very clear for me. I watched a video by MofigoDIY and he showed how to make high power resistors using a tubular heating element. He achieved different resistance levels by adjusting the length of tubular element he used. If I have a tubular element that has a resistance that is too high, couldn’t I just keep cutting it shorter until I got 2 ohms resistance? It seems like it would be quite short.
So my lathe came from factory with a brushed dc motor and a forward reverse switch. If I flip from forward to reverse while the machine is on, it very quickly comes to a stop (but doesn't start in reverse until I hit the start button again) Is this a safe braking method?
I don't know. I would assume there is a safety mechanism in there to eliminate problems but not knowing exactly how everything is wired, I am just guessing.
would a variable resistor be ideal to limit motor damage while also reducing time to stop? I'm thinking the resistance starts high to minimize sparking but then ramps down to a really low resistance. thanks for the vid!
Very interesting question, but I don't think I've ever seen a variable resistor with low ohms and that can handle the amount of electrical heat generated by a motor that strong.
It's an interesting concept. The first obstacle would be getting one with a high enough wattage rating. 1000 watts is A LOT. Second a 2Ω there is no arching at the brushes so I think it is probably the best compromise.
in-er-rest-ting -- I sorta remember in school machine shop trade school we had these outstanding japanese 14+" lathes with a quick stop break lever. the point i'm geting to is a momentary brake switch and litteral brake-a real p[hysical brake too and both activate at da same time-- like wit ah foot pedal--pushing the brake "pedal" (physical) wand the electrical switch at the same time- coupled. if U get where I'm coming from. some grizzly lathes have an emergency stop-(which can become habit forming) also a a lathe brake can speed up lathe production by maybe more than 30%. i.e by tha time it takes the late to stop you will have completed the measurement or etc. that U stopped the machine for. K :) PS: a simple brake pad brake is simple. and U cud stop machjoine on ah dime-- also may wanna investgate electric breaks - they already have those---I no nothing about them opther than they exist. I've wondered tho
Oh-another point-significant braking on a metal lathe requires that lathe chuck NOT BE A SCREW ON CHUCK cause like fly wheels they can come unscrewed real fast yikes 10+lbs of spinning castiron = no fun.. -- malso for a screw on lathe friction brake to chuck cud be possible BUT remember that it wud also tighten the chuck on the lathe spindle. ugh
A mechanical brake is a outstanding option but I like electric breaking only because it automatically engages every time the power is cut eregardless of how
not familiar with that machine. Just a reminder this technique works with DC motors, but I am not sure how effective it would be with an AC motor, I have not experimented with that.
I was just searching "add brake to lathe" and found your video. Makes me realize i should study more on Electricity.
glad you liked it
Thank you so much for all your videos on treadmills. Very well made, full of informations and very clear. It is nice to find people that are willing to share the knowledge they have. I will start to hunt for cheap treadmills today!
Glad I could help. Let me know if any questions arise.
I really like your channel, great information, great content!
Glad you enjoy it!
This is a great video. Great way of showing how the electrical braking works. Keep up the good work. Love your videos.
Thanks, will do!
Well done sir, another subject covered professionally. I have the treadmill motor set up on my Lathe and was trying to figure out how to set this up when I complete my Electric Leadscrew. Thanks again for the idea’s and explanation. I have some 50 Amp resistors left over from fixing flasher error with LED turn signals, a perfect use for them.
my only question would be, for what voltage are those resistors raited at 50 amps? Amps X volts equals watts and you will need to be in the 1000 watt range.
@@dazecars of course I can’t find the product listing that said 50 amp, most are saying 50W 6Ohm and 12 volt. I looked at a write up on adding a brake resistor to a DC motor, and a resistor like these was pictured, but I had no idea how it worked until your explanation
@@Richard-gh1gv I don't think that will be big enough for a treadmill motor. This is what I went through to determine that I needed 1000 watt resistor for my project. Watts is calculated by multiplying amps times volts. Most treadmill motors are 15-20 amps. Max RPM is usually around 90v so the motor is 1800 watts at max. As a generator output would be somewhere less than 1800 due to efficiency. Before I ordered a resistor I used my DPST switch to test the voltage being generated while free spinning. I hooked the meter up in place of the direct short/resistor and brought the motor up to max RPM. When I flipped the switch the motor was generating about 50v and dropped quickly. Using the same calculations, at max I was looking at 1000w (50V X 20 amps) I don't like having things like this at the limits of their capability but If for some reason the free spinning motor produced a little more voltage than 50 creating more watts a braking resistor can handle a quick burst of way more than it is rated at and the wattage drops so quickly that it is more than enough. Also my lathe is almost never at max it’s 2/3 or less so we’ll below the 1000w. Then when I considered the motor is going from max watts production to 0 watts In 1 second or less it is even less likely to damage the resistor I chose. But in your case you are way under that wattage, by a lot. The resistor you have must be for a smaller motor. Also at 6Ω it will not be fast enough IMHO
@@dazecars did some digging on this and many only use about 50W as it’s not taking much of a load and the load exponentially decreases as it runs. As long as it’s not used more than every 40 secs, it should stand up.
One of the recommended items to use is a water heater element. High wattage and made for heat. I also have a few used block heaters here, and they average 600-1000w in a compact size.
@@Richard-gh1gv I burned up some 50 watt resistors I had on hand before I "did the math" if it works for you fantastic, but the volts and amps of these motors are high even as a generator so you will likely need something bigger.
Very interesting, informative and good video. Thank you.
Glad it was helpful!
Another great video
Thanks!
great idea. thanks
You are welcome!
I need to stop a reversible AC motor quickly. Two wires under the cover plate are reversed to change the motor direction. This motor is a brushless 1/4 hp motor. (I believe it's brushless. The motor has a gray rolled sheet steel case, cast aluminum ends and no caps covering brush springs and no internal sparks when running)
I have not messed with braking on AC motors
Hello. Firstly, thank you for your videos. They are helping me tremendously. However, I do have a question. I see you are using two resisters to achieve 2 ohms. Why did you decide 2 ohms? I've seen resisters on the market @ 1 Ohm 5% 1000W. Can you tell me the calculation you used to determine what is right for a given motor. My motor says 16 AMP / 140 VDC @ 3500 RPM 3HP. Any response would be appreciated.
Not being an electrical engineer I do not have any calculations other than watts. I ball parked watts by multiplying amps and volts which is how watts is calculated BUT that doesn't take into account the rapid voltage drop as the motor brakes. To get the correct ohms I guesses and picked up the two 4ohm resistors knowing I could put them in parallel if 4 ohms was too high. The guessing /trial and error worked well as you can see the results in the video but I knew that my results were not accurate enough because of the rapid decrease in watts and I wanted to find the minimum ohms that would still protect the motor while maximizing braking. To answer all this I devised an experiment and made a video on it. th-cam.com/video/2p3-sUZ4VPE/w-d-xo.html It should answer all your questions. Please let me know if you have any further questions.
I was thinking that perhaps this is the generated force acting in opposing force to the magnets? This would (I theorized?) make a almost “reverse” force relative this the speed of the motor (generator)?
Also, I wonder if an incandescent light bulb would work in place of resistor?
I am not exactly sure what you are trying to convey. Putting the motor in reverse from forward is a BAD idea. Drawing on the current produced from the motor is what makes the braking action. It is kind of like using a gas generator for 110 when you plug something in and turn it on the gas motor will bog until the generator adjusts RPMs to compensate. producing electricity creates resistance.
I meant that shorting the windings actually causes the motor to resist itself. The motion of the windings (relative to the magnets) builds a magnetic field that opposes the rotation. That’s why it’s more of a break than just turning it off.
@@davidkask510 Thanks for the explanation of what you were trying to say, Thats an interesting way to look at it and makes a lot of sense. I am no electrical engineer but it is my understanding that the action of one magnetic field being forced against another magnetic field that creates the current and I do know any generator is harder to turn when there is a load. With that in mind your explanation seams to be spot on as I found one description online of what is happening is that "as electricity is produced in the coil the coil creates its own magnetic field and that field is what causes the braking action." That field would have to be in the opposit rotation of the motor or the motor would spin longer not shorter when you short it out so I think you are right on.
On a lathe, don't you have to worry about it potentially slowing down too fast because the momentum of chuck might make it unscrew and some off?
A lot of lathes don't have a screw on chuck, and it was my understanding that the ones that do also have some sort of lock so you can run them in reverse but not having messed with one I do not know that for sure.
Thanks for the great video! I would like to understand how you calculate that you need 1000 watt resistor. Also, do you think you could use an electric stove heating element as a braking resistor?
First you need to know that I am not an electrical engineer. I do know enough to do basic calculations but not the more complicated things. With that in mind I do the simple calculations and then err on the side of caution. In other words I overbuild to compensate for my lack of complete understanding. With that said the basic calculation for watts is watts = amps times volts. If you look at most treadmill motors they are 90V and 10-25 amps, so there power draw is 900-2250 watts. For the purpose of this explanation we will assume they are all 90V and 25A. When the treadmill motor goes from being a motor to a generator that same wattage should be produced, BUT that would be at 100% efficiency which will never be the case. I was not sure how efficient these motors were as a generator so before I ordered a resistor I used my DPDT switch to test the voltage being generated while free spinning. I hooked the meter up in place of the direct short/resistor and brought the motor up to full speed. Then when I flipped the switch and the motor began free spinning it was generating about 50v and dropped quickly. 50V X 25 amps would be 1250w which is more then my resistor but a braking resistor can handle a quick burst of way more than it is rated at and the wattage drops so quickly that the 1000W I went with is actually more than enough. Then when you consider It’s going from max watts to no watts In a few seconds or less it is even less likely to damage the resistor. With that info in mind I chose 1000 watts because I knew it would be enough at max. Because the wattage output drops so quickly I probably could have used a smaller resistor, say 500 watts but again I wanted to err on the side of caution. As to using a heating element I would think that would handle the wattage no problem but you would need to measure the resistance. There was a huge difference in braking speed between 4Ω and 2Ω resistor and if the heating element was more than 2Ω it would not be effective as a brake
@@dazecars Thanks so much for the lengthy detailed explanation, you made it very clear for me.
I watched a video by MofigoDIY and he showed how to make high power resistors using a tubular heating element. He achieved different resistance levels by adjusting the length of tubular element he used.
If I have a tubular element that has a resistance that is too high, couldn’t I just keep cutting it shorter until I got 2 ohms resistance? It seems like it would be quite short.
👍
So my lathe came from factory with a brushed dc motor and a forward reverse switch. If I flip from forward to reverse while the machine is on, it very quickly comes to a stop (but doesn't start in reverse until I hit the start button again) Is this a safe braking method?
I don't know. I would assume there is a safety mechanism in there to eliminate problems but not knowing exactly how everything is wired, I am just guessing.
would a variable resistor be ideal to limit motor damage while also reducing time to stop?
I'm thinking the resistance starts high to minimize sparking but then ramps down to a really low resistance.
thanks for the vid!
Very interesting question, but I don't think I've ever seen a variable resistor with low ohms and that can handle the amount of electrical heat generated by a motor that strong.
It's an interesting concept. The first obstacle would be getting one with a high enough wattage rating. 1000 watts is A LOT. Second a 2Ω there is no arching at the brushes so I think it is probably the best compromise.
varac into a 1000w resistor?
no the motor is connecting to the resistor
in-er-rest-ting -- I sorta remember in school machine shop trade school we had these outstanding japanese 14+" lathes with a quick stop break lever. the point i'm geting to is a momentary brake switch and litteral brake-a real p[hysical brake too and both activate at da same time-- like wit ah foot pedal--pushing the brake "pedal" (physical) wand the electrical switch at the same time- coupled. if U get where I'm coming from. some grizzly lathes have an emergency stop-(which can become habit forming) also a a lathe brake can speed up lathe production by maybe more than 30%. i.e by tha time it takes the late to stop you will have completed the measurement or etc. that U stopped the machine for. K :) PS: a simple brake pad brake is simple. and U cud stop machjoine on ah dime-- also may wanna investgate electric breaks - they already have those---I no nothing about them opther than they exist. I've wondered tho
i don't know why there's a line thru part of what I wrote -- it's all "good" stuff. K PS: DUDE U DO GUD WERK :) THANKs
Oh-another point-significant braking on a metal lathe requires that lathe chuck NOT BE A SCREW ON CHUCK cause like fly wheels they can come unscrewed real fast yikes 10+lbs of spinning castiron = no fun.. -- malso for a screw on lathe friction brake to chuck cud be possible BUT remember that it wud also tighten the chuck on the lathe spindle. ugh
I didn’t do it
A mechanical brake is a outstanding option but I like electric breaking only because it automatically engages every time the power is cut eregardless of how
Excellent point.
I wish that I could do this on my A.C. powered lathe ..............
I believe it can be done but it is way more complicated and have not had any need to look further into it
I have a minitor d360 with elec brake problems , this weekend with luck , I may...lol...May , solve it..
not familiar with that machine. Just a reminder this technique works with DC motors, but I am not sure how effective it would be with an AC motor, I have not experimented with that.