Variac as a Treadmill Motor Power Supply Is this Another Budget Option to Power a Treadmill Motor?
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- Опубліковано 8 вер 2024
- Like the PWM power supply and the SCR voltage controller a variac gives you variable output power so you can adjust the speed of a DC motor such as those found in a treadmill. Just like the SCR this power supply requires the use of a bridge rectifier. This unit seams to have a lot of advantages but I wonder if there is a significant loss of torque at lower RPMs.
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I burned out an old dc power supply a couple weeks ago and have been trying to find a suitable replacement since then. I am so glad to have run across your video about this. I have a 130v 5 amp variac and tried this out on a small dc motor...worked great. Now I have the same bridge rectifier and a 130v 20amp variac on order. Thanks so much for your video. You saved me a whole lot of money.
Glad I could help
Thank you so much for all of these videos. They are so very helpful to me. I am relearning/remembering a lot of the basics from my tech schooling back in the 90's. You sparked my brain with this one. I forgot all about these I have a few old Behlmen A/C frequency generators/ power supplies laying around I can use for clean power to use on an old WW2 Hardinge Precision Lathe I need to restore and want to convert to a variable speed DC after I finish my table-saw conversion. That has a 3phase motor in it I don't want to use cause of the rewiring I'd have to do for it. I got it for a steal and its been sitting now over a year doing nothing cause I couldn't think of what to do with it. Thanks!
best part is there is value in that three phase motor so you could probably sell it and get enough to fund the conversions.
Keep on the journey! I already have a 20 amp variac. In the last month I've picked up three different treadmills for free. One had a controller that I only had to add the potentiometer One had a MC 2010 and the other an MC60. Thank you so much for all you've taught me on your channel.
Glad I could help
I need a treadmill motor. Is there any for sale
source a free treadmill
Great demonstration, I was expecting a smoother voltage, but good to confirm it.
Thanks for sharing.
You're welcome
You should look into using a capacitor along with the rectifier to smooth out the output of the rectifier. It will result in a higher output voltage but I believe it would be worth looking into.
Also I think SOME variacs have a built feature to limit the max voltage by physically preventing the knob from turning past a point via a set screw. I seem to remember seeing something like that on mine when I took off the knob.
I have experimented with capacitors and found they surge under a load so I have removed them from my setup. As to the max volts on the variac I found one that maxes at 130. That is the one I have linked.
Wow, it goes all the way up to 230V. Most Chinese models only go up to 130-140V. You can use this one to power 230V devices too (as long as they work with 60Hz). That's cool.
Yes but only if the Variac can handle the amp draw of the 230 v device being run on it
Interesting approach. It’s bulky but we can definitely hear how much smoother it’s running to the other two options. Looking forward to the video.
Dyno build will take a while but I have devised a test I can do in the short term. Stay tuned.
It also has a feature of separating the input from the output electrically.
Actually it doesn't. That is one downside with this setup is the AC current is not isolated like it would be with a traditional transformer.
One think that you forgot to mention is the VA rating of the variac and voltages .
Here in Australia we have 240v ac single phase and all 3 of my treadmill motors are 180v dc at 8 amps so the variac must be able to handle this , that means that the VA rating has to be a minimum of 2000VA or it may over heat and fail .
It would be nice to see the dc amp draw in the testing that you have done when cutting on the mill .
Good work as always .
several people have asked for the amp draw numbers and that is something i will likely do in the future.
And the learning goes on...
I'm doing the deep dive into your channel and I love it.
A variac fell into my hands a couple years ago. Not sure of its values, but will dig it out of storage and find out. I'm liking the direction this is going.
"Motochassis" UA-cam channel has a video on modifying a treadmill motor to make it more solid/precise/air tight/dust free. It's a good video, but not sure about the over heating possibilities. You might check it out and give an opinion.
Let me know if any questions come up
I have the same multimeter with the lid broken off. Might actually have two of them. Nice little unit. I miss Radio Shack.
best meter I have even had. I managed to pick up a few of that exact same model off ebay but they are hard to find and people want way to much for them.
Yesssss! I’m super interested to see what the results are going to be! Awesome video as per usual!
Thank you!
Ok thats tames it down ,, I was concerned about something serious ,,,, there is a new treadmill DC motor on Facebook near where I live ,,, I would build something for it to power,,, you have been really helpful thanks a lot all the best
glad I could help
Not all Variacs go to 230 volts. Usually, if it plugs into 120 volts, it goes to about 140 volts max. BTW, "Variac" is a GE trademark, IIRC.
You might also point out that these things do not have a separate secondary winding which means that their outputs are NOT isolated from the power line. A major safety concern to be considered.
good information and points
From what I understand you can get an even smoother power band if you add a capacitor to the circuit as well but I'm not knowledgeable enough to tell you why or how
Its worth looking into but I am unsure what the benefit of making it much smoother than it already is would be.
@@dazecars possible longer brush your life
I think it adds power when there is a load spike I'm not electrically proficient either but I think an RLC circuit would act like an electrical flywheel.
👍
Why the heck are you not teaching school guy? You have the touch for keeping things simple and understandable.. even for us babyboomer generation that are retiring and looking for something to do with our time... Thank you for your effort to make these kind of vids..
The perfect job is the one you love doing the most.. and you have it.
Glad you like my videos, and thanks for the compliment!!
Maybe because his numbers are all wrong and auto-transformers are quite dangerous. The motor ratings are for DC. 90V AC from the Variac (tradename) is RMS and must be multiplied by the square root of 2. to see what will come out of the bridge rectifier. The 90V on the dial is 125 DC at the rectifier. 130V AC is 180V DC. Of course it was "screaming"!
And the auto-transformer needs a double pole switch (DPST) so that both the neutral and the hot are disconnected when off. Look at the diagram of a Variac. Old Variacs and some new ones have the neutral connection to the coil pass through to being the neutral on the output socket and the switch only switches the hot side. This means your neutral side wiring is always connected to the mains and neutral is not ground. You can be electrocuted when the switch is in the OFF position. Worse, old ones do not have a grounded plug and can be insterted in an outlet either way, which connects hot side straight though with no switch. We used to call these "student eliminators". To be safe you must add an extra power switch that truly disconnects both hot and neutral.
There is no isolation in a Variac. It isn't a transformer in the usual sense. When it is OFF, both out put linse have a pathway to the neutral input - which might be the hot side if the plug or outlet are wired wrong. www.nutsvolts.com/magazine/article/a_deluxe_test_bench_variac
I’m just a hobbyist not an engineer with a rudimentary understanding. There are no calculations because I didn’t do any. But I used logic and technique to complete. I simply used a volt meter to set the correct voltage after the rectifier and the motor is that particular RPM at that voltage. I appreciate the rest of your comment as it has lots of good information. For myself and others.
@@dazecars I'm not saying it is a bad idea. I just bought some SCR type speed controls and some rectifiers to try one of these motors on a mini-lathe. I was gazing at my big red Variac when your video came up and I'm going to try it. I was uneasy about the chopped waveform from the SCR anyway. Thanks.
My experience is the motor runs way smoother on this setup. Even better would be an isolation transformer between the variac and the rectifier but you would almost need to retrofit a microwave transformer to minimally effect voltage changes and insure big enough wires in both coils to handle the amps. I may need to try that experiment and do a video in the future. 🤔
At 15:55 "Amps are related to volts so as volts drop amp can drop". Yes this is true in a resistive circuit, as current drops the voltage across the resistive element will drop. But if we at talking about a DC motor current and torque are proportional, I=T/kT where I is current, T is torque and kT is torque constant inherent to the motor. Because of back EMF you will get the highest current draw and torque when a DC motor is stalled. To increase speed you will need to voltage. The Motion Control Tips web site has 2 article on it that are a good read if you are interested, "What’s the relationship between current and dc motor output torque" and "The relationship between voltage and dc motor output speed"
Those do sound like good reads and everything you have said makes sense. My statement has to do with resistance and is why I use the word "can". The copper wire in the coil has resistance and it takes a certain amount of volts to adequately overcome that resistance. That was easily demonstrated when I made an electromagnet from a microwave transformer. The strength of the magnet is totally dependent on amps but until the voltage was high enough to overcome the resistance of the coil the magnetic field was well under max.
I have one of them but it is the 130 volt not the 220 version. I got one before I found your channel. I plan on most of my things I'm going to go with your Scr application. This thing will work great for checking motors and I may use it for running my electro magnets where I can set it around 10 to 20 volts depending on how much down force I need.
130 is actually better unless your motor is rated for 180-220. The one I list in the description is 130
@dazecars That's what I thought also. You cover things so very well and make them clear. I have a basic understanding how things work and you have saved me tons of time trying to find the right info. I have found about 3 channels on u tube that are very good and yours is near the top. Then there are 300 channels with people that know just enough to be dangerous. Where abouts are you from. I'm at TN.
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Wonderful test, Daze. Looking forward to your torque video! Salute from NB, Canada!
Coming soon!
Hi. Thanks for providing this video as it gave me the much needed insight to muster up the courage to proceed with my treadmill project.
I have a proform treadmill and use it regularly.
The issue with my treadmill is that the electronics go bad too often and in the past I had to periodically request these parts via my extended warranty. However that warranty has ended.
As I do not want to purchase such replacements in the future, I am thinking that it’s best to disconnect the electronics and just set up the existing motor to run via the Variac -per your set up. [I really do not need all the bells and whistles that came with the machine. A speed knob and a cooking timer will do me righteous.]
I do have just 2 questions before jump in and ordering the require parts from Amazon.
1. Is my plan doable?
- I plan to mount the Variac near where I usually walk sonthat I can easily vary the speed.
- I plan to mount the rectifier inside the cabinet base where the motor is secured.
- I plan run a connecting wired from the rectifier to the motor.
- I will be using a power cord between the Variac and the rectifier like shown in your video.
2. What gauge wire do you recommend between the motor and the rectifier. I have not cracked open the motor compartment as of yet to see how the motor is getting its juice. I believe it coming off the main component board. -Maybe those wires will have ends that will fit the rectifier male blade. That would be convenient. If not it’s will be time to get creative. Amazon have such spade connectors. I really want to ensure that I am using the correct wire gauge to get it done safely.
-Please let me know if you feel if I am on the right track. If not please advise.
Thank you for your video. I am now subscribed and hope to learn more from your podcast.
James Daly Pahoa Hi.
Is it doable, Yes. Is it a good idea... maybe. the problem is all the electronics in a treadmill are designed with safety features like soft start and emergence shutoff. If you think the elimination of those safety feature is acceptable than I don't see any reason for you not to do it, just be careful "at your own risk". Put the rectifier as close to the motor as you can and connect the rectifier to the variable transformer with 16awg wire minimum, 14 would be better. Let me know if I can be of any further assistance.
They have servo controls to make those remote.,also stackable so you can run more than one at a time.make sure to get one that is capable of handling the required amount of current.
That is fantastic information. The problem is once you add another variac and or a remote servo you are now rapidly moving away from budget friendly 😁 Like all my other treadmill motor power supply options I am trying to keep it under $100 any more than that and you are getting to the point where a 3 phase AC motor and VFD is not that much more money at $200-$300 and is the superior option.
Do you have more info on this?
@@dazecars Agreed., just stating options. I work in radio where the budget is not so much the primary concern.
@@briana3467 I appreciate the comment. I will always be open to learning abut other options.
@@connorbabcock8197 what more are you looking for?
you can calculate torque for motors. T=((V-(WxK))\RxK. There are online calculators. Just need to measure voltage, amps and speed and plug them in.
Thanks for the information. I will use that to confirm my dyno is working properly once I build it.
Thanks for the easy to understand explanation.
Glad it was helpful!
Also you can physically limit the dial to prevent over voltage. I'm sure there's also ways to do it with circuitry
I mentioned a physical limit in my video if I was going to use it. As to an electronic option there is no circuitry. The way a variac works is a connection moving around a coil of wire. If you move the connection further up the coil the voltage changes.
@@dazecarsFrom an EE - You will find that on your variac, the input power is supplied to a fixed tap point half-way along the windings. If you move the input power to a different fixed tapping at or near the 'high' end of the windings, the output won't go much over 120V. (but the voltage numbers on the dial won't be right any more).
@@ridefast0 That is correct but my Variac came from a supplier with free returns so rather than modifying what I have I am sending it back and getting the one I linked with the 130 V max
I want to see the video you should have made - a slow crank up to maximum volts! You might want the motor outside on a very long cable for that one.
feel free to make that video asI will not be making it.😁
@@dazecars Hold my beer while I look for a treadmill motor!
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Subscribed, very interesting video, I have always wanted to do this experiment with a treadmill motor, always wondered if I would have sufficient "usable" torque at lower RPMs, enough to be used in different applications such as bandsaws, grinders, etc.
I did a follow up video that tests that very thing. Here you go ua-cam.com/video/AdGypyO_UuM/v-deo.html
Your presentation is good.
Thanks a lot
great video , i,m sold on the idea thanks
Glad I could help
Try using the pwm bord from the treadmill
Problem is they are designed to power treadmills and not other projects/tools so there are limitations. In this video I doo a shootout between the variac, an SCR and an MC2100 ua-cam.com/video/AdGypyO_UuM/v-deo.html
Thank you
my pleasure
just some kind of leaver to press against the drive pulley with a hook so that you can very the weight easily and precisely from one power supply to the next. will be interested to see what you come up with and the results of your tests.
Cool idea but rather than setting up a test ring (short of the dyno) I will use what I already have. After I made the video I was thinking it could be a month or more before I have time to do the dyno build and I wanted to know sooner rather than later which power supply was truly better. I originally planed on using the bandsaw with a dull blade as a test platform but didn't have a way to consistently push the material being cut into the blade, and didn't want the inconsistent work pressure to be a variable I couldn't account for, also the band saw has no RPM meter. Then I realized the mill would allow me to do all that testing variable free. With the mill I can set the same depth of cut, same RPM and then use the power feed to apply consist tool to work pressure. The only thing that will change is the power supply and the starting RPMs (in different tests) three tests per power supply 200, 600 and 1000. I will monitor the RPM drop as an unofficial way to measure torque differences. Stay tuned.
@@dazecars I think that is a good way of doing it as long as the density of the test piece is the same and the tool is just as sharp from one test to the next.
I was after a ball park to get a general idea rather than a truly repeatable A B test
Thanks for sharing.
My pleasure!
I do have one question, if I may. I worked on a ship and we generated AC and converted it to over DC to drive the ships DC motors. The chief mate explain that the volts tripled and the amps dropped to a third in the conversation. Is that true or am I missing something? I’m trying to learn and hope you know if it was right.
there is some piece missing there. Maybe 3 phase AC or something else. If I hook a wall outlet up to a bridge rectifier I get 105V ish DC. Some of the volts and current is lost to heat.
There is so much to be said about treadmill motors and controlling them in various ways. So much so, that it’s discouraging. For the life of me, I cannot understand why treadmill motor manufacturers do not sell their motors with a controller as a set. It’s quite obvious that there is a demand for these motors since they can be used for many applications. Right now I have a treadmill motor that I want to mount on a vintage bandsaw. The mechanical part of it is easy for me. It’s the wiring that I’m always fearful about. I still can’t understand why it is that there are so many kinds of motor controllers, big and small, and which one can be regarded as the most robust. It seems I might be better off, just using pulleys to slow down my bandsaw to cut metal. At least this way I won’t lose any torque.
Yes there is a demand for treadmill motors and controllers but not at the prices point that would make it worth a company putting together a motor and controller kit. There are lots of reasons to go treadmill motor the biggest of which is the fact that you can source the parts for cheap by scrapping a treadmill. A new treadmill motor is $100-$300 and most new treadmill control boards start at $100 so a "kit" would likely be $300 or more at which point a person is not far off the cost of the far superior VFD.
As to the best way to power a treadmill motor my channel is FULL of videos on making your own power supply and it is fairly simple. The best power supply for the shop environment is IMHO the SCR with bridge rectifier. It's robust, easy to hook up and versatile. Check out my videos on that. Also I have an entire playlist dedicated to my treadmill/ bandsaw conversion. ua-cam.com/play/PLg4j6XzBdSY8AkoE5YBqAHtnb5XDRIl8q.html
Lots of good info there on what to do and what not to do.
As far as torque that is the best part about a treadmill motor they produce full torque through almost the entire RPM range and in most cases is a massive torque upgrade over the AC motor especially when properly geared so that max treadmill motor RPM equals the max RPM the bandsaw was designed to go. In most cases that is a gearing of 3:1 or better and results in torque for DAYS
Nice video,
I was thinking about buying a variac transformer for my test bench.
Hard to get the amps I am usually looking for on a lot of my DC projects.
I think it’s well worth the money to have around.
Could be dangerous dealing with higher amps.
That is probably what I will end up doing with this one. Unless it performes way better then expected running equiptment I will use it as a power supply for other projects on the bench.
Ever mess with 3 phase washing machine motors? Many rated for 16,000 RPM. Some cheap controllers for those.
I have not but at some point plan to play around with one.
Firstly, love the video series on controlling treadmill motors - very nicely done! Secondly, the link to the knockoff Variac on Amazon goes to a 130VAC model, not the 230VAC model you have in the video. Can you update the link to that actual Variac? Pretty please.
That was done on purpose. The 130 is the much better option as you don't need to worry about it overpowering the the motor, it is better amperage wise and is a superior unit.
@@dazecars Great, thanks for the quick reply. Mine should be here tomorrow!
👍
You should be able to buy Variacs that can real line voltage as a maximum.
Thanks for the tip. I already found that exact thing and have one linked that is 130 max
Hook it up to your lathe and see if it has the same amount of torque. That's the only thing I could foresee it not doing as well with
You are reading my mind however I am going to do it on my mill instead of the lathe. After I made the video I was thinking it could be a month or more before I have time to do the dyno build and I wanted to know sooner rather than later which power supply was truly better. I originally planed on using the bandsaw with a dull blade but didn't have a way to consistently push the material being cut into the blade and didn't want the inconsistent work pressure to be a variable I couldn't account for. Then I realized the mill would allow me to do all that testing variable free. With the mill I can set the same depth of cut, same RPM and then use the power feed to apply consistand tool to work pressure. The only thing that will change is the power supply and the starting RPMs (in different tests) three tests per power supply 200, 600 and 1000. I will monitor the RPM drop as an unofficial way to measure torque differences.
@@dazecars will you still be able to run the encoder setup for thread cutting on the lathe with the variac? I assume yes but I'm not exactly sure how that system works yet
@@fladoodel the encoder is driven off the rotation of the spindle and does not care how the spindle is driven. AC motor, SCR, PWM, Variac, gas engine, pneumatic, or steam it all would function the same with the ELS
@@dazecars a gas engine lathe would be crazy
I’ve never used a mill but I’ve thought the power feed would keep the same speed but not the same pressure.
You might end up binding or breaking the end mill if it bogs down.
You could instead have the workpiece mounted in a dolly pulled by a cable with a fixed weight on a pulley. That would keep the pressure constant. The length of the cut and mill rpm would be good indicators of performance.
But I’m very curious about your dyno build.
I’ve just found and subscribed your channel. Good stuff!
Thanks for a great video , the Variac gets my vote for the way to go . I plan to use a treadmill / Variac set up on a small horizontal mill . Question at low speed will there be enough torque to power a cutter within reason ? Would you suggest a jack shaft ? . I'm a hobby machinist so no heavy cutting . But I will need decent torque . Also do you sell treadmill motors on Ebay ? Thanks Mark .
You are very welcome. Before you go Variac check out the shootout video ua-cam.com/video/AdGypyO_UuM/v-deo.html As long as you gear things down and have a treadmill motor with enough torque ua-cam.com/video/A_zBGJkhBAc/v-deo.html it should be fine On my mill I use a intermediate pulley shaft to gear it down enough ua-cam.com/video/C2p6pPNBPmg/v-deo.html I have a pile of treadmill motors and coupled probably sell you one. What are your size needs? I won't do it through eBay because I don't want to deal with their 15% cut
Hey Dazecars, thanks for all of these great videos sharing great infoation about this. With that controller is it possiable adding a reverse switch? maybe adding an 3 position DPDT switch somewhere in the output to motor wiring? Im not really goodd at makinng ciricits, but learning, itll be awesome if it could be done. The goal of my project is to threads into steel with the drill press.
Yes a DPDT center off switch is exactly what you need. It goes between the rectifier and the motor a serves to switch the polarity. That is how I have it wired up on my lathe.
@@dazecars I will give this a try! I Just bought variac you recommended from Amazon, just got to be patient for it when it come here. Mean time I'll figure out the schematic for the dpdt switch, or if you wouldn't mind sharing that part that would be super cool, I'll even share what I did on my project.
Also that thing is a ac to ac, but the motor itself is a vdc. I think I am missing something here I thought we can't just hook up ac to dc.
@@nicholasderbin7667 A DPDT switch that is center off will get you reverse. I show that in several of my videos. The Variac produces AC current and must me changed to DC. That is why I use a bridge rectifier in the video. I link that as well from Amazon.
Hi Daze, Great Videos! Got 4.25 hp 130vdc 24.4 amp 5195 rpm dc tm motor! What's the best speed controller setup for low rpm (1800 or less) wood lathe & lapidary grinder application? Thanks Steve
Probably the SCR due to the high amp/watt requirements of that motor.
What if you cleaned up the power even more on the DC side with electrolytic capacitor?
I ran one on several of my machines. the problem I as having is that under load the capacitors caused surging so I removed them.
good vid.
how or will it work on the ac motor that apparently isn't veriable speed ?
in many cases running an AC motor at lower voltage will slow it down BUT its not a good idea. it will effect torque and it is hard on an AC motor to run it at a voltage other than what it was designed for.
I came across a free treadmill. The motor however is a 3hp AC 3 phase motor. Any idea how i can hook up a speed controller to run off a 120 ac wall socket cheap?
you need to use VFD for a 3 phase motor. There are some available for about $150 on amazon or eBay but I don't know the quality.
I suspect you'll find lower torque at low voltage/rpm when using this versus either of the other controllers. Enough so that it's not going to be as useful at low speed use in an actual tool.
Not being argumentative just looking for more information. Is your statement based on using one, what others have said, or...? I have no doubt that there has to be a down side. The power is extremely clean and the unit is not overly complicated (cheap to produce) so if there was not a down side I would think they would be more commonly used for applications such as this. That is why I am going to do the dyno build I mentioned at the end of my video.
@@dazecars At the lower voltage on the output of the Variac there isn't the potential to push current to create the torque. With an SCR or PWM you have higher voltage and current, just at reduced intervals.
That's my thinking anyway. I haven't done much with a Variac since the 90s though. Hopefully I'm wrong and it works well for you.
@@Kevin.L_ I fear your thinking is correct and that is exactly my concern/reason for wanting to do the dyno test. I know when playing with DIY electro magnets made from microwave transformers that it takes at least 5 volts to overcome the resistance of the coil in order to have adequate amperage to create a significant magnetic field. I know the same will be true of treadmill motoras it is the same consept but I am not sure at what point full torque can be achieved compared to RPMS. The Dyno build will probably be a month or two out but I want to know sooner rather than later which power supply is truly better so I have devised a test on my mill. (upcoming project) I originally planed on using the bandsaw with a dull blade but didn't have a way to consistently push the material being cut into the blade, and didn't want the inconsistent work pressure to be a variable I couldn't account for, also the bandsaw has no RPM meter. Then I realized the mill would allow me to do all that testing variable free. With the mill I can set the same depth of cut, same RPM and then use the power feed to apply consistent tool to work pressure. The only thing that will change is the power supply and the starting RPMs (in different tests) three tests per power supply 200, 600 and 1000. I will monitor the RPM drop as an unofficial way to measure torque differences. Stay tuned.
Great video's, keep them coming. I was wondering if a large capacitor on the DC side would smooth out the switching noise?
I have not tried a capacitor with the variac because I don't see much need. The variac produces such clean smooth operation that there is not much room for improvement. Also when I have used a capacitor with other power supplies it has caused surging under a load.
Yes I agree the Variac sounds way better but I was thinking of the capacitor for the SCR setup as it seems to need the smoothing.
@@Rosscrymble1 it was with the SCR that I was getting the surging when I used a capacitor
Ahh my mistake, I will re watch that one. Great work nad thanks for the fast replies.
@@Rosscrymble1 my pleasure
Do you have a diagram to show how this Variac can be hooked up to a lathe using the same components that are already on my Lathe. (forward/reverse switch and E-Stop) Grizzly G0516. I have run the motor on the bench, but don't know how to connect it to my Lathe.
No I do not and its not that simple The direction for a DC motor must be done on the DC side. The F/R switch you are currently using is for the AC side and specifically directs how AC current goes into to the AC motor which in turn determine direction. The switch you have can likely be wired for direction on the DC side but not knowing the exact configuration of that switch I can not give you specific wiring instructions. With that said it is likely not big enough. AC components are capable of handling higher amperages because of the oscillating nature of AC. DC on the other hand results in a much lower amp rating for the exact same component because the DC current is continuously flowing through it. When I put a rotary switch in my combo I went with a much bigger switch as it was more capable of handing the amps. As long as the e-stop is on the AC side, in other words on the power going into the variac or on the AC line coming out of the variac but before the rectifier it will work just fine but is not high enough amps for the DC side. Please let me know if I can be of any further assistance.
@@dazecars Thank you for your help. I have decided to leave the original components in place and just buy the 3PDT direction SW and the E-stop that you recommend. If you ever do make a schismatic for connecting a Variac and Treadmill motor to a Lathe. Please let me know. Your Site is the best.
glad you like it!!
do you think there is a way to add a reverse and forward switch with a kill switch? as i am thinking of making a plasma cutter linear rail using a treadmill motor. also is there a better way to controll the speed much better ? i see that it was slower when voltage was not all the way up
A DC motor is controlled by voltage. You want to gear is first to get it into the operating range and then can fine tune from there. Forward and reverse is easy and so is a stop switch. I would think an SCR power supply would be better than the Variac given what you are trying to accomplish
do you think you would make a future video in this for people wishing to make something like im planning to make. so it makes it easier for ppl to see how easy to make it ?
I have already made tons of videos on the things you are asking about
I have 2 questions. In one of your videos you stated that you wire up the 2 blue wires between the power supply and the bridge rectifier. My motor's 2 blue wires are a smaller gauge wire than the red and black. Is this a concern? The second is, due you need a circuit breaker if the Variac has its own? Thanks
The blue wires are conducting AC so you can get away with smaller wire. I would still put a circuit breaker between the rectifier and the Variac.
Thanks for taking the time to answer.@@dazecars
Just to make sure i'm doing it right. I'm using a Variac The circuit breaker is wired directly to the Variac. The blue wires go between the circuit breaker and the bridge rectifier?
@@mattdanchris Based on your description, that sounds correct. you could also use the blue wires between the variac and the wall so it cuts power to the entire system if the motor overheats.
Another video showed 122v going in produced about 250v with this particular variable transformer (Variac is a brand). The knob and meter were said to not be trustworthy (as you mentioned)...so some of the voltage difference could also be the output before the bridge.
I still need one of these. Anyone know of a better variable transformer for the same money?
The one I link in the description is better. It’s 0-130 and a bit more accurate.
Where did you find one that goes from 0-220 volts? The link you gave is for a 20 amp unit that goes from 0-130 volts. Even though it would seem that those would be a better, safer option.
eBay, but the amazon one is the better choice and why I linked it.
Hi again another question ,,,,what does frenchcreekvalley mean when he comments "outputs are not isolated from the power line", what could happen ????????? please and thanks in advance
An isolation transformer has two windings (input and output) these two windings have no direct connection to each other. it is the creation and collapse of electromagnetic fields that allows power flow without a direct connection. the lack of a direct physical connection between input and output that gives the isolation. A Variac or autotransformer is a single winding with a tap. One side of the input and output are shared with each other. No Isolation. This is important where there is concern about electrical noise but is not an issue for a motor power supply
@@dazecars so its not like the current will back feed into the house's circuit and screw up a TV or computer ???
@@thrustprop67 nope its all about noise. The reason variacs having a non-isolated circuit gets brought up all the time is they are often used with older sound equipment and with ham radios and the like and in those situations the noise could be an issue. Someone sees a post in a ham radio group about the lack of isolation being a problem and they assume it's a problem else where and post it as a potential problem in other areas where its actually not an issue. Could a DC motor be effected by a little noise, slightly. Will it effect the motors function or lifespan no.
I'm looking at converting my 12 x 30 Atlas Craftsman 3/4 hp to a dc variable speed...
How will I correctly size it to match? Treadmill motors widely vary in RPM (2.5k - 8k) which seems to correlate to hp ratings.
The 3/4 equivalent is a 600w motor, but that's at optimal rpm / torque, correct? So if you're running at 25% of that, how much power is lost, if any?
Getting more confused the more I read...lol
Thanks!
First of all you want to gear it to maximize torque. In other words you want the final spindle speed to be the same at max RPMs. As to figuring out actual size I have a video on that very thing ua-cam.com/video/A_zBGJkhBAc/v-deo.html
@@dazecars DC, I did actually catch the video after I posted the question...good information. Right now I am at a quandary as to what I want to do vs cost / hassle factor. Your knowledge surpasses mine, some of your solutions seem very complex and require a lot of extras vs a 3 phase motor and VFD...is the xtra cost worth the hassle...I rechecked my lathe and it has a 1/2 hp 1725 rpm motor...which seems small to me, but it does the job especially with a direct gear drive function. I believe the Point of Sale lathe came without a motor and haven't been able to find any information on recommended size...so still dealing with that...
Thanks for the reply...enjoy your commentary on the videos...
glad you liked it
Hey Daze cars! How high do you comfortably run your treadmill motor to? Most of mine say 4k ish rpm max, but you've mentioned in a few videos running them to higher rpms. Just curious, thanks!
all the motors are different. The smaller ones I use on the bench have max RPMs of 7000-10K the bigger ones are a lot slower. My slowest it 3200
can you still use the braking diode with a variac setup ?
The power supply has no bearing on the braking resistor because you are disconnecting the power supply from the motor and at the same time connecting the motor to the braking resistor. So yes you can use it.
Great video! I have a motor that is rated 130v and 17.2 amps if I use a 130v and 20amp variac to power it will that damage my motor?
I need a lot more info to answer your question. Is your motor ac or dc, are you wanting variable speed or consistent speed. Are you in North American where the power is 110 or somewhere else where the power is 220?
Doing a little research, I think I may have found an answer to this. You can correct me if I am wrong.
Just because the power supply is rated at 20 amps doesn't mean that it will "push" 20 amps to the motor. The motor draws the amps it needs UP TO 20 amps. The amperage is determined by the voltage. The unit you used can only produce up to 130v which is what my motor is rated for and my motor, unless there is a short, will never draw more than 17.2 amps, well within the 20 amps available. So, I should be safe to do this.
I really appreciate you fantastic video. It got me on the road to fixing my lathe!
@@1VeritasNumquamPeri I can answer your question but you are leaving out key variables. Can you plese answer my previous questions.
I've seen these in the 0 - 130v range also. Good or bad idea?
Works great the 0-130 unit is actually the one I have linked.
@@dazecarshaha, I guess I should have read your comments to the video. I usually watch your videos on my TV and comments don't show. Thanks for the reply I enjoy all your videos.
glad you like them and glad I can help
Very curious to see a comparison of torque at the same RPM. Probably hard to measure, but ~200rpm, you could probably just test with a pair of leather gloves on the pulley.
excited to see the upcoming dyno runs
Rather than grabbing the pulley in gloves I have devised a test on my mill . After I made the video I was thinking it could be a month or more before I have time to do the dyno build and I wanted to know sooner rather than later which power supply was truly better. I originally planed on using the bandsaw with a dull blade but didn't have a way to consistently push the material being cut into the blade, and didn't want the inconsistent work pressure to be a variable I couldn't account for, also the band saw has no RPM meter. Then I realized the mill would allow me to do all that testing variable free. With the mill I can set the same depth of cut, same RPM and then use the power feed to apply consistand tool to work pressure. The only thing that will change is the power supply and the starting RPMs (in different tests) three tests per power supply 200, 600 and 1000. I will monitor the RPM drop as an unofficial way to measure torque differences.
Me two but that project is probably out at least a month before I will have video of the build. And then once it is built and I know it works I can do testing and shoot video of that.
@@dazecars yeh, that'll be great. I was thinking of comparing both on my bandsaw as well at first. My gut tells me the pulses of higher voltage may create higher torque, but it'll be really fun to find out. I should have commented from my other channel. I did a treadmill motor bandsaw conversion and some parts for a voltage/current display for an old variac over on my channel "Functional Print Friday".
@@netmagi This channel :)
I meant to say braking resistor .
👍
I have the same multimeter haha
I love that thing. I wish I could find a replacement of the exact same model. I have the older Radio Schack meter and it is not auto shut off so it is way to easy to leave on. I have the model newer and it is completely auto ranging. In other words it "detects" if it is seeing AC, DC or something else and in doing so it doesn't always work as well IMHO if something odd is going on.
@@dazecars I'm even missing the lid for it just like yours 😁
@@fladoodel I worked at two different Radio Shack stores, and even the one we used in each store had its lid broken off.
amazon prime 79.00 no shipping
The one I have linked in the description is actually $69.99
I am a new viewer. I have been subscribed bed for about a week now. I really like the clear , concise approach you take. I became aware of you due to my desire to convert a wood bandsaw to metal cutting capability. I have found I am fascinated by processes taken to accomplish that end. Thank you for presenting this information in a fashion that someone who has almost no knowledge on this subject can understand. I look forward to future videos.
So glad you like my channel. Don't hesitate to reach out of any questions arise in your project. @@williamlanphar630
If you going to test treadmill motors instead of a dynamometer why not a Prony brake. A Prony brake should be cheaper and easier. If you do do this I hope you add a current meter to your setup.
I was not familiar with a Prony brake. I will look into it.
Ayyy
credit where credit is due