# MC-60 PWM Controller Modifications



## Chucketn

I am cross posting this question to several forums.
I have 2 Proform MC-60 treadmill motor controllers, one of which is currently running my X2 mill with its (from the treadmill) 2hp motor.
I have it set up with the original heavy choke, and the original line switch/circuit breaker from the treadmill, and a 5k pot from radio shack for speed control. It works, but still has the soft start feature, and the pot must be turned up about 50% to start the motor. I found some instructions for modifying this controller to remove the soft start, and one that supposedly will allow setting speed and being able to turn the motor on and off at the last speed setting. Only problem, the controller schematic provided with these instructions, doesn’t seem to match the Proform MC-60 I have.
Has anyone modified this controller to remove the soft start? Will a 10k pot make the speed transition smoother?
I have a data sheet on the controller from Surplus Center which pictures the board and shows the connections, but not a proper schematic.

Chuck in E. TN


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## Rbeckett

I am a member at All About Circuits and it is a great source of electronic info.  If you need assistance registering please let me know and I will be glad to assist you in any way possible.  The MC-60 is very very common and has a long list of mods so if you get lost let me know.  AAC is the "Hobby Machinist" of the electronic world.  A very colegial and well run forum that has a great depth of knowledge.
Bob


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## Chucketn

I have joined the "All About Circuits" forum and have downloaded those files. Thanks for the link.
I also have found an old post from rec.crafts.metalworking that listed a couple of mods to the MC-60 controller to remove or lessen the soft start. One was clipping a resistor RPS3, and the other was removing Q7 and C7. I did all 3, but the motor became jerky in operation and made a loud humming noise.
I reinstalled Q7 and C7, but not RPS3, and operation was restored to that previous, except the motor starts with less turns from 0 position.
I get spindle speeds from around 50-60 rpm to 2700 rpm as it is now and can shut off the motor via removing the AC anywhere abouve about 300 rpm spindle speed and the motor will return to same speed when I turn it off and back on. Any lower than that I have to turn the speed pot up to get the motor started and then adjust speed.
Any other info or ideas? One mod from rec.crafts.metalworking  lists removing transistor T3 to eliminate the soft start, but all transistors on both boards are labled Q#. The two MC-60's I have are different revisions (G, and J)and some of the components are in different locations, but all connections to the board and the IC's and transistors are the same.

Chuck in E. TN


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## jbjoestjr

I just came across an old treadmill 2 hp motor and MC 60 controller and just started looking for info on why it won't run the motor. So far the only thing I have noticed is the SCR trigger led isn't doing anything nor is the CUR LIM led lit. Other two LEDs are on, done all continuity checks on motor, transformer and wiring so I am down to the board.
The old machine sat outside for awhile because it was headed for the dump but worked prior to being stuck out on the patio.
I am pretty good with electricity and have a good understanding of motors both AC and DC, but a rookie at circuit boards.
Most of them I have fixed has been by just replacing visually burnt or damaged components.
My goal is to try this motor on my benchtop mill, I am sick of changing speeds by belt changes. Mill is a 2 hp Rong Fu by Shop Fox. 
Besides I am a die hard tinkerer.
Thanks


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## Chucketn

jbjoestjr said:


> I just came across an old treadmill 2 hp motor and MC 60 controller and just started looking for info on why it won't run the motor. So far the only thing I have noticed is the SCR trigger led isn't doing anything nor is the CUR LIM led lit. Other two LEDs are on, done all continuity checks on motor, transformer and wiring so I am down to the board.
> 
> Thanks



How have you tested the board? You will need a 5K ohm linear pot connected to the board in place of the console control for testing/operation. This controller, as most if not all treadmill controllers, has a 'soft start' feature. The speed control pot must be set to zero and increased again to start the motor to prevent throwing the user off the treadmill. I tried finding a way to defeat that feature on the MC-60, but was not sucesasful. Instead, I added a Hall effect speed pickup/input to my DRO and use that to reset the speed when starting. Hope this helps.
I've gotten used to the soft start and it's second nature now.

Chuck


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## jbjoestjr

chucketn said:


> How have you tested the board? You will need a 5K ohm linear pot connected to the board in place of the console control for testing/operation. This controller, as most if not all treadmill controllers, has a 'soft start' feature. The speed control pot must be set to zero and increased again to start the motor to prevent throwing the user off the treadmill. I tried finding a way to defeat that feature on the MC-60, but was not sucesasful. Instead, I added a Hall effect speed pickup/input to my DRO and use that to reset the speed when starting. Hope this helps.
> I've gotten used to the soft start and it's second nature now.
> 
> Chuck



Hi Chuck,
I am testing these with the original wiring harness minus speed sensor, which does not seem to connect to anything but the digital readout board, though I have wondered if somehow beyond what I can see the speed pickup signal gets back to the MC60.
Since my last post I have bought two more 50 dollar treadmills and ironically they were both Sears Pro-forms and have the same 2 hp motors and MC60 controllers as the first one I started with, which came off a Weslo. The MC60 controllers are different part #s but all revision J and have the same resistors snipped. So now that I know I can make them work outside of the treadmill, I am back to trouble shooting the first MC60 to see if I can repair it and have a backup or extra controller to experiment with. My original goal was to get one of these for my drill press and the other for my Rong Fu 31 mill.

I am very curious as to how you use the hall effect sensor connected to the DRO to reset the MC60? Isn't hall effect the one that creates a small electrical pulse, and how does this get back to the MC60? Does it connect to the Pot and show it a on-off-on signal to reset it without actually moving the Pot. 

And do you think I will have any problem with just using a DPDT 15 amp toggle switch to reverse the motor? It should handle the load OK?

The other thing I am working on is to make a dual drive system on the mill where I can quick change from the original 2hp AC 220 volt motor over to the DC motor quickly, by building an intermediate shaft that has both motors connected to it by belt and shift cog between the two driven pulleys to drive the shaft which drives the original step pulley system on the mill. This would also enable me to have two extremely different speed ranges by using different input drive ratios to new intermediate shaft. Something like 10 to 1500 rpm and the other 1500 to 20000, leaving the original step pulley system intact. Though I do not know how stable the Rong Fu spindle would be at higher speeds? If I really get crazy, I have some small self contained hydrostatic transmissions from old equipment I use in my business I could put in the drive system.
I am much better at mechanical than I am at electronics so that is why the dead MC60 has become the challenge of the day, even though I know it is not worth the time to repair, it is more in "Can I Fix It". 

Thanks for the Input.

Goodbye for now


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## Chucketn

I don't reset the controller with the hall effect. I use the hall efect and a magnet epoxied to the spindle as a rpm input to my Shumatec 550 DRO. I still have to turn the speed down and back up to restart the motor.
The DPDT sw sounds o.k. Just check it for getting hot when running. Does the switch have a center off?

Got to run to Knoxville for a while. Be back this afternoon.
Chuck


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## Kernbigo

Cut the center wire on the pot ( wiper) and wire in your motor start and atop switch, now you start at the speed you left it at.


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## Chucketn

Kernbigo said:


> Cut the center wire on the pot ( wiper) and wire in your motor start and atop switch, now you start at the speed you left it at.



Can you explain where to put the start and stop switch and what kind of switches you used?

Chuck


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## Inflight

I've eliminated the soft-start feature on a handful of MC-60 boards, just by clipping the resistor labeled RPS3.  No other mods were required in my situation.

You can create a momentary Jog feature by defeating your potentiometer similar to this drawing:
Please ignore the motor wiring and other connections.  Just consider the POT and JOG components.




Matt


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## jbjoestjr

chucketn said:


> I don't reset the controller with the hall effect. I use the hall efect and a magnet epoxied to the spindle as a rpm input to my Shumatec 550 DRO. I still have to turn the speed down and back up to restart the motor.
> The DPDT sw sounds o.k. Just check it for getting hot when running. Does the switch have a center off?
> 
> Got to run to Knoxville for a while. Be back this afternoon.
> Chuck


The switch I have does have the center off position. 
Have you tried the on-off switch in the white wire to the pot, I seen a guy doing it on you tube and then I heard it again here, to restart at your previous speed setting? 
I am new to DRO, I just finished putting the Mtech three axis on my mill and I put the two axis Mtech on my 13 x 40 lathe a few months ago. I do not know their full capabilities yet.
Can the Shumatec do anything with the RPM reading or is it just acting as the display versus a separate display for the rpm. I was thinking about the speed display off the treadmills, if it could be re calibrated to read rpm.


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## Chucketn

The Shumatec has 3 axis display. To display rpm, you call a function (7) and select the axis (x,y, or z) to display on. There is an ad-on LCD display that could be configured to display RPM, but I didn't get it.
With the tach input it also has a function (8) to display feed rate, again by selecting the function, which axis to read, and which line to display it on. I actually only looked that function up just now after you asked the question. Didn't know I had it! I have also added a power feed on the X axis and it works great with the feed rate fubction.
The Shumatec ids my first experience with a DRO, but I asume these are standard DRO functions such as bolt hole circles and hole grids.
This discovery again makes me glad I purchased the Shumatec!
Chuck


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## Kernbigo

By installing a simple toggle switch in line cut the wiper wire and install it there.( center wire on the pot)


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## jbjoestjr

Kernbigo said:


> By installing a simple toggle switch in line cut the wiper wire and install it there.( center wire on the pot)


Feedrate is something I need to study on. Snapping these small carbide bits to learn their limits is getting expensive. You don't have much feel involved when running a 3/16ths or 1/8 inch tool on the Rong Fu. 
I also put the power feed on the X axis. Is there any way to connect the powerfeed to DRO, or does it just help you calculate the feedrate? Feedrate and chip loads are new terms to me, I thought this was something learned thru experience. I have been cutting metal and fabricating my entire 50+ years but never had any professional machine shop training, since a little in High School which wasn't much more than, this is a lathe, this is a mill, this is how heat treating works and that machinery can hurt you. The later of which I have probably learned the most. Still got all my digits though, so I must have learned something.   

Installing the switch to be able to return to the same speed after shutting the machine off would add some convenience to the swap.
I ran across one article that stated running the DC motor at more than 70 percent of its' rated RPM would cause excess heat. Have you experienced this or heard this before?

I am in the process of deciding what size sheave to use as a driver and what top and bottom speed I want to end up with, any thoughts?

I am also concerned about life span of the motor shaft bearing with any amount of radial belt load on it. I am thinking that I should make a end mount, C face style, for the motor with a bearing more suited to the radial load of the V belt and use a step pulley on it like the factory motor. Even had the thought to connect the DC motor end to end with the 2hp AC motor to let the AC motor carry the belt load and the rotor in the AC motor take the place of the flywheel that comes on the DC motor???? 
I'll be back, gotta go to work!


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## toolfan

I am new to this board, but not new to MC 60 speed controllers and treadmill motors.  I have converted several lathes, bandsaws and drill presses and find these motors extremely useful.  

I just came across another option to the MC 60.  It is inexpensive and seems to work.  I am tempted to purchase a bunch of them, but thought I would ask if anyone else has tried a DC 51 Speed Controller.  Here is a link on ebay https://www.ebay.com/itm/253215421869

This afternoon I received one from China, connected and was impressed with the way that it worked and the compact design.  Soft starting is possible although there is a warning not to start at high speed or the fuse will be damaged.  Soft starting at lower speeds does not seem to be a problem.

Any comments are appreciated.


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## gbfab

toolfan said:


> I am new to this board, but not new to MC 60 speed controllers and treadmill motors.  I have converted several lathes, bandsaws and drill presses and find these motors extremely useful.
> 
> I just came across another option to the MC 60.  It is inexpensive and seems to work.  I am tempted to purchase a bunch of them, but thought I would ask if anyone else has tried a DC 51 Speed Controller.  Here is a link on ebay https://www.ebay.com/itm/253215421869
> 
> This afternoon I received one from China, connected and was impressed with the way that it worked and the compact design.  Soft starting is possible although there is a warning not to start at high speed or the fuse will be damaged.  Soft starting at lower speeds does not seem to be a problem.
> 
> Any comments are appreciated.


     I also bought one of the DC51 controllers this week just to see if it would work.  Wired it up to a 2 3/4hp (1.4hp @ 90v)TM motor and it worked perfect.  Soft start is actually better than the MC60 that I have on my mill.  Just wondering how long it will last.  For $20 ( get a price break if you order more than one) its kind of a no brainer.


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## Ed ke6bnl

will this motor controller start where you left the speed at or do you have to start from 0 and got to a setting?


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## xcookpac

Hello all:

I saw thwe recent posting regarding the DC51 controller.  I found DC-51 motor controllers on ebay as low as about $USD12 (including S&H).  See link at bottom.  However, the DC-51s that I looked over on ebay were all specified as being input of 220V AC with 50hz.  I am in USA where the predominant residential current is 120V AC with 60hz.  I am throwing the following questions out to the group for their comment:

1.  If I input 120V 60hz into a DC51 controller will it likely be damaged permanently?

2.  If I input 120V 60hz into a DC51 controller will I likely obtain maximum DC voltage (most of these controllers are rated for 90V DC maximum)?

3.  Some ebay sellers are selling permanent magnet boards for about $24 which have a maximum power rating of 800W to 1000W  (if the rating is truly backed up by design and components this controller woulod appear to be more robust - although it would need to be mounted in an enclosure).  See link below.  It appears that maximum DC voltage produced by this board will be equal to AC input voltage (my understanding is that 120V AC input will get you 120V DC output).  Would you consider this board a better option than the DC51 controller (it appears so to me)?

PS I believe the maximum power rating for the controller linked in toolfan's post is 400W.  See  https://www.ebay.com/itm/253215421869 



*Link to cheapest ebay DC-51 controller (although listed as controlling 120W maximum) *(I have not tried or ordered this controller - merely set forth as an example of low cost controller): https://www.ebay.com/itm/dc-51-Dc-P...h=item2f246406c1:g:tj4AAOSw~jxbyF18:rk:1:pf:0

*Link to ebay permanent magnet controller board 800W to 1000W maximum with dual voltage settings) *(I have not tried or ordered this controller - merely set forth as an example of low cost controller): https://www.ebay.com/itm/AC-110V-22...h=item4d5ebbde4a:g:H6QAAOSw2kVbfq3E:rk:1:pf:0


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## xcookpac

Q.  "will this motor controller start where you left the speed at or do you have to start from 0 and got to a setting?"

A (my response).  Where the soft start has not been disabled on MC-60 controllers, I defeat the soft start by throwing a drum switch (you could just a dpdt switch instead) between the controller output and the motor.  Drum switch allows for reversal of direction and has three positions as follows: R-N-F.  When I stop using the lathe in the forward or reverse direction, I stop the lathe by shifting it into "N".  Then when I start again, I merely shift the drum switch into "F" or "R" without having a soft start wait.


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## xcookpac

xcookpac said:


> Hello all:
> 
> I saw thwe recent posting regarding the DC51 controller.  I found DC-51 motor controllers on ebay as low as about $USD12 (including S&H).  See link at bottom.  However, the DC-51s that I looked over on ebay were all specified as being input of 220V AC with 50hz.  I am in USA where the predominant residential current is 120V AC with 60hz.  I am throwing the following questions out to the group for their comment:
> 
> 1.  If I input 120V 60hz into a DC51 controller will it likely be damaged permanently?
> 
> 2.  If I input 120V 60hz into a DC51 controller will I likely obtain maximum DC voltage (most of these controllers are rated for 90V DC maximum)?
> 
> 3.  Some ebay sellers are selling permanent magnet boards for about $24 which have a maximum power rating of 800W to 1000W  (if the rating is truly backed up by design and components this controller woulod appear to be more robust - although it would need to be mounted in an enclosure).  See link below.  It appears that maximum DC voltage produced by this board will be equal to AC input voltage (my understanding is that 120V AC input will get you 120V DC output).  Would you consider this board a better option than the DC51 controller (it appears so to me)?
> 
> PS I believe the maximum power rating for the controller linked in toolfan's post is 400W.  See  https://www.ebay.com/itm/253215421869
> 
> 
> 
> *Link to cheapest ebay DC-51 controller (although listed as controlling 120W maximum) *(I have not tried or ordered this controller - merely set forth as an example of low cost controller): https://www.ebay.com/itm/dc-51-Dc-P...h=item2f246406c1:g:tj4AAOSw~jxbyF18:rk:1:pf:0
> 
> *Link to ebay permanent magnet controller board 800W to 1000W maximum with dual voltage settings) *(I have not tried or ordered this controller - merely set forth as an example of low cost controller): https://www.ebay.com/itm/AC-110V-22...h=item4d5ebbde4a:g:H6QAAOSw2kVbfq3E:rk:1:pf:0


I failed to mention that the motor speed control on this board is soldered to the board.  I would likely remove the controller from the board and mount it remotely so that speed control can be adjusted (a definite negative for use of this board).


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## markba633csi

If the DC51 is a true SCR phase control with armature feedback (like the KB controllers) then it's a great deal.  I suspect for that price though it may be a simple light dimmer type unit;  the motor speed would change somewhat under varying loads


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## gbfab

xcookpac said:


> Q.  "will this motor controller start where you left the speed at or do you have to start from 0 and got to a setting?"
> 
> A (my response).  Where the soft start has not been disabled on MC-60 controllers, I defeat the soft start by throwing a drum switch (you could just a dpdt switch instead) between the controller output and the motor.  Drum switch allows for reversal of direction and has three positions as follows: R-N-F.  When I stop using the lathe in the forward or reverse direction, I stop the lathe by shifting it into "N".  Then when I start again, I merely shift the drum switch into "F" or "R" without having a soft start wait.


Just went out and checked the DC-51 I have.   As it comes it turns the motor on at about 1/4 turn and works fine from a dead stop to full rpm.  Set the speed at 50%, turned off the power switch and waited until the motor stopped and then turned it back on. It  started and returned to the same rpm.  Slowed it down to maybe 100rpm and did the same thing and it started ok and returned to the same rpm.


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## gbfab

Ed ke6bnl said:


> will this motor controller start where you left the speed at or do you have to start from 0 and got to a setting?


Yes it does restart to the same rpm.


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## toolfan

gbfab said:


> I also bought one of the DC51 controllers this week just to see if it would work.  Wired it up to a 2 3/4hp (1.4hp @ 90v)TM motor and it worked perfect.  Soft start is actually better than the MC60 that I have on my mill.  Just wondering how long it will last.  For $20 ( get a price break if you order more than one) its kind of a no brainer.


Over the past 2 or so years I have purchased and converted around 20 lathes, drill presses and bandsaws to dc motors using dc51 controllers.  What I have learned is that they are not all created equal.  I would say that around 50% work perfectly but the rest either do not work or do not produce enough torque at low speed to be useful.  The suppliers have been very good at replacing (refunding) for the ones that do not work at all.  Since they are only rated to 400 Watts, perhaps I have been expecting too much.  However the fact that about half of them actually work well is an enigma that I have not yet been able to solve.

What I have done, is use the potentiometer and the box from the defective ones to house a mushroom cap switch and then  wired the pot to an MC 60 like I have done here.


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## markba633csi

The DC51 may not be well protected against inductive motor loads hence the reliability issues.  They are probably intended more for resistive loads like lamps
But for the price they are a bargain even if half of them fail


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## toolfan

You are correct in that they are a bargain except it would be nice to what is different between the ones that work and those that do not.

My theory is that they are just designed for smaller motors.  400 watts is about equal to 1/2 hp.  At full speed there is certainly enough power but at low speeds, the voltage is as low as 10 or 20 volts, so it is difficult to develop enough power.  That's my theory for the ones that do not work.  The ones that actually work seem to adjust, drawing more amperage producing the power.  I had one on a drill press that would actually blow a 15 amp breaker under a low speed load without bogging down the drill.  

I have ordered one of the 800 - 1000 watt boards and look forward to seeing how this one performs.


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## toolfan

Today my 800 - 1000 watt board arrived.  It appears to be well made.  However after I connected the ac power, motor cables and pot, all I got was a green light indicating that the board was hot.  There is a j4 110 220 connector that I do not understand.  Any suggestions?  Thanks

In the item description is says "need to set j4 conversion"


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## Z2V

It sets your input voltage. If you power the board with 110 volts you would bridge the center pin and the 110v pin, if you are using 220 you would bridge it to the 220 pin.
My board came in the mail today also but I haven’t hooked it up yet.


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## toolfan

Thanks!  I didn't realize that there was a sleeve type connector involved.  It came set for 220 and now it is set for 110.  It works now and my first impression is that there is more torque than the dc 51's provide at slow speeds, but still not as much as an mc 60.  This is just my impression based on how difficult it is to bog down the motor at a slow speed.


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## Z2V

While I don’t have an immediate need for it I’ll probably hook mine up this evening just to be sure it works.


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## toolfan

Mine is now connected to a Leeson dc motor running a  little belt sander.  At slow speed I can stop the motor quite easily by grasping the flywheel.  With an MC 60 at about the same speed it is much more difficult to stall the motor.  However, in this application, this control board is certainly adequate.


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## Z2V

My board will spin a motor, that’s good, so back in the box and put it on the shelf until needed.


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## toolfan

I tried to objectively compare the new 800 - 1000 watt speed controller with a DC 51 and an MC 60.  All will bring the motor up to the posted maximum rpm.  At low speed, the MC 60 provides more torque than the 800 - 1000 watt control and much more than the DC 51 (at least this DC 51).  As I have said earlier, they are not all the same.  

For the belt sander, I ended up using the DC 51 as I can not imagine that very low speed grinding is something that I will be doing very much of.


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## DenJon

xcookpac said:


> Q.  "will this motor controller start where you left the speed at or do you have to start from 0 and got to a setting?"
> 
> A (my response).  Where the soft start has not been disabled on MC-60 controllers, I defeat the soft start by throwing a drum switch (you could just a dpdt switch instead) between the controller output and the motor.  Drum switch allows for reversal of direction and has three positions as follows: R-N-F.  When I stop using the lathe in the forward or reverse direction, I stop the lathe by shifting it into "N".  Then when I start again, I merely shift the drum switch into "F" or "R" without having a soft start wait.



Wow that's exactly what I'm trying to do.
I posted the following question on the forum but it sounds like you might be the one with the answer. I was concerned about having the speed controller reved up with no load from the motor on it and whether it would damage the speed controller.

MC-60 treadmill  speed controller (controller needs a load ?)


Any help will be greatly appreciated. I have an MC-60 treadmill speed controller. I'm mounting the motor on a drill press. I put switch on the wipe terminal on the pot and added a reverse switch on the motor leads. I have it geared way down so that I can do some thread tapping. I'd like to have it start and stop immediately. I'm trying to eliminate the soft start and stop. Putting a switch from the board (red wire to the motor) gives me what I'm looking for but I am concerned about whether the board needs the load from the motor. Is it safe for the speed controller to run with a switch on the motor lead?


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## Inflight

DenJon said:


> ... I was concerned about having the speed controller reved up with no load from the motor on it and whether it would damage the speed controller.
> 
> MC-60 treadmill  speed controller (controller needs a load ?)



I've been running an MC-60 for about 10 years on my drill press.  I clipped one resistor on the circuit board so I don't have the "soft start" feature.  I regularly reverse the motor at speed. Never had any trouble.  Those MC-60 controllers are hard to destroy. 

Here is a video I did back in 2010.  youtube MC-60 drill press conversion

Matt
(By the way, I'm just down the road in Olympia now)


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## hman

Matt -
I liked your video!  What resistor did you clip?  I've been running an MC-60 for a couple years now, and sincerely dislike the soft start/soft stop.
Thanks!


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## Inflight

On each of my installations, I clip (remove) the resistor marked RPS3.


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