# variable speed motor on a myford



## firebird (Dec 30, 2011)

Hi

Well santa was really good to me this year, my wife got me a new motor and inverter/controller for my Myford lathe. I spent the last day fitting it. I haven't done any real work on it as yet but I can see the benefits already. Unbeleivably quiet, smooth and of course variable speed. Heres a few photos.
































Cheers

Rich


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## arnoldb (Dec 30, 2011)

;D Very nice Rich!

Sure brightens up things; from what I can see from your windows there it looks cold & wet outside!

Kind regards, Arnold


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## lazylathe (Dec 30, 2011)

Looks like a great set up and addition!!

Would love to see a video someday of it powering up!
Must make the setup a lot quieter!

It is white outside my window at the moment!

Andrew


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## firebird (Dec 30, 2011)

Hi Arnold

Yeah not very nice out today.

Andrew, I'll sort out a bit of video for you. It has a soft start, 6 seconds to build up the speed so very quiet and smooth.

cheers

Rich


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## chuck foster (Dec 30, 2011)

if i didn't know you better rich i would think that nice shiny myford has never done any work..................how do you keep it so new looking ??? :big:

the new motor should be a nice improvement to the lathe.

cheers and all the best in the new year

chuck


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## firebird (Dec 30, 2011)

Hi Chuck

I can assure you it doesn't normally look that clean. Too fit the motor I unbolted the lathe from the bench and turned it round so it had a strip down and thorough clean up while I could get at it. It wiil be a while before it gets that sort of treatment again.

Cheers

Rich


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## steamer (Dec 31, 2011)

Hey Rich. That looks great!

What's the range of that motor/controller?  My big old Logan has a variable speed pulley set up, but is a bit noisy and the big wide V belts are expensive. Makes me wonder if the next belt go around, if I shouldn't go this route.

Do they come in 2hp units?

Dave


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## firebird (Dec 31, 2011)

Hi Dave

There are several companies that market this type of kit, I chose this one because I had a chance to speak to them at a recent model engineering exhibition. I believed there sales pitch (rightly or wrongly) that they were the best.

http://www.powercapacitors.co.uk/Power_Capacitors_Site/IMO_Inverter_Downloads.html

The range is from virtually zero to maximum. The guy did explain though that it is not a substitute for the lathes own gearing. In the case of the Myford you cant simply fit the belt on to the fastest set of pulleys and run the lathe from there. It will run from almost zero to maximum but you lose torque at the lower speeds. You can pre set the maximum speed on the digital inverter by the way. The Myford having plain bearings should not be over run, I have my top speed set at around 690rpm. With the belt in the middle of the 3 pulleys the max speed is around 360rpm. The beauty of this set up is you can vary the speed by 100rpm or so to get the best cutting speed.

Cheers

Rich


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## steamer (Dec 31, 2011)

Does it also have a braking function?.....not waiting for a lathe to spin down is a nice thing....provided it doesn't spin the chuck off!...

Dave


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## firebird (Dec 31, 2011)

Hi Dave

Yes it does have that feature. By default it is set to have a 6 second soft start and wind down so I have left it at that for now. You have to go into the function settings on the inverter to change the peramiters.

Cheers

Rich


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## Ned Ludd (Dec 31, 2011)

Hi Rich,
Don't be afraid to go into the functions and change some settings. Although come to think of it you must have gone there to activate the remote switch box. 

The default 6 seconds sounds a bit long, try 1.5-2 seconds for both ramp up and ramp down as it saves a lot of time if you are continually stopping and starting to take precise measurements.
I appreciate that you hid the magic box for safety reasons, but it is quite helpful to be able to see the frequency readout, so you can better judge the speed of your lathe. 
Pete at Power Capacitors is a nice chap to do business with, that is why I bought two of his units, and he was very helpful recently when I had a problem with my VXR unit.
Thinking of the remote switch box, do you think it would be better if the red stop button was proud and not recessed? I have a thought to glue a red disc to the off button, to make it easier in an emergency.
Ned


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## Stan (Dec 31, 2011)

Steamer: The folks on the Logan boards say the same thing about converting the varidrives to variable speed motors. You still need a mechanical speed reduction between the motor and spindle.


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## HS93 (Dec 31, 2011)

I have a Newton-Tesla set up and one thing to watch out is the ramp down because we both have screw type chucks you can end up with a bowling ball going down the shop .

http://www.newton-tesla.com/index2.htm

Peter


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## steamer (Dec 31, 2011)

Stan  said:
			
		

> Steamer: The folks on the Logan boards say the same thing about converting the varidrives to variable speed motors. You still need a mechanical speed reduction between the motor and spindle.




Oh I figured I wouldn't be able to "bypass" the back gears.....but was curious.

She's still running well .......no urgent need to do something rash.

Dave


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## Stan (Jan 1, 2012)

Steamer: Not just the back gears but a belt reduction similar to all the belt driven lathes. Most are in the four or five to one ratio between the motor and an intermediate shaft. Lots of people have tried a VFD motor bypassing the first belt reduction without success. You have lots of speed control but not enough HP. The varidrive is just a continuously variable mechanical speed control while the motor runs at full power output.

My apologies for highjacking the thread!


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## steamer (Jan 1, 2012)

Yes Stan...I'm aware.

Thank you

Dave


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## firebird (Jan 1, 2012)

Hi

I haven't fully explored all the functions in the set up as yet but i was advised about making the slow down too quick because of the screw on chuck.

Cheers

Rich


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## el gringo (Jan 1, 2012)

Does not reverse tend to unscrew the chuck also?

Ray M


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## lordedmond (Jan 1, 2012)

quick stopping does unscrew the chuck take it from one who knows ;D


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