# Variable Speed Atlas 6" lathe progress



## minsk (Jan 27, 2019)

I thought it would be nice for others to see my Atlas 10100  6" conversion to a variable dc motor. I am starting with a MC 60 controller and a 2 hp dc motor. Here is a sneak peak of the control panel.I really do not want to compromise the original casting so i will probably just velcro the control box. The new control box will  have the ability to do forward and reverse. The tach will show spindle speed.


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## markba633csi (Jan 28, 2019)

2 hp is way overkill, are you going to be making prop shafts for ships on that thing? LOL
I'm using a 1/3 hp dc motor on mine with KB controller; plenty of torque
mark


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## minsk (Jan 28, 2019)

markba633csi said:


> 2 hp is way overkill, are you going to be making prop shafts for ships on that thing? LOL
> I'm using a 1/3 hp dc motor on mine with KB controller; plenty of torque
> mark



a 2hp tready motor is actually like 1 hp.  prop shafts...hmmmmm will the fit between centers


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## minsk (Jan 28, 2019)

markba633csi said:


> 2 hp is way overkill, are you going to be making prop shafts for ships on that thing? LOL
> I'm using a 1/3 hp dc motor on mine with KB controller; plenty of torque
> mark



where did you find a 1/3 dc motor?


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## markba633csi (Jan 28, 2019)

Surplus, a lucky find.  Servo motor of some kind- 4 brushes
You don't need to mount the control on the lathe itself- I put mine behind a panel underneath the bench in a handy spot


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## minsk (Jan 28, 2019)

minsk said:


> where did you find a 1/3 dc motor?


do you have any pics of your build?


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## minsk (Jan 28, 2019)

markba633csi said:


> Surplus, a lucky find.  Servo motor of some kind- 4 brushes
> You don't need to mount the control on the lathe itself- I put mine behind a panel underneath the bench in a handy spot
> View attachment 286056


im actually making my st up portable.

my set is based of a 20x20 aluminum extrusion frame...grab and go if i need to


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## matthewsx (Jan 28, 2019)

Velcro....

I just hooked up an Allen Bradley switch that I had laying around to the TECO VFD I'm using on my Seneca Falls lathe. The box already had velcro on the back so I picked up some of that fancy outdoor 15lb rated velcro from the hardware store and stuck it right on the gearbox cover. Not that I'm worried about keeping the lathe original, it just seemed easy and puts the switch right where I need it. I'm using a 1hp Baldor 3 phase motor and so far I'm very happy with the results. I don't need to make it reverse though since I already have a gearbox that does that. Will post pictures soon. Surplus store? My how I miss living in the SF Bay area with all those great ones.

Cheers,

John


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## minsk (Jan 28, 2019)

i find running the motor backwards is easier for cutting off parts..


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## markba633csi (Jan 28, 2019)

We just lost Halted specialties (where I got the motor), the last of the good surplus places.  Wozniak and Jobs used to shop there. 
mark


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## minsk (Feb 3, 2019)

Got the speed sensor all hooked up for the 10100. 3d printed bracket designed in fusion360. Will put the model on my thingiverse page if any others would like so use it in their build. works awesome...just have to to figure out how to wire the tach onto the mc-60 board now.


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## minsk (Feb 7, 2019)

markba633csi said:


> 2 hp is way overkill, are you going to be making prop shafts for ships on that thing? LOL
> I'm using a 1/3 hp dc motor on mine with KB controller; plenty of torque
> mark
> View attachment 286055


how do you get your images to show up big in your post.


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## markba633csi (Feb 7, 2019)

There's two choices when you attach files: thumbnail and full size


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## wa5cab (Feb 8, 2019)

I switched it to full size.


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## mattthemuppet2 (Feb 8, 2019)

minsk said:


> Got the speed sensor all hooked up for the 10100. 3d printed bracket designed in fusion360. Will put the model on my thingiverse page if any others would like so use it in their build. works awesome...just have to to figure out how to wire the tach onto the mc-60 board now.
> 
> 
> 
> ...


 cool bracket and build, but I'd suggest putting the tach pickup on the spindle so you can read actual spindle speed. Otherwise changing pulley ratios or using the back gear will result in a different spindle speed (what you care about really) for the same motor speed. I simply 5-min epoxied a magnet to my pick up and stuck it next to the outer spindle bearing, with another magnet on the spacer between the gear and rear bearing.

as for motor power, I can slow down my 1hp treadmill motor on my 618 with heavy cuts, though the crappy link belt will slip shortly after. The MC60 controller doesn't have as fine a response to load as a VFD would. Plus using a wide range of motor speeds to get the most of the variable speed, will considerably change the power the motor is putting out (less as speed drops)


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## wa5cab (Feb 9, 2019)

I would probably use an eddy current sensor on the bull gear.  62X the resolution.


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## minsk (Feb 9, 2019)

Finally Got all the electronics working correctly...the wall wart  psu and block terminal were key in getting the tach to work  nicely.


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## minsk (Feb 9, 2019)

wa5cab said:


> I would probably use an eddy current sensor on the bull gear.  62X the resolution.


hmm eddy current sensor...never heard of that.


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## minsk (Feb 9, 2019)

mattthemuppet2 said:


> cool bracket and build, but I'd suggest putting the tach pickup on the spindle so you can read actual spindle speed. Otherwise changing pulley ratios or using the back gear will result in a different spindle speed (what you care about really) for the same motor speed. I simply 5-min epoxied a magnet to my pick up and stuck it next to the outer spindle bearing, with another magnet on the spacer between the gear and rear bearing.
> 
> as for motor power, I can slow down my 1hp treadmill motor on my 618 with heavy cuts, though the crappy link belt will slip shortly after. The MC60 controller doesn't have as fine a response to load as a VFD would. Plus using a wide range of motor speeds to get the most of the variable speed, will considerably change the power the motor is putting out (less as speed drops)


im curious what the real speed diff is... perhaps ill do a test.


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## mattthemuppet2 (Feb 12, 2019)

you can work it out using the pulley ratios (or back gear ratio, whatever that is). A 2:1 pulley reduction with a 4000rpm motor at full speed = 2000rpm at the spindle. A 10:1 reduction at the same motor speed = 400rpm. Seems like an odd workaround when you can simply put the tach pickup on the spindle and read the speed directly.


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## minsk (Feb 12, 2019)

i didnt want to tap the chassis at all. im still designing.


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## mattthemuppet2 (Feb 12, 2019)

no need to, I simply epoxied a magnet to the tach pickup and that attaches to the rear bearing cover.


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## minsk (Feb 12, 2019)

mattthemuppet2 said:


> no need to, I simply epoxied a magnet to the tach pickup and that attaches to the rear bearing cover.


do you have any pics?
thank you for your input.


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## mattthemuppet2 (Feb 13, 2019)

here you go






it was meant to be temporary while I made a bracket. That was 3 or 4 years ago now


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## minsk (Feb 13, 2019)

ahhhh. hmm my spindle set up is diff...i think ill revisit my setup. i can still 3d print a front spindle holder 

thanx matt!


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## mattthemuppet2 (Feb 13, 2019)

that's true, I forgot that you had a Mk2. I've no doubt you'll be able to come up with something!


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