Replacing with Brush or Brushless DC motor

[Steamchick]

The analogy is a development of transport motors.
Once upon a time we had horses mules and oxen to power our carraiges and machines. One gear, good torque, easy controls. But high maintenance.
Then steam power. Not very efficient, especially at smaller sizes. Excellent low speed torque, but generally large plant, and for powering machines we had step belt drives to vary speed and have low speed torque and high speed for smaller diameters. Locomotives had single speed direct drive.
Along came electric motors. For smaller applications and transport like trams and locos we stepped the voltage to vary motor speed to optimise torque and speed.
Along came Infernal Combustion Engines. While some had automatic (stepped gearbox).transmissions and hydraulic torque converters, others had manual step gear changes. Machines also want down the route of gears with stepped torque-speed variation., using a constant speed electric motor.
But now transport is returning to battery electric, using clever electronics to give "seamless" variable speed optimising the motor to speed required. And machines are doing the same.
What goes around comes around, with th nice advancement.
K2

 

[Steamchick]

Dave, I finally cut some metal. but then remembered your request.
I made a short a video of the running machine. But 136Mb will not load.
Suggestions?
K2

 

[ddmckee54]

You could post it on a 3rd party site, like YouTube, then post a link to that site. I use Google photos for the pictures that I post, but there are other similar sites out there. I don't do videos so I don't know if that would work for videos, I imagine that it would. My Google photos is a free account so I keep usage to a minimum. I've got something like 380MB used and 17GB available yet before they want me to pay for additional storage, so 136Mb would be no problem for storage. I think Imgur is also free if you don't like Google.

If you go this route, be sure that you share the album where you store the video. Otherwise, YOU will see the video, but NOBODY else will be able to see it. This information falls under the category of DAMHIK, but it is definitely something that you NEED TO KNOW. (Took me a while to figure that one out, and I still forget it now and then.)

 

[SmithDoor]

Dave, I finally cut some metal. but then remembered your request.
I made a short a video of the running machine. But 136Mb will not load.
Suggestions?
K2

I gave up on videos
It to mush hassle so I just use photes for a simpler life.
There is software the will reduce the size.
I do like seeing videos
I had make video about 2 weeks ago for a warranty and change format for emailing.

Dave

 

[NapierDeltic]

Hi Steamchick.
You can use VLC to shrink the size considerably. It is not difficult and there are tutorials (Media/ convert/ save.....).
I don't pretend I chose the best option but I usually select Video for MPEG4 1080p... - enough resolution.
Attention: when conversion window closes, you have to press Play (or Rec -not sure) and to wait for the entire duration of video in order conversion to be made - at least this is how it works for me; I'm not an expert.

 

[SmithDoor]

The analogy is a development of transport motors.
Once upon a time we had horses mules and oxen to power our carraiges and machines. One gear, good torque, easy controls. But high maintenance.
Then steam power. Not very efficient, especially at smaller sizes. Excellent low speed torque, but generally large plant, and for powering machines we had step belt drives to vary speed and have low speed torque and high speed for smaller diameters. Locomotives had single speed direct drive.
Along came electric motors. For smaller applications and transport like trams and locos we stepped the voltage to vary motor speed to optimise torque and speed.
Along came Infernal Combustion Engines. While some had automatic (stepped gearbox).transmissions and hydraulic torque converters, others had manual step gear changes. Machines also want down the route of gears with stepped torque-speed variation., using a constant speed electric motor.
But now transport is returning to battery electric, using clever electronics to give "seamless" variable speed optimising the motor to speed required. And machines are doing the same.
What goes around comes around, with th nice advancement.
K2

I think most is thinking a pm brush motor is a cheap motor.
The brushless is lower cost to manufacture.
Three phase motors are lowest cost to manufacture of all motors. But they ard not lowest to buy. Typically they use high quality bears and wire.

Dave

 

[SmithDoor]

Dave, I finally cut some metal. but then remembered your request.
I made a short a video of the running machine. But 136Mb will not load.
Suggestions?
K2

How lathe running with new motor working on low speed?

Dave

 

[Steamchick]

Hi Dave, I have been away for a holiday. I shall probably be back in the workshop on the weekend.
See: https://www.homemodelenginemachinis...ou-been-doing-today.34299/page-47#post-415202

K2

 

[SmithDoor]

Hi Dave, I have been away for a holiday. I shall probably be back in the workshop on the weekend.
See: https://www.homemodelenginemachinis...ou-been-doing-today.34299/page-47#post-415202

K2

This about best graph I found for the brushless motors .
For speed from 100 rpm to 2,000 rpm or motor speed from 300 rpm to 6,000 rpm is a frequent of 5 cycles per seconds to 100 cycles per seconds.

The graph is used for 60hz motors up to 120 hz or cycles per seconds.
Top motor speed 7200 rpm

This about best I could find.
You see there is a top torque not high speed but middle.

Dave

 

[SmithDoor]

Here is photo of a Cat forklift had a little twist.
I am taking photo
The forklift weighted 35,000 pounds before the counter weight is add in back.
The forks are 8 foot [2.44 meters] long and 3½" [89mm] thick . The engine is a Cat 3208

Dave

 

[Steamchick]

I guess you straightened the twist...
I had a twisted back in the mid-70s. Given me gype (jip?) all my life. I know how the forklift feels! Can you straighten that as well? - I weigh less than 200lbs. But I am not painted yellow.
I run on Chips n Beer, not diesel. Don't look as good as your rig though.
K2

 

[Steamchick]

Dave, Post#49. Thanks! Interesting!
Looks like the motor over 3600rpm will be starting to lose torque, to 50% at max speed. As my motor has a max speed of 6000rpm, but the lathe is designed for max 4500rpm Motor speed, I'll be holding reasonable torque all the way. (only dropping to 2/3rds torque is I control to 3/4 max speed). - I guess it is a square function of frequency versus power above the input frequency from the mains? (Below mains frequency - Full torque, but current limited by voltage-control so a flat curve of the current limiter? Above mains frequency the power supply cannot deliver the power (current) through the switching inverter from the DC rectified mains due to some voltage limitation?). But I should have no problem as the lathe was designed so to go faster at the main-shaft, the belt swaps to the higher speed ratio that halves the spindle torque anyway, so actually less torque than this motor will do if I go to 6000rpm (Top speed).
If I get issues I'll write about it. (Silence is Golden - rule).
K2

 

[SmithDoor]

Dave, Post#49. Thanks! Interesting!
Looks like the motor over 3600rpm will be starting to lose torque, to 50% at max speed. As my motor has a max speed of 6000rpm, but the lathe is designed for max 4500rpm Motor speed, I'll be holding reasonable torque all the way. (only dropping to 2/3rds torque is I control to 3/4 max speed). - I guess it is a square function of frequency versus power above the input frequency from the mains? (Below mains frequency - Full torque, but current limited by voltage-control so a flat curve of the current limiter? Above mains frequency the power supply cannot deliver the power (current) through the switching inverter from the DC rectified mains due to some voltage limitation?). But I should have no problem as the lathe was designed so to go faster at the main-shaft, the belt swaps to the higher speed ratio that halves the spindle torque anyway, so actually less torque than this motor will do if I go to 6000rpm (Top speed).
If I get issues I'll write about it. (Silence is Golden - rule).
K2

The cycle for 4,500 rpm is 75hz

Dave

 

[NapierDeltic]

Dave, Post#49. Thanks! Interesting!
Looks like the motor over 3600rpm will be starting to lose torque, to 50% at max speed. As my motor has a max speed of 6000rpm, but the lathe is designed for max 4500rpm Motor speed, I'll be holding reasonable torque all the way. (only dropping to 2/3rds torque is I control to 3/4 max speed). - I guess it is a square function of frequency versus power above the input frequency from the mains? (Below mains frequency - Full torque, but current limited by voltage-control so a flat curve of the current limiter? Above mains frequency the power supply cannot deliver the power (current) through the switching inverter from the DC rectified mains due to some voltage limitation?). But I should have no problem as the lathe was designed so to go faster at the main-shaft, the belt swaps to the higher speed ratio that halves the spindle torque anyway, so actually less torque than this motor will do if I go to 6000rpm (Top speed).
If I get issues I'll write about it. (Silence is Golden - rule).
K2

For large diameter machining you have to reduce surface speed so motor RPM; so you gain torque. That's good!

 

[SmithDoor]

For large diameter machining you have to reduce surface speed so motor RPM; so you gain torque. That's good!

That is very true with brush motors. Lower speed great torque.

The AC or brushless is more consistent torque. What do have how much the torque may or may not increase. By graph I found on internet it is nothing.

That would problem with larger lathes but they gears.

With mini lathes there only so mush you torque you can get from belt.

The bottom line is the brushless has no maintenance for 20,000 hour and brush has maintenance at 1,000 to 7,000 hours. The torque is limited by belt and both are equal.
Buying new lathe or replacing the motor because is bad brushless is on top.

If using as power feed the winner is brush for low in torque. But we are working with mini lathe main drive anx the belt.

It took hours to find the differences.

Dave

 

[NapierDeltic]

If I'll replace my mini-lathe motor, I will never throw away my brushed one, but try to use it wisely.
I have 14 happy years machining on mini-lathe. As long as they were...

 

[SmithDoor]

If I'll replace my mini-lathe motor, I will never throw away my brushed one, but try to use it wisely.
I have 14 happy years machining on mini-lathe. As long as they were...

This first year with mini lathe working very well.
Add good tool post and add 1" travel to cross slide.

Dave

 

[NapierDeltic]

Lapping the cross table ways (in fact all of them) was the first and most important of all mods. I have also shimmed the gibs with brass sheet (glued) and increased the number of set screws. Also, as one youtube video mentions, have adjusted them a bit tight. Now it works without play and actually each day runs better and smoother. Of course, I continued with other mods.

Question SmithDoor; could you add that 1" travel without changing leadscrew?
I did it but honestly I cannot remember how. For sure I must have been following some tutorial.
I have later installed Sieg digital readout set that came with its own cross table leadscrew.

 

[SmithDoor]

Lapping the cross table ways (in fact all of them) was the first and most important of all mods. I have also shimmed the gibs with brass sheet (glued) and increased the number of set screws. Also, as one youtube video mentions, have adjusted them a bit tight. Now it works without play and actually each day runs better and smoother. Of course, I continued with other mods.

Question SmithDoor; could you add that 1" travel without changing leadscrew?
I did it but honestly I cannot remember how. For sure I must have been following some tutorial.
I have later installed Sieg digital readout set that came with its own cross table leadscrew.

There three different ways I look at one was
1) to mill part carriage and add a exstension to screw
2) Add a exstension to the screw, modifie the old one and and move nut.
3) make new screw and move nut.

I have made other cross slide screw pass it not hard to and all one piece and move nut. Works great.

FYI The screw on factory screw are short and ghey made a longer nut to add about ½" to travel

Dave

 

[NapierDeltic]

Thank you, Dave!
The fact is I see recent videos where maximum gain is 15mm of travel (by milling the slide); a bit more than 1/2". Could be this due to longer nut than before?
I haven't changed position of my nut.

Later edit: I found this very interesting:

Sorry for off topic.