|
My u90 motor finally gave out after many years of use. So while rummaging around I found a spare 1/4 HP. 1750 rpm AC Marathon motor from my old Taig lathe that I was considering hooking up and using with the Db200. My question is regarding using
a speed controller with the motor. I found one that seems to fit my needs, would probably work with the motor and was still pretty affordable. I would like to ask if their is anything I should look out for using this combination and If it would work. Here
is the motor info and speed controller info.? Do you guys think this would be a good fit? I really would like to run a single belt and have adjustable speed on my little DB200.? Please help.
|
I may be wrong here, but I thought using a DC motor w/power supply makes for easier/better speed control.?
toggle quoted message
Show quoted text
My u90 motor finally gave out after many years of use. So while rummaging around I found a spare 1/4 HP. 1750 rpm AC Marathon motor from my old Taig lathe that I was considering hooking up and using with the Db200. My question is regarding using
a speed controller with the motor. I found one that seems to fit my needs, would probably work with the motor and was still pretty affordable. I would like to ask if their is anything I should look out for using this combination and If it would work. Here
is the motor info and speed controller info.? Do you guys think this would be a good fit? I really would like to run a single belt and have adjustable speed on my little DB200.? Please help.
<Screenshot_20230711_231237_Samsung Internet.jpg><Screenshot_20230710_015423_Samsung Internet.jpg>
|
Before going too far I'd look at how the motor will fit. The usual DC motors will fit without modifying anything, and they are not expensive. The main reason for using the motor you have is that you have it. It looks a bit big, it has more power than you need, the revs are low for a Unimat, and decent speed control would require an inverter to give variable frequency. I'd go for the usual 24 V DC motor, which can be fitted straight on. You can now get variable voltage power supplies, like the usual 24 V PWM supplies, but with the speed control section built in, thus simplifying the electrics. Can't find a link to one at the moment. Otherwise using separate power supply and variable speed units is not too difficult to deal with. Making a case for it all is the biggest problem.
|
Keith has helped me a lot in the past and understands what he is talking about. I don’t think I would have had the knowledge to carry this out on my own without his help.
My Unimat now purrs like a kitten!
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
My suggested solution is different.? You already have a motor.? If you are using the Unimat only as a lathe, mount it on board, and hang the motor at the back.? Buy a Harbor Freight router speed control and use that to control the motor.? This has been mentioned in the past here.?
Yes, DC motors operate well on a Unimat.? But you have to buy a motor, a power supply and controller, mount it all and wire it.? With the Harbor Freight controller, you have spent $17.99 and your motor just plugs in.
|
Hello:
Varying
Voltage on an AC motor is very ineffective. It is worse than
on DC. For an AC motor a Variable Frequency Drive is a better
idea, but is offered mostly for 3 phase motors.
I have
a voltage control on my Smithy lathe and at slow speeds it has
almost no torque. I did buy the "back gear" pulley set that
helps a lot.
Perhaps
a better drive would be an Arduino / motor driver / stepping
motor. You could program the Arduino to control the speed of
the stepping motor and still have full torque.
Carl.
On 7/12/2023 12:54 AM, Keith S. Angus
wrote:
toggle quoted message
Show quoted text
Before going too far I'd look at how the motor will fit. The usual
DC motors will fit without modifying anything, and they are not
expensive. The main reason for using the motor you have is that
you have it. It looks a bit big, it has more power than you need,
the revs are low for a Unimat, and decent speed control would
require an inverter to give variable frequency. I'd go for the
usual 24 V DC motor, which can be fitted straight on. You can now
get variable voltage power supplies, like the usual 24 V PWM
supplies, but with the speed control section built in, thus
simplifying the electrics. Can't find a link to one at the moment.
Otherwise using separate power supply and variable speed units is
not too difficult to deal with. Making a case for it all is the
biggest problem.
|
The HF controller provides enough torque to run a router.? It has been reported here in the past that it works.? So you spend $17.99 and give it a try.? If it is not satisfactory, use it for something else.
|
I'm going to offer another solution, an industrial sewing machine brushless servo motor.? I replaced the 3/4Hp motor on my drill press with a 750W servo motor and I love it - mostly.? These motors are available from 250W up to at least 750W - if not 1KW.? You get a continuous duty servo motor, you set the speed and it will hold there.? And...You get the option to run in reverse if you want to, but that might not be a good thing.
There are some Pros and Cons...
Pros:
1) Variable speed - you can adjust the parameters in the servo drive so your minimum speed is 100Rpm, and the maximum is 4500 Rpm.? (Mine doesn't like to run at 100 Rpm, the motor speed tends to oscillate.? But if I bump the minimum speed up to 300 Rpm it's rock solid.)
2) Cheap - you'll get the motor and drive for about the same price as, or less than, the motor you have listed.
3) Small size - my 1Hp servo motor is probably 1/2 the size of the motor you have listed and it's continuous duty.
Cons:
1) The speed controller that will come with the kit is designed for an INDUSTRIAL SEWING MACHINE,?it hooks up to a foot treadle.? But it can be made to work with minor modifications.? Once you move the speed controller off the neutral position it will vary the speed from the minimum speed setting to the maximum speed setting.?
2) On my setup, the display shows the motor speed to the closest 100 Rpm.? I can live with this - it's just irritating.? I know it's the display that's the issue, because I can vary the motor speed slightly and hear the pitch of the motor change, but the displayed speed does not change.? (But really, what do you expect from a $110 servo kit?)
3) The drive is set up to brake the motor to a stop - REAL quick, on the order of less than 100 milli-seconds.? This parameter is adjustable in my drive and I currently have the brake disabled.
4)?Most of these units use a Hall Effect sensor in the foot treadle to control the motor speed, this complicates replacing the speed control unit with something else. If you modify the original speed controller, you must remember to set the speed to zero when you stop the motor.? If you don't you'll get an error from the drive when you re-start it.??
There are a couple of different videos out there on YouTube that show how to replace the Hall Effect sensor with a speed control pot.??I found an article on the Home Machinist forum, at least I think that's where it was, that showed the schematic for replacing the Hall Effect sensor with a speed pot and also threw in a Run/Stop switch as a bonus.? That's the route?I took.? Now I can run at whatever speed I want, flip the switch to Stop, do whatever I need to do, flip the switch back to Run and I'm back to the same speed as before.? (I do need to remember to flip the switch to Stop before I shut off the drive or I STILL get that same error as mentioned above.)
Don
|
You may want to consider a Consew sewing machine motor. It is a fully controllable servo motor, it comes with all the necessary controls, and it has been used on many small lathes and milling machines.?
120 bucks, price at Amazon:?
|
Shop JUKI at the Amazon Arts, Crafts & Sewing store. Free Shipping on eligible items. Save on everyday low prices.
www.amazon.com
|
95 bucks price at Ebay:?
toggle quoted message
Show quoted text
The HF controller provides enough torque to run a router.? It has been reported here in the past that it works.? So you spend $17.99 and give it a try.? If it is not satisfactory, use it for something else.
|
The Marathon motor used on the Taig lathe is a poor choice for variable speed, even on a variable frequency power supply.? It has a start winding, controlled by a centrifugal switch that will turn on if the motor slows down too much.? This winding is not designed for continuous operation, and will soon overheat.? This motor is designed to operate at a fixed speed, determined by the power frequency.? I rigged up my Taig lathe with a heavier version of the 24 volt scooter motor and pulse width modulated? control used by several people on Unimats.? My motor is a 1/3 hp Dayton 24 volt from an estate sale, connected to a heavy power supply and the usual pwm controller.? The Dayton motor is more powerful than I need for the Taig, but is far smaller and lighter than the original Marathon. It turns up to 4000 rpm, so I only need the slowest 3 speeds on the drive pulley. ? I think a permanent magnet field DC motor and PWM controller will give you the most bang for the buck.? There are several past threads on these conversions for the Unimat, some giving sources for the parts required and the procedures for the conversion.?
Chuck Daldry
|
Single phase AC motors that have a starting capacitor and a running capacitor are not suitable for variable speed. they also have the centrifugal clutch that will stop them dead if they drop below a set speed.?
The best motors for variable speed are three-phase AC motors, controlled via a Variable Frequency Drive (VFD) or a DC motor driven by a variable speed drive. See the two samples below.?
3-phase VFD:?
DC motor control:?
toggle quoted message
Show quoted text
The Marathon motor used on the Taig lathe is a poor choice for variable speed, even on a variable frequency power supply.? It has a start winding, controlled by a centrifugal switch that will turn on if the motor slows down too much.? This winding is not
designed for continuous operation, and will soon overheat.? This motor is designed to operate at a fixed speed, determined by the power frequency.? I rigged up my Taig lathe with a heavier version of the 24 volt scooter motor and pulse width modulated? control
used by several people on Unimats.? My motor is a 1/3 hp Dayton 24 volt from an estate sale, connected to a heavy power supply and the usual pwm controller.? The Dayton motor is more powerful than I need for the Taig, but is far smaller and lighter than the
original Marathon. It turns up to 4000 rpm, so I only need the slowest 3 speeds on the drive pulley. ? I think a permanent magnet field DC motor and PWM controller will give you the most bang for the buck.? There are several past threads on these conversions
for the Unimat, some giving sources for the parts required and the procedures for the conversion.?
Chuck Daldry
|
That is an AC induction motor. You aren't going to be able to
vary the speed with a router speed controller. To vary the speed
of that motor you are going to need a variable frequency drive for
that.
Clues include AC and 1725 RPM, which is a multiple of line
frequency less slip.
On 7/12/23 10:05, John Hutnick wrote:
toggle quoted message
Show quoted text
My suggested solution is different.? You already have a motor.? If
you are using the Unimat only as a lathe, mount it on board, and
hang the motor at the back.? Buy a Harbor Freight router speed
control and use that to control the motor.? This has been
mentioned in the past here.?
Yes, DC motors operate well on a Unimat.? But you have to buy a
motor, a power supply and controller, mount it all and wire it.?
With the Harbor Freight controller, you have spent $17.99 and your
motor just plugs in.
|
Good evening,
I've been using a 550w Husuper Sewing Machine servo motor on my SL for nearly 3 years now as detailed in some of my other posts.
I have nothing but praise for it, I use the lathe practically every day, both as a lathe and milling machine.
It was simplicity itself to fit and set up and is a joy to use.
regards,
David
|
Ebay has a "industrial sewing machine brushless servo motor for Consew sew machine".? It is $93, new.? It is 400-4500rpm, 600 watts.? There is an RPM indicator, buttons P, S, +, -.? It says "the positioner not included.? What is a positioner?? I do not quite understand how to control the speed for lathe use.? Turn it on and press buttons?? Is this the right motor to buy for a Unimat?? Is $93 a good deal?? Thanks for the help.
|
Can you link to the motor and some info on how you mounted it?
toggle quoted message
Show quoted text
Good evening,
I've been using a 550w Husuper Sewing Machine servo motor on my SL for nearly 3 years now as detailed in some of my other posts.
I have nothing but praise for it, I use the lathe practically every day, both as a lathe and milling machine.
It was simplicity itself to fit and set up and is a joy to use.
regards,
David
|
I have one of these motors on my Taig lathe. They are very good and lots of torque and speed. One interesting wrinkle. With the default setting on ramp down time, the motor stops quite abruptly.
?The first time I did it it actually unwound the chuck. A little unnerving the first time it happened. Because the motor has dynamic braking, it stops quite short.
After mounting the motor and running it alone for a few minutes, it is necessary to change the decel ramp down to the highest setting (slowest ramp down). This eliminates about 80% of the problem.
?My motor came with a spring loaded arm. I removed the spring and drilled and tapped the arm for a plastic screw 1/4-20. The screw pushes against the housing to keep the arm at the speed I set it. Now it works great and I manually ramp down the speed before I turn it off.?
toggle quoted message
Show quoted text
On Jul 12, 2023, at 12:44 PM, Steve Johnson <steve@...> wrote:
? Can you link to the motor and some info on how you mounted it?
Good evening,
I've been using a 550w Husuper Sewing Machine servo motor on my SL for nearly 3 years now as detailed in some of my other posts.
I have nothing but praise for it, I use the lathe practically every day, both as a lathe and milling machine.
It was simplicity itself to fit and set up and is a joy to use.
regards,
David
|
A router speed control is designed for an AC/DC motor. It'll burn out a 1/4 HP motor which is fixed speed only (1750 rpm).
24 VDC is the way to go.?
Neil Morrison?
The HF controller provides enough torque to run a router.? It has been reported here in the past that it works.? So you spend $17.99 and give it a try.? If it is not satisfactory, use it for something else.
|
Hi:
The
positioner is a sensor that will stop the sewing machine with
the needle in the up position.
Carl.
On 7/12/2023 12:38 PM, John Hutnick
wrote:
toggle quoted message
Show quoted text
Ebay has a "industrial sewing machine brushless servo motor for
Consew sew machine".? It is $93, new.? It is 400-4500rpm, 600
watts.? There is an RPM indicator, buttons P, S, +, -.? It says
"the positioner not included.? What is a positioner?? I do not
quite understand how to control the speed for lathe use.? Turn it
on and press buttons?? Is this the right motor to buy for a
Unimat?? Is $93 a good deal?? Thanks for the help.
|
On Wed, Jul 12, 2023 at 09:38 AM, John Hutnick wrote:
What is a positioner?? I do not quite understand how to control the speed for lathe use.? Turn it on and press buttons?
Positioner These servo motors were originally designed for industrial sewing machines.? The positioner would be used to stop the motor with the needle in the raised position.? We don't care about the positioner, and I believe that the drive settings default to not having a positioner. Speed control On the sewing machine that these servos were designed for the speed control would be by the foot treadle.? The servo kit contains a Hall Effect sensor that is connected to that foot treadle by a lever arm.? This lever is spring loaded to return to a neutral position.? You can remove this spring and just use the lever to control the servo motor speed.? Once the lever leaves the neutral position and gets beyond the minimum speed point the servo will start running at the minimum speed setting.? Continuing to advance the lever arm will increase the speed of the motor until the motor speed eventually reaches the maximum speed setting.? This lever arm CAN be replaced with a speed pot, but it does require some electronics work to accomplish this - it's worth the effort though.? Buttons The buttons are used to change the motor direction, and/or modify the servo drive parameters.? These are CHEAP servo drives so there's not a lot of parameters that they let you play with.? The only parameters the I've changed in my servo drive were for the minimum speed, the maximum speed, and the brake.? My drive had what it called a brake effort parameter that defaulted to 1, the range was 0-5.? I set this to 0 and now my motor coasts when I change speed instead of braking.? If I've got the motor at speed, when I flip the Run/Stop switch to Stop the motor it will coast down to the minimum speed and then brake to a stop.? I haven't been able to figure out how to get it to coast to a stop, so I keep my minimum speed set at 100 Rpm. Good deal? A servo motor and a servo drive for $100-ish is a great deal.? Yeah it's Chinese, but what isn't anymore? Is it the right motor for a Unimat? MAAAYBEEE?? You can get sewing machine servo motors from 250W up to 750W.? The 750W is what I've got on my drill press.? I think you can probably even get a 1KW version of these servo motors.? Most of our Unimats started out their lives with U90 motors, or U100 motors if you were lucky, those were 90W and 100W motors.? Most of the DC scooter motor conversions were 150-250W motors.? Just because you've got the extra power doesn't mean you HAVE to use it.? That's one of the reasons the Uni has a belt drive, to keep it from hurting itself.? I mean it's not like we're putting a 3Hp motor on a Chinese mini-lathe is it? Don
|
I am using a 24v DC scooter motor with a power supply and speed controller on my DB200 lathe. Unbelievably quiet and smooth running.
Actually, I have two of these. The second motor is used on my vertical milling setup. If I recall correctly I paid about 25$ each for the motors on EBay a couple of years ago.
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
Steve Johnson
OldToolmaker
Carl
Tool247