[rusmannx]

My motor burned up this week, so I figure it's time for an upgrade and a belt drive. I have a couple of those huge 3.8HP DC treadmill motors and a KBMM-225D-KB for the drive (plus heatsink, and all that other stuff), but I have also this 2.2kw (3HP) spindle motor and VFD (like this Sanven Water-cooled Spindle Motor 2.2kw Inverter Vfd 2.2kw Variable Frequency Drive 8000-24000 R/min, More Precise, Collet: Er20(4mm, 6mm, 8mm, 12mm, 12.7mm) - Power Spindle Sanders - Amazon.com).

I have been planning to run the spindle motor on the side of the head, but maybe it would also work as a drive motor and mount a pulley to it instead. The spindle is rated at 24kRPM, and I have no idea what RPM the DC motors run up to.

The two DC motors are a bit rough, and are going to take some work to get running (both took damage in shipping). The spindle motor is quite a bit lighter, so that would be nice. I have no idea if the spindle would work well as a driving motor for the actual spindle in the mill. Any thoughts?

Left to right is two 3.8HP DC motors (I have a controller for it too), the spindle motor, and the stock G0704 motor on the right.
Attachment 243416

[Al_The_Man]

They are both different animals, one is a 24krpm and the other being a DC motor is going to be limited to at best, 4krpm.
DC motors are fine in the lower end rpm, and the best drive for them are the KB or other, PWM version drives, the KB225D is not a bad drive, but the 1ph SCR drives are not as smooth a quiet a control as the PWM drive versions or a 3ph SCR drive.
Usually the High rpm water cooled induction motor type are limited to a fairly high minimum rpm, due to their low inductive reactance at lower rpms.
Not observing the minimum usually burns them out.
Al.

[rusmannx]

Thanks for the info.

I have read that people have been able to run this spindle as low as 200 RPM at 10amps, but if I did a 3:1 reduction 600RPM would be the same result. Its water cooled so I think if I could keep the water cooled fast enough, overheating may not be a problem.

[dwalsh62]

While it would be ideal to find a really cheap solution to this age old problem of powering your spindle, it's just not realistic if you need/want a solution that has good performance characteristics and almost zero maintenance (you have to clean the air-filter on occasion).

Those high-RPM spindle motors you see all over e-bay don't perform well below 3,000RPM and most don't recommend operating below 6,000RPM, anyone telling you they operate it at 100RPM is not telling you the truth, do the math, required thermal dissipation at 6Hz (300RPM) for a typical china 2-pole (18,000RPM or 24,000RPM) water-cooled spindle motor is 135W/cm2 requiring 23.15cuL/sec, at 60Hz (3000RPM), 42W/cm2 requiring 2.89cul/sec and most inexpensive pumps are in the range of 5L to 100L per minute so it's obviously not designed to run at such low speeds which is why people burn them up.

Yes, you can add a chiller making the thermal transfer co-efficiency higher (a bigger fan and bigger radiator) reducing the required flow but now your adding expense to make your unsuitable solution work for you so your $500.00 solution just got more expensive without improving it's performance (your spindle and VFD cost $400.00 and you spent $100.00 on a cooling system).

Asynchronous Servo Spindle Motors that are specifically designed for VMC's and milling machines will offer you the best performance for your dollar and despite popular belief, they are available in small/lighter packages.

A typical Asynchronous Spindle Servo Motors in the 1.5KW - 2.2KW power range weigh in at about 50lbs to 60lbs and are quite large in size (140mm x 140mm x 480mm is the smallest I could find), so utilizing these monstrosity is cumbersome and difficult at best and too large for most bench-top or home/hobby machines.

There are options in smaller packages and lighter weights but sourcing isn't easy as these products aren't generally offered in the retail market and usually have MOQ's associated with purchasing.

This is what I've been running for a few weeks now and wish I had done this years ago.

Motor Specs: (real) Asynchronous Servo Spindle Motor

• 1.12KW (1.5HP) Constant Velocity / 1.5KW (2HP) Constant Torque.
• Input: 157VAC-3PH / 220VAC-3PH @6.81A
• RPM: 12,000.
• Duty: S1@8,000RPM, S6@12,000RPM.
• Cooling: External 220VAC Electric Fan.
• Foot-Print: 95mm x 95mm x 240mm
• Shaft DIA: 22mm with 6mm keyway (standard).
• Encoder: Optical A/B/Z - 2500PPR
• Net Weight: 18lbs
• Supports Rigid Taping.
• Supports Orientation

I've been running this with a VFD sample I was trying to produce that didn't fund on KS, it has 4 programmable orient positions and a true servo mode, I've had no issues doing anything with this motor, RPMs from 120 to 12,000 are stable due to closed-loop tracking, in servo mode, positioning is accurate within 3ppr and in orient mode it's also less than 3ppr (5ppr is the default position auto-error correction margin, can be changed in the VFD) of the target position.

I've managed to have a manufacturer produce a single-phase input VFD with PG card and four programmable orient positions in a 2.2KW power range making it ideal for this motor and a sample is expected to arrive in about 38 more days with a price tag of $500.00 plus shipping.


At about $1K for the combo it's the best bang for the buck all things considered and it would be impossible for anyone with intelligence to conclude that a 3.8HP brushed DC motor solution could even come close to offering constant torque over such a broad RPM spectrum that can be achieved from an asynchronous spindle servo motor because low RPM is derived by lowering the voltage thus reducing torque to a point that it's just not effective.


Forget Yaskawa VFD's if your on a budget, even a new Delta VFD-VE (3PH input only as single-phase units were never produced) with PG card that will run on single phase 220V (derated) with sufficient power (5.5KW needed for 1.5KW-2.2KW motor) will run you over $800.00 plus shipping, used is less and sometimes old-stock can be found but sourcing the motor is where you run into difficulties as it's not likely you have a local source for special application motors and it's not something you will see advertised in your local hardware store.

Yes, a couple of people might find something suitable on ebay in the way of a mitsubishi VFD with PG card but it is unlikely more than a couple would find something

Attached is a picture of the motor and of one disassembled for those wanting to see what is being referenced in this post.

I made this post at the request of a friend who follows these types of threads and thought that showing there are real solutions available is needed.


Before you get any brilliant ideas of messaging me here to inquire about the motor and VFD combo, if you do message me here, don't expect a reply any time soon, I don't frequent here often and it may be 3-6 months before I return again and the message will have evaporated before this time, if you can't figure out how to contact me off-site, chances are you don't need to contact me.

[rusmannx]

While the above post is very detailed, I'm not looking to spend that kind of money on a machine this size. The poster said he won't see this response, but I appreciate the time spent on such a thorough explanation.

If the spindle I have isn't likely to work I'll go with one of my DC motors or something similar. If anyone else has an opinion or some experience, I'm still interested.

[carlowens]

he's been trolling for customers saying the same thing in other threads here recently.

[rusmannx]

he's been trolling for customers saying the same thing in other threads here recently.

Haha! Thanks Carl.

[Al_The_Man]

In fact DC brushed motors have been used extensively in motion control and CNC since its inception and in fact a DC motor has maximum torque at zero rpm, and in the case of servo or high end spindles, the torque remains fairly flat over the rated rpm range.
Al.

[rusmannx]

In fact DC brushed motors have been used extensively in motion control and CNC since its inception and in fact a DC motor has maximum torque at zero rpm, and in the case of servo or high end spindles, the torque remains fairly flat over the rated rpm range.
Al.

Thanks. I've been told the AC Spindle has a flatter torque curve than DC.

Also, as a 3phase spindle advertised to go as low as 4kRPM, a 3:1 reduction could give me a nice range of 1400RPM to 8kRPM. I think I'm going to try it, since I already have it.

[Al_The_Man]

Thanks. I've been told the AC Spindle has a flatter torque curve than DC.

.

Google 'Torque curve for induction motor'
Al.

[Stigoe]

I have a couple of those huge 3.8HP DC treadmill motors and a KBMM-225D-KB for the drive (plus heatsink, and all that other stuff)

Since you have a KBMM-225D, maybe you could help me out. I also have a KBMM-225D, but mine was modified by a company to be used in their film transfer equipment (can't remember the company name) by removing almost all the trim pots and adding a second PCB. I've removed the second PCB, but I need to find the values for the various trim pots. Are you able to find that out from your controller? Could you also check to see if there is a diode mounted in position D9B, and if so, what's the name of it?

Thanks,
Stig

[rusmannx]

Since you have a KBMM-225D, maybe you could help me out. I also have a KBMM-225D, but mine was modified by a company to be used in their film transfer equipment (can't remember the company name) by removing almost all the trim pots and adding a second PCB. I've removed the second PCB, but I need to find the values for the various trim pots. Are you able to find that out from your controller? Could you also check to see if there is a diode mounted in position D9B, and if so, what's the name of it?

Thanks,
Stig

Hey man, I took a pic for you

Attachment 243440

[Stigoe]

Great! Thanks! Now I just need to find time to complete everything...

[websrvr]

I also went the route of the 3.2HP DC treadmill motor and KBMM controller with heatsink and fan because for less than $300.00 I was up and running, I can't do rigid taping and torque at 150RPM sucks.

Adding a tach signal (hall-sensor) to the motor allows mach3 to attempt to maintain the RPM but when I'm drilling with a 1-1/4in drill bit (after a pilot hole) the drill bit stops as the response delay in mach3 can't be avoided at such low RPMs.

Above 300RPM it's not so problematic maintaining a fairly constant RPM as the motor is starting to generate some power but it's still nothing close to the motor that dwalsh62 describes and I've seen it in action.

When my first treadmill motor failed, dwalsh62 made a new 3/4in output shaft and pressed the armature on it, a new front bearing retainer / front motor cover to hold the upgrade 6004-2RS front bearing and this custom/rebuilt motor has been running for almost 2 years now and better performance than when it had the shaft with the integrated helical gear cut into it.

The KBMM-225D controllers used to drive DC brushed motors wont provide torque at 0RPM unless the two I have are broken and came that way when I bought them new and they forgot to add the instructions to achieve this in the manual.

Prior to the KBMM I was using an ElectroCraft DC servo amplifier and a 600W 180V brushed DC servo motor with a 500ppr renco encoder I salvaged from a broken surplus canadian military telescope that I got off of ebay, this would give full torque at 0RPM and the driver was configured to use analog -10V to +10V so rigid taping and direction control were possible.

I'm known to be resourceful while I play like many here do and I also don't have the money to toss around buying stuff like the described motor and VFD but eventually I'll pick something up used when the opportunity arises that meets my budget (cheap) as I meander through posts looking at other peoples concepts and solutions.

[websrvr]

While it would be ideal to find a really cheap solution to this age old problem of powering your spindle, it's just not realistic if you need/want a solution that has good performance characteristics and almost zero maintenance (you have to clean the air-filter on occasion).

Those high-RPM spindle motors you see all over e-bay don't perform well below 3,000RPM and most don't recommend operating below 6,000RPM, anyone telling you they operate it at 100RPM is not telling you the truth, do the math, required thermal dissipation at 6Hz (300RPM) for a typical china 2-pole (18,000RPM or 24,000RPM) water-cooled spindle motor is 135W/cm2 requiring 23.15cuL/sec, at 60Hz (3000RPM), 42W/cm2 requiring 2.89cul/sec and most inexpensive pumps are in the range of 5L to 100L per minute so it's obviously not designed to run at such low speeds which is why people burn them up.

Yes, you can add a chiller making the thermal transfer co-efficiency higher (a bigger fan and bigger radiator) reducing the required flow but now your adding expense to make your unsuitable solution work for you so your $500.00 solution just got more expensive without improving it's performance (your spindle and VFD cost $400.00 and you spent $100.00 on a cooling system).

Asynchronous Servo Spindle Motors that are specifically designed for VMC's and milling machines will offer you the best performance for your dollar and despite popular belief, they are available in small/lighter packages.

A typical Asynchronous Spindle Servo Motors in the 1.5KW - 2.2KW power range weigh in at about 50lbs to 60lbs and are quite large in size (140mm x 140mm x 480mm is the smallest I could find), so utilizing these monstrosity is cumbersome and difficult at best and too large for most bench-top or home/hobby machines.

There are options in smaller packages and lighter weights but sourcing isn't easy as these products aren't generally offered in the retail market and usually have MOQ's associated with purchasing.

This is what I've been running for a few weeks now and wish I had done this years ago.

Motor Specs: (real) Asynchronous Servo Spindle Motor

• 1.12KW (1.5HP) Constant Velocity / 1.5KW (2HP) Constant Torque.
• Input: 157VAC-3PH / 220VAC-3PH @6.81A
• RPM: 12,000.
• Duty: S1@8,000RPM, S6@12,000RPM.
• Cooling: External 220VAC Electric Fan.
• Foot-Print: 95mm x 95mm x 240mm
• Shaft DIA: 22mm with 6mm keyway (standard).
• Encoder: Optical A/B/Z - 2500PPR
• Net Weight: 18lbs
• Supports Rigid Taping.
• Supports Orientation

I've been running this with a VFD sample I was trying to produce that didn't fund on KS, it has 4 programmable orient positions and a true servo mode, I've had no issues doing anything with this motor, RPMs from 120 to 12,000 are stable due to closed-loop tracking, in servo mode, positioning is accurate within 3ppr and in orient mode it's also less than 3ppr (5ppr is the default position auto-error correction margin, can be changed in the VFD) of the target position.

I've managed to have a manufacturer produce a single-phase input VFD with PG card and four programmable orient positions in a 2.2KW power range making it ideal for this motor and a sample is expected to arrive in about 38 more days with a price tag of $500.00 plus shipping.


At about $1K for the combo it's the best bang for the buck all things considered and it would be impossible for anyone with intelligence to conclude that a 3.8HP brushed DC motor solution could even come close to offering constant torque over such a broad RPM spectrum that can be achieved from an asynchronous spindle servo motor because low RPM is derived by lowering the voltage thus reducing torque to a point that it's just not effective.


Forget Yaskawa VFD's if your on a budget, even a new Delta VFD-VE (3PH input only as single-phase units were never produced) with PG card that will run on single phase 220V (derated) with sufficient power (5.5KW needed for 1.5KW-2.2KW motor) will run you over $800.00 plus shipping, used is less and sometimes old-stock can be found but sourcing the motor is where you run into difficulties as it's not likely you have a local source for special application motors and it's not something you will see advertised in your local hardware store.

Yes, a couple of people might find something suitable on ebay in the way of a mitsubishi VFD with PG card but it is unlikely more than a couple would find something

Attached is a picture of the motor and of one disassembled for those wanting to see what is being referenced in this post.

I made this post at the request of a friend who follows these types of threads and thought that showing there are real solutions available is needed.


Before you get any brilliant ideas of messaging me here to inquire about the motor and VFD combo, if you do message me here, don't expect a reply any time soon, I don't frequent here often and it may be 3-6 months before I return again and the message will have evaporated before this time, if you can't figure out how to contact me off-site, chances are you don't need to contact me.

Like rusmannx I like this solution but it's outside my budget.

I'd be interested to know of an inexpensive controller for DC motors that will provide full torque at 0RPM, $1100.00 for a 2.2KW DC servo driver is also outside my budget so exploring alternatives is where I'm at right now.

[dick cnc]

Here is a picture of little mill I built with a professional treadmill motor very good low-end torque with belt change

[websrvr]

Here is a picture of little mill I built with a professional treadmill motor very good low-end torque with belt change

Looks like your using a 2:1 or 3:1 belt reduction, this will help for drilling 3/4in but still insufficient for 1-1/4in.

I've been going over the 225D manual, it does appear you can get high torque at extremely low RPM but requires a DC motor with field and stator windings.

I've done a quick search and the largest I could find like this was rated at 750W, I'll keep looking and see if I can find something larger and run some tests as it is theoretically suggested you can achieve 70% to 85% of the rated torque between 10RPM and 40RPM from a DC motor rated to run at 3600RPM.

I'll start by finding application which use this style of motor and then find a surplus/used source.

[Al_The_Man]

I'd be interested to know of an inexpensive controller for DC motors that will provide full torque at 0RPM, $1100.00 for a 2.2KW DC servo driver is also outside my budget so exploring alternatives is where I'm at right now.

There is only one way of obtaining maximum or rated torque from zero up and that is with a PID loop, IOW feedback of some kind, the KB versions with a tach improves things, but is working in the velocity mode, PID is the only satisfactory way.
Al.

[websrvr]

seems you need a piggy-back board for the KBMM or a different model to support field motors in constant torque mode so I may switch to a different model after I find a suitable test motor.

[Al_The_Man]

1ph SCR drives are OK for general purpose use, but the higher end type, KB included, now use PWM drives for smother and quieter control.
Al.