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View Full Version : How can I speed up travel on this Boxford router? What new stepper motors to get?



Nicholas Collier
04-03-2017, 02:36 PM
I have this Boxford 500HSR. The travel speed is very slow. If I try to make the travel faster using the external pendant controller, I get a sound like the motors are missing steps.

Maybe this machine is slow because it is more of a light milling machine than a router. I want to use it more like a router.

I can't identify the motors because they have no marking on them. The GS-D200S drivers are rated at 2amps at 2.5v output.

Perhaps somebody can suggest a stepper motor kit to use purely from experience, or at least the a ballpark figure of what Nm rating I should go for.

The machine is pretty solid with a ball screw pitch of 5mm. I will be cutting phenolic laminate 4mm thick with a 3mm cutter.

When I have cut this material in the past with a hand router, it likes to be cut at about 3meters/minute

209502095120952

JAZZCNC
05-03-2017, 12:16 PM
Hi Nicholas,

These machines where never built to go fast and it's the voltage that is limiting the speeds your getting.
About 18mths ago I converted it's bigger brother Hsr1000 for someone and re-used the old motors without any trouble so won't need to replace them. However I did Fit Fans because running higher voltage increases heat and being inside the cabinet didn't help. So fans will be needed to blow air onto steppers and pull air out of the cabinet. This is good idea anyway and IMO something the original should have had fitted, esp in the electrical cabinet.

The convesion I did replaced everything but the spindle Speed controller. It consisted of Leadshine DM542 Digital drives running 44Vdc using toroidal PSU and Cslabs IP-M Ethernet motion controller using Mach3.
This does mean the control panel on the front cannot be used like before as it's bespoke to the original controller but with some hacking you can re-use the tactile buttons. Then you can connect these to the IP-M inputs to allow jogging or turn on/off spindle etc.

This combination instantly doubled the machines usable speed with little spare if required. I seem to remember it left me tuned at something like 7000mm/min but would reach 10,000mm/min. The guy who own's it soley cuts 3D work and each job runs for 6-8 hours at time.

Hope this helps.

Nicholas Collier
05-03-2017, 01:14 PM
Hi Nicholas,

These machines where never built to go fast and it's the voltage that is limiting the speeds your getting.
About 18mths ago I converted it's bigger brother Hsr1000 for someone and re-used the old motors without any trouble so won't need to replace them. However I did Fit Fans because running higher voltage increases heat and being inside the cabinet didn't help. So fans will be needed to blow air onto steppers and pull air out of the cabinet. This is good idea anyway and IMO something the original should have had fitted, esp in the electrical cabinet.

The convesion I did replaced everything but the spindle Speed controller. It consisted of Leadshine DM542 Digital drives running 44Vdc using toroidal PSU and Cslabs IP-M Ethernet motion controller using Mach3.
This does mean the control panel on the front cannot be used like before as it's bespoke to the original controller but with some hacking you can re-use the tactile buttons. Then you can connect these to the IP-M inputs to allow jogging or turn on/off spindle etc.

This combination instantly doubled the machines usable speed with little spare if required. I seem to remember it left me tuned at something like 7000mm/min but would reach 10,000mm/min. The guy who own's it soley cuts 3D work and each job runs for 6-8 hours at time.

Hope this helps.

Yes that is very helpful.

Are you saying I should up the supply voltage to the drivers, or use new drivers that are designed to output a higher voltage?

Using a higher voltage must also increase the current.

I measured the hole spacing for the motor mounting. It is 48mm which is close to a NEMA 17. I was thinking of buying a whole new NEMA 23 motor kit. But you are saying that I could just send a higher voltage to the existing motors, this would save me a lot of time and money.

I could buy new power supply and drivers for NEMA 23 motors, and use it to drive my existing motors. Then I always have to option to upgrade the motors. However if I do this, do most drivers have the option to limit the voltage avoid burning out smaller motors?

Nicholas Collier
05-03-2017, 01:26 PM
Hi Nicholas,

These machines where never built to go fast and it's the voltage that is limiting the speeds your getting.
About 18mths ago I converted it's bigger brother Hsr1000 for someone and re-used the old motors without any trouble so won't need to replace them. However I did Fit Fans because running higher voltage increases heat and being inside the cabinet didn't help. So fans will be needed to blow air onto steppers and pull air out of the cabinet. This is good idea anyway and IMO something the original should have had fitted, esp in the electrical cabinet.

The convesion I did replaced everything but the spindle Speed controller. It consisted of Leadshine DM542 Digital drives running 44Vdc using toroidal PSU and Cslabs IP-M Ethernet motion controller using Mach3.
This does mean the control panel on the front cannot be used like before as it's bespoke to the original controller but with some hacking you can re-use the tactile buttons. Then you can connect these to the IP-M inputs to allow jogging or turn on/off spindle etc.

This combination instantly doubled the machines usable speed with little spare if required. I seem to remember it left me tuned at something like 7000mm/min but would reach 10,000mm/min. The guy who own's it soley cuts 3D work and each job runs for 6-8 hours at time.

Hope this helps.

Yes this is very helpful.

Are you saying I should get new drivers that can supply a higher voltage to the motors?

The hole spacing for the motor mounting is NEMA 17, I was thinking of getting a whole NEMA 23 new motor kit, but you are saying keep the motors, this would save a lot of time drilling and tapping new holes for bigger motors.

I could get the NEMA 23 kit minus the motors, and use it to drive my existing motors. Then I always have the option to get bigger motors in future.

If I do this, how can I make sure I don't burn out my existing motors?

JAZZCNC
05-03-2017, 02:13 PM
Well first things first don't go buying any kits as chances are they will be wrong for your needs. It's the most common mistake made by new users.

The Motors on the larger machine where 23's however doesn't matter performance will still increase with more voltage.
What's important is you don't run the current too much higher than the motors rating. Increasing voltage will increase the speed and to some degree torque however it will also increase heat and it's this heat that leads to iron losses in the motor which then lowers performance/life expectancy. However Steppers are very robust things so you won't kill one very easily, they are also often over specified for the machine which will 99% be the case here.

So we can safely say that because the drives are rated max 2A then the motors will be close to this so working on setting of 2A on the drive will be close enough and not cause any damage.
Voltage is mainly calculated using the inductance of the motor which in this case we don't have and can vary widly depending on motor quality and wiring type/numbers. ie: Bi-polar Series or parallel. 4, 6 or 8 wires. However if we use typical voltage rating given for larger nema 17 motor of say 2.5v and use the rule of thumb method of calculating voltage which is 20 x rated voltage it gives 20 x 2.5 =50Vdc.

So your safely within the motors ratings on voltage with 44Vdc and provided the current rating on drive is close to the motors rating you'll not hurt the motors. Also modern Digital drives run motors much cooler than Old analog technology which helps motor cooling.

Now your probably wondering "Well if that's that case why didn't Boxford do that.?" It's simple they always de-rate to ensure reliabilty and since these machines where intended for schools speed wasn't great concern.
Modern drives are worlds apart from the ancient tech used in these machines so will happily run close to there max without any issues and with much greater performance.

The trick is getting the right drives and voltage supply then matching with good controller. This you won't find in Kit form.

Nicholas Collier
05-03-2017, 09:06 PM
Do you mean increase the supply voltage to the drivers so that the drivers send a higher voltage to the motors? I assumed that they were regulated internally so that a change in supply voltage does not effect the output voltage.

Here is the data sheet for the drivers
http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/2666.pdf

Does your idea work because the drive is a constant current drive, which needs to supply a higher voltage the faster the motor turns, because the motor impeadace increases with frequency, so at some point the supply to to motor will reach the supply voltage of the driver and therefore not be able to get any higher. So increasing the driver supply voltage will give more headroom on upper frequency limit?

magicniner
05-03-2017, 09:18 PM
Do you mean increase the supply voltage to the drivers so that the drivers send a higher voltage to the motors? I assumed that they were regulated internally so that a change in supply voltage does not effect the output voltage.

Here is the data sheet for the drivers
http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/2666.pdf

I also don't know how it is possible to increase the voltage to the motors without increasing the current.

The drivers limit current, this does mean that they can limit voltage but the performance increase comes where higher voltages are required to deliver the rated current to the motor.
Your current drivers (no pun intended) will be delivering full available voltage on a regular basis without that being enough to deliver the full rated current through the steppers.

Nicholas Collier
05-03-2017, 09:22 PM
See my edit on the previous post, I think I figured out why it will work.
You advice is very helpful, I was just trying to understand the details.

JAZZCNC
05-03-2017, 09:59 PM
Does your idea work because the drive is a constant current drive, which needs to supply a higher voltage the faster the motor turns, because the motor impeadace increases with frequency, so at some point the supply to to motor will reach the supply voltage of the driver and therefore not be able to get any higher. So increasing the driver supply voltage will give more headroom on upper frequency limit?

Yes you got it pretty much spot on.! . . So you can see the motor windings makes big difference and motor with high inductance will require more volts to reach same speed as motor with low inductance. This is why it's not advisable to use large motors when not required. Often people think bigger is better but in CNC this is wrong and often cripples the machine.

However in your case you need to be careful increasing voltage with your old drives because while the drive max spec is 46Vdc you'll need to leave decent overhead to allow for EMF. Also they are Old tech analog drives and IME not very strong.
Modern digital drives work so much better than Analog drives and handle motor resonance so much better that there really is no comparison. If you had the same voltage and motors just changing to digital drives makes enough of an improvement to be worth the cost. The difference is night and day in some cases.

Edit: Also just to make you aware the pulse quality and rate makes big difference to speed you'll get from machine. For the full affect in performance you'll need to change the controller to one that allows running at higher frequency and better quality than parallel port allows. However without hacking the old controller you'll need to do this anyway I think.
The machine I quoted had the full treatment and the combination of digital drives with higher frequency high quality controller and more volts is what allowed the speed increase. Also the machine run much smoother because of these upgrades.