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Author Topic: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?  (Read 21213 times)

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Offline RICH

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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #20 on: September 21, 2012, 06:28:54 AM »
Hood,
Interesting when one starts reading about steppers.
Will assume that you are reading some of Mariss's postings on CNC zone. That is what i meant by digesting the info in the context it is written.
Must also say, same goes for a lot of info from manufactures sites. So it can get rather complex quickly and one needs to appreciate that it's dynamic, ie; not one static condition that a general comment will hold true for. It's interesting because the drive used makes such a big difference and that the other associated components also come into play.
Guess my learned saying "one dosen't know how lacking they are until they get into the expertise of another" still holds true.

Off to the sidelines,
RICH


 

Offline Hood

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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #21 on: September 21, 2012, 06:46:00 AM »
Rich , I read a few papers yesterday and most said that there would be a reduction in torque if comparing full step to microstepping but it was on holding torque. Throw actual motion into the mix and the torque may actually be better with microstepping as it lowers the torque sapping resonance which full stepping would suffer from.

So as you say it takes a lot of reading to actually be able to form an opinion and even then the conclusion will depend on many factors, especially the hardware used.
Hood

Offline RICH

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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #22 on: September 21, 2012, 05:03:17 PM »
Relative to the original 1600 in oz mentioned, then a few comments can be made.
1. Nothing beats having another users practical use of an similar rated stepper being used on a comparative machine.
BUT
That is a rather limited consolation. The power source ( voltage & amps ) available, appropriate drive, motor specs, and mechanics of the
axis come into play.
2. Next will be what the machine will be used for and the users desired performance. Then the compromises start and alternatives weighed
in for consideration
3. Then the money factor comes about and sometimes puts it into perspective or restrains desires.
4. Decisions then must be made.

Shoot...........all they guy asked was if his stepper was appropriate.  :)

RICH
Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #23 on: September 23, 2012, 07:19:06 AM »
I bought this set a couple of weeks before I saw this Newsgroup, so Ill really just have to put them on  to see first hand if they’ll be sufficient before buying another package. I had hoped the seller would have spend a little time tuning  the part to work within the same performance envelope, but as RICH says, its nice to hear first hand from guys who have a machine / stepper combination  that assembles the one witch is going to be retrofitted into CNC right…  Thanks for your inputs… really appreciated.   

This is the set I have ....

http://www.ebay.de/itm/3-Axis-Nema-34-stepper-motor-1600-oz-in-Driver-CNC-KIT-/270714833922?pt=LH_DefaultDomain_0&hash=item3f07dc8c02

All the best
Leif
« Last Edit: September 23, 2012, 07:36:23 AM by Gropper »
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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #24 on: September 23, 2012, 11:37:35 AM »
Those steppers will work, but their performance, particularly in terms of rapid speed, will far well short of stellar.  Those motors are VERY high inductance, which, on it's own, severely limits top speed.  Further aggravating the problem is the fact that the power supply, at only 60V, is WELL below the ~150V required to get the best performance those motors are capable of.  My guess is you'll probably be limited to rapid speeds well under 100 IPM.

Though the drivers allow micro-stepping up to 256X, this is essentially useless.  You'll want to use the 8X, or at most 16X setting, to keep your pulse rates reasonable.

Regards,
Ray L.
Regards,
Ray L.
Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #25 on: September 23, 2012, 12:57:21 PM »
Hmmm......

Dint Look like I hit the gold then, but Ill try them out next weekend and see what it all ends up to Ray, if the performance is under par, they will be used for a plasma cut project I have in mind... yes I know, I have lots of things on my mind LOL.... A plasma must go fast but I could build it with 2 fast ball screws like 16X10 mm.  I have one of those CUT 40 plasma cutters from China and that little thing really impresses me every time I use him :-)

Leif
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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #26 on: September 23, 2012, 01:14:04 PM »
OH.... I can see in the specs. for the 3 drivers that they ll accept 80 volt DC input, do you advice that ill buy three additional 80 Volt Switchmode supplyes for the steppers or are we just talking marginal improvements here ?

Leif
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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #27 on: September 23, 2012, 01:56:41 PM »
OH.... I can see in the specs. for the 3 drivers that they ll accept 80 volt DC input, do you advice that ill buy three additional 80 Volt Switchmode supplyes for the steppers or are we just talking marginal improvements here ?

Leif

Speed will increase, roughly, proportional to voltage, up to a point.  So, 80V will buy you 20-30% more than 60V, but then you also have to be concerned about whether that 80V rating has any real margin on it.  If not (which is common in Chinese designs), then an E-Stop when the machine is running at full speed could blow the drivers.  Personally, I wouldn't throw any more money at it until I saw how they worked.  You can easily swap out the motors later, and with a better motor 60V might be OK.

Regards,
Ray L.
Regards,
Ray L.
Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #28 on: September 23, 2012, 06:30:44 PM »
OK Ray..... I know more next Saturday,  I guess Ill need a couple of days to dig that Bridgeport out of  5 years of collected "gold"  in my cellar :-)   Thanks for your advice on the subject .

Leif
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Re: How much stepper power do a 1-1/2 HP Bridgeport need to do a good job ?
« Reply #29 on: October 12, 2012, 04:28:12 AM »
Those steppers will work, but their performance, particularly in terms of rapid speed, will far well short of stellar.  Those motors are VERY high inductance, which, on it's own, severely limits top speed.  Further aggravating the problem is the fact that the power supply, at only 60V, is WELL below the ~150V required to get the best performance those motors are capable of.  My guess is you'll probably be limited to rapid speeds well under 100 IPM.

Though the drivers allow micro-stepping up to 256X, this is essentially useless.  You'll want to use the 8X, or at most 16X setting, to keep your pulse rates reasonable.

Regards,
Ray L.

Yes,  after making the adaptors I tested the maximum speed and I don't get more than 420 RPM on the steppers, so I guess the only thing one can do here is changing the pitch on the ballscrews or accept the speed that they are cabable of right...  Maybe 3 new controllers will improve on things ?

All the best to you guys.....

Leif
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