MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > Electrical & Electronic > 702. Power Supplies
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Closed Thread
 
Thread Tools
  #1  
Old Thu 13 December 2012, 23:34
CNC On The Brain
Just call me: Glen
 
Indianapolis, Indiana
United States of America
Making Sure I understand the Power Supply Requirements

Hello All,

I posted this in my introduction thread but figured it would be better suited here. It may be my sleep deprived brain but i want to make sure that i understand the PowerSupply Requirements for my selected motor and driver selection and would appreciate any input.

The motors are from Deitech and are model 86HS9801. The stats of the motor are Current of 4 amps and inductance of 4.1. The drivers are Leadshine DM856 listed as input voltage of 20-80 and output iof 5.6 max.

I have calculated a required voltage of 64.8 at 695VA using the formula indicated. I would like to get an Antek power supply and it puts me with the model number PS6n63 series (63V 600VA) as the closest match. Am i in the range of where i need to be? Or am i completely off-base.

Thanks in advance.
  #2  
Old Fri 14 December 2012, 00:53
KenC
Just call me: Ken
 
Klang
Malaysia
The calculation is a guide, not something you must follow to the teeth, 63V is a good number. 300VA is good enuf for many builds. Nothing wrong with spending more than necessary.
  #3  
Old Fri 14 December 2012, 08:16
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I have used power supplies from 25VDC up for motors that could handle 55VDC. They all worked perfectly at the speeds that a CNC machine operates. The closer the power supply's voltage is to the motor's maximum, the higher the speed possible for the motor; however, you will never need 2,000 RPM in a CNC machine (there would be almost no torque at that speed with most motors).

A motor running at 750 RPM with a 1.25" pitch diameter spur gear attached to a 3:1 belt drive will move at about 16" per second.

A 35VDC to 48VDC power supply will allow the motor to run that fast.
  #4  
Old Fri 14 December 2012, 20:58
CNC On The Brain
Just call me: Glen
 
Indianapolis, Indiana
United States of America
Ken and Mike

Thanks for the replies....I think i have it. I suppose i just want to be sure before i purchase.

Thanks again.
  #5  
Old Sat 15 December 2012, 03:20
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I have always disagreed with Mike on the voltage issue - he tends to recommend lower voltages while I go for higher voltages. We started off using close to calculated voltages, based on the Mariss formula, but then replaced the transformers on all 4 machines to go 10 - 20% higher to get less incidences of lost steps at high loads/speeds. Yes, the motors do sometimes (rarely) get rather hot, but still within limits.
  #6  
Old Sat 15 December 2012, 08:53
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Gerald is correct - if you use PKA2A-SGxx motors. Oriental Motor underrates that motor by 1/3rd, because of its gearbox. It really uses the PK296-03A motor. The 03A motor is rated at 4.5A at 1.5mH inductance. The A2A motor is rated at 3A at 1.5mH. The maximum voltage, according to the Gecko formula is 39VDC. Multiplying 39V by 4.5A = 175 Watts, but multiplying 39V by 3A = 117 Watts. In his case, he could probably use a power supply up to about 58VDC before the motors ran at 175W.

The good thing about power supplies is that they're not too expensive. If you find that your motors are running cooler than expected, you can put in a power supply that has 10% or 15% higher voltage. On the other hand, if your motors are blistering your fingers, you can put in a power supply that is about 10% or 15% lower.

I have run the PK296-F4.5 motor (which is an eight-wire motor electrically the same as the PK296A2A motor) in both half-coil and parallel modes. With a 39VDC power supply and when pulling a high load at 1000 RPM or higher, that motor gets REALLY hot.

A close reading of Oriental Motor's specs reminds us that stepper motors are expected to be run intermittently. That's good, because that's just what a CNC router does. It stops and starts frequently. Oriental Motor also calls for a large aluminum heat sink for the motor, about 10" square and 1/4" inch thick (depending on the motor). The steel mounting plates help, but they don't dissipate as much heat as aluminum.

My method of working has always been to spare expensive components, even if it meant making multiple passes. My machine was a Shopbot PRT-Alpha, which had the largest motors available. It had a spindle, making it capable of one-pass cuts in 3/4" thick MDF or Melamine coated particle board, but I normally ran it two passes. The first past cut about 3/4 the way through, going in the conventional direction. The second pass cut the rest of the way through, doing a climb cut. I got edges that were ready to edge band and I didn't overload the machine.
  #7  
Old Sat 15 December 2012, 09:44
zumergido
Just call me: Fernando
 
BS AS
Argentina
if you going to use that motor do the maris formula and you will be allright.
i have some variant of the 86HS9802 with a 48v and no gear reduction and have a lot of power. the motor do not overheat and can be touch in any moment.
  #8  
Old Sat 15 December 2012, 14:55
CNC On The Brain
Just call me: Glen
 
Indianapolis, Indiana
United States of America
Gerald, Mike and Fernando

Thanks for the help. I guess then that heat is really the controlling factor in determining the power supply.

Thanks agauin as all information seems to add to my understanding and it is nice to get actual thoughts from people who have built and ran machines on a normal basis.

Glen
  #9  
Old Sun 16 December 2012, 00:21
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Glen

Just answered your PM and saw this.
Remember that the drivers can be set through a range of amps so if you feel the motors and drivers are just too hot then you can reduce the amps to control the heat buildup.
I have run the watt meter over a few systems now as they work away and they usually draw a whole lot less than what you might think.

The last machine I checked had a big 6 amp motor on the X and 2 x 4 amp motors on the Y and Z and it used around 3 amps.
That is also why a lot of people get away with using a 10 amp outlet when the theoretical power is well above that.

Regards
Ross
  #10  
Old Sun 16 December 2012, 02:44
CNC On The Brain
Just call me: Glen
 
Indianapolis, Indiana
United States of America
Ross,

Thanks for the response. As i said earlier the more i read the more I understand. I think i am having the same issue that many have had in ensureing that i completely understand something before i jump in.

Again thank you all for the help!

Glen
  #11  
Old Sun 16 December 2012, 09:47
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The reasons that we own CNC routers are varied. Some people just want a sophisticated tool. For them, the cost of replacing parts may be a major concern. They may not mind making additional passes if the lighter load minimizes wear on their machine. Others may be paying workers to run the machine. For them, the cost of labor may be greater than the cost of maintenance. Their break-even analysis probably includes replacing motors and drivers on a regular basis. Still others may have contracts to fulfill in a time sensitive manner where they have to push their machine to its limits. Hopefully, they include the price of unexpected maintenance in their contract.

In other words, there is no "one best solution".

Almost all of the recommendations that I've read on this entire website are things that I would consider doing myself, if I were building a MechMate. I tend to stay away from buying anything on EBay, preferring instead to source all parts and pieces from places where I have high confidence that they will have replacements parts as long as I need them.

Reading the build treads is an excellent way of following the process. Many of those threads report on "missteps" and the solutions for those "missteps". When I designed process control computers, I soon realized that the the first two or three designs would reveal the flaws in my thinking and that the third or fourth design would be correct enough to do the job intended. If you consider owning a CNC router as being a road that you enjoy traveling and not the destination, the journey will be more pleasurable.
  #12  
Old Sun 16 December 2012, 12:07
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
For the record, 4 production machines (16 motors), paid staff, contracts to fill, often run night shifts. No motors burnt out in 12 years.
  #13  
Old Tue 18 December 2012, 08:18
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I have removed a few posts in this thread that were not related to the topic. I am also closing this thread since I think the question that was asked was answered.
Closed Thread

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Why not use an adjustable, regulated power supply? Bob Cole 702. Power Supplies 19 Thu 25 August 2011 10:33
Need Help with Power Supply Selection F2DVasek 702. Power Supplies 2 Wed 19 May 2010 04:25
The Power Supply needs only to supply 2/3 of the rated motor current Gerald D 702. Power Supplies 0 Sat 05 December 2009 21:09
making sure a power supply is correct baseball43v3r 702. Power Supplies 77 Tue 17 November 2009 12:15
Home Supply Requirements jbmclain 70. Control Systems 3 Thu 23 October 2008 08:30


All times are GMT -6. The time now is 08:13.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.