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Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #10 on: May 07, 2008, 10:31:30 AM »
Hey Fellas,

I have been watching this thread as I am also in the planing phase of building a 'large format' router.  I am a little confused about some of the numbers you are throwing around for motor sizing.

Gecko Mariss wrote once in another thread

"So, how do you figure the power you need?

Method 1: You have a plasma table, wood router or some other low work-load mechanism. You have a clear idea of how many IPM you want but your'e not sure of what force you want at that speed.

Pick the weight of the heaviest item you are pushing around. If it weighs 40lbs, use 40lbs. Multiply it by the IPM you want. Say that's 1,000 IPM. Divide the result by the magic number "531". The answer is 75.3 Watts so use a step motor.  Eq: Watts = IPM * Lbs / 531"


Taking the above as 'gospel', according to my calcs to move 150lbs at 3000 IPM you need around 850 Watts.  Seems like the 1KW Med inertia motor would do it with ease.  But, Scott said if you want higher accels go with the 2K.  Is this just to to be able to overcome the inertia in reversing directions frequently?  Is there some formula for figuring where the crossover point betweeen the 1Kw and 2Kw.

I tried working with the Sizing software from AD but it's kinda weird the way the have the rack and pinion config'd (i.e. the rack is the moving part on their sizing software which is not really the way I envision setting up my machine).

Thanks,
Sid
Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #11 on: May 07, 2008, 04:52:18 PM »
Brett,

Thanks for the exact info.  I can see now how that ratio is needed.  Looking at the video again, that is a  heavy looking gantry.  Looks like a lot of steel and cast iron darting back and forth :)

Scott.

I am located in Suwanee Ga. about 30 minutes northeast of Atlanta.

ok, I see now about two slots occupied with the ethernet module, and the analog card for inverter speed using 0-10v.  That all makes sense.

Why not write frequency via modbus?  is is a pain, or does it present difficulty over the analog signal?

I have primarily used the durapulse in the past on a handful of occasions.  I believe it's made by Delta of Taiwan, as is the sureservo drives.  I Used 2 GS's in the past, one developed an intermittent ground fault error after about 3 months of operation.  I replaced it with a durapulse of the same size after I was sure there truly was not a GF condition, and have never looked back.  You are right, I wasn't thinking about the carousel system clearly.  I was thinking from a simplicity standpoint, of using the internal indexer, but absolutly could write rev/pulse via modbus and also trigger positioning via modbus for an infinite number of tool positions.  The only limitation then would be carousel size.  The air assist would definatly be a proportional valve (forgot to mention that in my last message), the axis would have *some* weight as the amount of air would be limited to prevent full weightlessness. 

My main consideration for the 2kw is the supply power requirement of 220/3.  I have been leaning towards the 1 kw since it will accept 220/1.  I would gain an additional 1000 rpm over the 2 kw.  My thought was I could use the extra 1000 RPM of the 1 kw, and adjust my ratios to gain aditional torque, since the 2kw have a max RPM of 2000 anyway.  I don't think I would get as much torque as the 2Kw servo, but could certainly make up for some of the loss.  What do you think?  Feesable?

Thanks,

Jeremy



Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #12 on: May 07, 2008, 05:13:49 PM »
Yo Jeremy,

a couple of observations...

How are you going to power your 5HP Colombo spindle on Single Phase?  I think once you crack the 3 HP barrier you're pretty much going to need to be in 3 Phase land. 

Also, I'm kinda curious what it is that your going to be cutting?  For a machine that's designed to travel @ 3000 IPM, unless your cutting styrofoam, I don't think that 5 HP is going to be enough.

Just my $.02

Sid
Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #13 on: May 07, 2008, 05:19:39 PM »
Sid,

I'm questioning the magic number "531"......

The formula you show does not reflect any gearing information, which would definatly affect the presented load on the servo motor, regardless of weight.  I am assuming the magic number of 531, somehow relates to an unknown gear ratio.

For example a 1:1 ratio will present an actual "true" load on the servo motor, and the motor would have to be sized accordingly to handle the weight.  Now say the same load with a 50:1 ratio, will drive much slower, but a smaller servo would easily be able to handle the load, its would be gaining torque at the cost of RPM.


From what I have researched and found, the motor sizing is directly related to the mass of the object being moved, the presented inertia of such mass, and the "drag" or friction of the moving components such as linear bearings, rack and pinion, ball screws, etc, combined.

Im interested to hear more on this as it is a bit mysterious to me also!

When in doubt, just oversize the servo! :)

Jeremy
Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #14 on: May 07, 2008, 05:40:12 PM »
Jeremy,

Yeah I agree- I don't know where he came up with the 531 and what you say makes perfect sense.  I guess what you say about oversize it makes sense but then again, it seems everywhere I go, I see dudes oversizing the HELL out of everything (gauges of steel, amount and pressure of concrete, Engine sizes (i.e. do most people really NEED a 5.0 liter V8?)  Where does it stop?

Have you looked at the SureServo visual sizer software?  I think the true answer lies in there but, as of yet I have not been able to figure it out  :-\  Maybe I'll hollar at Brett and see if he can help me with it?

Sid

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Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #15 on: May 07, 2008, 06:00:53 PM »
Jermey,

     The reason I said go with an analog input for spindle is so you can also have "Manual" external pots for speed control at the machine (for overrides). If you dont plan to use a Pendant, OR, manual Spindle speed override pots then there is no issue with going to the modbus direct write of the Fx. BUT, if you want manual override then you will have to go in with a card, otherwise they will conflict and cause you probs/errs.

   Motor Size: If you going to do high speed CUTTING, that would also include small frequent direction changes (like 3D work, or complex segment 2D work). I would consider more power, I am NOT a mechanical engineer (thus the reason I use the sizing software).
I guess you could try the 1kw's and if your not happy, you could sell them to me, or Ebay............   :)

You are gonna play hell with a heavy gantry if you truely plan on cuttin at 1000ipm, that will be ALOT of inertia to change, Honestly, I think when you set up the ADC motor Accell curves (recommend double s), that for them not to clip your accel/decel rate will be longer than you think. Also, your gonna Drop that energy as Back EMF you are probaly gonna have to buy and extra disapating resistor for the dynamic brake. If you moving that fast, with that much wieght, you gonna be dumping a lot of heat of of the that same resistor so heat control will be a consideration.

You where saying that you might use the 1kw's but gear them down, to increase the torque, you gonna loose the speed.
at 3k top rpm, with lets say 5tpi screws your looking at 600ipm and that is without gearing. So if you then drop the ratio for more torque you will drop that speed further.

scott

Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/

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Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #16 on: May 07, 2008, 06:15:29 PM »
I dont like it when servos are talked about in KW or HP, I prefer to see the continuous torque rating. To me that seems a much better way of sizing a motor, granted the torque will be related to the KW but I have seen quite a variance between similar KW rated motors and the actual continuous rated torque.
 I you have the machine already built the easiest way to get an idea of the torque you will need is to get a 2m length of flat bar, bore a hole in the centre and mount that to where your motor will connect. Get a spring balance or some weights and find out the Kg it takes to start it moving, multiply by 9.806 and you know the Nm that you need to move an axis. Obviously you will need a bit more than that but in reality it wont be much more. I did this with my Lathe and found I needed about 0.75Kg (if I remember correctly, it was a good while ago) I ended up with 10Nm AC servos and things work great 1:1. Did try a 6 Nm motor on and although it moved the axis its acceleration was poor.
 Obviously you USA guys with your old fashioned measurements can use a 2ft long bar and measure in Lbs :D

Hood
Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #17 on: May 07, 2008, 09:50:46 PM »
Yo Jeremy,

a couple of observations...

How are you going to power your 5HP Colombo spindle on Single Phase?  I think once you crack the 3 HP barrier you're pretty much going to need to be in 3 Phase land. 

Also, I'm kinda curious what it is that your going to be cutting?  For a machine that's designed to travel @ 3000 IPM, unless your cutting styrofoam, I don't think that 5 HP is going to be enough.

Just my $.02

Sid


Sid,
Thanks for the observation, but everything is theory at this point.  3 phase is not out of the question...just can't do it at the moment b/c I don't have access to three phase at my home where I plan to do the initial build.  I do have access to a static and a rotary phase converter, but they aren't very nice to electronics.  The reason I said a 5hp spindle is because that is the smallest I have found with an ATC, a machine with a multi tool ride along tool changer is a goal I have set for myself.  And yes, I think 3hp is the cap for a drive to manufacture 3 phase on the output side of a drive.  3000ipm Rapids are the high end of the scale.  1000ipm or 25m/min max is suitable for the applications I have in mind.

Jeremy
Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #18 on: May 07, 2008, 11:18:13 PM »
Scott,

Wasn't thinking of the pendant and the override pot, but it makes perfect sense.  Have you used a particular MPG unit that works well with Mach3? I have seen a few out there but looking for one that is recommended or easy to work with in terms of connecting and setup.  Do you or does anyone else know if the Mach3 software has any built in programming for machines with vertical drill blocks, both in the X and the Y axes?  The vertical drill blocks are usually on 32mm centers and usually include at least 2 or 3 drills in each axis.  If you don't already know, the drill blocks are used primarily for line boring, and depending on the programming the controller interprets the Gcode and activates as many of the drills as possible to drill multiple holes on 32mm centers, or through a post processor the GCode produced in a manner that calls multiple vertical drills to activate for a drill cycle.  Each vertical drill is usually considered a "tool" in the controller.

Okay, I too agree the 1kw motors will be on the small size for a heavy gantry.  I will consider larger drives and servos, or will cut down on feed rate to compensate.

Im just trying to conceptualize everything first, before I take the plunge.

Jeremy

p.s. Are you proficient with directsoft and AD PLC's? 

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Re: General Q's about Mach3 and AD sureservo drives and smooth stepper
« Reply #19 on: May 08, 2008, 02:23:16 PM »
"p.s. Are you proficient with directsoft and AD PLC's?"

Yes

Drill Blocks: The good thing about Mach is you can make any machine you want with in its axis limits. The trick will be how you will program you device, i.e. Custom Wizards, v. Pre-existing CAM software for they type of machine your trying to emulate.

scott 
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/