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Author Topic: Kress FME-1050-1 + Inverter?  (Read 3948 times)

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Kress FME-1050-1 + Inverter?
« on: January 04, 2017, 02:53:26 PM »
Hi,
   I google searched on Kress FME-1050 speed control via Inverter and the closest link is:
http://www.8020cnc.com/improved%20cnc%20spindle%20speed%20controller
I know cnc4pc used to sell a AC speed controller but is not there anymore.
I'm thinking of modifying the"Electronic Speed Controller for Kress 1050 FME Spindle Motors" : http://cnc-plus.de/en/Spindle-Motors---Spare-Parts/Spare-Parts/Electronic-Speed-Controller-for-Kress-1050-FME-Spindle-Motors-.html,
but need more info on how this "Electronic Speed Controller for Kress 1050 FME Spindle Motors" works, my idea is to use analog 0-10V to speed control the Kress spindle. The 0-10v comes from a Wago Analog module and this is fed to a Inverter which turn the motor to a speed depending on voltage output. Most of the Inverter are either 1 or 3 phase input and 3 phase output, could not find a 1 phase output 220vac.
Does anyone know if there's any Inverter that output 220VAC single pahse?

Thanks,




Re: Kress FME-1050-1 + Inverter?
« Reply #1 on: January 05, 2017, 05:10:46 AM »
Hi,
correct me if I'm wrong but aren't Kress universal motors, ie wound armature/brushes and wound stator?

Inverters that you are talking about are 3 phase output for induction machines, different animal.

Craig
My wife left with my best friend...
     and I miss him!
Re: Kress FME-1050-1 + Inverter?
« Reply #2 on: January 05, 2017, 06:27:47 AM »
Hi Craig,
            Thank you for the notice.
My plan is to control Kress spidle's speed via analog module 0-10VDC where 0VDC = 0rpm and 10VDC let say 20000rpm, any suggestion if there's such controller board exist?

thanks
Re: Kress FME-1050-1 + Inverter?
« Reply #3 on: January 05, 2017, 12:34:18 PM »
Hi,
you can control the speed of a universal motor by changing the input voltage but the input frequency stays the same,
ie 50 or 60 Hz depending on where in the world you are.

One way to do it is with an autotransformer widely called a variac. Downside is it has a knob on the front not electronic
control. Old school way of doing things but simple and reliable.

Another way is triac control, a bit like a light dimmer. Most light dimmers have a knob of the front as well but that knob
could be replaced, conceptually at least with a control voltage. Triacs are not the best choice for inductive loads, if the
inductance is to high they don't switch off to well.

For highly inductive loads anti-parallel SCRs are the way to go. They are as robust as each SCR even a $10 SCR can handle
20A or more. I'm not familiar with any particular commercial off the shelf product that would do the job. I made one
a while back for a customer who had an old (very old) school pin welder.

Whether you buy one or build one you may be disappointed tho. Just reducing the speed does not increase the torque so at
low speeds the spindle will have very low power and will be very easily stalled.

On the Kress there should be a makers plate and that could be used to make some pretty fair calculations as to how it might
work at low speeds. One problem to be aware of that the fan will also be slower than normal and the motor will run hot. In
some cases its necessary to provide a separate fan.

Craig
My wife left with my best friend...
     and I miss him!
Re: Kress FME-1050-1 + Inverter?
« Reply #4 on: January 05, 2017, 01:25:48 PM »
Thank you Craig for the explanation.
I will take into consideration whether to use a dimmer to control the speed of the Kress motor or alternatively use a Chinese Spindle + Inverter and feed analog input to the inverter which sound quite complete.

thanks,
Re: Kress FME-1050-1 + Inverter?
« Reply #5 on: January 05, 2017, 03:17:38 PM »
Hi,
that's the combination I use and it works well. They too suffer from low torque and while they run at low speed often with
not enuf torque to be much good.

I have a German made 750W 24000 rpm unit which produces 0.3Nm of torque. At 6000 rpm it still only produces 0.3Nm torque
scarcely enuf to spin a 3mm tool when cutting steel. All of the high speed spindles suffer this problem.

Best approach is to determine the torque required to do the machining you want and work backwards. Say you want to be able
to cut steel in LIGHT cuts with a 6mm tool at 3000rpm  then you will need about 1Nm minimum. At 24000 rpm that works out to 2.5kW.
This means to get useful lowspeed torque you need a big spindle motor.

Most of the spindles you encounter on Ebay are 2pole (same as 1 pole pair per phase) and at 400Hz input synchronous speed
is 24000 rpm, they will spin a bit slower than this because of slip, which is after all how induction motors work, say 23000 rpm.
A 4pole motor (2 pole pair per phase) would spin at 12000 rpm with 400Hz input but twice the torque. If you had an inverter
that could produce 800Hz then you could get back up to 24000 rpm, assuming of course that the motor is rated for it, otherwise
you will explode the rotor. Downside is that an inverter like that is becoming quite specialised and expensive.

6pole motors can be had but are not common. 8pole can also be had which spin at 8000rpm @ 400Hz but with 4 times the torque and
are very useful but reasonably rare. The same company that I bought mine from do one which produces 8Nm torque but
power limited to 2.4kW for around $2500 US. I really REALLY want one but don't have that sort of money.

If you want good torque at low speeds ie metal cutting using a servo type motor is a good way to go, medium size servos, say
1kW are often rated to 3000 rpm is a torque of 3.2Nm. That enuf to cut steel in moderate cuts with a 10-12mm tool. Still
have to provide spindle/bearing and toolholding.

I bought a second hand servo of Ebay good for 14Nm up to 3000rpm for $300 US including shipping, a bargain. Downside is
I cant buy a drive for it, or least a drive I can afford. I'm making one. If I'd known just how complex a job that is I probably
wouldn't have started. Mind you I have had to learn ALOT about all sorts of things along the way so you can say that
this hobby is good for me. Not that I've even been good, and I'm not sure I want to start now!

Craig
My wife left with my best friend...
     and I miss him!
Re: Kress FME-1050-1 + Inverter?
« Reply #6 on: January 05, 2017, 04:29:58 PM »
I am using an old Makita router I bought from Ebay, I only use it for carving wood etc, I fitted a cheap chinese speed controller and it worked fine, I have it constantly set from 23,000 rpm to 12-15000 and it works just fine.

https://www.aliexpress.com/item/Electric-Best-Promotion-2000W-50-220V-Adjustable-Voltage-Regulator-PWM-AC-Motor-Speed-Control-Controller-Approx/32660251031.html?spm=2114.13010608.0.0.iHmow2

I noticed that superPid had a 30% sale in October so I bought one, its very cold here in Norway so going into my garage to fit it is yet an option.

SuperPid have a feed back system that keeps the torque constant (ish)

regards Ford
Re: Kress FME-1050-1 + Inverter?
« Reply #7 on: January 06, 2017, 03:06:01 AM »
Thank you guys for the feedback.
@Craig, as long as the spindle cuts wood is good enough for me and the weight has to be under 3Kg(spindle + atc module).
I'm familiar with high speed spindle, HSD 919A, is 24000rpm at 800Hz with atc, very nice spindle:


"If you want good torque at low speeds ie metal cutting using a servo type motor is a good way to go, medium size servos, say
1kW are often rated to 3000 rpm is a torque of 3.2Nm. That enuf to cut steel in moderate cuts with a 10-12mm tool. Still
have to provide spindle/bearing and toolholding."

This reminded me of my previous post on cnc lathe conversion: http://www.machsupport.com/forum/index.php/topic,24686.50.html
Servo is a good option too but expensive.


"I bought a second hand servo of Ebay good for 14Nm up to 3000rpm for $300 US including shipping, a bargain. Downside is
I cant buy a drive for it, or least a drive I can afford. I'm making one. If I'd known just how complex a job that is I probably
wouldn't have started. Mind you I have had to learn ALOT about all sorts of things along the way so you can say that
this hobby is good for me. Not that I've even been good, and I'm not sure I want to start now!"

Oh man! you are making one  ???, is very complex electronics specially the PID control!!, it would be better off just buy one from the net, I'm familiar with Mitsubishi MRJ2S.
Re: Kress FME-1050-1 + Inverter?
« Reply #8 on: January 07, 2017, 04:17:07 AM »
Hi cncfreakcncfrea,
that looks like a mighty nice spindle, ATC as well, bet it costs a bomb! You may have noticed 800Hz inverters are as rare as 'rocking
horse s...t' and also like to cost a bomb.

To be honest I don't care what you cut 'the slower the speed the greater the torque required'.

To take my spindle for instance 750W at 24000 rpm, its good, plenty of grunt for a small motor. The same spindle slowed down to
6000 rpm is only 187W, scarcely enuf grunt to get out of its own way. I make a lot of circuit boards and for those it goes great and
does a nice job on aluminium too. But when it comes to steel or larger diameter tools torque is king.

By comparison to a decent sized high speed spindle which is still capable of good torque down low suddenly servos don't seem quite
so expensive. Providing spindle and bearings with tool holder adds to the cost certainly but if you make them yourself well....
A 1kW Delta servo AND drive for about $650 (AliExpress) is pretty good buying.

I really wanted about 10Nm torque at up to 3000rpm. The servo I found does 12Nm and short duration overload of 48Nm. I'm hoping
to spin 16mm tools in steel at an engagement ratio of 25%, ie serious grunt for a benchtop mill. The servo itself is quite old, think
manufactured in '94, it looks brand new. Downside is it has an 8 pole resolver, old school stuff, simple and reliable and easily enuf
rotational accuracy for rigid tapping. Resolver capable drives are few and far between. Could change it to an encoder.

Electronics is my thing so I thought I'll make one. Easier said than done of course but I've proved its not impossible. Using a Texas
Instruments TMS320F 28069M micro on one of their Launchpad boards. $50 gets you the micro, isolated JTAG all pinned out and ready
to go. 32bit @90Mhz,single cycle floating point, all the peripherals you could possibly eat, free to use IDE and libraries. Had to learn C
to write the code, learn about field oriented control. Coded up and working well including my resolver-to-digital. Working on the inverter now.
Using Texas Instruments ISO5500 isolated drivers with de-satSD/UVLO and all the fruity bits, $5 each to drive 500V 50A MOSFETS @ $15 each.
Using heavy copper (420um copper layer cf standard PCB 35um) board. Rated output 14A per phase, 30sec overload 28A, momentary overload
48A. Input current (rated) 27A @230V.

I've got NSK 7204P4 matched angular contact bearings and a genuine 'you beaut' Regofix (Swiss made, real shiny!) ER20 spindle and a full
set of Jones&Shipman collets.

All up about $1000. Not finished yet but its coming along. I've put serious thought and effort into it.

Craig
My wife left with my best friend...
     and I miss him!
Re: Kress FME-1050-1 + Inverter?
« Reply #9 on: January 08, 2017, 04:14:33 AM »
Hi Craig,
            Those high speed spindle were imported from Italy and I sold them to customers in Taiwan, the spindle matches Inverter from the same company but some user do not need 24000 rpm therefore I offer them Delta VFD-B series Inverter max frequency = 400Hz = 12000rpm, around 19000NTS (Taiwanese Dollar).
My electronic skill may not be as good as yours, I can create a pcb boards using Diptrace then have the PCB board done by someone, but designing a electronic circuit specially programming is not my thing.
I remember 6-8 years ago I purchased 3 DC servo board from a guy called ULI, he is the maker of UHU, those were great boards, but none of boards aren't working now, short circuit!.
Also Gecko Drive, G320, spent quite a lot on those servo product back in those years but I still prefer Industrial grade AC servo Motor they last long.
Looking forward seeing your Servo boards soon,

Cheerio,