[bigspike]

I am getting ready to buy & CNC an RF45 but need to be sure of all the bits needed before I pull the trigger. I plan to swap out the motor for a VFD controlled better quality motor. Nothing has been ordered yet. I do not have 3 phase power available. I have to date selected the Hitachi SJ200-015NFU VFD which converts single phase to 3 phase and controls speed, and a 3 phase Leeson motor. Depending on which version of the RF45 I buy it will come with either a 1.5 or 2 HP motor. Various posts on here suggest the VFD & opinions vary regarding using a 2 or 3 HP 3 phase motor.

Part 1
I did my best to search for the information I need and have read this forum until my eyes crossed and searched the internet as well. I have read that when powering a 3 phase motor with 1 phase through a VFD that
- the motor HP is reduced by 20%
- or the HP is almost at the nameplate rating up to the nameplate speed rating and at speeds over the rated level the HP drops dramatically or
- the HP at low rpm is reduced by as much as half.
So generally what is the real story? Should I spend the extra money to buy a 3 HP motor and VFD or will the 2 HP suffice?

Part 2
I am still confused about the electronics.
Based on what I have read, I plan to use:

• 1125 oz NEMA 34 servo motors 90VDC/40A
• US Digital: E5-500-250-N-S-E-G-2 Shaft-Mount Optical Encoder 500 CPR
• gecko 320X - one for each axis
• Honeywell Limit Switches SZL-VL-A
• Mach 3

This is where I get confused. I want to fully isolate my computer from the controller, control the VFD while protecting the CNC control, control a pendant, and many of the breakout boards have identical descriptions. One pdf manual said that if you connect the gecko then you lose isolation. A lot of these boards look like general purpose interface boards for many different types of uses.

• C11 - Multifunction CNC Board
• C11G - Multifunction CNC Board (for Geckos)
• C11T - Multifunction CNC Board w/Driver Control
• C23 - Dual Port Multifunction CNC Board
• smooth stepper USB SS1 contoller
• C25 - Smooth Stepper Terminal Board
• C1 - Parallel Port Interface Card

Then the C11's, the C23 and the smooth stepper board all have safety charge pumps and variable speed control, yet I have read where a C4- Safety Charge Pump and/or a C6 - Variable Speed Control Board is needed. I have read where a smoothstepper motion control was added to a C11.

Don't forget about all the different wiring diagrams posted by different people. Nearly 10 years ago I started to build a CNC mill and the state of information has not improved all that much. Too much is written by non English speakers which just make a complicated issue worse.

So - What combination of these boards do I need? Which additional boards should I consider? and why?

I appreciate all the assistance that members here provide, I have learned a great deal and once my project is completed I will share my results here.

[bigspike]

I forgot to include the power supply question. In the above plan, I have a couple of PC power supplies that I can use to isolate the 12v & 5v supplies from the PC and from the main power supply such as the keling KL- 7220 72V/20A 1140watt power supply. When powering each board where should the various 5volt supplies and accompanying grounds come from?

[Al_The_Man]

What is the obsession with isolation?
Al.

[rowbare]

Have you checked out Bob Warfield's IH conversion blog? I haven't read through it all to see what break out boards he used but I know he used geckos and brushed dc servos. http://www.cnccookbook.com/CCMillCNCHome.html

bob

[bigspike]

What is the obsession with isolation?
Al.

Noise and circuit protection from what I have read. I don't want to let out the magic smoke that can be so expensive to replace.

[Al_The_Man]

When powering each board where should the various 5volt supplies and accompanying grounds come from?

That is rather a confusing question? Do you mean commons or ground(s)?
If you are bent on isolation, logically the commons will all be separate and ungrounded and come from their respective sources.
Al.

[bigspike]

That is rather a confusing question? Do you mean commons or ground(s)?
If you are bent on isolation, logically the commons will all be separate and ungrounded and come from their respective sources.
Al.

What I meant was for each board, where should the power & common come from. For example,
the main power supply would power the geckos, but where should the 5v for the gecko come from?
then what should I use to power the smoothstepper. A 5v leg from the main or 5v from a PC power supply
and then the speed control, does it need to get power from a different source than the breakout and geckos?

if the main power supply 90VDC is power1
a PC power supply is power2
another PC power supply is power3
the computer USB cable is power4

I know that the controllers should be on a different circuit from the VFD & mill motor, not a 120vac leg of the 220vac circuit.

Is there any value in having the 12v & 5v legs on the main power supply?

[mattmark]

hey bigspike,

as for the magic smoke.. check your connections many times and test each axis one at a time, ie connect power to the geckos one at a time. don't switch the DC side of the power on an off, ie between the power supply and the geckos.. only kill the ac for on/off..

the 5v enable for the gecko g320x can come from the 5v lead of the gecko itself.. or if you decide on the master control board (c17 from cnc4pc is what i'm using with the smoothstepper), i bought a separate 5v power supply, which powers the c17 and when the e-stop is not engaged, it feeds 5v to the g320x.

the smoothstepper can be powered from the computer via the USB hookup.

hope this helps...

[ninefinger]

[QUOTE=bigspike;789304]Part 2
I am still confused about the electronics.
Based on what I have read, I plan to use:

• 1125 oz NEMA 34 servo motors 90VDC/40A
• US Digital: E5-500-250-N-S-E-G-2 Shaft-Mount Optical Encoder 500 CPR
• gecko 320X - one for each axis
• Honeywell Limit Switches SZL-VL-A
• Mach 3

QUOTE]

I don't know what the big obsesion is with huge servo motors for these mills. Even in the Nema 34 size there are readily available 2 other motors that are likely beter suited to this mill (600 oz-in peak or 850)

Start rant...

I really should be saying that its not just the oversized servo vrs the machine that I have issue with, it is the mismatched drive for it. The gecko is limited to 20 amps max @ 80 volts. Why pick a servo motor that:
a)wants to draw 40+ amps on acceleration?
b)has a terminal voltage of 90VDC when the Gecko is limited to 80V max?
Your going to be runing the Gecko at its "limiter" on every acceleration - that can't be good for it. Also - as your running at less than the terminal voltage of the servo the performance will be down significantly too..

End rant...

Also - look into the CUI AMT encoders available from Digikey - the settable CPR is awsome. See Pete's Finally getting started thread too...he has some recent comments on them.

Mike

[pete from TN]

First, Understand that no matter what motor you buy you are using Geckos your power supply voltage will be limited to 80vdc and even at that most setup for slightly less for safety reasons.
Second, I have the 1125 oz inch motors on my mill. I have them on there and they run perfectly, my rapids are very fast( more than enough for a machine of this size) my accellerations are crisp, and I have turned things down considerably from when I first got it as it was just too fast and with my fat fingers things got really dangerous really quickly. These motors are of course overkill for this machine. I have them because I got them for a great price from a fellow CNC zoner and I could not pass up the deal. They are VERY strong motors and could easily throw around a machine that is MUCH heavier. DO you need these motors, absolutely not, are they the ideal motor for this machine, well that depends really, an 850 oz inch motor is more than enough oomph for a machine of this size and the IH machine comes with like 600 motors I think so anything more than that is really unnecessary. However that does not mean that it is wrong to do it. My machine runs very fast, very strong, and moves the table with authority, I have no problems with that and it has now run for MANY MANY hours without issue. If I had not gotten this deal on these motors I was planning on buying the 850's from keling.

If you intend to make your own power supply that is fine but I gotta say that I spent some money and bought my power supply and when I ordered it I asked for a 12v and a 5v lead installed. It has come in very handy as well as made wiring the machine for this novice much more simple. I would highly recommend it.

There are about a million ways to build these machines and none are really wrong, just find yourself the best components you can afford and make sure they work well together and you should be fine. If you do decide to go with what you are talking about here, then my build thread may come in very handy for you since it is just what I did except I did not want the smoothstepper....

Good luck man and make sure you take a lot of pictures... peace

[Al_The_Man]

As regards VFD sizing on 1 phase, check the manuf. Lit. Some do not require de-rating.
As for power supplies, I make full use of the PC supply where possible.
If you buy/make a linear power supply with a Toroidal transformer, it is very easy to put on an overwind for a 5v-24v supply that may be needed.
As to the issue of isolation, here is another view of the issue:
http://www.cnczone.com/forums/showthread.php?t=71923
Your PC power supply common is most likely at ground potential and so is your mains powered spindle motor (see above link).
Al.

[bigspike]

Pete from TN ... I have read your thread and found much useful information, thanks.
rowbare ... thanks for the link, that site has a lot of good information, but he didn't finalize some of the details. He talks about different boards and then his drawings don't include them.

Since this is a very heavy bench mill and others had used the larger 1125oz motors, I assumed that the slight up front price of $10 more than the 850oz & $20 more than the 600oz (which may not be big enough). And all three are 90vac peak. It would be better to get the larger motors first instead of needing to buy them later.

I never intended or contemplated "making" my own power supply, not sure where that came from. I just wondered if the optional added 12v & 5v legs could cause a noise issue or would be redundant since I have PC power supplies.

I read that noise/isolation thread and it helped, but there are some slight clarifications I am seeking.

Lets say the 1125oz motors are overkill and I will probably not be milling multi hundred pound blocks of steel.
And since I am not in a production environment, the 3hp motor is more than I will require to compensate for the possible loss of HP with 1phase conversion and I can just take more time to mill something.

My revised plan is as follows.

• Hitachi sj200 vfd 1ph-3 ph 2hp controller
• Leeson 230 V 3 phase 2HP 3470 rpm 192074.00

• 850 oz NEMA 34 servo motors 90VDC/30A
• US Digital: E5-500-250-N-S-E-G-2 Shaft-Mount Optical Encoder 500 CPR
• gecko 320X - one for each axis
• Honeywell Limit Switches SZL-VL-A
• Mach 3

• smooth stepper USB SS1 controller
• C17 – MASTER CONTROL BOARD
• C6 - Variable Speed Control Board
• C4- Safety Charge Pump
• gecko 320X - 4 axis
• Antec 70VDC 1000W Power Supply PS-10N70R5R12 (has 12v & 5v legs
• and some sort of relay board for a vacuum and compressed air valve

Yes there are a thousand ways to build this conversion and many may be right. And no matter how many times you check and recheck connections, if you bought the wrong parts or didn't buy a crucial part...or a board that will allow better performance for just a few bucks.

If the Geckos are limited to 20amps and you need more, what else is there?

Is the system above a closed loop system or does it support wiring as closed loop? I can't remember what I have read at this moment.

[degreaser]

Also - look into the CUI AMT encoders available from Digikey - the settable CPR is awsome. See Pete's Finally getting started thread too...he has some recent comments on them.

Mike

These?

http://search.digikey.com/scripts/Dk...me=102-1307-ND

Very good price - less than $30 each.

[arizonavideo]

The Z on the RF-45 is vary heavy, the 1125 OZ servo is a good match here and you will be able to run a smaller pulley. Small 5000 RPM servos make you run a larger pulley and will get quite hot if run for extended time.

The 1125 is a 7.8A continuous current servo which is a lot different than a 40A servo.

There is no real need to use the 1125 OZ servo for the table in fact the 850 OZ should give you a faster reversal time because of less rotating mass. Some say the 850 OZ is a bit over rated so perhaps is is more like a 750 OZ which is about right for a 45 machine.