Spindle control?

[LeeWay]

Not sure where to put this, but I am looking for a way to control both start and stop as well as RPM's on my spindle. I would like to get Mach 3 to handle it.
Here is what I have.
I have a 180 VDC treadmill motor mounted on my mill that I am building. Right now the controller is too small to get much power from this. It is a 2.5 HP. I am probably only getting 3/4 HP at the most with this controller.
http://www.surpluscenter.com/item.as...tname=electric
I want to order this one, but wanted to see first what all my options are and which will best fill my needs and work best with Mach.
http://www.surpluscenter.com/item.as...tname=electric
http://www.surpluscenter.com/item.as...tname=electric

It doesn't quite get the 2.5 HP rating on this motor, but I think 2 HP will work nicely. I have a two speed belt drive setup on it as well. Here is an image of the motor mounted.


I have 220 running right behind the new location on an opposite wall of my shop. It also has concrete floor there. It is sitting on a wooden floor now. I will install a junction box there. The 220 is running outside in a lean to shed that I use to powder coat parts. It powers my curing oven. It should work fine as long as I only use them one at a time.

Is there a better solution? What would I need to get Mach to handle this motor setup the way I described?

I was considering going with a large servo and a Gecko, but not sure how well that would work. Any experience there from anyone?

Would a simple DRO work and be accurate enough for mach? Could Mach even control it with input from one?

Looking for best bang for buck here. Not necessarily cheap. I want it to be controlled fairly accurately and not bog down easily in steel.

Thanks.

[mackeym]

If you find a controller/drive that will control the motor and also accepts step/direction control signals, then your setup should work fine. For it to work with Mach 3, make sure your drive has step/direction inputs (compared to analog input).

"Would a simple DRO work and be accurate enough for mach? Could Mach even control it with input from one?"

Usually, the DRO signal (motor feedback) does not connect to Mach 3...it connects to the drive. Mach 3 tells the drive what to do, and the drive sends appropriate power to the motor while continuously reading the motor speed from the feedback signal and adjusting the power. Find out what kind of feedback your motor has (encoder or resolver)...and then find a drive that accepts this kind of feedback.

One very accurate solution that won't get bogged down in steel is to go the high performance brushless AC servo route..ebay has a lot of motors (and drives) to choose from. Find a match (i can give more info on this if you want) and u'll be ready to go. AC's are maintenance free and capable of very high transient torques (up to 3-5 times normal operating power but for a short period of time; 0.1 to several seconds). There's always some nice Servostar drives for $200-$300. You can definately find a nice motor to match a Servostar drive for ~$150-$250. These drives accept both single phase and 3-phase 220VAC. When single phase it used, the drive power is derated to something like 85%. Even at this there may be enough to drive a 2-3hp motor...you can check the numbers. If not, then a rotary phase converter is a possibility (these can be expensive though ~$1000 is a good deal for a 15hp phase converter).

[mackeym]

Also, you'll get more responses in a more appropriate forum

[LeeWay]

I wasn't really sure where to put this question. I did call myself looking for the appropriate spot, but this place is huge. Could a mod please move this to a more suitable location? Thanks.
Thanks for the info. That did help. Gave me something to compare prices on as well as knowing that an ac motor with a vfd is easier for Mach to control with the right boards.
I guess I can stick with the manual operation for awhile. It's really not that critical at this point. I still include spindle speeds and things on my Gcode from Sheetcam so in the future when I do get Mach running them, they will not need to be modified.
I went ahead and ordered the DC drive for the 220 volts. If I actually get 2HP out of this 2.5HP motor, that should be all I need to keep from stalling. When this motor stalls, it doesn't really stop with this little drive. It just kicks into a lower speed and keeps on cutting. That is better than stopping completely, but it doesn't cut work a crap at that slower speed.

I did order one of those elcheapo digital tach's that read a reflective tape of Ebay. I figure I can use this on the mill, the lathe and perhaps my router as well. It comes with two feet of tape. We'll see how that works. It will be better than just eyeballing the speed like I have been doing. Thanks again.

[mackeym]

"Gave me something to compare prices on as well as knowing that an ac motor with a vfd is easier for Mach to control with the right boards."

I don't have experience with DC motor drives, but would expect some to also have step/direction input signals. This being the case, a DC motor and drive would interface with Mach3 the same as an AC motor and drive.

[Adamj12b]

You should be able to control the motor with either speed control you use, with this board from cnc4pc.com. It takes step and direction signals from the parallel port/ mach 3 and turns it into a 0-10 volt signal. All you have to do is replace the potentiometer with tis board and adjust the output voltage on the board. It should work.

Also, keep us informed on how the treadmill motor works on the mini mull. I have the same mill and am thinking about doing the same thing. -Adam

[LeeWay]

Originally Posted by Adamj12b You should be able to control the motor with either speed control you use, with this board from cnc4pc.com. It takes step and direction signals from the parallel port/ mach 3 and turns it into a 0-10 volt signal. All you have to do is replace the potentiometer with tis board and adjust the output voltage on the board. It should work. Also, keep us informed on how the treadmill motor works on the mini mull. I have the same mill and am thinking about doing the same thing. -Adam

Will do. I read the blurb for that board the first time down to the mention of VFD. I must have dismissed it then. It does appear like this would let Mach control it somewhat. At least to start and stop and get in the general vicinity of the RPM I shoot for. I was also wondering if a typical optical encoder could be installed on one of the permanent mag motors. If they could, then that might make the control more like that of a servo and would be more accurate for RPM's.
The research I am doing here, while for this mill, will be helpful when I start a 3 axis lathe build. I will need the tailstock motorized, because most of the parts I make in production need to be drilled @ 1/4" through. The little mini lathe I have works fine for making these brass stepped bushings, but that tailstock really sucks for drilling. The throw is too short to get enough hole for two of my longer bushings without moving the stock. These are all cut on only the chuck.
The spindle motor on it is my major concern. I just don't think it is big enough for cnc. Barely is for manual turning. It bogs down fairly easy and that certainly isn't desirable for cnc. Absolute accurate control of the spindle is ideal on a lathe.
Has anyone mounted a hobby sized servo with encoder as a spindle motor here. I called myself searching for that, but seen only the questions and not the results. Thanks.

[LeeWay]

I went ahead and ordered the board you mentioned, Adam.
We'll just see how that all works out. I will document the steps as well as I can. Scratch that. This board seems to be backordered. I will update when I get a reply on the time frame estimate from CNC4PC. I had to wait on an email when I signed up.

Another concern I have is the spindle bearings. This motor is rated @ 4000 RPM.
I am pretty sure that is approaching the max rating on an X2 spindle. I thought about simply running another coolant line into the housing so it will flow around the spindle and at least the lower bearing. This would help keep the casting and everything cooler and possibly allow a higher RPM. Anyone ever heard of or tried that?
I am just using the standard belt drive conversion from Steele that I bought through LMS. The normal X-2 head and motor in high gear have a max of 2500 rpm. This belt conversion increases max speed to 4300 on the big pulley.
The original motor was capable of turning 6000 RPM according to the labeling, but I don't think it ever turned even near that. I could be wrong. I never clocked it. My label is messed up at the end and it might have said 600 rpm instead. If that is the case, then the bigger motor should turn a lot faster and still get some torque at some slower speeds.

Anyone else able to read the rpm rating of an X2 motor? How do I determine what the actual pulley ratio's are? This will be mute once I get the digital tach, but would allow me to look for some better spindle bearings. Anyone know what ABEC rating the X2 bearings are? This is an R-8 spindle. I have found some bearings @ Mcmaster Carr that may work. 7000 rpm rating.

[Adamj12b]

The stock motor is rated at 6000 rpm. I have had the same belt drive on my mill and can say that it dose put some more stress on the berings. After about 10 minutes of running, on high speed all the way up, the spindel is hot and the head is warm. I was thinking about using the head of the mill as the coolant manafold, to cool the berings. Be sure to keep us posted about your progress, I am looking to do the exact same thing to my mill. -Adam

[LeeWay]

I did get a reply to the email I sent asking about the backorder. He said he is on vacation until the end of next week, but could ship after that.
I did manage to get the motor drive in and connected to the 220. Nice! That is a very nice little Minarik drive. I am getting full power out of it now I think. Full speed anyway. The drive has settings for torque as well as speeds, accel, decel, etc.
I haven't adjust any of the pots. The manual says they are factory set at the highest setting.

With the belt drive kit on this motor, I was getting just over 1000 rpm in low and right at 2800 in high. No trouble with the bearings there. I may make some 1:1 pulleys so it will at least turn 4000. If the torque is still good then, I may up it some more. I would buy those higher speed bearing from Mcmaster Carr though if I was going to go higher than 4000. Then I might not have to fiddle with running coolant through the head.
I will have more info after some good testing.

[LeeWay]

I just took it for granted that the drive was set the way the manula stated. It wasn't. I get 3730 rpm max on the high speed pulley. I let it run at max with the torque setting at halfway (about max for this motor according to the manual). The spindle barely got the chill off the cast iron head. The motor was still cold to the touch. It says you can adjust the torque to 140% of the max current rating on the motor. In this case it is 7.5 amp. 10.5 for this motor. In the manual, they show that pot right in the 12:00 o'clock position for that rating.
They tell you how to set it using an ammeter and by locking the motor shaft. No way to easily do that on this motor without removing the fan, so this setting will work unless I find that it isn't enough. Then I will design a lock for it and set it for max the motor can take.
Still haven't cut anything. Maybe later today.
Here are a few images of the drive and box. I got a closeout toolbox from Ace for $5. It was dented some and the latches don't work. It is great though for this. Plenty of room for expansion and relays and whatnot.

[LeeWay]

I ordered a few things from CNC4PC. The speed board. Relay board and a pulse index card. May not be able to use it on the mill, but will come in handy when I start the lathe.
I had a solid state relay, but in doing some research as to how it hooks up, I found that I can't just simply use a relay. It needs some sort of diode and a buffer something or other. CNC4PC to the rescue.

The computer I had running the mill just started working like crap today. Not sure why it did it all the sudden, but it is back running fine with a different computer. I think it was a cpu issue. It would even loose steps when jogging slow. I had it running 300 IPM yesterday with no trouble. Maybe I overclocked it.

Oh what a deep dark pit I entered when I first found the Zone.