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  • $6,500 paper weight

    Hi newbie here to this site. I have a problem. I have bought a cnc jr milling machine. I built a shop for this machine. The machine runs on 120v at 15 amps. When I wired the shop I tied into the home with a 30 amp breaker to a 100 amp breaker box in the shop. The shop has only 125v pulling off the 100 amp service (no 220v). The main motor of the machine is wired to a 125v 20 amp circuit by itself. The problem I'm having is, When I turn the mill on, the motor runs for about two minutes. The O/L on the motor trips. I have turned everything off in the shop and it still happens. When I first set this mill up, I ran it for about 10 minutes with no problems. Now I have this one and can't use it. The machine is under a 1 year warrenty. But I want to make sure it's not on my end. Thanks for any help in advance..

  • #2
    Re: $6,500 paper weight

    120 V/15 amps sounds like a small milling machine, but it that is the rating, and you have a 120/20 amp circuit, then it should run.

    Comment


    • #3
      Re: $6,500 paper weight

      Yea it's just a bench top machine.That's what i thought, but it won't. The O/L on the motor keeps tripping. Don't have much hair left, probable won't have any left trying to figure this out.

      Comment


      • #4
        Re: $6,500 paper weight

        Do you have a good digital multimeter or a good VOM type meter? If you do, check Voltage at the receptacle, or wiring box of the machine with the machine off and again with it running. If there's more than 5 Volts difference (120 Volts nominal) you need to bring heavier electric service to your shop. In addition if when you don't have much load in your shop the Voltage reading is outside of the 110 - 125 Volts range you may have problems back at your service entrance.

        How far (wire wise) is it from your main load center (breaker panel) to the sub-panel in your shop and also over to the milling machine? What gauge wire did you use? If you check the name plate(s) and/or manual, what is the total load draw of the milling machine when run on 120 Volts?
        Last edited by Woussko; 07-04-2009, 11:21 PM.

        Comment


        • #5
          Re: $6,500 paper weight

          is the motor getting up to speed? is any thing dragging or stiff, that could be putting a load on the motor and not kicking out of the start winding, check under the wiring cover, (many times there is a wiring diagram under the cover), and see if the motor could have been wired for 220 or check on the motor label or plate and see if it could be the wrong motor and one for non north American use. (220volt, 50 cycle,)

          is there a spindle brake that is on?

          if you have a amp meter clip on one of the wires and see what the amp pull is, is it with in specifications?
          Push sticks/blocks Save Fingers
          ~~~~~~~~~~~~~~~~~~~
          "The true measure of a man is how he treats someone who can do him absolutely no good."
          attributed to Samuel Johnson
          ~~~~~~~~~~~~~~~~~~~
          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

          Comment


          • #6
            Re: $6,500 paper weight

            OK, I check with a volt meter. It read like 202. I know that ain't right. So I brought the meter into the house for a standard.The plug in for the coffee pot read 202. If 202 is the standard ( probable had the volt meter set wrong).The plugin for the mill read 202, with it running it read 197. When I first started the mill it read 168. I have 75-80 feet of 10 ga of wire with a junction box at about 50 feet. From the sub panel all wiring is 12 gauge. The shop has it's own earth ground. Not to code, but still has it's own. The mill specs. calls for 10 amps, but they recommend 15 amps for safety purposes.????My thinking is if I ran it on 15 amps, it would trip the circuit breaker and not the O/L on the motor. I could be wrong ( been there done that before). I'm trying to start my own buisness, I reeally need to figure this out.

            Comment


            • #7
              Re: $6,500 paper weight

              BHD, On the mill, there is no brake, it's running with no load.

              Comment


              • #8
                Re: $6,500 paper weight

                A) Please try the Voltage measurements with another meter. If you really do have 202 Volts at a 120 Volt receptacle it would be disastrous as I'm pretty sure you know.

                B) BHD has very good points of things to check out. Please do what you can and post your findings.
                If you can access a known good clamp-on AC Ammeter, checking current draw would be a big help.
                The thought that the motor may not actually be for 60 Hertz (cycles per second) power or for 120/240 Volt operation would explain why you can't successfully run it. Please do look the motor over and check name plate(s) and any wiring diagrams.

                C) You might give this a try and see what happens. This is assuming you have a duplex receptacle and the milling machine has a power cord. (A duplex receptacle is like in the picture below) Plug in a table lamp or other lamp with an incandescent light bulb in it and turn it on. When starting the milling machine does it dim quite a bit? With it running and then switched off does the lamp get a good bit brighter?

                Note: The idea of a test light is to use it in place of a Voltmeter. It's a very basic and crude way to check for major Voltage drop when starting a motor on a given circuit. If the light bulb dims much when starting or if it brightens enough to notice with the motor running and then switched off, there are problems.

                If all of this is just too much for you to deal with, please do yourself a big favor and call a licensed electrician to come by and check things over. If you have a local friend that's an electronics tech or is big into Ham Radio, he/she should have a good meter for checking line Voltage.

                Special question: Is your main building a private house or is it a commercial building. If a commercial building, then a reading of 202 Volts makes more sense. Many have 120/208 Volt, 3 phase power. If you read from any of the three hot legs to another hot, you should have a reading of 190-230 Volts measured. If you go from neutral to any hot leg you would get around 110-130 Volts.

                Put simple, either your meter is at fault or you may really not have the expected Voltage on the circuit for the milling machine. This is where a test light with 120 Volt light bulb can help for simple checks.

                Please always practice SAFETY and if you aren't sure about something call in professional help.
                Last edited by Woussko; 07-05-2009, 01:27 AM.

                Comment


                • #9
                  Re: $6,500 paper weight

                  I hope my post just under this one didn't blow you away. If all of this is too much to deal with or you're just not sure, please do yourself and your business a big favor and give up. Then call in a good licensed electrician and have him/her check Voltages, current draw and also any name plates, wiring diagrams and the manual for your milling machine. $200 or so for a service call and some measurements is cheap compared to the cost of the machine and it's dirt cheap compared to your getting injured or worse.

                  The part about the coffee pot and 202 Volts has me thinking seriously something had to have gone wrong with the Voltage measurements. I would try another meter and be sure what range and function it's set to.

                  Comment


                  • #10
                    Re: $6,500 paper weight

                    NO HEY, I really want this to take off. I was laid off in April from a great job. This is my future.. I live in a rural area where my trade is not really needed. So I'm gonna do this. Hate the drive (last job was an hour one way). I'm gonna get this fixed come hell or high water (live on a big hill, If I flood alot of people are hurting). I know some electricians in my area. I'll call them Monday...

                    Comment


                    • #11
                      Re: 700 LBs. paper weight

                      Have you tried starting the Main Drive motor without the Control unit?

                      Something just doesn't add up...

                      If the main motor is 2 Horsepower, it requires 25 Amps to come up to speed, 12.5 after reaching operating speed on a 120v line and the Control Unit requires another 5 Amps... (maybe it really isn't 2 horsepower) You would need 30 Amp capability to operate this mill. 10 Gauge wire minimum from the main panel to the sub.

                      After reading all of the troubleshooting you have done, my next step is to check to make sure that the 125v power cord was not wired to the motor as if it was a 240v power cord.

                      Is this thing really 700 Pounds? I would want to try plugging it in somewhere else, as close to the Main Panel as possible. or running a different tool that requires 30 Amps where the Mill sits now.

                      I wish I had toys like yours!
                      Attached Files

                      Comment


                      • #12
                        Re: $6,500 paper weight

                        Just had a service call the other day where the customers booster pump motor was set for 220 and he wired it 110. He said there was a panel problem and he was blowing breakers. I just pulled the end of the motor and moved a couple of jumpers (after I measured the voltage, looked at the diagram, the panel, etc..).

                        I kind of felt bad when I told him I had to enforce the 2 hour minimum at $75/hour for 30 minutes tinkering, bet then we found some extra work he needed to have done (outlets and switches) to fill out the time.

                        Comment


                        • #13
                          Re: $6,500 paper weight

                          I would suggest some one that is more knowledgeable of electricity to check out your set up,

                          some thing is not right, meter, wiring, both, who knows. and if this is a CNC machine you be paying big bucks to get things fixed, motors are usually fairly tough in there simple construction, but electronics are not, over voltage or under can fry them in a hurry,

                          I just ask this is not a three phase set up trying to be ran on single phase?

                          the 202 volts give me reason to be concerned and you need to get the wiring or assured knowledge of wiring there could be a number of things that I can think of wrong, but I would suggest a qualified electrician, to check it out.

                          the reason I asked about the brake is most mills have some type of brake to lock the spindle to help in losing or tightening the draw bar, in the spindle, (guessing this is a R8 collet),

                          wish you the best in your venture,


                          please report back and tell us what you find out, OK
                          Last edited by BHD; 07-05-2009, 10:05 AM.
                          Push sticks/blocks Save Fingers
                          ~~~~~~~~~~~~~~~~~~~
                          "The true measure of a man is how he treats someone who can do him absolutely no good."
                          attributed to Samuel Johnson
                          ~~~~~~~~~~~~~~~~~~~
                          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                          Comment


                          • #14
                            Re: $6,500 paper weight

                            Morning all, I found another battery for my volt meter. I rechecked the coffee pot and it now reads 123v. I would have never guessed the low battery would cause a false reading. They usually just quit working. So I went and check the circuit in the shop and it read 122.9v, 90v when I started the mill, And for the few seconds the mill would run it leveled out at 119.1v. The mill motor and the control unit operates separately. The mill is on own circuit. I really don't know about the wiring of the motor. It has a diagram but the wiring doesn't look like the diagram. The diagram only shows low volt and high volt. The motor has to run at more than 12.5 amps, cause the 15 amp O/L on the motor keeps tripping. Don't know Oh and it does weigh every bit 700 lbs.

                            Comment


                            • #15
                              Re: $6,500 paper weight

                              Originally posted by tradesman351 View Post
                              The problem I'm having is, When I turn the mill on, the motor runs for about two minutes. The O/L on the motor trips. I have turned everything off in the shop and it still happens. When I first set this mill up, I ran it for about 10 minutes with no problems. Now I have this one and can't use it. The machine is under a 1 year warrenty. But I want to make sure it's not on my end. Thanks for any help in advance..
                              Hi, tradesman.

                              Can you clear something up for me? You mentioned in several of your posts that "the O/L on the motor trips". This says to me that it's a button on the motor that you need to press to reset... as opposed to the circuit breaker in your breaker panel. Is this correct? Or is it the 20A breaker in the subpanel that's tripping? If it's the reset on the machine itself, this says that it's likely (but not 100% certain) a problem with the machine rather than your wiring. If it's the panel breaker that's tripping, then it STILL might be the machine that's bad. If it's the motor that's tripping, are you certain it's a current overprotection device? It could be thermal protection. Often you can tell because the thermal protection will require you to wait a minute or so (while the motor cools off) before you can reset. An overcurrent protector will normally allow you to reset very quickly (few seconds or even immediately).

                              You mentioned that the machine should run on 120V 15A. But who knows what they sent you. Can you post more info, for instance, the wiring diagram? Can't make a lot of sense out of "low volt" and "high volt". A 120 volt machine should wire very simply with one black hot wire, a white neutral and a ground. The motor should have a plate on it with specs. Take a look and make sure it says that it's a 120 volt motor. If they sent you a 240 volt version of the machine, and you wire it to a 120 volt service, an AC induction motor will pull more current than it's supposed to and overheat, causing the motor protection to trip. Many machines are supplied "dual voltage", which can cause cause the problems you're having if you wire it wrong. Does the manufacturer have phone support that you can call? It could be as simple as getting the correct wiring diagram.

                              Do you have close-by access to any other outlets that are on different circuits? A 10 amp motor is nothing special, basically any outlet in your house will support it. You can get away with a large gage extension cord for a quick experiment.

                              If you unplug the mill and plug another high draw device into the dedicated 20A motor circuit, (say, a big air compressor or electric space heater) does that device work ok? This will help build confidence that your supply wiring is ok. May or may not be up to code, which is a whole seperate issue, but at least probably not responsible for the motor problem you're seeing.

                              It's impossible to be sure, but since you say the diagram doesn't look like the wiring, it seems sounds most likely like the motor is connected up incorrectly. If you correct that or discover that it's correct, AND other high draw devices work ok on that same circuit, then it seems to me that the motor is most likely bad.

                              Unless you're very comfortable with electricity, keep in mind that this sort of thing can kill you or start a fire very easily. An electrician may well be the most sensible thing you can do. In particular your comment about grounding is worrisome. A subpanel to a detached structure requires its own ground rod, and I believe the current NEC says that you have to run your safety ground back to the main panel. But I do not know what the requirements are in your area. I do know that having a wrong or questionable grounding scheme is a disaster waiting to happen that can have very serious or fatal consequences. You could touch your machine and get fried. When in doubt, call a licensed pro.

                              Good luck. I'll be interested in what you finally find. Be sure to post the final findings.

                              -Andy

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