[LongRat]

Thanks for all the replies so far.
Digits - I took the DC motor apart, there was no debis in there but a couple of the copper windings were very loosely crimped to the commutator segments. Not definitely a source of a problem, but certainly far from ideal. The internals were totally clean and chip free. I always ran it with the steel covers on the motor anyway.

[LongRat]

I have bought a 1.1kW 3-phase motor for the mill, 2800 RPM 2 pole. I don't think the 2HP motor is going to be necessary (24mm shaft diameter!).
Just to be safe I went for a 2HP capable VFD to run it. The added bonus of all this is that running the speed from Mach is pretty easy. I'll post when it has arrived and is all mounted up on how well the system works.

[digits]

I have bought a 1.1kW 3-phase motor for the mill, 2800 RPM 2 pole. I don't think the 2HP motor is going to be necessary (24mm shaft diameter!).
Just to be safe I went for a 2HP capable VFD to run it. The added bonus of all this is that running the speed from Mach is pretty easy. I'll post when it has arrived and is all mounted up on how well the system works.

I'll be very interested to see how you get on!

Have you got any specs on that motor you could share? I'm mostly interested in its weight/volume...

Cheers and good luck!

[LongRat]

Digits - it is an 80B frame size motor. Weight 11kg, mount diameter 120mm, total height 247.5mm. Dia19mm shaft.
I was thinking of a 2HP motor originally but I think that will be excessive, for example it has a dia24mm shaft. That's 10mm thicker than the stock motor shaft.

[LongRat]

I have everything hooked up and working. Not without some drama. But first, here is a picture of the set up and a video of the spindle running up to approx 4500 RPM.



There you can see the 1.1kW motor and the VFD on the wall. This motor is considerably bigger than the stock DC motor and I am very glad I didn't go for the 2HP motor with the 90 size frame. This motor clears the column by 1mm and that's with a screw removed that holds on the fan shroud (3 more left holding it fine).

[nomedia="http://www.youtube.com/watch?v=oJxjLQf9_qU"]YouTube - Weiss WMD30LV spindle at 4900RPM[/nomedia]

I had some trouble with the VFD that isn't properly resolved and would appreciate some feedback here. When I connected the single phase input power for the 1st time it tripped the RCD on my household supply. Did it many more times while I tried to figure out what was wrong. In the end I called Drives Direct who told me that it sounded like an excessive leak to earth and to disconnect the earth line to the VFD (sending it only to the motor ground). This worked but they advised it would leave the VFD backplate and mounting screws at half mains potential (120V). This seems crazy to me - if there is 120V on that case, then connecting it to ground was always going to trip the RCD. But don't connect it and it works but renders the VFD a deathtrap should you touch it. I've seen a post elsewhere where it was mentioned that powering up the unit with an inline resistor and then bypassing it with a relay would fix the issue, but I would think the VFD should contain these electronics if they were actually necessary. And while that would reduce the surge load, WHY IS THE CASE AT 120V ANYWAY?

[Al_The_Man]

It possibly could be due to the earth leakage detection circuitry in the VFD is causing enough leakage to trip the RCD.
Although I have never heard of it before.
Check the voltage from the backplate to the ground conductor, if it measures 120v, it is most likely that the circuitry is voltage dividing between 240 and neutral.
Al.

[Maglin]

Not to sure what drive that is. But it looks a lot like the Teco Units. I know it's not a 3HP version but maybe this manual will help you out at least with a few settings and how it should be hooked up. I don't have one yet just been reading on it. Sounds scary though in it's current state.

[arizonavideo]

The new motor looks great.

You might say thanks to AV for saying that the 2HP was too big....Ha

With the new increase in RPM and power I can't wait to see a milling video with a 3/8" or 1/2" EM at 5K doing some hogging.

I would think others might want to do the same, can you tell us a bit more about where you got the motor and its cost and style?

[LongRat]

Yeah thanks for that, it helped in the decision. That and the fact that I would take the factory 1100W motor rating with a big pinch of Chinese salt too. Having said that I never felt that the stock motor lacked power at all.

It possibly could be due to the earth leakage detection circuitry in the VFD is causing enough leakage to trip the RCD.
Although I have never heard of it before.
Check the voltage from the backplate to the ground conductor, if it measures 120v, it is most likely that the circuitry is voltage dividing between 240 and neutral.
Al.

Al, can you explain further please? This is the point I really need to understand. The back plate (and therefore mounting screws) of this VFD is permanently at 120V with respect to the ground of the incoming 240V single phase AC supply. If I connect the ground to it, obviously a huge current will flow from the backplate to ground and trip my RCD as I have seen. I can't see how this could ever possibly work with the ground pin connected. But this is how the manual states it should be wired! I have the manual and have read it fully. With the ground wire disconnected from the backplate, I can use it but it is a deathtrap. This doesn't sound like something that you would do by design.

[Al_The_Man]

All the VFD's I have seen require a earth ground which normally would carry on to the motor frame.
Most also have earth leakage detection in the event that any of the outgoing phases have leakage to ground, in which event they will shut down the VFD and show an alarm.
In your case, either something is amiss in this particular model you have, or the detection circuit is such that it is tripping your RCD.
If there were some divider circuitry that was connected in the VFD between power and ground then it could form a voltage divider that normally would not support enough current to blow a fuse etc, but enough to trip your earth leakage detector.
I am only guessing here as it is a job to say whether this is just an exception in your case.
Out of interest I would disconnect in & out power and measure resistance to ground terminal to each power terminal, I would expect very high resistance, if any.
In any event, the fact the manual requires a ground connection sounds like a problem in the unit?
Also out of interest, power it up with the motor disconnected and see if it still trips?
Al.

[LongRat]

The motor frame is currently grounded, I'm just bypassing the terminal on the VFD backplate so that isn't grounded.
I measured the live-to-earth and neutral-to-earth resistances as you said. Both register over the max on my meter (200 MOhm). Power up with the motor disconnected and it behaves the same way as it does with it connected.
It also sounds to me like a problem in the unit, but the vendor told me to do it like this. This suggests he thinks it should be like this. I can't say I like that, I'll give him a call tomorrow.
The good news is this mill will remove metal some 5 times faster running at 5000 RPM. I know that's only just over double the stock spindle speed but I guess with the surface speeds so much closer to optimum, the whole material removal process has become much more optimised and efficient. This mill needs this set up from new!

[Al_The_Man]

Another thing to check to see if the leakage will support any kind of current, and indicate a fairly definite problem with the unit is to test this with a test lamp around 25w say, and place the leads between the ground wire and back plate and see if the lamp should light before tripping.
Al.

[Maglin]

Something just hit me. Check you wiring from your 220v source. Might be one is shorted to ground. Could be if you are hooked up to say a drier outlet that it isn't even wired correctly. You might have a floating ground now which is not safe to say the least. It wouldn't be inconceivable that the solid wire shielding is cracked and shorted somewhere. If the wire is good I would also back check the outlet you are getting your power from. With the circuit off of course. Personally I kill the main when messing with any wiring from the outlet back. It's the proper safe way to do it. Just sounds like that could be the issue, but it's a guess. Doesn't take long or much to ensure the wiring is right

[Al_The_Man]

Something just hit me. Check you wiring from your 220v source. Might be one is shorted to ground.

Don't forget LongRat is posting from the UK so one side of the 240 WILL be at ground potential, unlike N.A. where the 240v is centre tapped to ground.
Al.

[Maglin]

Ahhhh. I forgot we in the States are backwards from the rest of the world when it comes to power. Wish we where 220v standard.

[LongRat]

I've done some long runs now, over 1.5hrs machining each with no breaks. I have come to the conclusion so far that 4000 RPM seems just about comfortable, but I wouldn't exceed that for prolonged periods. This is based on feeling the temperature of the lower TR bearing in the spindle. I'll borrow a temp gun and check that during the week. The bearings look to be 44mm ID and 64mm OD but if someone who has stripped their spindle could confirm that it would be great. I'd like to get a handle on what the actual speed ratings for these bearings is.
Even at 4000 though the performance is night and day from stock. Checking this video, machining a railway wagon wheel pattern in aluminium. Running at 1000mm/min, this would be very uncomfortable at the stock spindle speed of 2250.

[nomedia="http://www.youtube.com/watch?v=DRZSY8a0es8"]YouTube - 4000RPM.mpg[/nomedia]


I made a plastic casing to stop access to the mounting screws on the VFD and the backplate, so it is safe. Still haven't contacted the supplier about it yet.

[LongRat]

I ran the spindle for 40 mins, checking at intervals the temperature of the lower taper roller bearing in the spindle. I used a non-contact IR thermometer with a piece of black tape on the spindle housing. Looks like it is levelling out at a pretty safe temp. I might try it at 5000 yet...

[ghino]

Hi LongRat,

how is going with belt conversion ?

can I ask to you how did u fixed the pulley on the top of the spindle ?

on the first pic of the topic seems as you have add a alu piece also to top where is the screw to remove the endmills MT3 support

[LongRat]

The belt conversion is great. It is a massive improvement for the mill.
To update the topic, I must add that my previous testing at '4000' RPM was actually at 3600 RPM. I've now got a tacho and measured the speed properly. The increase in cutting performance is perhaps even more surprising given what is actually only a modest increase in the speed!
Ghino - the pulleys are press fitted on to the shaft and have 1x M5 grub screw for extra security. The grub screw bites in to the spindle itself - there is no flat for it. The section of the spindle shaft that the pulleys fit on is where the encoder disc used to be for the standard set up.

[tef9]

Hi LongRat,

Just curious to see how the spindle is running? Did you ever repalce the spindle bearings or did you feel there was no need? Would it be possible to run the stock spindle faster?

Thanks

Tef9