Warco VMC

Well tachometer arrived today and was able to see exactly where i was up to with actual spindle speeds.

From trials I am playing with two options to set belt speed at for 50Hz.

Have option of 1380RPM or 1800RPM.

For the time being I am going to run with 1800RPM setting at 50Hz.

On my Teco going into parameters Group 12 have set parameter 12-03 to show 1800 RPM at 50Hz. Have set parameter 12-04 to read display in RPM ( up to 5 fig integra ).

Display now shows spindle speed as you go. Spindle speed at 75Hz ( Tec's max rated speed ) is 2700RPM or a tad more if I wanted to push it. Will see how we go and monitor motor temp any periods on lower speeds. May fit digital thermo on it.

Edited By MalcB on 31/01/2017 19:12:36

Malc,

Does the Teco have the capabilty to utilise the in built thermistor in the motor?

My invertek drive can accept a thermistor input, but I chose not to use it even though my lathe and mill both have TEC motors fitted...

My lathe ( a WM 290 equivalent) has a 2800 rpm motor fitted and I run it at 4000 rpm ( 75 hz ) to give me the same spindle speeds as before...it replaced a 1.5kw dc motor.....

Malc

Good place to start. Should give you a similar speed range to what I had on the fast belt setting which was quite workable.

But maybe a little on the fast side for the one and only / normally used speed range. My experience suggests that 2,000 - 2,200 rpm top end and bottom speed pro rata would work out a bit better for a single range. With my 125 to 1,400 and 250 to 2,800 speed ranges I often enough found that it would have been better if I could have gone a 100 rpm or so slower in high or 200 rpm or so faster in low. Not quite far enough out to be worth changing speeds just for that but just made life that bit harder. Fortunately the speed overlap on mine was sufficient that for a goodly range of jobs it didn't really matter which belt setting it was on.

If you use a wiggler, edge finder or co-axial indicator its desirable to have a nice low speed on tap. Say 100 rpm or less. Run much faster and things start getting a bit frantic.

Clive.

John,

Yes it does and the thermister block is there in the terminal box as well. It has ability to display the temperature but I am not sure if is able to do any further controlling. Its unlikely I will use it, but I will research it further out of pure interest and learning.

Clive,

Very interesting, If I opt for the lower 1380RPM setting at 50Hz the top speed hits about 2100 RPM at 75Hz or 2200 if i squeeze it a bit. May be better running with this option with a belt change for higher speeds than 2100/2200. Will give it a few weeks and swap over. I do use wigglers and edge finders.

Edited By MalcB on 31/01/2017 21:54:19

Malc,

Does the Teco inverter have the ability to set a different frequency that is switchable using a digital input...,?

I have Teco inverter on my lathe ( a smaller version of yours, .75 hp) but havent really read the manual.....

If inverters had the flexibilty to set the frequency switchable from 0-50 and 0- to x hz it would make belt changing un-necessary if it could be changed by a switch.....

Something for me to look into......

Malc

Do please report back. As VFD solutions become more popular we need more data points as to what constitutes the most useful general purpose speed range for HomeShop folks. Which will undoubtably be different for different sizes of machine and different types of work. Think we will always have to accept that there will be some belt changing as a VFD alone will rarely be enough. (These days I drive a Bridgeport with 2J2 infinitely variable speed head. The majority of my work gets done between 400 and 1,500 rpm as I don't often use flycutters or large face mills. 50 rpm for centre finding, alignment and wiggler duties.)

John

In similar applications switched resistors can be used in conjunction with the potentiometer to set the variable fraction of the range relative to the whole range. I can see no reason why it shouldn't work with a VFD. If you just want switch selection from a range of pre-set speeds you could use a bank of resistors with a multi position switch. I've done such for other purposes but wouldn't advise going beyond 12 positions. Switches start getting expensive and the resistor bank cumbersome if restricted to simple DIY techniques.

Clive.

Hi John,

Reading your question in conjunction with Clive response as well.

I have two Teco inverters that i have installed. Both models have a variable frequency potentiometer on the face of the inverter, like on the more expensive Inverteks.

I have a 2.2kw Teco EV series on my Harrison M300. Its a late machine (2003) which has  more contactors and overload protectors than the earlier models. MEW 145 covered a conversion for mine. The logic control to the inverter in this article seemed overly complex so i did my own circuit diagram, got my electrical wizard friend check it, went ahead and rewired it all to utilise all the machine controls and interlocks, not really wanting to do any with the inverter, which i left set at 50Hz max. I can still use the pot on the front to vary speed if needed, but the M300 has such a good speed range i think it will never be necessary.

The Teco I have just installed on the VMC. is the L510 series 1.5kw model, which is to be used opposite to above in that i am using frequency range to change speeds.

I do not understand what you would gain by having switched frequency ranges. If you programme the inverter  to use the potentiometer with a speed range from say 0 to 100Hz why would there be a benefit switching in between? I cannot see in the manual that you can use different ranges, only a min and max, but does not mean i have not missed it.

 Its as Clive has established, setting a wide frequency range and then setting the belt position to achieve the optimum compromise of max speed, lowest speed, satisfactory motor cooling at lower frequency and minimum amount of belt changes if needed.

If its an issue of knowing exactly what speed you are doing and your inverter does not have the ability to display revs then its still really simple.

Once you are satisfied with the fixed initial belt position,  buy yourself a digital tachometer like I just have.

You can get a decent one for not a lot of money. Use the tacho and at each of the potentiometers markings, take a reading and the do yourself a chart of frequncy setting vs RPM, which is what I would have done had I not got the parameters to do this on the Teco.

To generalise a little.

One of the big learning curves for me is using inverters and I have a lot to learn yet. When I first started looking at and learning about them, I download quite a few manuals ( and i mean quite a few ). I found some very easy to tead and follow right thru' to those that were megga difficult to understand. Loads of Youtube videos watched, each time gleebing a little more understanding.

I actually found the Invertek and Teco not to difficult to follow and these were makes high on consideration list.

Edited By MalcB on 01/02/2017 09:20:07

Clive,

Thanks for input and yes I will keep you all in the frame with results when I finalise settings.

The new Warco VMC with variable speed drive is available as R8 metric and the two speed ranges are 100-600rpm and 425-2500rpm, motor is 1.5kw. Priced at £2269 delivered, I wish it had been available when I bought mine!

Mike

Edited By Mike Poole on 01/02/2017 18:12:24

I assume this is so new its not on there web site yet

No sign of it yet, but it was on display at the London ME show. The details provided came from my enquiry on the Warco website.

Mike

Edited By Mike Poole on 01/02/2017 20:14:28

Jumping back to the rubber protective sheet. I have just discovered that the Warco fitted DRO X-axis read head is mounted on top of the plate that that holds the bottom end of the rubber sheet.

This means that to get the remains of the existing sheet out to replace it. I will have to disturb the DRO installation which I really don't want to do. Further more it looks like the read head alignment is determined by the compressibility of the rubber??? I think I will be looking for an alternative fixing method that doesn't disturb the DRO.

Stuart, I find it hard to believe somebody actually fitted a DRO scale directly on top of the rubber. Personally if it was my machine, i would remove and re-fit the scale and reader assembly just for piece of mind. At a minimum i would remove its cover and clock up the scale to check it out before any real damage could happen.

Not a lot of room to get some photos, but here we go. The head is not directly on the rubber, but on the plate that is clamping the rubber, still seems  a dodgy mounting technique?

Edited By Stuart Bridger on 01/02/2017 22:15:27

Edited By Stuart Bridger on 01/02/2017 22:16:26

I cant believe Warco would do such a thing if they in fact fitted the readout themselves, the mind boggles.

Its certainly not what I think can be perceived as good engineering practise.

The scales are supposed to be held in correct alignment within a couple of thou.

They must not be bothered by the fact that at some time in the future the owner will need to replace them and try and get the scale back aligned, but heyho, its going to be out of warranty by then.

I was somewhat surprised as well. The machine was ordered complete with DRO from Warco and is long out of warranty. I have had it about 7 years.