Motor advice

[DaveL]

I think this is one for Bob!
I cannot afford to change the motor on my Wade metalwork lathe just yet but would like to decide what I am looking for and keep my eyes open for a possible replacement. Here is the plate on the current motor, sorry about the odd angle, it's not that easy to get to.

So it's a 1HP single phase 4 pole motor, I checked the speed of the spindle with a cheap optical rev counter, which has now eaten it's battery (that explains why it was disconnected when I got it out of the drawer).

It claimed it was doing 1128, which I think is a bit fast as the slowest of the direct speeds on the lathe.
I plan on fitting a 3 phase motor with an inverter to give variable speed control, like I have on my Jet wood lathe. I think a 1 HP motor should but OK, the question is would a 4 pole like being run at half speed or less when cutting metal, or should I look for a 6 or even an 8 pole motor?

 

[9fingers]

Ideally the motor should be running at nominal plated speed when doing most of its work to keep the fan cooling adequate and with the inverter you can drop the speed for the odd big job and speed it up by a factor of two when needed. I don't tend to recommend more than double the plated speed especially for older motors to be kind to their bearings.

You might find 6 and 8 pole motors to be hard to find unless buying new so an alternative might be to fit a countershaft and/or reduce the motor pulley diameter and stick with a 4 pole motor.

hth

Bob

 

[DaveL]

Thanks Bob, you confirmed my thoughts. I think a counter shaft may well be the solution, the later models of this lathe had one so that's the next thing to look into.

 

[DaveL]

So had a rummage and found the motor that my Dad had on his Myford, it's only 1/3 hp but it is 3 phase, the problem is its only 400/440 volt. There are only 3 terminals.

Bob, how hard is it to get to the windings to swap over to delta from star?

 

[9fingers]

Take great care opening up the star point. Insulation on older motor can be very very fragile indeed.

Good luck

Bob

 

[DaveL]

Bob,
I have found a motor listed on eBay,
http://www.ebay.co.uk/itm/172285710564?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Does it look a possible one for my lathe?
Of course the next thing I will need I a VFD for it, do you have any in stock or could you recommend a make / model to look out for?

 

[9fingers]

Hi Dave,

That will be fine, dual voltage and a good make too.

I'll have a look and see what I have and PM you. I don't tend to have many low power ones but a few came in during the summer and I need to check them over.

Bob

 

[DaveL]

Thanks Bob, motor ordered. [emoji41]

 

[DaveL]

Well it arrived yesterday afternoon :

Very well packed:

Did I mention it was well packed?

It was setup for 440 volts

But in the lid of the connection box

So I have moved the links

So it's now ready for being connected to a VFD, but there is lots for me to do, changing it over with the old single phase motor. I will need to make an adaptor to fit the drive pulley as well as one for the mounting foot, should keep me busy for some time.

 

[9fingers]

Sorry Dave I've been distracted by finger joints and domestic duties. I will try and test out inverters today for you. Fingers crossed!

Bob

 

[DaveL]

Well Bob pointed me at a suitable VFD, after I had picked a dud. I bought it and am pleased to say it all works OK.

That's it connected up to the mains and the motor.

I have currently connected the motor with two lengths of 3 core flex, only using 2 cores in each.
The controls will need a little more work:-

That's the speed on the left with forward and reverse buttons next, you have to keep a finger on the button to make the motor run. I need to look round for a box and workshop friendly buttons and knob.
I now have to sort out the motor into the driving position under the lathe.

 

[DaveL]

I bought some screened 4 core and cable glands.

Just waiting for the industrial style buttons and pot to arrive from China.

 

[9fingers]

Looking posh with the CY cable! Nasty plated steel braid on that stuff that can prick your fingers.

Have you sorted the programming out so the start command holds on now Dave?

If not, the momentary press green to start, press red to stop convention that we are all used to can sometime be referred to as "3 wire control" in inverter manual speak.

Let me know if you need any assistance.

Bob

 

[DaveL]

Yes Bob, I am going to use 3 wire control for the inverter, only reason for testing it with the 2 wire was no push to break buttons in my current stock of bits.

 

[9fingers]

Yes Bob, I am going to use 3 wire control for the inverter, only reason for testing it with the 2 wire was no push to break buttons in my current stock of bits.

OK understood. Some manuals are particularly poor on how to do 3 wire control - strange as it must be one of the most common configurations needed and a diagram would save ploughing through the Chinglish :lol: :lol:

Good Luck
Bob

 

[kirkpoore1]

Bob, have you ever seen a bracket that will attach to the VFD that allows you to fix the cables in place before splitting out the individual wires? I find that problem to be a real PITA. I usually build a bigger mounting board and adapt some kind of conduit bracket, but that's not a great solution as far as I'm concerned.

Kirk

 

[9fingers]

Bob, have you ever seen a bracket that will attach to the VFD that allows you to fix the cables in place before splitting out the individual wires? I find that problem to be a real PITA. I usually build a bigger mounting board and adapt some kind of conduit bracket, but that's not a great solution as far as I'm concerned.

Kirk

Kirk, It all depends on the manufacturer. I use quite a lot of secondhand Siemens inverters. Most of their early ones have a gland plate to take up to 4 cable glands. Newer Micromaster 4 series have an accessory to fit each of the 3 case sizes to do the job. I rarely supply them as the new price takes all the margin away from the job.
http://uk.rs-online.com/webdocs/00cc/09 ... 0cc2fd.pdf

A few p clips on each cable usually provide enough mechanical support for the cable and I split out from there for the wiring.

HTH
Bob

 

[Tusses]

LEGO is your cable friend ! lol

 

[Malc2098]

:lol:

 

[DaveL]

I had to wait for all the different bits for the switch box to arrive, some came all the way from China.
I bought 3 push buttons, red, green and yellow for stop, forward and reverse, a pot with nice screw terminals for the speed control. A plastic box to mount them in along with some more screened cable and a strain relief cable gland.
The switches have nice looking contacts,

Normally closed on one side and normally open the other.

It looked like they should all fit.
I covered the lid with masking tape and marked the holes

This picture is for Roger, I know he liked the drill guide.

I them used a tool I have had for over 40 years to open the holes to 22 mm.

I then ran into the first problem, after fitting the switches, the lid was 0.5 mm off the bottom of the box. After wandering abound muttering about buy the wrong box, I looked for some washers, I found some nice black ones, 1 mm thick, I think they are meant for flanges on water tanks. Once they were fitted everything went together as planned.
The control cable was then fitted into the box and wired to the nice screw terminals.

I connected the other end to the VFD and reprogrammed it to use 3 wire control. On trying it out the speed control was very odd, only having a very small range. I tracked that down to putting the wires in one hole to the right of where they should be been, luckily it did no damage and it all works as planned now the wires are in the correct position.

Next is the hard bit, swapping the motor and making the adapter to allow the drive pulley to fit the new motor shaft.

 

[TrimTheKing]

Gaaaaahhhhh why are the holes for the buttons not perfectly spaced, or is it the photo distorting???

My OCD is going bonkers here! [emoji23]

Cheers
Mark

 

[AndyP]

OMH but fascinating done the less.