new lathe daydreams

[JWD]

Hi everyone, hope summer has been good to you all

i have a few Q's for the experienced among us. The new lathe dream is soon becoming a reality, and i am debating whether to take up an offer on an older woodfast model and convert it to a vari-speed drive, or wait until a readily done unit comes along in my price bracket - £500 give or take.

if i choose the former, i'd like some clarification - would i need an inverter and dual voltage motor or is the dual voltage not important as the inverter changes voltage supply prior to it interacting with the motor? would this be a suitable unit - i'm thinking 2HP as it is a larger lathe.

https://www.ebay.co.uk/itm/Set-Up-Ready ... %7Ciid%3A1


what are your thoughts/opinions

TIA
joe

 

[Duncan A]

The inverter does not change voltage. It changes single phase to 3 phase without changing the voltage - in this case 220V according to the eBay post. UK mains supply is nominally 230V but is legally allowed to vary from 216V to 254V so the stated 220V ought to be OK. There's a good explanation here: https://www.schneider-electric.co.uk/en/faqs/FA144717/.

You would need a 220 to 240V 3 phase motor - which would normally be a dual voltage motor connected for the lower of it's two available voltages.
Bob Minchin is the source of all knowledge on this matter and a good first step would be to download his PDF file: https://drive.google.com/file/d/0B_GZrX ... JtUDQ/view.
He is usually found on thewoodhaven2 forums, under the name 9fingers. I believe he sometimes has motors and inverters for sale as well, although don't quote me on that.
FWIW, the eBay link shows a tidy setup, but it's not particularly cheap in my view.
Good luck
Duncan

 

[JWD]

appreciate the help duncan, clearly my knowledge isn't up to scratch! do you know if the potentiometer is easy enough to connect up if purchased separately, i'm trying to reduce faff.
cheers

 

[Duncan A]

A separate potentiometer would be straightforward as long as you have the manual and know which terminal to connect it to. Bear in mind that a "proper job" would have the inverter in a steel cabinet with a proper isolator and that the local controls (potentiometer, reversing switch, stop button ) would also need mounting in a nice little box as per the eBay link.
Having said all of that, I put an inverter on my pillar drill and it is mounted out in the open with no cabinet, although it is out of harms way. I have also "not got around" to fitting local controls, mainly because the inverter has all I need for occasional speed changes.
One point to consider, if you like a speed readout on the lathe, you may need to derive it from the inverter output frequency - which probably won't change the displayed speed when you change pulleys, or fit a rotor on the lathe spindle with a pickup and digital display - which may be quite simple or rather complex.
Duncan

 

[Lazurus]

Sounds like a lot of faffage to me when there are many lathes within your budget albeit second hand. Get a ready to go package and put the effort into learning the dark art itself.

 

[JWD]

ok folks, so i have the lathe now!!

its a heavy heavy woodfast mc903 in lovely condition. It came with a tormek grinder, a few big sorby tools and loads of rests and accessories - its perfect.

Still needs a new motor and VFD - faffage indeed but a learning experience - i can get the motor for around £100. then a VFD on ebay at 56.99 with separate control panel. i've emailed asking about a warranty but im dubious as to its quality.. obviously :lol:

https://www.ebay.co.uk/itm/1-5KW-2HP-22 ... 0005.m1851


i really appreciate your thoughts and advice folks - i'll post a new thread of the paint job and installation in the coming weeks

 

[stewart]

Good luck with getting the variable speed set up. I've wired up the controls for mine from the inverter, but like others have said, getting a metal box to keep the inverter in out of the dust is needed.

 

[JWD]

Stewart -
got all the stuff for it including a very basic switch and Potentiometer, once i get an ip65 rated box it can all go in there and be ran remotely! It's annoying but the inverter fits so well where the NVR used to be

 

[Duncan A]

Looks like you're well on the way.
Chances are it'll be fine, but remember that you don't want to come to a halt too abruptly or the chuck with workpiece may unscrew themselves. If the default decceleration does seem too quick, have a read of the manual and adjust the slowdown ramp to be a bit less aggressive.
If the manual is in incomprehensible Chinglish, download a few manuals from more respected manufacturers such as IMO, Invertek, Yaskawa, Mitsubishi, Hedy etc, and you'll almost certainly gain enough understanding to wing it.
You'll have a very nice lathe once it's all done.
Duncan

 

[JWD]

Hi Duncan - I didn't fancy taking the risk so i forked out for the Invertek E3, I've just set up all the basics and it Lives! The motor sounds a bit irritating but it'll all be enclosed soon enough. Now to get a decent isolator and IP65 box for it all

 

[Jonzjob]

About 12 years back I converted my old Record CL1 from 1ø to 3ø and have never looked back. It is a different machine now and so much better. I can't remember what kit I have but I had to pay a bit more for the motor because it is an imperial set of pulley wheels. One of our members on here very kindly made me and extension for the shaft as it was too short. That was just the icing on the cake! I still remember who and I say thank you again numerous times!

My set is braked and as long as the chuck is on correctly I have not had any problems with the chuck trying to escape. That's even with my Axy K10 chuck fitted with the 10" button jaw set fitted. Or the clock case for my 13" diameter wooden clock case below. You can see the inverter in the background.

 

[JWD]

Looks great John! Well its all together and the pulley is (badly) rebored and on which will do for now! VFD works really well and an enclosure and isolator is on the way.

One question - has anyone ever used more than 50Hz with the inverter to boost the speed above the inherent 1500rpm of a 4 pole motor?

look forward to your responses
Joe

 

[Sideways]

Not on a lathe but I have a 1hp three phase motor which has max speeds listed on the plate at various voltages, currents, frequencies. I programmed my vfd to drive it at 60Hz as this gives slightly higher speed and lower current than the 50Hz settings. The drive doesn't care. As long as you know any of the rated combination of V F and I you can programme that into the drive.
It's a 4 pole and the max rpm at 60 Hz is listed as 1700.

 

[Duncan A]

Well done on getting set up and running. Nice innit?
The usual advice on frequency for a new 50Hz motor is max 75Hz. I'd a bit wary of going that fast on an older motor but in theory it should be OK provided it's in good condition - it will be noisier though. You need to be aware also that running at minimum speed for long periods can cause motors to overheat as they are cooled by a shaft mounted fan which is less effective at low speeds. I wouldn't worry too much unless you're planning on running for long periods at high torque at below 25Hz.
By the way, if you want to improve your pulley/shaft fit, pulleys can be matched to motor shafts by boring out, as you've done, or by buying a Taperlock bush and pulley. The bushes come in a wide variety of imperial and metric bores and a number of standard outside diameters to suit the pulleys.
Full info here: http://www.fptgroup.com/dss/docs/689_06 ... ixings.pdf.
They can be bought quite cheaply online and are now also made by Dunlop and other power transmission companies.
Duncan

 

[JWD]

thanks for the help guys - The motor is brand new! I'm going to leave it at 60 until i need to change it - the invertek is super easy to program!
yeah i'll have to look into the taperlock idea, or see if any of the metal masters could make me one hmmm

I am very pleased with it and i'll share the christening on here!
JD