New member, little help?

Fortheadingley · Dec 20, 2012

Hi, I've just purchase my first lathe, a 1942 Heavy 10 and I'm a bit (a lot) new to this, an I have a couple of power questions. I should point out I'm in the UK. The lathe has been converted from 415v 3 phase to 240v single phase and is fitted with a 3/4hp electric motor which seems ok on the fastest pulley setting, but labours and stalls at lower speeds, particularly when the traverse is engaged. Should I be looking for a slightly more powerful motor, say, 1-1.5hp or should I be looking for something else? The lathe has been extremely well looked after by its former keeper who had it for over 40 years, and I have adjusted the belt to give about 1/2" play at the headstock.

Best Regards

rw1 · Dec 20, 2012

I think the 3/4 hp is adequate; most Heavy 10s had this or 1 from hp factory. Mine is 1hp 3ph. I would take the motor apart and inspect/replace the bearings. Vacuum and brush out all the gunk in the motor.

Do you need a new belt? Look on this forum for the "Serpentine Belt" conversion....lots of good info. Gives much better gripping power that leather belts and easy to do.

Congrats on your SB and send us some photos!

ChrisK · Dec 20, 2012

My Heavy 10 has a 1/2HP motor and runs OK. According to the SBL-1934 catalog, SBL supplied a 1HP motor up to the 16in lathes, so seems like it should be OK on a 10in. You can disconnect the lead screw (set reversing tumbler to neutral) and run the motor at all speed settings. Then you will know if the problem is in the headstock or carriage.
Good luck
Chris

Fortheadingley · Dec 20, 2012

Thanks for that, motor appears brand new, I did wonder about belt slippage though, but I'm still at the 'Don't want to fiddle, in case I bust it' stage, I've spent the last week or so getting various manuals and reading though the post on this site and I may try the serpentine belt conversion when the confidence is built up a bit. I've looked at lathes for the last 8 years or so, but couldn't justify the expense, knowing very little about how to operate one, then this one comes up at a price that I really couldn't turn down and won't hurt me too badly if it all ends in tears so I thought 'why not?'

I'll post a couple of photos when I can get back to my main PC

Fortheadingley · Dec 20, 2012

Well, I've just been out for a little bit of a play and by disconnecting the lead screw I seem to be able to cut on the middle pulleys as well as the high speed without issue but on the slow speed the motor still stalls, traction doesn't seems to be the problem as the motor stops, but maybe I'm being a little to gung ho and trying to take off too much/ cutting too fast for the slower speed?

Anyhow, here's a couple of photos

kitno455 · Dec 20, 2012

The pulley on the motor looks much too large. What speed is that motor?

allan

dvw · Dec 20, 2012

She's a little beauty!

Nice t-slot compound!

On the motor, I'd also check for belt slipping or tight things. Does the motor or any bearing area get hot?

And please forgive this foolish question, but is it a 50hz motor? A 60hz motor will run on 50hz, but will run slightly underspeed.

rw1 · Dec 20, 2012

kitno455 said:
The pulley on the motor looks much too large. What speed is that motor?

allan

That's a good catch Allan. Motor pulley on my 10L is 3.5" o.d., grooves for the pulley are probably 3" or less o.d.

Fortheadingley · Dec 20, 2012

You'll have to forgive me, I don't know much about the motor as I assume the spec plate is pointing towards the floor, I'll have a look with the mirror tomorrowand see what I can establish.

Fortheadingley · Dec 20, 2012

....or I'll have a look now. Motor is 3/4hp, 50hz, the pulley is 5"OD and about 4"OS in the grooves, nothing gets hot and lathe runs quiet (save the clunk of the belt join).

rw1 · Dec 20, 2012

Sounds like its manageable, I'd say just take lighter cuts. It is a small machine.

kitno455 · Dec 20, 2012

Those numbers don't tell you the speed of the motor. You need to know RPMS, or the number of poles, we can work backwards from that.

allan

steve-l · Dec 20, 2012

dvw said:
Nice t-slot compound!

On the motor, I'd also check for belt slipping or tight things. Does the motor or any bearing area get hot?

And please forgive this foolish question, but is it a 50hz motor? A 60hz motor will run on 50hz, but will run slightly underspeed.

Whoa.........be careful here. A 240V, 60 Hz single phase motor will NOT run on 50 Hz without overheating. 50 Hz motors will always run on 60 Hz, but not the other way around. There are some 60 Hz motors that will run on 50 Hz, but not many. This especially true with the SB factory reversible single phase motors.The speed difference is 20%, 1725 vs 1425 for a 4 pole induction motor and 3450 vs 2850 for a 2 pole.

Fortheadingley · Dec 20, 2012

Thanks for that, as I say I am a complete novice to lathes so this is a learning curve for me. On a lighter note I have had some success this afternoon working a bit of scrap steel with the lead screw turned off and for the most part I'll be using it for bushings, spacers and the odd piece of bling for my classic motorcycles, which I'm hoping it will be more than capable of producing.

Fortheadingley · Dec 20, 2012

Apologies RPM is 1340, looking at the part number its the 3/4hp, 4 pole one of these

http://www.machinemart.co.uk/shop/range/guid/758758F0-FE9C-4B1C-B04E-92F2EE40584C?da=1&TC=SRC-motor

Regards

dvw · Dec 20, 2012

steve-l said:
A 240V, 60 Hz single phase motor will NOT run on 50 Hz without overheating.

My bad. I had three phase on the brain. :crazy:

yachtsmanbill · Dec 20, 2012

I think the motor pulley is way to big! Get a smaller one, or even a variable speed pulley. That type you screw the two sheave halves together to chang the belt dept/diameter. The pulley shown is actually a junker I had in the box. The OEM two step pulley was maybe an inch bigger on the diameter. Speeds seem OK for now... ws
MVI 0548 - YouTube

hitandmiss · Dec 20, 2012

That is an iron bearing headstock, top speed is around 1400 RPM.

With a much oversize motor pulley, the top speed is way too high.

Check spindle lube oil also.

kitno455 · Dec 20, 2012

In this case, you want a motor pulley that is around 1.3 times the diameter of the original.

But, back to the original question. Why would the motor stall when the belt is set for slower speed? If anything, the motor has an easier time at lower spindle speeds, since it has greater mechanical advantage. That almost makes me wonder if there is something else going on, like the belt tension on the small end of the cone causing something to bind?

allan

Fortheadingley · Dec 21, 2012

OK, so what size pulley is recommended?, a search has seem to suggest 3", but would that be total outside diameter or at the bottom of the "V"?

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