Thumping sound from new lathe... errr... help?

[sploo]

I've just taken delivery of a new Axminster 1416VS. On starting it I noticed it makes a "whup whup whup" sound between 400-800 rpm. By 800 rpm it's so strong it's like someone's tapping the bench it's on with a rubber mallet. You can certainly feel the "thumps" if you put your hand on the bottom of the motor.

I moved the belt to the middle and high speed ranges on the pulleys and it's fine at all speeds (even down in the 400-800 rpm region).

Putting the belt back to the low range, the thump is back.

At ~823 rpm I counted the thumps at around 272 beats per minute, so a pretty accurate 3:1 ratio. But, with the lathe on the lowest range the motor would be going faster than the spindle, so I'm getting one "thump" for every three revolutions of the spindle (and more revolutions of the motor - which doesn't really make sense to me for a pulley related problem).

I've tried a range of tensions on the belt, and I can't immediate spot any belt or pulley damage. Obviously Axminster tech support has now finished for the weekend, so... anyone got any ideas?

 

[sploo]

I've confirmed that with the belt on the largest pulley at the headstock (slowest ratio), 3 turns of the handwheel equals one complete revolution of the belt. That ties with my findings above and indicates it's belt related.

The lathe however is now knocking at all ratios (but still worse on the lowest).

I can just about eliminate it if I apply very little tension to the belt (so little I can deflect the belt with my finger by at least 1.5cm), but that requires lifting the motor slightly when tensioning. Even tensioning with the weight of the motor is too much. That does seem pretty loose to me, or is that correct?

I've checked the grub screws on the pulleys, and they're fine. A visual inspection seems to indicate little if any wobble on the pulleys. I notice the headstock isn't bolted to the bed completely square, but it lines up well with the headstock, and I assume a few degrees shouldn't cause a problem with the belt anyway.

Another visual check of the belt doesn't show any obvious problems. So... just leave the belt loose?

 

[Paul Hannaby]

If you leave the belt loose it will slip under higher loads so you need to get the problem sorted out.

 

[sploo]

If you leave the belt loose it will slip under higher loads so you need to get the problem sorted out.

Thanks Paul. I'm trying to work out what constitutes "loose" though. I'm a brand new turner, so I can't just chuck something on the lathe and get an experience based feel for whether it slips in what should be normal cutting conditions.

From memory, old farm type machinery tends to have belts that flap about quite a bit. I also found a lathe related discussion where a guy was saying that 3/8" to 1/2" of deflection with light finger pressure was about right. It might be around that, though it does seem loose to me.

I had assumed (perhaps incorrectly) that the tension applied by the weight of the motor would be "about right", but maybe that's too much?

 

[CHJ]

Take the belt off the pulleys, has it taken a 'set' resulting in a 'flat' or 'kink' in its profile instead of being a smooth circle or ellipse?

If it has, it might work itself out if run under reasonable tension for a few minutes.

But before you try prolonged runs do a 'Screwdriver' sounding of headstock bearing area to make sure the knocking is not a bearing cage are similar cyclic catching on debris.

 

[sploo]

Take the belt off the pulleys, has it taken a 'set' resulting in a 'flat' or 'kink' in its profile instead of being a smooth circle or ellipse?

If it has, it might work itself out if run under reasonable tension for a few minutes.

But before you try prolonged runs do a 'Screwdriver' sounding of headstock bearing area to make sure the knocking is not a bearing cage are similar cyclic catching on debris.

I'll check - I don't recall seeing any flats or kinks when I first looked.

By 'Screwdriver' sounding do you just mean tapping parts?

I dived in and roughed a 2" square length of stock (actually the first time I've ever done that), but it was still knocking at the end (several minutes later). I was running the belt pretty loose though.

 

[Robbo3]

By 'Screwdriver' sounding do you just mean tapping parts?

Nope. Stick the blade end somewhere near but not on a revolving part then your ear on the handle. Any knocking will be magnified & you'll hear a rumble/drone if the bearings aren't running right.
By moving the tip to other places you can pin down where the noise is being generated.
It should go without saying that care should be taken when using this method.

 

[Sheptonphil]

Hmm. My 1416 was as smooth as a sewing machine when I tensioned the belt with the weight of the motor.

I guess the knocking is without a chuck on as you rounded 2 x 2 stock?

Phil

 

[Lons]

My 1416vs is good as well. I'd get Axminster involved as it's a new lathe.

 

[sploo]

By 'Screwdriver' sounding do you just mean tapping parts?

Nope. Stick the blade end somewhere near but not on a revolving part then your ear on the handle. Any knocking will be magnified & you'll hear a rumble/drone if the bearings aren't running right.
By moving the tip to other places you can pin down where the noise is being generated.
It should go without saying that care should be taken when using this method.

Got it - thanks.

With the belt completely off the motor pulley I used a screwdriver on the motor body - nice and smooth.

I checked the belt all round, both sides. No kinks, debris, flaws, or obvious bumps as far as I can see.

Putting the belt back on (lowest ratio) and tensioned with just the weight of the motor I used a screwdriver on the headstock. At low speeds there's a "distant helicopter" rattle. Slowly bringing the speed up you start to hear the "heartbeat" thump begin, and by the time the motor's running at full speed the thump is deafening through the screwdriver.

My benchtop is definitely magnifying the sound (acting as a diaphram) but you can feel the machine the knocking so it's definitely got an issue.

I guess the knocking is without a chuck on as you rounded 2 x 2 stock?

Originally with just the supplied faceplate screwed onto the headstock. I later removed it and fitted the 4 prong drive centre, but the sound is there all the time (and still was with some stock between centres).

My 1416vs is good as well. I'd get Axminster involved as it's a new lathe.

That looks like where it's headed. I'm sure hoping it can be fixed without a) time I don't have, and b) sending the darn thing back.

I've not had too much luck so far - a Sorby ProEdge turned up from Yandles with some paint missing* (and a damaged belt), and the belt tracking was so far out when I first turned it on that the belt removed more paint from the inside of the removable side cover before I could switch it off.

The 10" bowl gouge (from Axminster) was packed in a way to maximise shipping damage risk. If I put a straightedge underneath the shaft (touching the underside of the tip, and underside by the handle) there's a ~2mm upwards bow in the middle along the length. I don't know if that's normal or whether it did get bent in transit.

So far it's all a bit disappointing considering the money spent. I guess it'll be sorted in time.

* The missing paint on the ProEdge looks to be a factory issue, rather than transit damage

 

[Sheptonphil]

Feel for you. There's nothing like taking the shine off excitement of the shiny new kit than having these niggles.

I agree this lathe is almost certainly going to be a return and replace. I can't see a gouge being bent in transit, but all mine are true straight.

Only way is up from here.

Phil

 

[sploo]

Feel for you. There's nothing like taking the shine off excitement of the shiny new kit than having these niggles.

I agree this lathe is almost certainly going to be a return and replace. I can't see a gouge being bent in transit, but all mine are true straight.

Only way is up from here.

Phil

I suppose the bearings and headstock shaft will be user replaceable? Maybe that could be done in the field. It'd be quite a lump to have to send back!

As for the gouge - I did check the other (spindle) gouge. It's shorter, but it's also not perfectly straight. I guess if a bowl gouge has a gentle vertical curve along the length (~2mm tall curve over 250mm) it's not really going to affect it in use?

 

[NazNomad]

I wouldn't argue with your postman if he's managed to bend a bowl gouge. :-D

Re: the lathe. It's obviously not something an in-depth inspection has cured, and I wouldn't expect you to need to delve any deeper trying to solve it. The machine isn't right, get Axi to sort it out.

 

[sploo]

I wouldn't argue with your postman if he's managed to bend a bowl gouge. :-D

Re: the lathe. It's obviously not something an in-depth inspection has cured, and I wouldn't expect you to need to delve any deeper trying to solve it. The machine isn't right, get Axi to sort it out.

The TNT guy actually carried the box with the lathe (50kg) all the way up the drive on his own. It's been a few years since I've been able to do that.

Unfortunately Axminster had opened the box and put the bowl gouge on the top, as the second box (with shorter tools and some other bits) was too short for the bowl gouge. Problem is: there isn't space in the lathe box, so it was squashed between the polystyrene and cardboard top - with only a sheet of cardboard protecting it from damage in transit. Not very clever - and the poly and cardboard have a clear gouge shaped depression.

I'm sure Axy will sort the lathe - I've always been impressed with their customer service. The problem is the hassle of getting it sorted as I obviously need to be in for something to be picked up and replaced. I had to pay for a Saturday delivery this time as I couldn't be around during the week.

I'll just have to wait until Monday before I can talk to them - that's the frustrating bit

 

[sunnybob]

I dont know this machine, but the noise you describe sounds like the motor mounting bolts are loose.
You say the motor weight tensions the belt? That doesnt sound right to an old fashioned guy like me. The belt should be tensioned and then the motor securing bolts tightened.

 

[sploo]

I dont know this machine, but the noise you describe sounds like the motor mounting bolts are loose.
You say the motor weight tensions the belt? That doesnt sound right to an old fashioned guy like me. The belt should be tensioned and then the motor securing bolts tightened.

The motor is slung underneath the bed, and is on a hinged plate. When you loosen a Bristol lever at the front of the machine the motor can swing down (with the belt preventing it from dropping too far).

The hinged plate has a lever, and you use this to lift the motor (or push down on it to increase belt tension beyond just the motor weight), then you lock the Bristol lever to hold everything in place.

I did just check to see if the bolt around which the motor swings was loose, but it seems reasonably smooth (i.e. with no belt and the Bristol lever released the motor just swings, but doesn't otherwise rattle).

Here's another problem I've spotted though - unless you really apply significant downward pressure on the motor lever, the bolt/washer arrangement that holds the banjo to the bed will catch the ventilation cover at the back of the motor (it's a slightly larger diameter than the motor body).

This prevents you from bringing the Banjo near the headstock. You could twist it and just about get the toolrest where you need it to be, but I'm assuming that shouldn't be necessary. Obviously the top/rear of the motor is now scratched to b*ggery

 

[sunnybob]

sounds like a warranty call then. We tried.

 

[sploo]

sounds like a warranty call then. We tried.

Indeed. Thanks Bob.

I can't believe it should be possible to catch the back of the motor with the banjo. To prevent it you need to push down on the motor lever way beyond what I'd consider sensible for belt tension, so that doesn't seem right.

 

[sunnybob]

Its possible its the wrong belt. My 2 month old axminster bandsaw drive belt failed, completely snapped. When I checked its length it was so long that the jockey wheel had the belt bent right back on itself. I got a smaller one locally rather than fit another from then in case it was the same over length.

Axminster service is first rate, but I have found the original factory quality control to be sadly lacking on the last two machines I've bought.

 

[selectortone]

Are the pulleys in proper alignment with each other?