Chester DB8VS

[SquarepegParticipant @squarepeg]

Hi all, I bought a Chester DB8VS a couple of months ago 2nd hand, but not actually used. It's been fine but recently started to make a ticking/knocking noise. The noise speeds up with increasing speed, but after using the lathe for about 5/10 minutes completely disappears until the next cold start. I sent a video of this to Chester who told me that it's the motor or possibly the brushes. I took the brushes out which were fine but loose so I tightened them up, put it all back together and no more noise. Until last night…

On closer inspection I found that changing the belt tension changed the pitch of the noise. I then removed the belt completely and ran the motor and there's no noise, but also granted no load. It's leading me to think that it's the tensioner, although the bearings feel OK and there's no odd movement in it. I don't want to over tension the belt in order to get rid of the noise. I've ordered bearings for the tensioner as a starting point but I was wondering if anyone has had a similar issue and also, what kind of slack there should be in the belt under the correct tension?

Thanks

[SquarepegParticipant @squarepeg]

Knocking

[Tony Pratt 1Participant @tonypratt1]

Is it a faulty belt?

Tony

[SillyOldDufferModerator @sillyoldduffer]

Amazing difficult to track down where odd noises are coming from. Next time I have to do it I will buy a stethoscope, but try a wooden rod, about 12 to 20mm diameter, 200mm long. One end to ear, other to suspected source. Take great care not to get caught in a running machine!!!

Dave

[JasonBModerator @jasonb]

Could be the belt has taken a "set" if it was sitting around unused for some time.

[SquarepegParticipant @squarepeg]

I'll have a proper look at the belt tonight, but I'm not sure that the noise would disappear if the belt was faulty.

I did think of using a screwdriver to have a listen, but as I had one hand on the safety switch due to the cover being off and the other on the speed control it was pretty tricky. It was late last night when I was at that stage so I'll have another look tonight – I suppose I could jam the cover safety switch to free up a hand.

What do you mean by taken a 'set'? It hasn't sat around for long at all so I doubt it but it could still be possible.

It is very frustrating as it's not glaringly obvious what the problem is. Thanks for all your help.

[JasonBModerator @jasonb]

If a belt sits under tension for a long time it can take on the shape or set of an "egg" due to being stretched around the two pulleys for a long time in one position. So when you start it up the bit that was around the smaller pully and make a bit of noise until things warm up and the belt is more easily flexed.

Not sure what type of belt yours has but the Poly-Vee on my 280 can make a bit of noise when cold or under heavy load even though it gets regular use.

[SquarepegParticipant @squarepeg]

Ah thanks Jason. I'll take a proper look at the belt tonight.

It just a single vee belt, but the noise definitely doesn't sound like it's from the belt, even though it could be caused by the belt. It's hard to describe really but it's a metallic noise, it sounds as if there is a metal ball just bouncing around randomly in there somewhere.

[JasonBModerator @jasonb]

The other thing you could try is swinging the change gear banjo slightly towards you so that the first gear on the banjo disengages with the one on the spindle. If the gears are badly meshed or spaced they can make a noise though that usually doe snot go away as the machine warms up.

Edited By JasonB on 04/08/2021 18:31:29

[SquarepegParticipant @squarepeg]

Thanks Jason. I've replaced the bearings now, and the noise was still there so it wasn't them unfortunately. However, I did notice that the belt wasn't running true when in it's original position so I've aligned it a little better by moving the motor pulley and that does seem to have stopped the noise for now. I'm glad it's stopped but also puzzled due to the type of noise that it makes. Time will tell if it was that I guess…

I then had a look at the gears anyway and found that a couple of them were actually loose, but in tightening them I managed to snap one of the quadrant bolts! I didn't even put much torque on it, but I also didn't realise that I should have held the flat on the head whilst tightening the nut. Without doing this I was tightening an M12 nut that turned the bolt with a much smaller thread on the end. It broke way easier than it should have but I get these will just be made from cheap steel. It's annoyed me, but it's also another lesson to add to the list! Now all I need to do is try and source a replacement, which doesn't seem as easy as I first thought!

[SquarepegParticipant @squarepeg]

Just for future reference if anybody comes across this thread again, this problem turned out to be the belt. It looked absolutely fine but swapping the belt solved the problem. It seemed to be the ribs on the back of the belt somehow pinging the edge of the headstock pulley as they merged with a slight twist in the belt.

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