Should I use anti-vibration mounts under Boxford AUD cabinet?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nigel Monk on 12/10/2022 10:20:39:

…

Damn the thing is loud! The whole cabinet shakes and rattles. There is a fairly loud hum from the motor but overlaid by everything shaking. Not panels oscillating so much as the whole thing going. I could try to tighten the mounts and screw the cab to the floor, but I think I will try to find a properly balanced motor first. I have access to a couple as well as the original 3-ph it came with.

Looking on the positive side, this will hopefully mean the lathe itself is not the source of noise and everything is ok. Time will tell.

Nigel

That's progress! As it means something is significantly wrong, I suggest ignoring anti-vibration measures until root cause is identified.

I'd start with a close inspection of the motor and it's mountings. The mountings usually have an arrangement allowing the motors angle and position to be adjusted. Possibly one end has come adrift so the motor is free to move and is unbalanced in itself, and/or relative to the drive train. Missing bolts, perished rubber mounts, physical damage etc. Try heaving on the motor in various directions to see if it moves.

Assuming the lathe has a belt, these can cause quite severe vibration. Elderly belts left tensioned in one position for a long time tend to harden around the pulleys, causing bumping when the motor spins. Easy fix – new belt.

With luck the it's something simple and a new motor and anti-vibration feet won't be needed. A problem with diagnosing older machinery is the possibility it has two or more mild faults which confuse the issue by interacting. Also possible that an inappropriate 'fix' was applied by a previous owner who misdiagnosed the issue or applied a bodge. So keep an open mind and check everything.

Dave

[John HaineParticipant @johnhaine32865]

Posted by Nigel Monk on 12/10/2022 10:20:39:

….. It is a Benedikt and Jager K16 3-phase wired so that the 3 phases are in parallel and share the current.

….

Nigel

Well I'm not sure what you mean by "in parallel" but it doesn't sound like a good way to connect a 3 phase motor!

[Martin ConnellyParticipant @martinconnelly55370]

An earlier post said it was rewired and a single phase motor was put in that is not original. I would bet the motor is the source of a lot of the vibration, either it needs servicing or it is broken (a rotor coil fault for example) and needs scrapping off. A single phase motor is not a good way to produce smooth torque for the relatively low inertia drive train that most lathes have. I think brushless DC or 3 phase will always be smoother. I would suggest replacing the original motor and driving it directly with a VFD, you can still use the original controls to operate the VFD.

Martin C

[OldironParticipant @oldiron]

Nigel. The flap on top of the headstock is supposed to be hinged. It is there so you can oil the backgear shaft.

I just have 6 small squares of 1/8" insertion rubber under the pads on my AUD. No need for anymore.

regards

[Dave HalfordParticipant @davehalford22513]

Nigel,

Check the pulley has not been sleeved to match the single-phase motor shaft. They sometimes don't fit well enough and the pulley wobbles due to the bolt pushing the pulley off centre.

[Nigel MonkParticipant @nigelmonk]

Thanks everyone for your suggestions, I can't keep up with them all!

Dave – I will take the pulley off and re-check the vibration. That would be a nice easy fix. Well, except I'd need a lathe to true things up lol.

Oldiron – did you bolt through the pads into the cabinet? Do you recall how tightly the bolts were pulled down onto the rubber pads please? The headstock flap had been riveted in place but my father had drilled these out. Perhaps the rivets were a safety measure in the school workshop? I will see if I can put some small allen screws in when I get to that stage.

Yes, I'm please to have found a definite source to work on. I can't think the motor left the factory with a vibration problem? In which case 'something has changed'. I have a vague memory the motor that's fitted is not overly powerful, but I need to check the plate to verify that. Another reason to ditch it if so. There wasn't much choice in the 1990's, at least not with the self-imposed constraints (local paper or Exchange and Mart and cheap!). In any case, the 3-ph plus VFD does sound attractive, just one more thing to look into. I'm so looking forward to being able to make something!

thanks again

Nigel

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Nigel, if the motor was changed from the original 3/4 hp 3 phase one to a single phase one, it is recommended that the single phase one should be a 1 hp, that however, shouldn't produce excessive vibrations if it isn't, but if the motor is under powered, it can prevent you using the higher speeds. A good quality motor is what is really needed. When I changed mine, I was lucky enough to get one from a guy at one of the shows, who had bought it for his own Boxford but then he decided to fit a VDF instead. This was 16 or so years ago and cost me £80.00 and is a really good quality one and has never been any trouble.

Regards Nick.

[Nigel MonkParticipant @nigelmonk]

Hello again, back on the horse. Happy new year – I've been distracted. I think it started with making Xmas cakes x3 following my mother's recipe which we've had for 60 years – she's resigned from the responsibility now she's reached 90 (happy days ).

I managed to buy a VFD at a reasonable price, £115 iirc for a Mitsubishi FR-D720-070 which bizarrely I'm struggling to find a rating for, but I think it's 7A output so approx 1500W.

Both the replacement 1P and original 3P motors are 550W. The 1P is stiff to rotate and winds down after 4 turns from a good spin using the pulley. The 3P runs for 12 turns after a spin of the shaft. Hopefully a good 'un.

My question now – please advise if I should start a new thread – concerns the bearings for the intermediate / lay (?) shaft. These were also noisy and having stripped them from the shaft and pillow blocks, one rumbles while the other is gritty and scratchy.

The old bearings are shielded. Is that an old thing, because I can't think of a reason not to use fully sealed bearings? They will be somewhat stiff and may rob a small amount of power, presumably reducing as the grease warms and thins during use, but they should stay lubed and I can't foresee the need for a metal shield – what potential problem is that guarding against? Swarf? Appreciate any advice, thanks.

The bearings measure 2" x 1" x 0.5" and eb*y discovers 700,000 suggestions on an initial search! Can anyone suggest a reliable source for reasonable price and quality please? KOYO are supplied by Cromwell Tools and eBay at about £20 each. PGN read well but appear to be available only in the US. Had a quick look at Simply and Henderson, etc. Are the 'Budget Quality' bearings ok in practice? I thought stainless was typically quite soft so was surprised to find stainless bearings?

Thanks, Nigel

[Dave HalfordParticipant @davehalford22513]

Careful, budget bearings can be mild steel, good for garden windmills, but not much else.

Did you test the noise with the leadscrew turning or not? The gearbox can double the racket.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Nigel, nothing wrong with shielded bearings for your layshaft, they will keep general dirt and particles that wear from the V-belts out and won't have any drag on the shaft. Get good quality or better still, high quality bearings, which should last many cheap ones out and likely to be cheaper in the long run and if you go to Simply Bearings, look in the Brand/Quality box, unless of course you like the job of changing them. Martensitic Stainless steel can be hardened and tempered in a few different ways, but I wouldn't think you would need them and they are dearer.

Regards Nick.

Edited By Nicholas Farr on 02/02/2023 18:59:05

[Niels AbildgaardParticipant @nielsabildgaard33719]

I once had a Boxford A and made it behave.

Best motor was a 6 pole(1000 rpm) 1.1kW three phase and a VFD.

You can see picture here

Box on Rock

and judge noise after having put motor on top of headstock.

Low noise Box

[OldironParticipant @oldiron]

Posted by Nigel Monk on 13/10/2022 10:58:23:

Thanks everyone for your suggestions, I can't keep up with them all!

Dave – I will take the pulley off and re-check the vibration. That would be a nice easy fix. Well, except I'd need a lathe to true things up lol.

Oldiron – did you bolt through the pads into the cabinet? Do you recall how tightly the bolts were pulled down onto the rubber pads please? The headstock flap had been riveted in place but my father had drilled these out. Perhaps the rivets were a safety measure in the school workshop? I will see if I can put some small allen screws in when I get to that stage.

Yes, I'm please to have found a definite source to work on. I can't think the motor left the factory with a vibration problem? In which case 'something has changed'. I have a vague memory the motor that's fitted is not overly powerful, but I need to check the plate to verify that. Another reason to ditch it if so. There wasn't much choice in the 1990's, at least not with the self-imposed constraints (local paper or Exchange and Mart and cheap!). In any case, the 3-ph plus VFD does sound attractive, just one more thing to look into. I'm so looking forward to being able to make something!

thanks again

Nigel

Hi Nigel. Sorry for the tardy reply. Not sure sure how I lost the thread until now. The lathe is not bolted down so the pads are just placed under the feet. My lathe runs very smoothly and is fairly quiet unless I crank the speed up nreally high. With my VFD I leave the belt on the centre pulley this helps with the torque and I still have more reduction if I ever need it. I have done some pretty big jobs but the lathe has coped so far with no belt changes. I only use back gear if I need to drill a big hole ot tap a thread into something. I have Fenner Nutlink V belts on the lathe and they run fine.

regards

[Nigel MonkParticipant @nigelmonk]

Thanks each for your replies. I have an aversion to cheap 'n nasty, almost as strong as re-doing a job I've done in the past 60 years…

I haven't progressed to remounting the lathe back onto its base yet – stil lining the duck boards up. If the motor, layshaft and new V belts are anywhere near as quiet as Niels' set up, I shall be extremely pleased. I found I couldn't remove th emotor pulley in-situ so couldn't complete that test. Unfortunately, I will find out when I re-assemble.

I've just shortened a 5-drawer filing cabinet to 4-drawers so that it fits closer to the up and over garage door. I mainly wanted to keep the cabinet to block the view from the pavement of the lathe when the door is open. Not that I'm expecting anyone to come in and pinch the lathe, but it just gets people interested where they don't need to be.

That's made enough space to work around the base so I can get on with de-rusting and painting. Emptying the drawers of 15 yo paperwork, removing identifying names and addresses, took a while. The drawer space will allow stuff to be sorted off the floor and bench some more. Do you find things have to happen in a sequence to arrive at what you're actually trying to achieve? I will be organised one day!

Thanks again, Nigel

Edited By Nigel Monk on 02/02/2023 21:39:58

[Nigel MonkParticipant @nigelmonk]

Next step: bearings are bought and received, via eBay; Koyo R16's from henderson c.£14 ea and KSM R12's from bearingsrus c.£9 ea, lower and upper countershaft respectively.

I plan to split the inner races of one each of the old bearings to make well-fitting spacers for refitting, probably using an angle grinder. I think that will make them easily removable after fitting?

My question for today is what or whether to grease the shafts and/or pillow block rebates before pressing the bearings into place – any advice please? I think doing so will prevent rust creeping in, as well as reducing friction while fitting, but I've no idea whether to use copper slip, LM grease, hypoid oil, 2-stroke oil, Castrol M (yep, a very old tin, mostly goes into model diesel fuel), 3-in-1, sewing machine oil is the lightest I know of, WD 40 (just kidding) or simply rely on the light grease that is already on the bearings?

Also, I will cleanup the shaft and rebate fitting areas but presume I shouldn't use a degreaser at risk of pulling any lubrication out of the surfaces?

Or should it all be completely oil free and de-contaminated, including bearings?

Too much imagination, not enough practical experience!

Thanks, Nigel

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Nigel, just use a light oil smeared on the journals and inside the bearing inner race.

Regards Nick.

[Ady1Participant @ady1]

I've got a concrete garage and use a bit of scrap rubber mat under all my "bigger stuff" feet and it makes a huge difference, I do it before I even plug in a new unit now

The shaper in particular made the house rumble, probably more resonance noise than HP, but you noticed

[Author]

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