Thread: Broken machines :-(

1) Factory neighbour needed some 45° cuts in 100mm square gal steel. No problems. We load it into the big bandsaw:
IMG_2399.jpg
cut a few meters off, and rotate the table.
Except the handle is stuck.

I spend a few minutes pushing and hammering the handle, tried loosening a little cap screw underneath, but all that happened is the handle bent (20x40mm tube). So, I'll have to fork or crane the vice and table off, to get underneath it, to un-seize the handle and weld/fabricate something new. Sigh.



1.5) Luckily, I have a generic 6x4 bandsaw. Except that the vice won't hold 100mm at 45°. So, remove the floating jaw, and apply some dodgy extra clamping:
IMG_2387.jpg
which works until the front blade guide hits the stock: IMG_2389.jpg


So, some modification with an angle grinder needed:
IMG_2391.jpg

and some re-clamping to get the rest of the way through.
IMG_2392.jpg



3) Tool maker got a "new" surface grinder:
IMG_2396.jpg

Unfortunately it was a late night delivery, and the forklift operator managed to damage the guard casting:
IMG_2397.jpg IMG_2398.jpg

So, in addition to disassembling to repair the blocked oiler lines, and maybe scrape the work cross feed Vs, there will have to be some Alloy casting repair



4) The shop vac was getting a little noisy, so I emptied the base, and air blasted out the filter.
Then re-assembled, and turned on. A terrible noise.
Stripped the motor out, and the brushes are arcing like crazy.
So, I gotta find some of these "cartridge" style brushes:
IMG_2402.jpg



P.S. Went to use my countersinks the other day, and they were rusted into my base:
IMG_2386.jpg
Timber is probably Mahogany. I made it to fit them, and thought I oiled it well, but obviously not.


Maintenance, maintenance everywhere

I realize this doesn't apply to some of the above but an old (well he he was probably 10 years younger than I am now) senior techo at the uni workshop used to say, The amount of actual maintenance, is proportional to the number of machines, and the amount of regular preventative maintenance undertaken.

I was the techos line manager at the time, and my boss and I were having a workshop review with the Techo when my boss asked him why he needed to have friday arvos dedicated to maintenance when he could be doing real work!

This is when buying quality gear can come into its own. Unfortunately this is not always possible in DIY situations.

Originally Posted by nigelpearson

4) The shop vac was getting a little noisy, so I emptied the base, and air blasted out the filter.
Then re-assembled, and turned on. A terrible noise.
Stripped the motor out, and the brushes are arcing like crazy.
So, I gotta find some of these "cartridge" style brushes:
IMG_2402.jpg

Maintenance, maintenance everywhere

Hi Nigel,

It might pay you to check that the commutator is not damaged or worn, look for loose segments as well !

Originally Posted by nigelpearson

So, I gotta find some of these "cartridge" style brushes:

These guys have heaps. Good service too.

https://schunk.com.au/index.php?rout...ategory&path=1

I share your frustration. Seems every project is complicated by an issue with a tool.

Building gantry crane - bandsaw is playing up. Blade stalling intermittently but motor still going. Pulley or gear must be slipping.

The ones that get me are when I plan poorly and get stuck modifying a machine because I have already pulled it apart and I need that machine to perform the modification.

This happened several times when modifying the bandsaw and the DP. Its a good excuse to own a couple of each machine or at least I keep telling myself this but who has the room?

Well, I hopefully just fixed the problem with the bandsaw. Of course, I was sure I had eliminated this possibility at the start, but looks like not... Driven pulley just has a set screw, no key. Looks like set screw was loose. There is some scoring on the shaft - pulley has clearly slipped on the shaft. I was sure I had checked this pulley was not slipping on the shaft when the blade was stalling. Some threadlocker and tightened up - hopefully fixed. Time will tell.

Of course, in the mean time I've drained the gear box thinking the issue was in there. And I have no replacement oil and the local place is out of small bottles of suitable stuff. 5L is about 100 times what I need. So I can't confirm fixed until I get a chance to pick up some replacement oil.

At least it forced me to do some maintenance I'd put off - the gear box oil needed replacing.

Improvise, Adapt and Overcome.....lol

If it makes you feel better… my clean the 9” project started out two weeks ago as a clean it and replace worn parts type affair has now had sufficient scope creep to become a full bare metal resto with upgrades..

Originally Posted by BaronJ

Hi Nigel,

It might pay you to check that the commutator is not damaged or worn, look for loose segments as well !

Good thinking. A little worn, but they don't seem horrible:
IMG_2444.jpg


I threw it in the Hercus, emery'd the surface, and gently bevelled the edges to get any burr off:
IMG_2446.jpg IMG_2447.jpg




Let's see if that does anything with the "current" brushes

Hi Nigel,

Thanks for the pictures ! That comm looks to be in good condition.

More than can be said for the splines on the end of the shaft .

I have a couple of four or five inch long square section stones about 50 or 60 grit, maybe 3/8" inch square, I/we called them "Comm" stones and were used for cleaning commutators whilst the motor was running. Quite safe to do because the stones are not conductive. When you got a motor that was arcing and sparking, you used the end of the comm stone to rub the commutator and clean it. The effect was that the sparking quietened down and the motor became smoother and less noisy, this also had the effect of cleaning the old carbon brush contact surface and bedding them to the comm by removing the patterning on the contact end. You didn't press hard on the spinning comm and adjusted the pressure as needed.

It saved a lot of time stripping a motor just to clean the comm and was a very quick operation, maybe two minutes. if the motor didn't quieten down using the comm stone, then it was a matter of replacing the armature.
Very often you found a loose or open segment in this case.

The brushes still arced like crazy. Hard to capture in a photo:
IMG_2421.jpg


All segments measured at the same resistance, so I looked closer at the brushes. Plenty of graphite – length about 20mm in the sleeve – so it must be something else. I don't know what spring tension motors use, but they seem to be pushed in well enough to make contact.

Then, when turning the motor shaft, I noticed the brushes moving in and out maybe 0.5mm. It looks like there is a high point on some of the comm' segments?

So, pull the armature and shaft out again, and put in a lathe. This time, put the comm' end closest to the chuck, and tap the jaws to dial it in to a few microns TRO. Then, a light cut:
IMG_2748.jpg

Two of the segments seem high?

I push and tap, to make sure they are not loose, but no. Very odd.


A scientific mind would have checked each one at this point, but I have already spent too much time on this annoying vacuum cleaner, so just a final cut to mostly level all the segments:
IMG_2749.jpg

(note that one or two there still have graphite marks. I'm thinking maybe the comm' wasn't concentric!)


Cleared the copper shavings out with a thin blade, bevelled the edges with the same blade, cleared the new shavings out, assembled the motor and tested.


No arcing this time, just a spray of sparcs from the brushes bedding themselves into the copper at many thousand RPM! (I forgot to attach the motor cooling fan, so it was spinning nasty fast)

Put the rest of the vacuum together, and used it (to vacuum the car's carpet and mats).



So, only 3 hours work to get a dead, former side of the road, vacuum to suck.

And, last week, another old vacuum choked and burnt out.
(I had it on the table saw, and it filled up with too much wood dust)
So, I will be stripping, and checking its motor, tomorrow when the light is better

Originally Posted by nigelpearson

IMG_2421.jpg

Is that the vacuum cleaner or an inter-dimensional time portal that exists in your shed?

Michael

Originally Posted by Michael G

Is that the vacuum cleaner or an inter-dimensional time portal that exists in your shed?

Michael

Hi Guys,

It looks like a picture of the internals of the International Jet Torus at CERN !

Fusion reactor.

Sent from a galaxy far far away