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25th May 2023, 11:17 PM #1
Waldown 6" bench grinder restoration (and lots of questions)
So where do I start, I picked up this grinder a few weeks ago for $20 and lets just say I got what my money was worth (I did keep my expectations low) but it still has potential I think and I hope
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So plugged it in and it did run. The paint was terrible (different colour coats peeling off) and some rusty spots.
Decided to slowly start taking it apart to inspect the internals and prep it for paint.
Most of the rust and paint came off using a wire wheel. The motor shaft and other parts cleaned up well. The bearings (Italian made) are good, dropped them in a jar of kerosene and gave them a clean coat of oil and they run smooth. Seems to have been replaced recently.
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First issue I encountered during the paint stripping and wire wheel work was that the right hand guard appeared to show a hair line crack which upon light finger pressure cracked off. I am not sure if it was attached with some kind of jb-weld or something but it just snapped off with 2 fingers. Oouch! Decided to call it a day before I destroy anything else
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I just woke up the next day thinking I am going to put a wire wheel on one side eventually but I need the right hand guard because it actually helps house the bearing in place. Another issue was that the casting also appeared to deformed (probably relieving some stress) and even brazing it back on would never have been the perfect fix (based on my limited experience and limited skill set).
And so I started getting evil thoughts that the Waldown fanboys are going to frown over and decided to take it to the next level
Chop chop with an angle grinder followed by a quick lathe turning operation holding the chopped off center part in the outside jaws of a 3 jaw chuck to carve out the central bearing retaining part. The interrupted cut barely last a few minutes because the casting was super easy to machine.
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Well we are at a point of no return at this stage
So while I was at all of that there were other discoveries (basically information overload in my mind):
- Was this oil lubricated? Or greased? I did find grease in the bearings but then there is an oil hole at the top of the casting with easy access to provide lubrication to the bearing housing and other sliding parts. There are also faint oil grooves on some of the parts. Obviously oil is a slightly better option vs grease when in contact with grinding dust and is easier to clean and replenish? I may just be obsessed with the thought that most quality machines built several decades ago I have come across always suggested oil instead of grease as a lubrication choice. Any suggestions?
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- No fan? Never had one from factory? Heat is being dissipated through the metal casting? I have seen some old grinder restoration videos and photos online that when pulled apart did have a shaft mounted fan? But the motor appears to be completely enclosed so no way for any air circulation? Am I imagining things here?
- The centrifugal contact arm assembly appears to be in good condition and so does the rotating conductive contact wheel that closes the circuit. I can see some mounting holes but no weights attached that will enable it to open at the correct RPM? I did hear the clicking sounds when I was testing the grinder before taking it apart, so it probably doesn't need additional weights? Probably it was a standard switch used on various motors back in the day and unless the weights were required to balance the centrifugal switch to open the circuit at the correct RPM they were not installed?
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- The static contact switch for the centrifugal switch mechanism that is mounted onto the right bearing housing has seen better days and shows considerable wear. Basically the contact disc has slowly eroded out the contacts. It appears to be a fairly simple assembly with conductive contacts mounted onto a bakelite board and held in place by rivets. There are through holes at the back which I can probably punch a pin through to drive out the rivets (assuming they are not the type that mushrooms to secure the contacts into the bakelite board or worst case drill through them carefully and replace them with replacement rivets). The contact strips are easily replaceable in any case however my concern is about the metal used: copper will be too soft and will wear out pretty quickly; brass is not as conductive as copper but has slight better wear resistance; or perhaps some type of conductive bronze since it will act as excellent bearing material (but is expensive and not easy to find)?
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- And finally the windings? Well if one sentence can describe it: the start windings do not appear to be in a good state. The run windings appears to be in good nick but that doesn't matter because when we re-wind the motor we need to get it all done. Probably too many starts/stops or not allowing the grinder to come up to speed before driving a tool into the grinding wheels? Although at this stage it does not seem to pose any issues as the motor does run, but in the long run the enamel is pretty much burned up (I tried cleaning it with a soft tooth brush and isopropyl alcohol).
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I know at this stage many will consider the restoration as "not economical" considering rewinding costs here which are basically reflective of labour costs. We are talking about $500 based on local rates here.
I actually know shops around Asia that will do it for about $65 (actually did this for a pump motor). So I am slowly developing a plan towards this idea.
The stator block appears to be welded to the motor casting. The assembly weighs about 5kg which should not exceed any checked-in baggage limits for me
In the meanwhile and as time permits I am going to make a quick map of the windings (I am sure I can find a generic diagram online as well) and wire count per winding and some estimated wire gauges (I know this has to be done with the enameled removed but running guestimates here). If I find the courage I might rewind it myself
This is definitely going to be a slow restore that will spend most of its time on the backburner which should give me ample time to plan.
Any thoughts, any experiences, any encouragement? Keen on hearing your thoughts.
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26th May 2023, 07:46 AM #2Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,542
On the motor, there is a rewind shop at the start of Beulah Road; they have done several motors for me so if you are worried about the state of the varnish and changing the windings, taking it there may be an option.
It would have been oil lubricated but these days most motors are fitted with bearings that are lubricated for life. As long as the bearings are not some special size or shape, a set of new sealed bearings should not cost you much and then you don't have to worry about a) remembering to oil them and b) mopping up the oil from the floor.
Michael
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26th May 2023, 08:48 AM #3
I will take it over to Statewide and see what they have to say.
Agree with the suggestion to replace them with modern and greased for life bearings that should not cost much if they are in the standard size.
The current bearings are open type on both sides made by Riv.
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6th Jun 2023, 03:06 PM #4
Over the few relatively warm days we had in Adelaide, I managed to do a few things:
Painted all the parts I had. Dulux cottage green was the only spray can I had apart from black and I just didn’t care to be fussy matching paint. I might give it another clear coat for added protection at some stage.
I also made a base cover plate and replaced the worn out centrifugal contacts with some copper strips about 1mm thick.
The base plate was a bit of an after thought while waiting for the paint to dry. I am not sure if the grinder had one from factory. I will drill the holes (i didn’t want to transfer punch holes from the base till the paint is completely cured). Again I will paint it at some stage.
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