mike 109444
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- Thread starter alancaddy
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the snooper
getting older by the day
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the op states
The motor runs at full speed when I turn it on but the disc turns slowly and stops completely under load. Taking it apart there is a small bevel gear on the output shaft of the motor, which turns the larger one. The small gear is completely free to spin on the shaft and has a few mm up and down play also. Should it be fixed solid to the output of the motor? It seems to me like the motor is turning but the gear isn't, although I'm no expert.
The motor runs at full speed when I turn it on but the disc turns slowly and stops completely under load. Taking it apart there is a small bevel gear on the output shaft of the motor, which turns the larger one. The small gear is completely free to spin on the shaft and has a few mm up and down play also. Should it be fixed solid to the output of the motor? It seems to me like the motor is turning but the gear isn't, although I'm no expert.
brightspark
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so either clean and locktite it which will do the fix as i have done one of mine or throw it in the bin and buy new .one . nowt to loose
Ok guys I will loctite the gear in place and make sure all screws are tight...
To the guy asking for photos, I did take a video of the grinder running when dismantled, can post up if you want.
Separate grinder for cutting disc/flap disc sounds good actually, lazy but tempting...
To the guy asking for photos, I did take a video of the grinder running when dismantled, can post up if you want.
Separate grinder for cutting disc/flap disc sounds good actually, lazy but tempting...
Rig Pig
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There are a few people on here who need to try out a petrol driven grinder!
sardine
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I refurbish a fair few grinders, and I always find all the grease has been thrown off the bevel gears, when I open them up. What the answer to that is I don't know, a sealed oil filled bevel gear would be impractical. I doubt its even worth greasing them.
Jan
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In the past I've noticed that a lot of this type of gearing relies on a thin 'cotter pin' running through the gear and shaft to maintain drive. These are designed to snap under excess load so as to not stop the motor and cause it to burn out. Although in itself it's a good idea, finding replacement pins can be a nightmare after a few years as models are changed far too regularly for suppliers to keep on top of the need for more & more parts to keep older models working.
Wallace
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Not being pedantic, the cotter pin you refer to is termed a shear pin, usually a softer material than the shaft they are designed to protect. Boat props are a common place to find them as I found out on holiday once in Greece as the bent piece of wire replacing the correct shear pin left us bobbing helplessly on the ocean!
Air turbulence from the crown wheel circulates the grease (especially when it's warm) and provides a constant thin film for less friction.
It's a question of having the right amount of grease. Not so much that the gears are ploughing through it and not so little that they run dry. Just enough so that the vibration and turbulence (as Wallace says) make sure that there's a constant supply of bits of grease which find their way onto the gears.
sardine
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I don't think any grease stays on the gears after the first few seconds of running. I'm one of the crazy people that open up my grinders and clean and re grease them. Unless they gearbox gets hot enough to melt the grease it just stays flung out against the sides of the casting.
On the other hand the Makita, Bosch, and Hitachi ex hire ones I have the mitre gears aren't worn anyway.
On the other hand the Makita, Bosch, and Hitachi ex hire ones I have the mitre gears aren't worn anyway.
If you grease a gear and spin it at 10,000 rpm, most of the grease will come off because of centrifugal force, but you'll still have a very thin film. All you need to lubricate things generally, is a very thin film. In a grinder if a bit of grease finds its way onto the gears, even every time it stops, that's probably enough.
Having a greased gearbox in an angle grinder seems like a rubbishy system on the face of it, but the gearbox in a decent quality angle might last for 50 hours plus at 10,000 rpm. I think it's one of those schemes which seems hit and miss on the face of it, but it's simple and surprisingly effective.
Having a greased gearbox in an angle grinder seems like a rubbishy system on the face of it, but the gearbox in a decent quality angle might last for 50 hours plus at 10,000 rpm. I think it's one of those schemes which seems hit and miss on the face of it, but it's simple and surprisingly effective.
the snooper
getting older by the day
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well with nothing to lose stick the gear back on the end an weld it to the shaft, just protect the windings with something
pedrobedro
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When the gearbox gets hot the grease turns to liquid and drips back onto the gears lubricating them in the process. I had a grinder from Wickes which lasted many years and finally burnt out in a spectacular fashion melting the casing in my hand (which is another reason I always wear gloves when using them) I had a couple of cheap Aldi grinders which lasted about 6 years for under £10 and they both conked within two weeks of each other so I splashed out on a 5" Metabo and still keep a couple of cheap grinders for light duty like paint stripping etc. to save frequent disc changes.
I did think about this, gonna give it a go!
