Lobotomy of an Angle Grinder

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Here’s a 20 photo step-by-step pictorial of how to 'Power-UP' your angle grinder!The Problem – Slowing Down!-My 4.5 inch angle grinder seemed to be slowing down when I leaned on it; it didn’t used to do that!-Also, my second 4.5 inch angle grinder (I have six – 6!) equipped with a cutting disk was varying in speed – just holding in the air!The Solution – Lubricate!The usual cause of the slow-down problem is dried-up grease - spelled greese in my photos!The grease lubricates two gears in the gear box.  The fix is to get rid of the old dried-up grease and replace it.  Lubricate both gears and fill the gear box with new grease – not too much, you have to allow space for the gears!  Most anything will likely do; I replaced the light-brown colored grease with black wheel-bearing grease and added in a little 10W30 motor oil.  You want that grease semi-wet!Here's How to Do It!I took my grinders apart and fixed them… eventually… but I often took out the wrong screws and disassembled more than I needed (and lost time) to fix the problem.  So, to save you that headache, I provide a photo journey of how to do it right – the first time.The photo sequence is self explanatory – notes in the photos.How To Do It - Photo Sequence I’ll just add a few cautions:1 – Make certain you note the alignment of the gear cover before you remove it; it has to go back the same way.  This is where a wife may be useful – use her red/pink nail polish to mark the front of the gear cover; that way you can get it back on correctly! 2 – After lubricating, when re-installing and screwing down the gear cover, be certain the wiggle the shaft and press down so that you properly mesh the gears.  You can tighten the screws with the gears misaligned – NOT RECOMMENDED!If at first, the shaft is hard to turn – back off the screws, wiggle and press down on the shaft.  You should fee the shaft drop when the gears mesh – and the shaft will be easy to turn.  The you can tighten the screws.  When done, you should be able to turn the shaft yet feel the resistance of driving the gears.Folks, for me, it made an amazing difference.  Power – just like when my angle grinders were new!Rick V  Attached Images
Reply:Hey good tutorial. Should help a bunch of folks. I've got an ancient bosch that I've had apart at least twice.
Reply:Great idea.  Thanks for the step-by-step.Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:Thanks for the nice comments.Would it be useful to add another picture section on say - how to access, clean up and/or replace the electrical carbon brushes?Sometimes these brushes cause problems - like you switch on your grinder and nothing happens until you shake it or bang it against something.Rick V
Reply:Ha!  That's funny.  One of mine just did that yesterday -- dust in the brush holder.  I'm assuming the brush got stuck and then wore to where it no longer made contact.Must be common enough problem so maybe a step by step would be a good thing.Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:Do you have one with out the external access to the brushes??
Reply:Thumbs-up Rick!  Good reminder to folks about put it back the way it came apart and to make sure the gears mesh before you tighten it all up or apply power.Grinder slowing down?  Clean (dust, grit, crud out of machine), lube (old grease out and new grease in), and check/replace brushes.Brushes are -so- much easier to check and replace when there are the screw-off covers   .  Instead of having to disassemble and then reassemble the whole %^#$ case.
Reply:Rick...I dub you the offical Lobotomy Doctor of the site.. I have no power here.. But you get the title anyway.. ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Good call, Rick. I fry a sawzall every now& again, and the dead grease is always the reason...And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:I had a Mikita do that with me a couple years ago...Wish I knew that then..I tossed it weld it like you own it
Reply:When I look at my post with the photos, it kind of reminds me of those Haynes and Chilton auto-repair manuals.  I usually had both manuals for whatever car I owed at the time but... is it me or why did those manuals (with all their photos) never quite seem to have the view I needed to fix something?  OK - I'll do a sequence on replacing the carbon brushes.  Do you have one with out the external access to the brushes?? - Sandy
Reply:Ouch, Rick V!  "Carbon" motor brushes are engineered with specific mixtures of materials to give optimum performance and motor and commutator life.  While expedient substitute brushes made with carbons from Leclanche batteries and gouging rods or arc lamp rods may work for a while, I would expect rapid wear of the commutator and excessive arcing.I would recommend against such an expedient unless the tool owner is willing to sacrifice tool life in exchange for getting some emergency job completed.Except for that quibble, excellent tutorial!awright
Reply:Orrrrr, I could ship all my grinders, drill motors and other electric tools and you could demonstrate complete rebuilds!!! Yeh, inner bearings, re-cord and all.
Reply:Ouch, Rick V! "Carbon" motor brushes are engineered with specific mixtures of materials...while expedient substitute brushes made with carbons from Leclanche batteries... I would recommend against such an expedient... Except for that quibble, excellent tutorial! - awright
Reply:Excellent post Rick. When I buy a new grinder that is the first thing I do. They never seem to put enough grease on the gears or in the gear case. I use Slick 50 Wheel Bearing grease. It's not as hard and thick as most wheel bearing greases.Clarke 130EN C25Lincoln 225 AC Stick(1968)Smith O/A RigHF 4X6 Red BandsawBlack & Decker Pro Chopsaw16 Speed Drill PressSpeedglas XL HelmetHarbor Freight Stuff
Reply:How to Replace Your Carbon BrushesWhat follows is a sequence of step-by-step photos over two posts showing how to do this.  The explanation is written on each photo, so it should be easy to follow.  Here we go…the first 20 photos.Continued on next post.... Attached Images
Reply:Continued from previous post...WARNING – VIEWER DISCRETION!  THE FOLLOWING IS NOT FOR QUIBBLERS!SOME SCENES DEPICT UNUSUAL MODIFICATIONS OF INANIMATE CARBON RODS!IF YOU CAN’T HANDLE THE ‘MACGUYVER APPROACH’ – SKIP TO PHOTO 33.WELCOME BACK QUIBBLERS!Here is the final sequence of steps to reinstall the carbon brushes and close up the grinder.  By the way, most grinders have two sets of carbon rods – placed 180 degrees apart… so you may have to repeat this work again on the other side BEFORE closing the cover.OK, we are done.  The most important step in this sequence is #36 (clean the carbon off your hands).  If you skip #36 and handle your wife’s white clothing – you may generate more heat than welding!  Rick V  Attached Images
Reply:Nice job Rick.One thing I'm missing is once you drill the hole, how do you secure the copper braid?I also have some master craft tools and I really like them.. My wife is Canadian so the in laws have given me some very nice Christmas gifts. Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:If you skip #36 and handle your wife’s white clothing – you may generate more heat than welding!
Reply:Step 6... cleaning the brushes...bet that´s your wife brush too!man, she´s more usefull than you tougth!nice tutorials  thanks!My Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Permit to respond to those who point out some of my oversights...Ouch, Rick V! "Carbon" motor brushes are engineered with specific mixtures of materials to give optimum performance and motor and commutator life. While expedient substitute brushes made with carbons from Leclanche batteries and gouging rods or arc lamp rods may work for a while, I would expect rapid wear of the commutator and excessive arcing. - awright
Reply:One thing I'm missing is once you drill the hole, how do you secure the copper braid?
Reply:One thing I'm missing is once you drill the hole, how do you secure the copper braid?