Electric grinder - what I learned last night...

[gto406]

I wanted to pass on a lesson I learned 'the hard way' - hopefully this saves someone else from learning this rather painful lesson.

I picked up some 3M (I think they were 36 grit) fibre disc's for finishing cleaning up my frame (decided to remove the paint, and primer) - http://products3.3m.com/catalog/ca/en001/auto_marine_aero/-/node_S9GHM4DD1Zgs/root_VJ3G0N3T7Ngv/vroot_G75KJBMR4Kge/bgel_0PRDK14KM1bl/gvel_FBX0QTLHQLgl/theme_ca_en_automarineaero_3_0/command_AbcPageHandler/output_html

I was mounting it up to my 5" electric grinder, and didn't have a backing pad. I happened to look over on my work-bench and saw a thin cut-off disk, and I thought 'hey wouldn't that be a good idea' to use the cut-off disk as a backer for the disc! Note too I have had the 'guard' off because I was working around the frame horns.

Long and short, I was working in a confined area (and yep had particulate mask, full-face shield, ear protection, steel toes, my work coveralls, and Irwin work gloves) and 'bang' :machine: the cut-off disc lets go into three (3) pieces - one of them going into my left index finger.

I took off my glove and thankfully, just a nasty bruise and a slight 'skin removal' on part of my index finger.

What did I learn with this lesson?

1. Always keep the 'guard' on - even if it is a bugger getting the grinder into tight spots, if the blade or thing spinning lets go, that is what is between you and that spinning piece of 'shrapnel'. Never again will I use a grinder without the guard (repeat after me).

2. When purchasing fibre disc get the right parts for the backing. I failed to do this, which paved the way for me to try this 'home brew' hair-brained solution. Turns out 3M makes a wonderful backing pad with a 5/8" arbor with adjustable depths.

Info on the backing pad (for the 3M disc) is below:

http://www.oki-bering.com/mktg/pdfs/Individual_Vendors/OKICAT07-3MA.pdf

Page 424 (in the document, page 395 in the PDF itself), part numbers of relevance are:

051144-45205-7 (hub adaptor)
051144-81734-4 5" ribbed (medium face plate)
051144-81732-0 5" ribbed (extra hard face plate)

051144-05622-4 (3/8" deep nut) -- choose nut that matches appropriate depth of your arbor.
051144-05620-0 (5/8" deep nut)


I will be trying to pick up this backer before proceeding to finish the frame.

Hopefully my pain is your gain. :fingersx:

Cheers,
Brian. :cheers:

[D Impala95]

Sounds like a bumbletard move. You should have used a grinding disc as a backer. ;) NOT!!! With high speed revolutions and fiber discs, don't use them for applications other than their intended use.

Sorry for your pain and you letting us know. I hope someone will learn from your mistake.

[garickman]

I made a few bone head moves like that before, and I still have not learned my lesson. "People may think my middle name is safety, but it's not, IT'S DANGER!

[John Wright]

Wow, lucky that it wasn't worst...I had my imagination in highgear when I started reading this thread. Lesson learned...and noted!.....I had a wire wheel grab my glove on a 4.5" grinder and it gave me a quick awakening(no injury due to the heavy welding gloves)...I wised up pretty quick after that and put the guard back on. I had taken it off to work on a flat surface without tipping the wheel up on it's edge.

[sniper]

Complacency will bite you in the butt everytime. I wish I could say I am safe all the time, but I have a ways to go before I get there.

Quick story; I had a cut off wheel break at full speed and hit me dead square in-between the eyes. If I hadn't had my welding helmet on, it would have probably stuck in my brain. There was a 4in gash in the helmet and nothing on me. Everytime I go to grinding on something, that incident reminds me to throw on some protection.