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Bench grinder/buffer setup advice?

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I usually research things into the ground before acting, but there's a "possibility" that I may have gone a bit light on this one. :-)   

So.. I now have what I have (a 3.5A, 3500rpm 6" grinder), and if you have advice on how best to make-use-of while minimizing risk, I'd appreciate that.  Yes, I wish I'd bought something different...

My intention is to try my hand at making blades for spokeshaves and wooden planes out of 1084.  Maybe knives in the future, but the aforementioned woodworking blades are the focus right now. 

I have a Worksharp and am setting up both a Taig Mill and Lathe for general use, so I think that with the addition of files, those can cover me for primary shaping of the blades, as well as finish sharpening.

Which (I think...) leaves me with both cleaning scale off (w/wire wheel?), and buffing (w/cotton/sisal wheels).  Agree/Disagree?

This is a 6" grinder (pic attached), and from other posts here, I think I should remove the guards. Agree/Disagree?  (Fyi: I intend to wear gloves).

I do understand that the workpiece needs to be held between 3 o'clock and 5 o'clock on the wheel.

Standard advice seems to be to mount grinders on a post rather than a bench.  Agree/Disagree?

The default is of course to use 6" wheels.  But...the grinder has enough height to use 8" wheels if the guards are off.  Or, I suppose I could use 4" wheels.  Work area vs. inches per minute.  What diameter do you think might be best?

From other posts I see here, I think I should be mounting the blades on a board for buffer/grinder operations.  It's not like plane and spokeshave blades have much of a handle... Agree/Disagree?

I do understand that flying buffing compound is not great for the lungs or the general basement shop area, so I need a face shield (during Covid? sourcing might take a while...), respirator mask, etc.  Maybe even just do the work outside?  Thoughts? 

Anything else?

Thanks in advance for any help with this!

- Bob


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Thanks!  That would have been my thought coming in to this, but after searching older posts, I think I was seeing some debate about that.  Concerns seemed to center more on keeping the wheel from catching the workpiece and flinging it at you (while simultaneously entangling gloves...), than the usual concern about not getting yourself caught up in rotating equipment.  

Just trying to figure out what gets the job done safely...

- Bob

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Remember you really want to keep GRIT from grinding operations off your buffs!  "Step by Step Knifemaking" had some tricks to using a stone grinder; but you might be better off doing a lot of drawfiling on your blades to get nice smooth bevels. (Though remove the scale layer with a grinder will make your files last longer.)

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I am going to introduce you to the concept of three little words that you do not want to hear: "Voids Your Warranty". If you knowingly change anything at all,  the responsibility is now yours. Up to and including voiding your health and homeowners insurance coverage.

Grinder accidents are always near the top of US OSHA violations causing death or injury. Mostly hand held units, but some bench mounts as well.

The guards are not there to keep the grinder from catching stuff and throwing it, as much as they are to keep you from trying to use the sides of the wheels and weaken them, and keep chunks of broken wheel out of your cranium. And a pound of stone moving at 200 mph WILL bust you up, and you may get to take the Room Temperature Challenge  and Darwin Award.

Board backers for knives and other small parts give you more control while grinding, as well as keeping the part from being sucked into the machine. Possibly damaging the machine and/or operator.

Taking the guards off and using bigger wheels, which may or may not be rated for the speed generated by a smaller motor is double trouble. The bearings in the motor are probably not rated for heavier loads, and may fail sooner. If the shaft starts to wobble, it becomes a positive feedback loop, spiraling out of control in seconds.

Mounting the grinder on a stand, or a projection from a table, allows you to work in various positions around the stand on long and complex items without catching on obstructions. Same idea as blacksmith's leg vises.

Cloth and leather gloves are always a no-go around rotating tools like grinders, lathes, mills and drills. Nitrile or latex is OK to keep your hands clean.

3.5 amps is a wimpy little motor, even on 240V power outside the US, and you may stall it if you press items into the wheel. That developed bad habit may come back to haunt you if you try that with an industrial duty machine.

Adequate ventilation is never a bad idea. Sometimes having a small fan blowing across the work is enough with large particles, but fine mists and light particles like fibers demand some sort of filtration PPE, or extraction at the source.

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Thanks for the detailed response! 

When asking about guard removal, I should have been clearer that I meant in the context of a fabric buffing wheel, not a grinding wheel.  Lots of buffers appear to operate in the open and different wheel sizes would give you different inches per minute for that operation, just wondered if there would be any benefit to moving off 6" as the machine has the swing for it.  

I do have a very clear idea of the risks inherent in stones that give way while travelling at ~3500 rpm, so no, it was not ever my intention to run a stone wheel unguarded.  No worries on that score.  :-)

- Bob

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Buffing wheels- I have removed the guard from my bench grinder for this very reason.

When grinding- usually you're working a specific smaller area at a time. Even in the case of a blade- you draw the blade across the stone, but the contact area is still small... just the surface of the wheel.

Buffing/polishing you are spreading the force across a larger area. The cloth buffing wheel will compress and spread out across the flat surface of the steel. Instead of removing a certain area at the contact point- you are fine finishing across a surface area.

This, and the ability to turn, get into grooves, polish along the length of a blade... makes it easier to do without a guard.

Like the others stated, temptation to grind on the side of the stone, unbalancing it, having hard mass... you dont have that with a cloth buffing wheel. They flex, they give and move around in use. This is also where a guard can cause issues catching on a cloth wheel.

A decent cloth buffing wheel will come with shaped washers to mount on your grinder shaft with. They're necessary... won't work without them.

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