Friday, January 27, 2017

Cleaning Up An Old Hand Crank Grinder

I've needed a grinder for a long time.  Sandpaper on plate glass just doesn't cut it.  I didn't want an electric tool - they're heavy and bulky and I just don't have the space.  Besides, I'm fascinated by the tail-less variety of tools.

A few years ago, Shannon Rogers did a post about what to look for in a hand crank grinder.  With that information and my own research, I made a list of what I was looking for.
  • Clamp mechanism - must not be bent and has to hold the unit firmly to a table top.
  • Wheel nut not frozen.  I almost purchased a hand crank grinder on Etsy recently, but the seller couldn't get the wheel off.  (I suspect the wheel nut had a reverse thread and the seller tried to take it off the wrong way.)
  • Smooth working gears - should be no "chunky" action or roughness when cranking.
  • Wheel capacity - must be able to take a 6" wheel.
  • No wobble - the wheel should run true without side to side wobble.
  • Arbor size - should match whatever wheel I purchased (this turned out to be unimportant, as there was a flange that fit on the arbor and the wheel fits on the flange).
  • Tool rest - I didn't want to have to make something myself (though I might do something in the future to make it easier to hold an edge to the wheel more accurately).
After getting outbid on eBay a few times (I hate eBay), I started looking at Etsy and Craigslist. Finally I found someone nearby looking to sell the grinder he bought several years ago.  I talked with the seller to verify a few things before even looking at it.  I bought it for $30.  E-Bay would have been about $65 plus shipping!
As-found: really grungy like all old grinders
This grinder was originally from a local distributor (local for me, that is).  That doesn't actually say who made it.  I found zero information about Taylor-Sales on the interwebs.
Taylor-Sales Co. label
Well the clamp on this grinder is awesome!  That thing holds onto a plank like a drunk holds onto his last bottle.

The wheel on this unit was a 5" Norton with "coarse grit" aluminum oxide abrasive and a 1" arbor hole.  This grinder can easily take a 6" wheel.  The current wheel is still about 4 7/8" diameter, so not overly used, but I'm still replacing it.  I recently bought a new Norton 6" x 3/4", 60 grit Aluminum Oxide wheel.  I'll keep the old wheel.  It looks a little more coarse than the 60 grit wheel and might come in handy sometime.
Surprisingly, the wheel that came with the grinder was in decent condition
I was excited to take it apart, clean it up and learn about it.  But not without consulting the internet. Jonathan White did a fantastic grinder restoration here.  I'm not going to go to near that level of restoration, but I'll clean it up as best as I can, lubricate it, and hopefully be able to use it for many years.

The wheel nut is a reverse thread.  This is common on grinders with the wheel on the left side.  I think most (if not all) power grinders have a reverse thread on the left wheel.  This way, as the wheel turns towards you, the nut won't loosen.
Can you tell it's a left handed thread?  Look at all that crud in the threads!
There were three washers between the nut and wheel.  The middle one is cardboard.  Not sure what that's about, but maybe it gives a little cushion.  I think it's wise not to over-tighten the wheel.
The lineup of nut and washers that tighten up the wheel
The flange was disgusting and needed serious cleaning.  I used Simple Green and a toothbrush to degrease and clean all parts and they came out much nicer.  Used a wire wheel in a drill on some parts, too.  On the left side of the flange there is a 1" diameter section that the wheel fits on.
Filthy!
On the recessed side of the flange there were two washers.  You can see one in the above picture. Inside the recess was the other washer.  But at the 12 o'clock to 2 o'clock position you can see a chunk of this washer is broken off.
Broken washer stuck in the recess
When I took the washer out, I found that it was not metal, but flexible like plastic.  I don't know if this will affect how the grinder works, but I'm keeping what's left of the washer in the flange.

The top of the gear box was covered by a piece of metal, held in place like a spring.
Top of gear box
Removing the cover by sliding it to one side (viewed from below)
This reveals the gear
Full view of the gear - note the angled teeth
Here's how it meshes with the drive gear
I didn't count the teeth, but one full turn of the crank results in about 13 full turns of the wheel.

One funny thing I found was a washer stuck to the inside of the gear box, smothered in grease.  I'm not sure if it is supposed to be installed somewhere on this grinder, but there was no obvious need for it.  I wonder what else I might find in there if I could get the gear out!
Arrow is pointing to a washer stuck in the muck on the wall of the gear box
Here's the drive shaft (or is that "arbor").  Notice the step about midway along the length.
Drive shaft / arbor (cleaned and oiled)
Close-up of the step in the shaft
When the shaft is installed, the smaller threaded end protrudes through the grinder body on the handle side and there is a nut that holds it in position.
Arrow points to the nut holding the back end of the shaft
This nut only threads on so far until it stops.  When the nut is tight, the step in the center of the shaft is just proud of the grinder body (on the wheel side of the body).
Arrow points to step in shaft
When the wheel is installed and the reverse thread nut tightened, the wheel is held to the flange and the flange is held to the step.  If the step was not there, the wheel would be tightened to the grinder body and it would not be able to turn.  Similarly, if the nut on the smaller threaded end could be tightened so that the nut touches the grinder body, it would not turn.

So I learned something today.  When tightened, the shaft is free of the body.  It touches the inside of the shaft hole, of course, but it is free to spin as it is not tightened to the body.

The large gear in the gear box is on its own shaft, one side of which protrudes out to the handle.  The handle is held to the gear shaft using a set screw that fits into a hole in the shaft.  There's a little play, but that doesn't bother me at all since I'll only turn in one direction.
The setscrew in the handle tightens into the hole in the shaft
Speaking of the gear box, that was one area I couldn't clean well.  If I could get the gear out I could clean it.  I was able to clean the teeth with a toothbrush, but not the rest of the gear or the inside of the box.  I've seen pictures of other grinders where the gear box opens up with screws and the gears can come right out.  But this box is a solid casting.
Handle side of casting with gear shaft protruding
Left side of casting
A look inside the casting on the wheel side of the gear
I thought about trying to tap the shaft out using a wooden dowel and a hammer, but I'm afraid of damaging the shaft.  The dang thing had to be installed sometime, so I'm sure it can be uninstalled.  If anyone has any ideas about this ...

Well, after cleaning it up and liberally oiling all threaded or moving parts with 3 in 1 oil, I reassembled with the new wheel and tried it out.  I first had it clamped to a T&G 2x6 board and had the board clamped in a vise (see first and third pictures at top of this post).  But I soon realized that I needed to get the grinder further from the bench top.  Getting my finger caught between the handle and the bench was not fun.  Now I have a 7 1/4" wide board and my hand clears the bench top easily.
View from above
View from side showing clearance between hand and bench when cranking the handle
The gears run very smoothly.  When I crank it up a few times and let go, the handle still goes round several times before it stops.  Very happy with this.

I still need to get a wheel dresser - they're on backorder from TFWW, where I got the wheel.  But I tried it out anyway on a plane blade and a crappy chisel.
Action shot of grinding a chisel (sorry, no sparks show up in the pic)
It's going to take a while to get used to holding the blade in one hand while cranking the wheel with the other.  Buy hey, it takes practice to use all the tools in our shops, right?

Oh, one last thing - when I tried it for the first time, the wheel was wobbling about 1/32".  I tested for wobble by holding a pencil to the side of the spinning wheel to see where it marked the wheel.
See pencil marks on the side of the wheel?
Not sure what the problem is, but I suspect the step in the shaft (arbor) is worn.  I was able to minimize the wobble to almost nothing by loosening the nut, holding the wheel steady and rotating the flange a little bit.  It took a few tries, but it runs fairly true now.

Grinding capability - finally!!!  Now it's time to practice!

EDIT (16-Feb-17): The broken plastic washer from the recessed part of the flange was 0.031" thick.  I replaced it with a washer made from a piece of plastic milk jug that was 0.019" thick.

10 comments:

  1. Looks like it cleaned up well. A grinder is a handy thing to have around the shop. Now that you have one you will find that you use it all of the time.

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    1. Hi Greg. I'm really looking forward to it and have thought of a couple things that need it. Right now I'm looking into methods of setting the tool rest to get the proper bevel angle. Still more work to do.

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  2. Congrats, hand grinders can be fun.... until the novelty wears off :-)
    There are a bit ackward to use at first, but you will soon get the hang of it.

    Whish mine was bigger, i dont think i can fit a 6 in wheel on it, should have a harder look perhaps...

    Bob with Rudy on my lap

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    1. Thanks Bob. I've been practicing a bit. The tough thing is sliding my left hand (and the tool) left and right while grinding. It's just not a fluid motion yet. I'll keep working on it.

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  3. Did you find out eventually how to take the larger gear out of the housing?

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    1. No, never went that far with it. I'm sure it's just a matter of knocking out the shaft, but I was a little too chicken to try it.

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    2. Thanks, I just bought one which looks almost similar to yours, so your post is extremely helpful.

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    3. Oh, and another question... If the flange is tightened to the step on the shaft, why are there washers inside? In mine, which as I said looks very much like yours, there wasn't any washer(s) (or maybe it just got grinded over the years??)

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    4. Itamar, I'm not certain of the answer, partially because it's been a while since I worked on the grinder. But it might be that the washers take the brunt of the wear so that the flange doesn't get ground down as if it touches the step. It's better to have an easily replaceable washer take the wear instead of the more expensive flange.

      Try things out. See how it works with and without washers.

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  4. This comment has been removed by the author.

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