Tuesday, January 31, 2017

More on the Hand Crank Grinder

I've been playing with the new (to me) grinder.  It's clear that it will take some practice to be able to use it well.  Fortunately I have a really crappy set of chisels and some old plane irons to mess with.

The main issue with using this grinder is holding the chisel or iron in one hand while cranking with the other hand.
Cranking with the right, holding blade with the left
Here's a closer picture.  I'm pressing down (not too hard) on the tool rest with the thumb and using my first finger as a fence against the lower edge of the tool rest.
Hand position for holding a chisel
This tool rest is not exactly rigid.  So when I move the blade to the left where the tool rest has less support, it flexes more and I can end up grinding too deeply if I'm not careful.

Another issue is where to set the tool rest so that I grind in the center of the bevel.  If it is not set just right, you will grind too far forward or too far back on the bevel.
Front of bevel is too far off the wheel
Now back of bevel is way off the wheel
This looks to be just about right
I can change the location of where the wheel contacts the bevel by nudging the tool rest forward or backward.  Just a millimeter or two can make a big difference.

I wanted to take the guess work out of this, so I made a stick with a 25° bevel on one end.  The lines I've drawn are perpendicular to the bevel.  The left line represents the back of the bevel on a tool.  The right line is 5/32" forward of the first line.  Most of my plane blades are about 5/64" thick.  For a 30° bevel, the total length of the bevel would be twice the iron thickness, or 5/32".
Try to set the tool rest so that the wheel touches the center between the two lines
This would be different for chisels because they have thicker blades.  Later I drew another line on this stick that would help me set up for chisels.  It was about 5/16" from the leftmost line because the chisels I looked at were about 5/32" thick just behind the bevel.

While researching this, I found a great article online by Bruce Wedlock that discussed the geometry involved in setting up the tool rest, including making a jig to help out.  He even sent me some info on how the geometry was worked out.

Unfortunately, my tool rest is too wimpy to worry about being so precise.  For me, the bottom line is this.  Set up the tool rest with the wood block above to get close.  Then mark the bevel with ink.
Bevel marked with red Sharpie
Grinding lightly (can use your right hand to slowly turn the wheel, rather than turn the crank) to see where the wheel is contacting the bevel.  Note that on this chisel, the bevel is WAY too long from previous poorly executed sharpening.
Grind marks a little too far back
Adjust the tool rest by bumping it forward a tiny bit.
The new grind marks are better located
When satisfied, grind away.  But be careful not to overheat the tip.  Gotta keep water handy and dip it in there frequently.
Grind until a millimeter or less of the tip is still red
Then it's off to the sharpening stones and a strop to get a nice sharp chisel.

Here's another example.  For this plane iron, the bevel was too long and I marked the extent of where I thought the bevel should end with a red line.  I wanted to grind midway between the tip and the red line.  My first attempt (before adding the red line) was too far back.
First grinding was too far back
After adding the line and nudging the tool rest forward I got the grind centered between tip and red line
I thought about how much better this would be if I could use two hands.  I tried a couple things that ultimately didn't work out, but it was fun trying.  First, I rigged up a "treadle" to see if I could keep the wheel spinning with my right foot while holding the tool being ground with two hands.
Working the treadle while holding the tool with two hands
The treadle was simple - the vertical part was a board with a hole in it that fit over the handle of the grinder.
Grinder handle is taped to prevent damage
This was attached to a foot board with a loose bridle joint pinned with a dowel.
Lower part of treadle
In use, I would step on the lower part to get the handle cranking.  But I'd have to pick my leg up before the momentum of the grinder arm would pick the treadle back up.  If I wasn't fast enough, I would stop the grinder quickly, which would loosen the reverse-thread nut that tightens the wheel.
That's my shoe stepping down on the treadle
At one point I even tried to rig up some bungee cords to lift the treadle and thereby lift the grinder handle on the up-stroke.
The bungee cord setup
I think with enough practice this might have worked.  But in the end, I dumped the treadle idea and I'll just practice grinding one-handed.  I have to realize that grinding does not need to be a precision operation.  I just need to get close so I can sharpen easier on the stones.  On a bright note, I learned a little about making a treadle - might be useful someday with a lathe idea I've had for a while.
BTW, adding the hollow grind has made it MUCH easier and faster to sharpen my chisels and plane irons. The amount of metal you need to remove during sharpening is far less.  I learned sharpening from Paul Sellers' videos and he sharpens to a convex bevel.  I guess time will tell if I miss any features of the convex bevel.

I've a question for anybody reading who cares to comment.  What safety precautions should one take when using a hand grinder?  I normally wear glasses when I work, but are goggles recommended? Where to stand or where not to stand when grinding?  Breathing protection?  Other things?

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.
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.

Tuesday, January 24, 2017

Bringing a Stanley #4 Back To Service

A few weeks ago I answered a Craigslist ad for a long wooden jointer plane.  That plane turned out not to be worthy of purchasing, but the seller had several other planes to sell.  Including a nice little Stanley #4 smoother - for $13, so I couldn't resist.  This post is about cleaning up the plane and getting it back in working order.
Stanley #4 circa 1902-1907
Turns out the plane is a type 9, which is from the 1902-1907 time frame.  I was able to figure this out thanks to the Hyperkitten plane dating page and Bob Demers' blogs on plane dating.

On Hyperkitten, just two simple questions nailed down the type: "how may patent dates are on the bed behind the frog" (there are two - MAR-25-02 and AUG-19-02) and "is the frog rib the enlarged and arched type" (No).  Bingo - Type 9.  I wasn't quite sure what was meant by the frog rib, but Bob's blogs made it clear with pictures.  He calls this the center rib in the frog receiver, which is a better description.  Tremendously helpful, Bob.

The tote had been broken and repaired, though not perfectly.  It is very solid, but there is a little offset where the broken surfaces were glued together.  I decided to leave this as is.  If it ever fails, I'll repair it more properly.
A repair with a 1 mm offset
It's interesting to compare this with my type 19 #4.  The sides of the type 9 are noticeably thinner than those of the type 19.  And the type 9 is shorter, too - it's 9 3/8" long versus the 9 11/16" type 19.
Very obvious difference in side wall thickness
Here are the two with lever cap and irons removed.  Big difference in the frogs.
The innards are quite different
Here are all the pieces before cleaning.
This is not really a refurbishment.  Just a clean up.  So I'll show some before and after pictures.  After some cleaning with simple green to get rid of obvious dirt, dust, grease and other assorted junk, the metal parts were cleaned with light sanding, then a citric acid bath.  Flatt-ish parts got more sanding.  Screws and washers got a wire wheel in the drill.
Preferred method of cleaning up screws
The plane body had some surface rust, and that cleaned up easily.
I did an initial flattening without the iron in place to see what I was up against.
Lines drawn to judge progress
Telltale signs of wear down center of sole
A little while later all marks were gone.  I redid this later with the plane fully assembled to be sure there was no flex in the body that would pull it out of flat.  While I got the sole flat, it doesn't seem very smooth.  I may have to go over this again with some finer and finer sandpaper.
Sole flat, but not so smooth
The top of the plane body was grungy and needed a good cleaning.
The frog was interesting.  The machined surfaces where it mates with the plane body had very obvious machine marks.  I was a little worried about this, but when the frog was installed, it didn't rock at all.  So I'm confident the fit is adequate and won't cause any chatter.
Machine marks on underside of frog ...
... and where it mates with the body, rear ...
... and forward near mouth
The bed of the frog was pretty gnarly, so I cleaned it up by rubbing it on sandpaper taped to plate glass.
Top view - cleaning and flattening frog bed on sandpaper
This always makes me nervous.  I'm not comfortable taking out the pin that holds the lateral lever to the frog casting, so I have to rub one side at a time on the paper.  It's important to try to remove material equally on both sides of the frog's bed.
Speaking of the lateral lever, it was loose so I peened the pin a little and this tightened it up some.  First I just used a hammer, then went to a nail punch for more precision and better results.
Peening the pin that holds the lateral lever to the frog casting
The hardware was in decent condition and cleaned up nicely.
Tote and knob hardware before cleaning.  No after pic, but all came out fine.
No "before" pic.  These cleaned up nicely.
There were a few oddities with the hardware.  The lever cap screw had something on it covering half of the threads.  It wasn't tape.  Not sure what it is, but it seemed metalic.  Perhaps it is something put there so the screw and lever cap slot wouldn't wear each other down over time.  Fortunately I don't need the threads that are covered.
Lever cap screw
One of the washers used in bolting the frog to the plane body had interesting evenly spaced marks on it.
That's odd
It turns out these marks match the millimeter marks on a metric ruler exactly.
An exact match
At first I thought maybe someone needed a washer and cut one out of an old ruler.  But I'm not convinced.  Who knows?!

The last oddity concerned the attachment of iron and cap iron.  The fit of the bolt wasn't right so that they would not tighten to each other very well.  I had to find a washer (spacer) that would allow the bolt threads to engage better with the female threads of the cap iron to pull them together tighter.
Washer helping out
I was worried that this washer might not fit into the recess in the frog, so I measured the depth of the recess.
Almost exactly 1/4" deep
Bolt and washer stick up just under 1/4", so they fit in the recess
The iron and cap iron were fairly dirty, but not nearly as bad as I would have thought for being over 100 years old.  The iron is a bit short, though, after having been used so many years.
Iron and cap iron
Other side
The lever cap was in good condition, only needing a little clean up.
Lever cap with straight slot, not the kidney shaped slot.  I like these old ones better.
After some cleaning
The cap iron needed a little work on the front edge to mate better with the iron.  But I can still see a tiny gap on one side when they are put together.  This cap iron seems very worn - like there should be a couple more millimeters of metal at the curved edge.  I'm not certain if it can be fixed.
Straightening the leading edge of cap iron
There were problems when flattening the back of the iron.  The sides and front edge were very low.  I guess the back had a "belly".
After several minutes on a diamond plate (outlined area has been flattened)
Almost done, but sides still low
After a long time I realized that the sides were too low to get this truly flat along the whole edge.  So I decided to go for a back bevel.  To do this, I made a little jig to hold the back of the iron 9/16" off the sharpening bench.  The diamond plate is 1/2" high, so this gives a very low angle (about 1°) bevel.
Setup for putting back bevel on the iron
Eventually I got this
I sharpened the bevel in the usual manner and couldn't wait to give it a whirl.
First shavings
This is a piece of fairly hard maple and that shaving is 0.001" thick.  I think I'm going to love this little smoother.  I'm going to try my hand at putting a very slight curvature on the edge by sharpening a little more at the sides than in the middle of the blade.  Maybe that'll be the subject of a future post.