Thursday, August 20, 2020

Sharpening a Drawknife

My drawknife is nothing special.  I bought it about 5-6 years ago off Etsy.  But the steel seems fine, the handles are firmly attached and it's comfortable to use.

Unknown maker 8" drawknife
The bevel side is fairly heavily pitted.
Fortunately the back side is in better shape.

There are some drawknife sharpening videos on the internet.  Curtis Buchanan has one here and Mike Dunbar shows a different method (with a different sharpening philosophyhere.  Although I've sharpened my drawknife and used it (a little bit), I've never gotten it truly sharp.  But a couple weeks ago I took an online class about drawknives with Elia Bizzarri.  During the class, I learned a few things that really helped.  When I got out to the shop to try out the new method, I was able to get the knife sharper than I had ever gotten it before.

The real trick for me was to create a hollow grind (definitely not Mike Dunbar's preferred method).  But don't stop at hollow grinding the bevel; you've got to hollow the back slightly so it is easier to flatten it right up to the edge.  Of course, I'm doing this with a  hand-crank grinder and that creates challenges of its own.

The grinding setup

The grinder is attached to a board that is clamped into the end vise.  A block of wood, with a smaller piece of wood on top of it that is set back 1/4" from the front of the larger block, is clamped to the benchtop.  That small piece of wood creates a little ledge across which the drawknife slides.  The distance of that ledge from the wheel determines where on the knife the grinding wheel will hit.  The block of wood is at an angle to the wheel - if it was perpendicular to the wheel, the grinder's handle would hit the right side of the knife every revolution.  

Here's a birds-eye view of same

Because I'm using just the corner of the wheel to grind the metal away, I used the wheel dressing tool to create a little flat at the corner.

In this close-up shot, you can see the chamfer on the wheel's edge

Because the part of the wheel doing the work was so small, it needed frequent dressing as I ground the knife.  Grinding the bevel went fine, but was slow because I was very careful to creep up to the leading edge.

Holding the handle, I tried to keep the knife in the same line as I
moved it across the wheel.
The bevel evenly ground.  It's deeper at the right because (for some
unknown reason) the knife is thicker there.
A close-up.  Could this knife be laminated?

Grinding the back was similar, but had to be done in steps because there is a broader surface that must be taken down.

Red marker to guide the way
(ignore the prior grinding marks from a hack attempt long ago)
First quarter of the knife's depth done with care.
Pen points to where I still need to grind.
After two more rounds, moving further towards the back each time

Now it's on to the diamond paddles.  You can see them lying on the bench in the pictures of the grinding setup above.  These things really come in handy and are the right tool for this job.  The hollow grind on the bevel gives two reference surfaces to rest the paddle on.  It's a matter of rubbing back and forth to abrade away a little metal at the front and rear edges of the hollow grind.  But be careful!  A little slip and you could slice your finger to ribbons.

You can see the front and rear edges of the hollow grind getting shiny at left end

The grip of the knife is important here.  In the picture above, one handle is firmly on the benchtop and the other end is held in my hand.  The tool's edge is pointing away from me - this is important for safety.  Another grip that I really like is shown below.  Hold the far handle and pull the near handle into the chest for a nice stable knife.  This allows me to hone the hollow grind easily.  Again, be careful!  The wrist can get a little close to the cutting edge, so pay attention.

Holding the knife handle between hand and chest ...
... allows good control when honing with a diamond paddle

I used the fine and super-fine paddles, on both bevel side and back side, switching back and forth until the burr was ready to fall off.  Then went to the strop.  This was also interesting - you've got to find a way to hold the strop so the drawknife's handles don't get in the way when stropping.

Sliding the knife left to right as I pull back towards myself

I used about 20-30 strokes on the bevel side and a few on the back side.  I typically use a thumb-nail to test sharpness of my edge tools.  This method of sharpening has by far given me the best edge that I've obtained on the drawknife.

That's all well and good - the proof for me was in the cutting.  I just finished a 2/3rds scale "democratic" chair (one of Curtis Buchanan's designs).  And I don't have access to green wood!  But the drawknife cut the (presumably) kiln dried red alder nicely.  I'll post about the chair next time.

Thursday, August 6, 2020

The Mongo Scraper

About a year ago at my local PAST tool collectors meeting, I had a winning raffle ticket.  My prize was this scraper by The Dikeman Mfg. Co.
The mongo scraper
The handle has a neat mechanism that allows it to swivel and tighten in any direction.  Just turn the handle counter-clockwise, move the handle to the position you want and tighten it up again.
The swivel mechanism
On the swivel cup: PATD. AUG 9, 1910
The iron is just shy of 3" wide and fairly beefy at 1/16" thick.  The method of securing the iron in the tool is a cam mechanism.  A bar that squeezes the two plates together to hold the iron is held on each side by a screw.  The two screw thread into the ends of the bar off-center and when the bar is turned (using the bent rod attached to it), the plates are forced together.
(Iron not present) Arrow points to one of the two screws of the cam bar
Arrows point to the contact locations of the cam bar
Another view: can see the off-center screw at left
In use, the forward U-shaped handhold really helps apply some downward pressure.
Cutting action is drawing the scraper back towards me
I would have liked to take the whole thing apart to clean it up.  To do that, one just needs to remove the two screws that hold the cam bar.  But both appeared to have the screwdriver slot peened so that you can't unscrew them.  Either that or many decades of rattling around in a toolbox resulted in the same effect.
Dental tool pointing to the peened screwdriver slot

To be honest, I really didn't know what I would do with it, if I ever used it at all.  But when I needed to remove the finish from a large blanket chest that I salvaged, it really came in handy.  At first I just used it in as-found condition and it worked fine.  But later I took the time to sharpen the iron and SWEET FANCY MOSES!!  This thing cut like a beast!
One of the boards
Pretty gnarly - lots of junk stuck to the finish
After a few swipes with the mongo Dikeman scraper
I was truly shocked at how well this tool worked.  I thought it was basically a large paint scraper, but I was getting shavings like a Stanley #80 cabinet scraper when I used it on bare wood.
Shavings from the bare wood
Some references I saw on the 'net called this a paint scraper and a floor scraper.  My guess is that it's one of those more than a cabinet scraper, but when properly sharpened and carefully used it can be put into service to smooth boards.

Here's a little info I found about the Dikeman Mfg. Co. or Norwalk, Conn.

In a post on, Sandy Moss referenced a book entitled "American Marking Gages", by Milton Bacheller, which indicated that the company was founded in 1906.  They produced mechanics tools and metal goods, but fell on hard times during the depression and finally went out of business in 1939.

On a 1922 list of Connecticut manufacturers, Dikeman is listed as making "screw machine products and machinists' tools".

Sunday, August 2, 2020

Found: Large Blanket Chest, Part 2

This is a continuation of the last post, in which I described a chest I found on the street.

With the exception of the bogus piano hinge (I would have preferred three beefy solid brass hinges), there was some cool hardware.  First up is the lock.
The lock from outside - unfortunately no key
Lock from inside - mostly solid brass
Lock removed showing mortise
Overshot knife-lines used to lay out the mortise (can see
them on the edge as well)

The catch for the lock, mortised into the lid - solid brass
Excavations were cut with a very small gouge to accommodate the peened(?) catch backs
There were solid brass handles on each end (very tarnished)
Solid brass lid stay
The wood used was red alder, which I think is a very beautiful wood.  I don't know if the finished used on the chest was yellowish at the start, or if it yellowed over time.  Either way, it's a shame to cover up the beauty of this diffuse porous wood.
End grain (and some 45° grain) from a piece I cut, planed and chamfered
I don't know what type of glue was used to put this together, but it was very easy to take apart.  It may have been hide glue, judging from some crystalline remains inside the plugged screw holes.  The chest may have been left outside, which would have affected the glue strength.  Even so, it looked like the glue was used very sparingly.

After taking it apart, I've got a nice pile of lumber that I can do something with.  There are seven 5-foot long boards that are 7.5" to 10" wide, as well as a couple narrower 5-footers and several shorter pieces.
Can't wait to put this to good use
All for now.  Catch you next time.