Krenov Smoother 3 – Bed and Ramp

A perfect bed is imperative for proper plane performance. Irregularities will allow the iron to shift or chatter as you are planing, which is exactly what you DON’T want.  Take extra time on this step.  Make sure that the bed is absolutely flat and at a perfect right angle to the side of the body.  I used a block plane and a file to get everything just so.  One good trick is to get in the ballpark, and then fine-tune the bed after cutting the slot for the chipbreaker knob.  This allows you to only have to work with the outer edges and front of the bed, much like flattening a hollow-ground chisel.

Most plane irons with a chipbreaker have a knob that screws into it from the opposite side of the plane iron to hold the two firmly together.  Since this knob is on the beveled (bed) side of the iron, a slot must be cut into the bed to allow it to project while the iron still sits firmly on the bed.  In the case of Hock’s Krenov-style iron, this knob will fit comfortably in a 3/4″ wide slot.  While there are several different ways to make this slot, I chose to do it on the router table.

I realized during editing that one of the shop cats had jarred the tripod during the shot, rendering this particular picture unusably blurry.  Due to this, the picture below is a reshoot with a different piece of wood.  You will notice that the bed piece in the picture  is longer than the original – waste not, want not – but the setup is the same.  Just remember that the end of the bed piece actually will project slightly above the top of the fence.

Smoothing Plane 18
I set the fence to center the groove in the body, and set up a 45 degree stop block to match the angle of the piece.  This was necessary to ensure that I didn’t rout all the way through the sole of the plane.  I had marked a line to indicate the stop point on the bed of the body, and wrapped this line around the side.  The blue tape was used to mark the location of the end of the bit so that the stop block could be positioned accurately and clamped in position.  While a groove depth of 1/4″ was sufficient, I still routed the slot in two passes.  The last thing I wanted was for the wood to be grabbed by the bit with my hand that close, and light passes were good insurance.

Smoothing Plane 8
This is what the finished bed block looked like.  You can see the stop-mark at the bottom of the groove.  You can also see how much easier it is to do a final truing of the bed with this chunk of wood gone.  The only place that presents any difficulty is near the mouth, where a continuous strip remains.  However, with the upper parts trued, this last bit becomes much easier.  Once again, take all the time necessary to get things perfect – not only flat in all directions, but at a right angle to at least one cheek of the block.  Check, recheck, take a break, and check again.  You’ll be glad you did.

Next, it was time to turn my attention to the ramp block.  The surface of this part doesn’t need nearly the amount of precision required by the bed block, since it merely forms the front of the mouth opening, and this will be tuned later.  This is where I decided to modify things a little (as you knew I would).  The greatest point of wear on a plane sole is the point just in front of the mouth, since this is where the shaving starts to curl up in front of the blade.  White oak is a relatively tough wood, but I wanted to make sure that this plane would have a long life.  As a result, I decided to add a mouth insert.

Smoothing Plane 19
I had some 1/4″ ebony left over from the grooving plane project and, knowing how high it rates on the Janka hardness scale, had decided it would make a perfect mouth insert.  I started by scribing a line slightly less than the thickness of the insert and cutting just short of it with the bandsaw.  Then, I clamped the ramp block between two pieces of scrap wood level with the bottom of the block, and routed the opening to give a level surface.  I used a small router plane, but an electric router would work as well.

Smoothing Plane 10
I cut the insert slightly oversize, and prepared to glue it into the opening.  At this point I realized that I didn’t have a good clamping surface.  I should have followed Finck’s recommendation and installed the insert before cutting off the wedge that created the face of the ramp.  Oh well, spilled milk.  I decided to take advantage of my face vise’s natural tendency to open up a bit at the top, and, after applying liquid hide glue, placed the block and insert completely in the vise with the insert pointing down.  The slight angling tendency of the vise applied more pressure at the bottom than top, holding the insert firmly in place.

24 hours later, a little plane work had the block looking like the picture above.  The insert is flush on both sides, and just a bit proud of the sole.  This will get flattened after glue-up.  I left the intersection of the sole and ramp a bit blunt, as this will give me more room for error when adjusting the mouth opening later.

Next time, we’ll make the pin and put the whole thing back together.  Stay tuned!


2 responses to “Krenov Smoother 3 – Bed and Ramp

  1. looks like it’s coming along well

  2. Pingback: New Little Good Pieces blog post: Krenov Smoother 3 – Bed and Ramp : LumberJocks RSS feed

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