In homage to the late James Krenov, Iain Green makes a handplane in the style Krenov popularised.
Linda Nathan’s interview of the now late James Krenov in the last edition brought back for me the enormous influence that he has had over the international woodwork fraternity since he published his first book in 1976. His designs have an unmistakeable style that has influenced a generation of woodworkers; he had deep insight into the beauty and mystery of timber and he had mastery of fundamental technique.
However, Krenov’s books are unique in the way they express the ‘romance’ that affects almost everybody who attempts to create something out of wood. They explore the way he felt and thought about his craft through the various dimensions of woodwork – design, use of wood and woodwork technique.
While Krenov used machinery over the years, his strong preference seems to have been the use of hand tools in order to keep an intimate contact with and control over his woodwork. Krenov popularised a style of plane that he developed from European designs and which played an important role in his own development as a woodworker:
'The first little attempt with a plane that succeeded may have been the turning point of my life because it opened up the fact that tools can be better,that tools can be more personal and intimate. ‘It was comfortable with two hands on it. It was comfortable with one hand doing a tiny little edge or corner. It had a new dimension because it did not force me to relate to it very rigidly in one certain way.
‘I think the emotional difference is the main difference,not necessarily performance only. It’s a connection, an intimacy. The really good plane becomes an instrument.’
So what differentiates a Krenov style plane?
- The shape is simple and designed to be comfortable either pushing or pulling the plane, and to allow a comfortable grip over the top of the blade.
- The blade is short (around 90mm), thick (4–5mm) and has a chipbreaker. Blade widths range up to 2 inches and have either straight or curved cutting edges.
- The blade is set at 45° and held in place with a wedge that fits under a wooden cross-pin that rotates to fit the blade.
- The blade is set back about 43% of the length of the plane, from the front. By comparison, Japanese planes are set 60% back and traditional western steel planes are about 27% from the front. It is this difference that enables Krenov planes to be used with both a pull or a push stroke.
Some months ago, I was re-reading Krenov’s second book, The Fine Art of Cabinetmaking and was inspired to make a plane in the style he used, to investigate the relationship with planes that he describes. This plane was influenced by my experience with Japanese planes as I cut the throat from a solid block whereas with Krenov style planes, side cheeks are usually glued onto front and back blocks. This led me to use a steel pin rather than a rotating woodencross-pin. While this plane has been really successful, I wanted to make a plane that followed all aspects of Krenov’s approach.
Blade selection
For my initial plane, I used a cryogenically treated blade from Academy Saws, Qld and it is holding its edge really well.
However, they don’t make a chipbreaker and in retrospect, it is simpler to go to Professional Woodwork Supplies in Melbourne (www.woodworksupplies.com.au) for a complete Hock plane iron assembly made specifically for a Krenov style plane. For this new plane, I went for a cryogenically treated blade from David Finck, USA (www.davidfinck.com). Another option, if you have an existing blade with chipbreaker, is to cut it to 90mm long.
Timber selection
The timber for a plane should be straight grained, hard and durable. There are many Australian hardwoods that should be suitable—gidgee and Cooktown ironwood have been used with success, for example. For my first Krenov plane, I used some forest oak (Allocasuarina torulosa) as it is really hard and I thought the medullary rays would help prevent split- ting. Shuko-kai* strongly recommend a pale coloured timber in order to create a contrast between the colour of the blade and the sole which helps to see the blade as you are adjusting it for a fine shaving.
While options for suitable pale Australian hardwoods are limited, this time I found some quite blonde spotted gum that should work well.
If possible, I like to use a backsawn block which is oriented so that growth rings run across the width of the block and with the outermost ring on the sole at the front of the plane.
Shuko-kai suggest this stablises the block and reduces friction. Another option is to make up a plane blank by gluing a 6mm hardwood sole onto another block.
1. Cut the Cheeks and Block
Cut the cheeks and the central block from a single block so the rings will be continuous when the plane is assembled. Initially, I cut the cheeks oversize and left them a few days to make sure there was no movement in the timber. I then reduced them to size. The central block should finish 3mm thicker than the blade width and care should be taken to ensure that faces are flat and the blocks are of even thickness as this affects accuracy of the final assembly.
Mark and cut the ramps on the front and back blocks—62° and 45° respectively (see fig.1). It is essential that these ramps are smooth and perfectly true as the front ramp defines the mouth and the blade must bed squarely and with good contact onto the rear ramp. I used a high angle plane to flatten and square these faces. Test the blade on the back ramp for good contact.
2. Cut Cap-Screw Slot
A cap screw on the back of the blade binds the chipbreaker to the blade. The ramp on the back block needs a slot that will allow this screw to slide down sufficiently for the blade to pass through the mouth. The dimensions of this slot depend on the screw for the blade assembly you choose, but as a guide these should be 6 x 18mm wide and should end 18mm from the bottom edge of the ramp. I cut the slot on the router table using scrap as a safety guard. I used double-sided tape and another piece of scrap to hold the block and to keep fingers well away, and found that the triangular offcut from the central block worked well as a stop for the router.
3. Cut the Cross-pin
The blade is held in place by a wedge that fits under a cross-pin with round tenons on either end that fit into the side cheeks. Prepare a 13mm square pin about 75mm long. I used a tablesaw to cut square cheeks for the tenons, fractionally closer than the width of the back block. I carefully reduced the tenons with a chisel and then rounded them over with a small file. An 8mm hole in some waste was a useful test for final fit.
Flatten the bottom of the cross-pin, making sure that the tenons remain equal heights above the bottom. Clean up the other faces and round over the top edges.
4. Initial Assembly
I used 8mm dowels in the top corners of the front and back blocks to fix the location of the cheeks to the central blocks. The location of the front block must be adjusted so that when the blade is placed on the front ramp of the back block, the cutting edge touches the ramp on the front block, about 1–2mm up from the bottom edge of the ramp. This allows room to adjust the gap at the mouth after assembly.
5. Locate Cross-pin
The cross-pin should fit so that it can rotate easily but without wobble. It should be placed just high enough that it doesn’t obstruct shavings but not so high that it compromises the top profile of the plane.
It should allow enough space for a wedge to fit under the cross-pin. If the front and back blocks or the cross-pin aren’t square, it is painfully obvious when you look down the throat of the plane.
Mark the location for the cross-pin on the inside of each cheek, 32mm above the bottom and 20mm above the front ramp on the back block. The 20mm is the thickness of the blade + chipbreaker (8.8mm) + wedge (5mm) + ½ thickness of the cross-pin (6.2mm)—adjust to suit your dimensions. Remove one face and drill the cross-pin hole from the inside, making sure the back of the hole is supported on some waste to prevent tearout. You can drill the other side the same way if you are confident of your markings, or you can clamp the assembled plane onto a drill press and drill through.
6. Assembly
Test assemble the plane to confirm that everything is square and that a wedge can fit between blade and cross-pin. Adjustments now are difficult but not impossible. Check that sufficient clamps are available.
I used epoxy to assemble the plane as I am confident that it will be robust in this situation. Make sure that you don’t glue the cross-pin.
7. Mark and cut the profile
Clean up the sides and mark a profile that you think will be comfortable. A bandsaw works well to cut the profile. Shape the profile and round edges and holding surfaces for comfort. Krenov liked to keep the top at the front flat as this helps alignment of the plane as it is being used.
8. Cut a Wedge
You need a fine angle to the wedge, a curved front edge and a rear edge that rises above the blade, to make contact with an adjusting hammer easier. My wedge ended up 50 x 55mm long and 5mm thick under the cross-pin. As you test fit the wedge, check the feel as it contacts the cross-pin to make sure that it pushes home straight. Also, check the shiny contact spots on the top and bottom sides, to confirm that there is even contact across the wedge.
9. Adjust the Sole
Krenov recommended a flat sole as compared to the slight profiling I described for Japanese planes in AWR#57. He mentioned flattening the sole on a jointer and then finishing with sandpaper on glass. However, I couldn’t bring myself to do this as I know from experience how rapidly the gap across the mouth can expand. Rather, I used a scraper plane and then sandpaper to flatten and reduce the sole until the blade is contacting the front ramp, about ½–1mm up from the sole. While you are flattening the sole, the wedge should be firmly inserted with the blade raised slightly from the sole. As you finish flattening the sole, check that the sole is square to the sides and that the blade contact with the front ramp is parallel to the sole.
Check the flatness of the sole with a straightedge across, along and diagonally on the sole. I don’t find that sandpaper on glass automatically leads to a perfectly flat sole. My experience with Japanese planes is that fine tuning the sole is an almost daily task as temperature and humidity changes lead to movement in the plane body. Krenov on the other hand, talked as though further adjustment is infrequent. My experience to date has been negligible movement in the sole of the forest oak plane and continuing though small movement in the spotted gum plane.
When you are happy with the sole, remove the blade and use a file to bevel the edge in front of the blade, checking frequently whether the blade can come through. I strongly recommend that once the blade can come through the mouth, you use the plane a bit before opening the blade gap further. One of the biggest risks is that you suddenly find that you have a coarse mouth when you wanted a narrow mouth (say 0.5mm) for fine work. On a regular basis, check that the sole remains flat and that a straightedge along the sole, contacts the sole in front of the blade opening. Over time, you are likely to get wear in front of the blade that widens the blade opening unacceptably.
You can correct this by inserting a small block in front of the blade to re-establish the blade gap.
10. Setting the Blade
Insert the blade centrally in the throat and hold it just back from the sole with fingers across the mouth. Insert the wedge and give it a light tap with a small hammer—choose one that won’t damage the body as you adjust the blade. Don’t over-tighten the wedge as this can distort the sole. Krenov suggested that the wedge should be firm but that it should still be possible to wiggle the wedge to loosen it.
Hold the plane so you can sight down the sole from the back and so that you can get a reflection off the polished bevel. Tap the top of the blade until you get the barest hint of a light reflection uniformly across the width as you sight exactly down the sole. If (when) you go too far, tap the back of the body to bring the blade back, re-tighten the wedge and try again. If the blade comes through more on one side that the other, tap the top of the blade on the side to square it. By way of contrast, the tuning of the sole on Japanese planes means that the blade is always adjusted by sighting from the front.
11. Tuning and Using your Plane
Krenov suggested that shavings should swish up out of the plane in a curl or almost straight. If they are creased or folded, there is a problem with the mouth or the chipbreaker. He suggested that the chipbreaker should be set back from the cutting edge by 1/32” for a fine shaving and up to 1/16” for a coarse shaving (1–2mm). If shavings are catching under the chipbreaker, then check the fit to the blade. I suggest that you start with the smallest possible blade opening and then ease it until shavings flow cleanly. The difference can be remarkable if these things are working well. It also takes some practice to adjust the blade for a fine shaving and to adjust it so that you don’t leave steps between adjacent shavings.
The sole needs to be perfectly flat and needs to stay flat, if you are to plane a true surface. The ultimate objective is to plane a burnished surface without streaks. Uneveness in the sole, shavings that catch around the mouth and blade sharpness and setting can all contribute to these streaks. Your planing stroke also affects the finish. Weight needs to move from the front to a balanced position to the rear of the sole, as your stroke progresses. The finest of shavings require a very light touch—pull the plane along the surface without bearing down heavily.
A Krenov style plane is probably not a project for a beginning woodworker—however, it is not that difficult for anybody with a little experience. While I know that it is impractical for woodworkers to make all of their tools, I feel that this project develops familiarity with fundamental aspects of fine woodwork which makes it worthwhile. Certainly, I really enjoy using these planes and think I have realised some of the emotive differences Krenov described.
* Shuko-kai is a traditional woodworking group in Japan.
Iain Green
References to Krenov’s comments about his planes have come from The Fine Art of Cabinetmaking by James Krenov, Sterling Publishing Co., Inc, 1992 and Making Music with a Plane, a short article by James Krenov published in 1997.
Photos/illustrations: Iain Green