Technical Notes - Making an A13 smoother.
The Norris A13/No 13 (the ‘A’ indicates that there is an adjuster) is one of those planes that caught my attention in my earlier days. I found that it was a well thought out attractive design, but the original was lacking in finish. Those that are familiar with this plane will notice straightaway that my interpretation includes additional features such as the moulding to three sides of the bun; a removable lever cap; fabricated using dovetails not cast; and the side profiles are enhanced with deeper chamfering. The plane is now a little heavier and better specified.
Since my reintroduction of this A13 it seems to have become the bench mark instead of the original. This document has been put together leaving some voids which I hope to address in future writing.
Lever CapsThe picture (left)shows my A13 lever cap set up for drilling the hole for the pivot screw. As it is going into a brass sided plane I am using my original machine screws instead of my removable lever cap system. These pivot screws are, as in everything else, made in house. This screw is of a cheese head type for positive bearing contact. I would not recommend countersunk screws here, because if tight it will have a pinching effect on the plane sides and lock everything and you will impede the lever cap rotation. If it is not tightened it could allow the lever cap to float a bit. It must be positively stable with a good bearing contact. A cheese head screw has a flat underside to the head which tightens down on to the side of the lever cap locking the screw without any undesirable effects. The head sides are parallel with the bore in the sides and it is important for this axis to be truly perpendicular with the plane sides.
As some of you will know most sand castings are far from perfect. They can come with quite a lot of distortion and the contours need truing up. When my lever caps come back from the foundry I have to achieve workable datum and reference points. This usually means flattening the underside, milling the pinch dimensions so that they are parallel and square to the underside and insuring that the pivot hole and front edge are perpendicular. This also applies to the drilling and tapping for the thumb screw and making sure that this hole is exactly central. When this is all done the cosmetic contoured areas are draw filed into their true shape. The pictures above show (left) lever cap filing and (centre) shows the lever cap with a reference template which has the top and bottom contours either side of its centre line. After the top side has been draw filed the lever cap is blued so the side contours can be scribed from the template. The picture (above right) shows the lever cap edge polishing after filing.
The picture (above left) shows the technique of using light reflections as the best reference for showing up errors in the compounding contours and (above right) are the finished lever caps. After much filing the polishing is done with an abrasive paper and graduated down to 1200 in 6 stages. Then the lever caps are lightly buffed and polished with one of many metal polishes available. With a high polish finish like this any irregularities are shown up which is why the previous steps are so important.
Making the Sides and BottomsOften it is necessary to resize the raw materials. The mill does the job quite well as it also removes the unwanted scale and puts things into true perspective. The picture (right) shows bottom thicknessing on the mill.
I use the milling machine for boring my holes for true co-ordinates. As you can see all the holes are drilled after the raw materials have been thicknessed and prepared. This way each hole can be a datum on its own, used for fixing to the holding plate when being profiled, and then it becomes the actual rivet hole.
The rivet holes have a slight 60 deg chamfer the same as my jig screws. This assists the positioning on the milling jig and then again providing the retention for the riveting through the sides of the plane.
The Rear Infill and Handles
Much of the infill work is always trued up flat and square before any of the work commences, as in most woodworking projects.
The picture (right) shows the rear infill after the frog area has been routered away. This gives me a datum stop helping me to work out the drilling positions and its position in the plane. This will also be the same with the handle.
This recess then fits tight up behind the frog creating a positive stop for the rear handle and infill so that there is no chance of the infill creeping forward – not relying on the rivets alone.
This (picture left) is one pair of A13 rear infills being drilled for rivet spacers. Note the frog cut out being used as a stop. After this is done I can drop a template over the holes to mark out the cutting line for band sawing.
The picture (right) shows the handle being drilled for rivet spacers using the same stops as the rear infills. As you can see I am making planes with rosewood and boxwood infills at the same time. The picture (below)shows the finger hole and handles being roughed out. Whilst the holding fixture is in position on the CNC milling machine it is often prudent to use it for other work as all the datum positions are set up. Setting up and breaking down for each job can be very time consuming. This contouring and shaping is only a rough process, the wood will still require a lot of hand work to get the final shape.
(above) I am taking advantage of the holding fixtures before they are taken down. This is the final cut after using the band saw to cut the infills out. I use the CNC mill to cut the true form of the sides, adding on a few thou all round for better finishing and reducing the possibility of profile corruption.
Using a manual milling machine with a cutter I made myself to produce a moulded form on the front bun. This is very accurate on a milling machine used with a DRO for navigational reliability.
Milling the dovetail pins on the A13 plane bottoms (picture right). Milling these is very advantageous on a CNC milling machine as I can work two bottoms together face to face in mirror form. I have a left and a right side of the bottom being worked together. With a dovetail form cutter and tracking in a butterfly pattern this allows me a left and right cut. I use three different cutters for this process – roughing, finishing and dovetail cutters. This method provides a true compound form.
The picture (left) shows the bottoms after milling still clamped as a pair. With some very careful setting up I can produce a near perfect fit between the sides and the bottom without filing. This also helps to keep a true alignment between the rivet and lever cap pivot holes in the plane sides.
The picture (right) shows the process of machining a rebate over the dovetailing. This adds extra support to the plane sides and also provides a light stop (by this I mean light as in a beam of light). This is something I currently do to the shoulder planes and it will be a new feature to all my dovetail planes.
Machining the mouth and bed and fitting frogs.
The picture (above left) shows rough machining of the bed area to the mouth. This area is rough machined prior to the frog fitting to facilitate better access around the mouth. Picture (above right) shows milling to the front side of the mouth. This is one of the main reasons for leaving the finishing of the bed until last so that I can gain better access for an end mill to the front and rear sides of the mouth.
The picture (far left) shows the frogs waiting for riveting and (centre) after riveting. Most of the surfaces are surface ground and especially the contacting surfaces which will be air tight once the frogs are riveted. All that remains now is for the flushing of rivet heads and the bed machining. The picture (above right) shows the finishing cut to the blade bed. As mentioned previously this area was only rough machined and an allowance of 8 thou was allowed for the final surfacing. There is now better access to these areas after the pre-milling.
(above) Work holding for bed working. The highest standard of bed working on a true plane with no azimuth error and the bed pitch is exact to 51 degrees to within 1 minute. This might not seem that important but it is to me because I know where everything else goes then. I want to know exactly where the pressure points are when the blade is clamped. The pitch graduations on the swivel vice are only a rough guide and I find this little digital protractor from Moore and Wright is extremely accurate.
Picture (right) shows the plane bottoms complete. This is a milestone in the project and represents a large percentage of the work. With the sides and the bottoms complete it is now mainly hand work.
I now rough out the dovetails in the brass sides (picture left) working 6 pairs at a time. It takes several pecks especially with brass as it tends to chatter more than steel.
(below left) The final dovetail cut in the brass sides and (below right) checking for fit. Now we are starting to look like planes, there will be a lot of temporary assembly of these parts to complete other fitting operations.
These photos (left) show chamfer polishing. After the sides have been milled and chamfered the chamfers still require the tedious job of draw filing and polishing.
They need constant blueing to maintain the true flat angle all the way round the contour. This is another one of those jobs that eats away at the precious hours.
(picture left) No not a piece of origami! The sides after chamfer polishing and the blade kickers riveted in place. Now I am getting close to assembly.
Piening(top right) Peining the underside. This is the first stage of peining. The body is clamped by a milling vice onto an aluminium former by two surface ground steel pressure plates. These are castellated to match the dovetails. These provide constant pressure over the whole of both sides especially the dovetails and prevent the pinch dimension between the sides getting larger. It is important to emphasise that any distortion created here such as bending and twisting cannot be corrected. Meticulous attention to detail is essential. The precisionally milled aluminium former and surface ground pressure plates help to ensure against any migration.
(middle right) With the sides and their dovetails firmly supported, I can then pein the tails by starting in the centre and working to the outside. Without this kind of support the sides would blow apart. The object is to expand the dovetails inside which normally cannot be reached as these dovetails are true compounds and not the illusions that are often practised. In short this clamping arrangement behaves like a die.
(bottom right) Side peining. The dovetailed pins are peinned straight off the flat of the hammer. All the joints here are already tight and have not moved or wandered due to the clamping arrangement as described above. By peining with the flat of the hammer it makes the metal expand and flow, keeping all edges straight and maintaining the true dovetail form.
The reason I do not use the punch here is because I am making the harder steel flow into the brass. The punch would leave individual indentations in the steel and this disfigurement would print into the brass which is the softer material. The dovetail could lose its form. Using the flat of the hammer dissipates the material more evenly, although care is needed as a miss hit could leave an unwanted dink in the side of the plane. Everything is sharp and crisp when flushed off. It is this attention to detail that gives the dovetails a true sharp form.
The picture (below left) shows the side view after peining, with one dovetail left undone for comparison. (below right) The plane body after dovetailing, showing the milled recesses for the sides in the aluminium former. The recesses provide a positive rest for the peining of the dovetails on the underside.
The Adjuster Recess.
(above left) Somewhere under these shavings there is an adjuster recess in the making. (above centre) Shows the first stage in the adjuster recessing which also includes the additional recess for the peined end of the spigot of the adjuster nut. (above right) After a tool change to one with a radius form, the adjuster stem recess is routed out.
The photo (right) shows the recessing completed. You can now see everything clearly including the recess for the peined end of the spigot of the adjuster nut.
Picture (above left) shows drilling for the brass handle spine. The picture shows me using a centre spotting drill which only works by continually pecking. The reason for using this drill is that it does not wander or flex like an ordinary drill. (above right) This picture shows counterboring for the brass spine head. I have never been sure just how many makers of infill planes have used additional support in the handles but I have come across several Norris planes where there is a 4” screw. I have chosen to do this with a purpose made ¼” brass stem with a 9/16 plane head.
It is difficult to believe that these two pictures (below) of the boxwood are the same handle. It is amazing what you can do with light. Note the handle showing its brass spine head now flushed off.
The finishing of the handles is basically tedious. The abrading that you can see is particularly extensive as I have to remove every bruise or tear to the fibres which are left behind after the shaping. I start at 80 and work down to 400 grits. Then final finish is with 0000 steel wool. Polishing with lacquers or button polishing can hide some blemishes but my chosen finish for wood infills is always oil. This is very clean, business like, mellows the wood nicely and is easy to maintain. The only downside is that the preparation work for oiling is considerably greater than for French polishing; this is because the finish has to be absolutely perfect as the oil will show up every scratch and blemish.
These photos show me making spacers. (left) Parting off and trimming spacers which I use on all my infill planes for better dimensional stability. These spacers sleeve the rivets which retain the handle and infill. The reason for using these spacers is that if the wood should shrink then these prevent the sides from moving due to the tension which was generated during the peining. (centre and right) The spacers are drilled and reamed for the 7/32” rivet, from both ends for better concentricity.
Preparing the Infill
The picture (above left) shows four dovetailed bodies waiting for their infills. The foreground showing riveting spacers and a boxwood rear infill. (above right) Flushing off the rear infill. Flushing the rear infill is done with a temporary spacer to represent the handle as it is too difficult to do this with the handle in position. I also use sleeper rivets and spacers for location. This might look quite simple and straight forward but as with most of the work care is also needed here. There are already polished chamfers and any overzealous material removal will lose some uniformity of chamfers and edge width, and could corrupt the contours.
(below) The polishing of the infill is done after excess materials have been removed. I work down the grades of abrasives as mentioned previously.
(left) Flushing the end of rear infills. At this stage the plane with its infill can be put into the milling vice to flush the end, which then needs further polishing. The infill is then dismantled and the thicknesses of the sides are adjusted – to make the combined width of the infill and handle fit snugly into the plane body.
(centre) Drilling for adjuster nut. Even without any machines this is one piece of equipment that everyone should have – just an ordinary drill press. This picture shows the drill press being used to drill the hole for the brass bar (sometimes called nut) which is then drilled and tapped later on in situ for the adjuster fixing. There are sleeper rivets in the handle to ensure true positioning. The picture (above right) shows the fitting of the adjuster nut.
Picture (above) shows facing up the bed area of the rear infill and handle, in the milling machine. Yes, you could say this is dangerous and if you try this in your milling machine with a face mill you will need to approach each contour with care or you could end up with a lot of split ends. It is worth it in the end as I get a true flat plane without any tearing.
Picture (left) using edge finder. It is important that I get things back to centre at this stage and I do this with an edge finder. I always establish a centre line to work my co-ordinates from.
Adjuster Nut and Blade Pads
Picture (below left) Drilling through the adjuster nut. Now that everything is back on centre I can drill through the hidden brass bar/nut for the adjuster. (below centre left) Tapping the adjuster nut. Whilst I still have all my co-ordinates and work holding in place I hand tap the previous drillings for the adjuster fixing. I am using the collet chuck to keep the tap perpendicular. (left and centre left below) Blade Pads. There are many jobs in the making of this plane which don’t get mentioned and these pictures show the blade pads for bedding. The length and depth of these pads can be variable and I prefer that they come to rest against another metal structure or otherwise have some depth as to act as a pile. On these A13 planes I am bearing on the rivet and spacer. The reason for using the pads for the blade is that they are more reliable than resting on the wood alone. I allow for some material to be removed from the tops of the pads to level them off to match the plane of the frog. There is a space between the wood and the blade as I don’t want any blade contact in the centre area. The only support for the blade is the frog and pads.
Picture (above) Boring for the blade pads. I drill using an end mill cutter in the milling machine to a suitable depth where I can engage part of the plane structure. The pads are then cemented in - on the previous pictures you can see the retention recess keys for cementing turned onto these pads.
Picture (right) shows the handles ready for fitting and trimming pads.
Picture (below) shows the rear handle in position. I have used temporary rivets at this point as there are a number of other processes to be considered before final fitting.
The Front Bun
Picture (right) I prefer to use the milling machine for moulding the front buns as not only does this give me much better control but the accuracy is unrivalled. It always makes sense to do the end grain first so I can catch the breakout.
The photo (below left) shows the moulding to the sides of the front bun. With the end grain moulded then it is reasonably safe to mould the sides with little fear of breakout. The picture (below centre) shows the shaping of the front bun. Now the bun moulding is almost complete it is necessary to put a small rounding on the two front corners and polish the bun. The apron you can see provides some protection to the integrity of the edges and contours during this work and the polishing. I much prefer to wear away the masking tape than my skin!
Picture (far right) shows the final polishing with a 0000 steel wool of the front bun prior to oiling. Oiling can darken a lot of woods and lose contrast but in some of the rosewoods this can work to its advantage as contrasts can be a little ‘loud’. Different woods need different considerations. Each piece of wood has to be treated individually.
(above left) Here I am using the DTI to replicate the angle of the frog, this enables me to trim the blade bed studs on the same plane as previously described.
Picture (above right) shows levelling off bed studs. Once the level of the frog/plane bed is established then I can level off the bedding studs. I like to leave these about 2 thou high to allow for settlement. The reason for this system is so that the blade will be supported in the places that matter. There is little risk then of coming to rest on any unwanted debris or irregularities.
Picture (left) shows the the bed after completion of levelling.
Dovetail Flushing and Final Assembly
This picture (above) shows the dovetails ready for flushing down in the mill. (right) Interesting view after the sides have been milled. Showing the true form of the dovetails and rebate that the sides come to rest in. At this stage the front and rear ends still require chamfering and edge polishing. Also the sides and sole require lapping.
It is nice to go to my stock cupboard and find components that I made earlier. I dread having to make more when they run out. Notice that the banjos are ball generated so that the whole item is made from one piece. There will be a complete article to follow in the technical section.
Here is the completed adjuster which goes in most of my infill planes; mainly A13, A6 and A1 (which has a slightly longer stem).
Here the planes are completed, ready for boxing up and sending out.