24 August 2011

Horizontal mortiser

My favorite woodworking machine is the horizontal mortiser.

It is quite,  with 3000 maybe 3600 rpm it is a lot slower than a router.   Powerful, 3 hp for the model displayed.  Due to its low speed it produces limited amounts of fine dust.  Precise, the depth is set to the front of the workpiece where in a drill press the bottom is the reference.  Also precise when making frames as the frame front is locked down to the table giving predictable alignment.  Goes straight, where a hollow chisel keeps it (mis)direction,  the drill is free to realign itself after being pushed sideway by an irregularity.  ROUNDED mortises?  True, these look very machine made, but ... in engineering holes must have rounded corners to avoid excessive stress.

Drilling a mortise with a horizontal mortiser can be done in a succession of: drilling the two extremities, adding free standing holes in between,  drilling extra joining holes,  and finishing with shallow sideway passes.  Personally I prefer a two handle system, where one hand is used for positioning and the other for  movement, keeping at the same time both hands away from the drill.

It is possible to make tenons with handtools (a saw) and straighten up  mistakes when in excess (mainly a router plane).  Where for mortises the process is mostly more brutal and it is more difficult to see and correct mistakes. So, it allows to say: give me perfect mortises,  I will try to deliver appropriate tenons even using only handtools.

Do I need one?  No, only if I was a regular tenon and mortise guy,  or if I was looking for a possibly cheaper or beefier loose tenons alternative to a Festool Domino thing.  The model on the top picture shows a doweling indexing system,  the black tube under the x-y table. But it is unclear to me how to drill in panel fronts.  Speed wise,  based on William Thomas evaluation, I think that longer positioning time gives it half the speed of hand held free tenon alternatives, be it a biscuit joiner, the Mafell Duo-Dowel or the Festool Domino.

Its origins?  I always imagine it is a logical add on to a jointer-planer.  The drill head is an extension of the cutter head.  And the x-y table can be directly attached to the internal planer table,  or like in this example has its own raising mechanism.  Of course it is a fight between space and comfort, where more comfortable is when the table stands on the back of the jointer.

I have an example of simple bed probably made by a finish carpenter around 1930. Pictured leaning against a wall during transport - hence the leaves, to catch the chiseled pairing markings. The joints show that the workshop used a horizontal mortiser.

Matthias Wandel at Woodgears,  made its own horizontal mortiser using a (noisy) router, drawer slides, and some wood. Why buy one, when it is so 'easy' to make one.

09 August 2011

gRounded

Lately I encountered two projects where I needed rounded forms.  And then,  I got grounded.  Where  in woodworking  flat, straight and square has numerous problems and solutions,  round has its own needs.

James Krenov's coopered doors.
After reading his book The fine art of cabinetmaking,  I decided to try to emulate one of his small cabinets with coopered doors (minus the choice of better woods).  I agreed with him that using boards of variable width gives a more interesting curve,  and used three boards to make a five piece progressive rounding.
The glue up is done two  by two pieces, with rounded supports on the sides.  Things got more difficult in the end glue up,  where I missed a central down force to control the bulging. I solved this by clamping down only the sides and wedging the center (and stacking a number of heavy items on top), but a centrally placed edge clamp pushing downward would have been  a more controlling alternative. It's now on my needed list.
Flattening (rounding) the exterior can be done with any plane.  The interior is another problem.  Krenov says he uses a number of rounded planes of his own made. If I have round profile planes, I have nothing close to a number 300 needed to do the job. I looked to Robert Wearing for an alternative and in his tool list I found:
- A compass (circular) plane,  the right form but not the right orientation. Who knows, tomorrow Chris Schwarz finds a use for them,  and we follow. The plane is also mentionned by Charles Hayward for his list together with a curved edge plough .  This one is on ebay UK 50£ and four days to go. For new ones there is Anant, Kunz, ECE and Virutex (powered).
- A rounded spokeshave,  the right form,  but the handles are too low making it unusable.  Veritas has a rounded spokeshave with a central handle and Lie-Nielsen a small convex sole plane,  these could do the job, but the price is far from the low budget project I started with. While the short (rounded) sole is a weakness for this project.
- A firmer gouge,  it has the rounding similar to a normal round profile plane,  there is no gain here if both are available.
- Half round rasps and files, presented in his book without handle. With some creativity about handles set on the flat side, this could be a solution.
- Abrasive papers.  Most probably this is closest to a solution,  it is easy to make rounded form and fix sandpaper on it.

My starting idea was to follow the Krenov approach with dedicated round planes.  I could take a cheap wooden plane and round it and sharpen the blade with an appropriate curve. Or as an alternative take my cheapest n°3 plane,  glue a strip of hardwood on the sole and round it as well as the blade.

All this written,  I think I drop the n°3 modification  and give sandpaper a try.  For me the Krenov project is already innovative,  adding plane making to it doubles the load.

Looking at my other gRounded project is for another time. It's making a sector based on a description of Jim Tolpin in Measure twice, cut once. I thought I had 'improved' his design, and created some new problems in the process.