Monday, May 11, 2009

Precision Woodworking

When I started out in woodworking every project was laid out in full scale on MDF on the floor on my hands and knees. I had a giant (shop-made) t-square, a good set of knee pads and a box of colored pencils (different color for each layer). These layouts were critical to my process. Having taken three years of drafting in school I was fairly proficient with drawing instruments and prided myself in being accurate. Every minute detail was worked in these layouts - from complex joinery to use of hardware and even some of the aesthetic decisions. Every project meant a new piece of MDF to be placed in my storage bin - after a while my storage bin would begin to bulge so from time to time I would have to perform a selective purging. This system served me well and I was quite content with it. But change was on the way. And as change often is, it came in small incremental pieces.
The first step in that change came while I was working at a large high-end commercial shop. At this shop there were nearly 100 employees on the floor – most of whom loved to buy tools – which we often did in bulk to get a good price. One time we purchased vernier calipers – not because we had a need for them but because it sounded like a really neat idea. So we had nearly one hundred woodworkers with calipers: and nothing to measure. After some discussion it was decided that all work coming out of the mill department (where I worked) would be subject to a standard of .005. Soon 1/32” seemed like a large number! This was great stuff and we all became a bit drunk with it – it was not long before someone bought a dial indicator (on magnetic base) to set the slip (suicide) knives on the shaper and not long after that we were setting the knives on the jointer with a dial indicator as well.
Working with calipers and dial indicators soon became a part of how I did things - it greatly increased my accuracy - especially with things such as intricate joinery. But change does not come easy for some. A few of the older guys did not buy calipers - in fact they took every opportunity to chastise us for using the new technology and speaking in thousandths. At one point I made a rather embarrassing mistake on a project. It was a ripe opportunity for one of these old guys to level his most damning insult at me - and I could see it coming as he walked over to me and said “I bet you own a calculator – don’t you! “.
A few years later I found myself back at HLD (Harry Lundstead Design) – a shop I had worked at years earlier building custom conference tables. I described my new position as “fireman”. Since I had left the company, they took my old job and divided it up amongst several people - no-one knew the entire process anymore. So I was hired back on swing shift – and my job, since I knew the entire process was to step in at any point and “put out the fire”.
Since I had left a CNC router had become a part of the process - so I learned how to operate it. This was not the CNC machines of today – this thing operated in DOS, which often meant entering coordinates and programming it myself.
This was another step in changing the way I approached woodworking. The opportunities the CNC opened up were immediately apparent. For instance - no more giant router trammels that stretched all the way across the shop and took several people to manage. It was now possible to run a 360” radius followed by a 360.0625” radius with extreme precision in a matter of 5 minutes verses several hours the old way!
The technology bug had now bitten me in a very big way. I was actively seeking new technologies and not waiting for them to bite me first.
Learning CAD was high on my list. But I had spent many years with the t-square and was quite efficient with it. So it was considerable time before I was faster with CAD and could fully retire my drawing instruments. CAD opened up a whole new world and was probably the biggest move forward of them all. Complex joinery and compound angles became much easier. I could draw a curved part from a chair and rotate that part so that it would fit into the smallest rectangle possible thus making the most efficient use of material. Within that rectangle the joinery could be placed within .001 “. With my Incra precision marking tools I could layout the joinery on a piece of wood to within 0.015625” (1/64”) - which would serve as the “rough layout”. With my Multi-router (an incredibly accurate machine) I could make a rough test cut. With my calipers I could then measure the cut and adjust the multi-router to within a couple of thousandths with my dial indicator.
A fundamental premise of woodworking had changed. Instead of fitting each part to the next I could, for the most part, make individual parts with a high degree of certainty that things would either fit on the first try with little or no fussing.
The combination of CAD and CNC has also dramatically changed the way I approach jig and template making. Jigs are easily made to hold odd and curved shapes while complex joinery is performed. A would-be tricky operation such as a pierced tsuba is now a simple matter.

But these new technologies have their limitations. If everything were done by machine with absolute precision – then everything would be rather lifeless and sterile. There must be some sign of the human hand in our work - there must be a little imperfection. What gives a person’s face character is the fact that one side is slightly different than the other. I let technology do what it does best – precision measuring and machining, but the pillowed ends of finger joints and ebony plugs are all shaped by hand – they are all just slightly different than the next piece. The same is true with my “straps” - final shaping is by hand and all are slightly irregular. The final sanding of a rounded edge is always done by hand.
Precision woodworking does not make new things possible it just makes things done the old way dramatically easier, thus greatly reducing the labor required and ultimately making things more affordable.
So embrace new technologies and let them do what they do best but let a little imperfection and character show in your work as well.

3 comments:

  1. Hi Darrell .. I enjoyed the above post on design, drawing and the place for technology in the workshop. My experience, except for working in the big shop, mirrors yours almost exactly. I have a rack in the cellar of my shop with many, many rolls of full size paper drawings done over the first 24 years of my furniture building career. We still pull them out when needed but all new designs are done using our CAD programs. We have made the leap and purchased a CNC router which, as you say, has opened up new thought processes and newly affordable design and construction possibilities. I think the Shakers would have loved having one and I’m always amazed at the number of Amish woodworkers patrolling the CNC maker booths at woodworking shows. The computer, if you include email, websites, blogs, CAD and CNC as part of that, has become the most used tool in our shop.

    I also wholeheartedly agree with your comments on imperfections. “mark of the hand”, from David Pye’s book on workmanship, is the phrase we throw at the little imperfections in our pieces as construction proceeds, and we still handscrape virtually every finished surface with our Stanley #81 two handled scrapers. Woodworkers striving for ‘perfection’ in their pieces would be wise to also consider the phrase “perfectly ‘executed’ ”, as another guide on the way to successful furnituremaking …

    Keep up the great writing … good luck …. dan mosheim, dorset custom furniture, dorset, vt

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  2. Hi Dan,
    When I set up the new shop I left a space for a CNC machine - hopefully I will get one someday. Currently I send out to have CNC templates made. When I have my own CNC - I won't need nearly as many templates - they will be in the machines memory.

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