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[Peter Wiltshire]

  Here is a question for the group.  When making interlocking puzzles where tight tolerances are key; do you ever rely on a pencil mark?, or is everything cut with jigs?  The reason I ask is with a pencil mark I have run into all sorts of confusion. "Do I Leave the line after the cut?" "Do I cut on the line?" etc.

My second part to this question; On internal surfaces of the puzzle do you measure and then account for sanding, finishing, and wax when making the cuts, or are the internal surfaces (where precision is critical) left untouched after the cut?  Hope I am not sounding too dumb

Thanks in advance

[Mark McCallum]

For interlocking puzzles, all pieces are cut using jigs.  There is no way you will be able to maintain accuracy otherwise.  So using a jig is the way to go.  Typically I cut a few pieces, measure with a dial caliper and adjust the jig if needed.  Ditto to John's comments.  Using those methods and the blades we've discussed in another topic, you really won't need to sand much at all, if at all.  But you have to take great care when making the jig, I can't stress the importance of that enough.

[Peter Wiltshire]

O.k. Great, thanks for both responses.  Lee's instructions are a great help.  So I assume with proper blade setup and a good quality blade that all the internal cuts are clean enough that they do not require sanding.  Do you find that internally the puzzle does not require a finish other than possibly wax?

[Eric Fuller]

Buy a set (or three) of machinist's gauge blocks; you can get a "B" set on Ebay for cheap.  All my acuracy comes from them and the planer.  You can make any length you want with accuracy up to .0001 and transfer that to a preacher stick for pretty much anything you do.

[Robert Yarger]

All pencils have to go!!!!  If no one else metnions it, I will.  A pencil will leave variences just in the fact that its tip is not as pointy during the second stroke as it is in the first.  I have to agree with everyone that a jig is the way to go.  An adjustable jig is even better, then you can use it for future applications.  Even then, a jig can be just as easy as clamping a piece of wood to a cutting table so that it stops or measures the same exact cut every time.

Personally for really really exact pieces, I overcut pieces by 1/100" and use a sanding jig for follow up.  (I know that most of you don't agree with this method as it adds an extra step, but I stand by it for cuts that have to be absolutely exact).

Im my experience, laquering does not add enough dimension to a piece for it to really be an issue, especially if you follow it up with steel wool sanding.  Also wax does not add anything because it just fills in the holes and pores.  If you do use wax (which I recommend), my favored approach is to cover a piece liberally with wax and then put it in the oven on its lowest setting for 5 minutes, then wipe off the excess with a towel and let it cool.  There are other techniques that you guys have presented, but this seems to work the best for me, as it gets the way into the wood just a bit, and not just on the surface (better protectin against humidity).  However, I am very impressed with the results tha John Devost gets with his buffing system, and that forces wax into the wood as well and leaves a very nice finish.

What I really want is for Scott to also respond with his reasearch on humidity and altitude effecting wood.  We all know for a fact that humidity effects wood, and the perfect piece you cut in the shop is no longer exactly perfect when you take it inside and expose it to different temp and humidity conditions.  Jigs, will also produce slightly differnt results with changes in humidity (and we are talking very small variances, but it is worth mentioning). 

I had a lengthy discussion with Scott about altitude changing the dimensions of wood, and I don't care to spend another 3 pages going over it all again, but personally I know for a fact that it does happen.  (Scott, have you heard back on this from the science community you were researching it with - because a lot of people are starting to think I am crazy- but I would bet my other 9 fingers on it).  For any number of reasons, the perfect puzzle you make in the shop will eventually be too loose or too tight based upon the temp, humidity, or altitude or environment of the collector it is eventually sent to, so you just make it as perfect as you can in the shop, cross your fingers and hope for the best.  That is the best you really can do unless you move on to metal, but talk to Eric about the hassles of that. 

Robert

[Scott Peterson]

I agree - jigs are the way to go.  If I do need to mark something, I tend to use a razor knife - but only when a jig can't do the job.  I get far better and consistent accuracy with a properly built and set up jig - and this is lots easier than measuring so many times.  The machinist's gage blocks Eric mentioned are for setting the right offset to make a cut (among many other uses) - I use them a lot for making stop blocks.  Also, Robert's approach for cutting a little oversize and then sanding is a good thought.  However, for the Coffin building blocks, this can introduce error in all the angles - so I try to cut to the correct size.  I think my Freud Ult Cutoff blade leaves a better (glass smooth) surface for gluing than sanding too... 

As far as the internal surfaces go, the first thing is to have all the blocks for a puzzle as close to exact as possible.  Then, there are some options.  If there is a joint which tends to be really tight without finish and wax on it, you can use wax paper shims to create a tiny little gap between the pieces (can't actually see this).  The wax paper sometimes allows the 2 tight pieces to slide a little easier in the beginning - the same job the wax finish does for the final product.  If that doesn't work, I leave 2-3 carefully selected joints within unglued for the first round of gluing.  This allows me to take the puzzle apart easily (not following the real solution procedure) and I have a chance to sand some of the pieces just a little bit if the fit is too tight.

I use lacquer thinned 2:1 (thinner:lacquer) and I warm it on a coffee cup warmer w then brush it on.  I have about 20 little spring clamps on a string hanging above my workbench where I hang the pieces to dry.  This requires a second step for finishing, but I think it leaves a nice finish.  The thinned lacquer soaks into most woods really well - and if it soaks in too much, I will put on a 2nd coat on the outside/show surfaces to make a glossy finish.  I don't wipe it off like some of the others do, but I have really put in a lot of work to improve my technique and process so no brush marks are left.  Finally - the wax goes on, very important for the internal surfaces since this allows the pieces to glide past each other easily - and it adds a nice luster to the outside too.

I have heard back from the guys I know at the Wood Materials and Engineering Lab (WMEL) at WSU - but alas, they have not seen any research on the effects of atmospheric pressure on wood.  They all said it is a good question though!  I am still digging a little to see what there may be out there - and I don't think Robert is crazy!

[Robert Yarger]

I just know that a guitar will go noticabley out of tune while going up a mountain, and once tuned, it will go out of tune again when you go back down.  It is either the wood bending its shape, or the strings. 

The finger's fine, just a flesh wound.  I am typing with it right now without much discomfort.  It seems that my pride will take longer to heal.

Robert