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[John Lofy]

Hello!

New to the forum.

I'm frantically working on finishing a Coffin-like puzzle for the contest.  It is a slight variation of Scrambled Scorpius.

Fortunate to be able to make some gluing jigs on a rapid proto machine that we have here at work.

Wondering if there are any "lessons learned" that anyone can share.  Things that I've been thinking (e.g. worrying !) about:

  -- since the final fit for this type of puzzle has to be "perfect", should I make up the first subassy, put it together with rubber bands with all the other loose pieces to see how they fit, then make up the second subassy, try the fit, continue ?

  -- if I finish making all the subassys and they go together tight, do you just do "micro samding" where necessary ?  Or does this end up ruining the appearance of the puzzle ?

  -- what type of glue is recommended ?

  -- how to prevent glue squeeze out ?

  -- tips for sanding endgrain ?

  -- Acceptable to just put lacquer on outside exposed wood pieces ONLY ?  (I assume that if I apply lacquer on inside wood surfaces, the fit will become too tight.)

From a first time puzzle maker . . . .

[Kerry Verne]

I'm new to this too, but I've learned a couple answers to your questions:

Lacquer the whole thing with a reasonable thin coat. Several of us use the HarborFreight HVLP turbine kit (~$80 in store http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44677) Mine actually fit better after lacquering as it removed some of the wood-to-wood friction.

Eric seems to go by the +.005" rule for looseness.

Titebond II glue works well for me, but use little enough that it doesn't squeeze out. I read Coffin's books in the competition thread. (http://www.cubicdissection.com/forum/index.php?topic=139.0) (For assembly, just hold it steady for 30 seconds and it stays put. ) Modern glues are as strong or stronger than the wood you use. Lacquer does make glue squeeze out fairly obvious, so keep a wet rag handy and use the glue sparingly.

For endgrain, get a good blade and keep it sharp. (Sears has a sale on the Freud LU85 80tooth blade right now.) Once you start sanding, you start to move away from accuracy.

If it does have to be perfect, gluing as much of it while assembled as possible will help.

[Robert Yarger]

I think you will have as many answers to your questions as there are woodworkers.  I use elmers wood glue with good results.  I apply a thin layer to both sides and press together. 

Clamp your project once to squeese out any excess glue and get it in all wood pores.  Until you figure out exactly how much glue to use, clamping will cause wood to shift slightly, so I would clamp it once, take off the clamp, wipe off any extra glue, reposition the pieces if necessary, then clamp it again to bond.

It is sometimes akward that glue does not stick well to lacquer, and yet if you glue first and accidentally get any glue on the exterior of the wood, it will leave a pale mark in that spot when lacquered.  (This can happen even if you wipe off excess glue with a damp towel, as it still leaves and invisible glue layer). 

It depends on the project, but I prefer to glue first, but instead of wiping off the squeesed out excess, just allowing it to dry mostly, then scrape off with a razor and sand lighlty before lacquering.

Of course, you can prevent glue squeese out by using less glue, but then you really don't know if you have enough glue for a tight bond.

If you cut perfectly, there is no need to sand the endgrain, except just a tad with fine grit.  If you have a rough end, then you probably need a better blade or refined method of cutting.  IF you do have a really rough end piece, it is better to use a fine grit (in circles) and take a long time as opposed to a course grit, as a course grit will leave deep scratches that will take forever to get out with a fine grit.

I would agree that the entire thing should be lacquered, even places you don't see unless it is taken apart.  Lacquer thickness is nominal and can be reduced if necessary with steel wool.

   

[Kerry Verne]

One other aspect of lacquering is that applying lacquer/poly/etc to only one side of wood can result in warp as moisture from the air will be absorbed differently on either side.

Bottles like these: (http://www.woodcraft.com/family.aspx?familyid=344) can be helpful to regulate the amount applied.

[Robert Yarger]

I used to use those, and while they are not without thier charm, you should put apply a drop of glue to the tip (to keep any glue from drying in the tube) before storing it for any lenght of time.  The metal tube is nearly impossible once it gets clogged.

I currently use the syrenges left over from my ink refill kits and fill about 20 of them at a time.  They work alsmost as well, but you have to make sure that there are no air bubbles inside or they will keep oozing after you have stopped pushing.

A neat trick for either method is to put the glue in the microwave for 5-8 seconds with plastic wrap over it before refilling.  The heated glue will suck more easily into the despinser.  You have to use the plastic wrap of the glue in the mircowave will develop a thin skin.   

[Eric Fuller]

Hi John,

Nice to see you on here!  Please don't get frantic about the contest...it's more or less dead...I've only received two entries, so it's gonna be consolation prizes all around.

You raise a lot of interesting questions.  Unfortunately I have to get ready to go out right now, but I'll revisit things this weekend and give a better reply.

[John Lofy]

Wow!

Thanks for all the tips (sanding, gluing, lacquer). 

I'll try to use the glue very sparingly and maybe do some trials on scrap lumber to see how thin I can go and still have the strength needed. 

Sorry to hear about the sparse turnout for the contest -- it sounded like a great idea to me.  Unfortunately, I am finding out that my OWN weekend has become filled up and I will not be able to finish by Monday anyway (oh, well).  Maybe a new invitation sent out and an extension could work.

I guess the thing I am most concerned about is the final fitting of the pieces for gluing.  I know that if the angles of 2 pieces that are glued together are off by even 1/2 deg, the puzzle won't go together very well. 

This next request is addressed to either Eric or Mark McC, both of whom I know have made these types of puzzle in the past (I have Coffin-style puzzles that I have purchased from both of them -- and the fits have been perfect !) 

Can either of you post pictures of the glue fixtures that YOU used ?

Also, how was the sequence in which you performed the gluing ?

(I REALLY like this forum -- it's what the web was made for!)

John

[Eric Fuller]

OK, I keep getting distracted, and I also keep forgetting to take a picture of my scorpius jig!  So I'll try and address this verbally.

Gluing up Scorpisu vs. Scrambeled Scorpius is a completely different ballgame.  I have a basic jig for Scorpius which is a 4 sided pyramid with blocks glued on.  Does a good job of keeping stuff in place.  Scrambeled is a *pain* to glue.  Like Mark said, the best jig is the puzzle itself.  Using the old elastic and microwave trick will get your perfect fit. 

I use Titebond II to glue everything that's wood.  CA glue of varying thicknesses for everything else, when I don't mechanically fasten it somehow (rare).

As far as squeeze out, that's just an experience thing.  Different woods absorb more or less glue, and endgrain will always suck up more than side or face grain.  I have a bunch of little squeeze bottles which have disposable tips that I use for gluing.  I generally put a dot in the middle and spread it out with my finger until the face is completely covered up to about 2mm from the edge.  Use more or less (bigger or smaller dot) depending on species.  Keep a sharp chisle handy - wiping off glue just smears it around.  Wait about 2 minutes for the glue to set up a bit, then scrape it off.

As far as sanding, I never really do it unless we're talking the outside of boxes.  I know Robert is a big fan of it, but I find it impossible to keep things square.  Plus for me it's just easier to cut stuff to the proper size the first time.  Robert's a glutton for punishment like that.  Whenever I do sand stuff like boxes, it's on a belt sander.  Not entirely happy with the streaks it leaves, even with 220 grit.  One of these days I'll get around to fabbing up a mount for my random orbit sander so I can use it for the final touch.

As far as lacquering outside only, I guess it's a personal preference thing.  With a box, no big deal.  With an interlocking puzzle, I think it gives too much of the solution away, so I personally would never do it.  Same goes with rounding the edges of a cube - tells you immediately which pieces go outside and really spoils the solving process.