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Forum topic by mileskimball posted 04-11-2013 06:29 PM 710 views 0 times favorited 9 replies Add to Favorites Watch
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mileskimball

85 posts in 761 days


04-11-2013 06:29 PM

Topic tags/keywords: question milling paper mold cedar airfoil dowel tenon

I’m trying to mill some pieces of tight-grained cedar for parts of a traditional paper-making mold, and so far I’m stumped at getting consistent results.

Here’s what I’m aiming at:

The part is a support bar that holds up the wire mesh – there will be fifteen of them, and they need to be really consistent. As you can see, it has an airfoil shape (thin edge up), but with a dowel-tenon end that inserts into a hole drilled in the side of the mold. The whole mold will look like this:

In a row like this, the airfoil shapes create a venturi to suck the water out of the bottom of the mold (pretty smart for something designed 500 years ago!)

I’ve been able to mill the airfoil shape with a combination of a router and a table saw – I use a beading bit on a 7/8” thick plank to form a bead, then rip the plank at an angle to form first one side, then the other side of the airfoil.

But forming the dowel tenon has been a challenge. I’ve tried cross-cutting on the TS to form the shoulder and create a flat bottom of the dowel, then just whittling to get it round – works, but slow and inconsistent. I’ve also tried a hollow auger – it was too easy to snap the dowel off, the cedar being pretty brittle. Same thing using a plug cutter. A log-style tenon cutter wouldn’t work—they make curved shoulders, and I need the shoulders to be flat.

Any thoughts?

-- Miles


9 replies so far

View BinghamtonEd's profile

BinghamtonEd

1593 posts in 1116 days


#1 posted 04-11-2013 06:39 PM

Could you make a jig for the TS that holds each end with a small screw or nail, allowing the thing to pivot, then raise a dado blade slowly, turn the stock on the nail/screw pivot, raise the blade, repeat, etc, until you arrive at 1/4”? Sort of a lathe-like holder over the dado blade? Should not be a safety issue so long as you don’t try to take too much off in one pass. Or something to hold it vertically instead, while it pivots around the vertical axis and keep nudging the jig closer to the blade (use some sort of stop to get 1/4”)? I remember watching an episode of Rough Cut where he made a circle cutting jig for the TS.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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BinghamtonEd

1593 posts in 1116 days


#2 posted 04-11-2013 06:43 PM

Also, stupid question, but does it have to be a single piece, or could you use a smaller dowel in a dowel joint on the end to attach a 1/4” dowel? That seems like it’d be the easiest.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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bondogaposis

2746 posts in 1098 days


#3 posted 04-11-2013 06:47 PM

I’d use brass pins inserted into the ends.

-- Bondo Gaposis

View JustJoe's profile

JustJoe

1554 posts in 785 days


#4 posted 04-11-2013 06:53 PM

Can’t you just make the airfoil shape using the method you described, then route a 1/4” halfround in the bottom of it and glue a 1/4” dowel the entire length of the piece plus the required 1/2”?

-- This Ad Space For Sale! Your Ad Here! Reach a targeted audience! Affordable Rates, easy financing! Contact an ad represenative today at JustJoe's Advertising Consortium.

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John Ormsby

1281 posts in 2484 days


#5 posted 04-11-2013 07:29 PM

I think Alaskan Yellow Cedar might be a better choice of wood. It is extremely fine grain and is a bit harder than cedar. Or is cedar a traditional wood to use on this?

-- Oldworld, Fair Oaks, Ca

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mileskimball

85 posts in 761 days


#6 posted 04-11-2013 08:19 PM

Good ideas, everyone – thanks!

Traditionally it’s all one piece, so I’d prefer not to go with composite methods.

The traditional material is actually larch, but cedar was as close as I could get. It needs to be light, straight-grained, and water-resistant. Any other suggestions?

Ed, I think your idea makes a lot of sense. Particularly if, as it occurs to me, I make the airfoil maybe an inch longer than it need to be, then mill the dowel in the “middle” (that is, from 1” – 1 1/2” from the end), then trim off the end.

I’d have to go pretty slow, though – maybe a pass straight across first to cut away most of the waste, then turning. I think probably just a regular FT blade, too, rather than a dado set.

-- Miles

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RogerInColorado

306 posts in 701 days


#7 posted 04-11-2013 11:38 PM

I’m not trying to be a jerk here, but . . there seems to be a disconnect between your emphasis on traditional construction (no composite methods) and your use of a table saw and router to construct it but achieve a 500 year old appearance. Have you looked into how the originals were made?

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mileskimball

85 posts in 761 days


#8 posted 04-12-2013 12:39 AM

Oh, believe me, I have; there’s precious little information to go on. Dard Hunter’s seminal work on papermaking is the best source, giving a good general description of the process of paper mold making (not only in Europe, but in Asia as well). But he was a scholar, not a woodworker, and a lot of the specific construction techniques are simply left out or glossed over. Other sources, even contemporary ones, are even more vague (probably a matter of trade secrets).

I don’t feel too badly about applying modern tools and techniques, but an accurate replica is really important. The paper mold is going to be used as a demonstrator for students, so I want it to look as close to the originals as possible.

Hunter also describes paper mold makers drawing their own wire – I’m not going to do that, either! ;-)

There is precisely one guy in the world who makes these things in a historically accurate way—we bought a couple on a grant. I’ve hesitated to ask him how he does it, because I don’t want him to think I’m horning in on HIS trade secrets. The ones we bought from him are too expensive to use ($2500 apiece), so I’m just trying to replicate something that will look accurate, yet that we can use with students (who will inevitably destroy them!).

Besides, it’s a good challenge. And if it makes you feel better, I’m doing all the other joinery and milling and screen weaving by hand.

-- Miles

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mileskimball

85 posts in 761 days


#9 posted 04-12-2013 02:23 AM

Oh, and also I tried making them by hand, using a molding plane with a beading blade, a block plane, and a rip panel saw. It went OK, but it took me about 15 minutes to get close to right, and I have 30 of them to make (I’m building two molds).

-- Miles

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