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Author Topic: A Sticky Subject...  (Read 13102 times)
RoughboyModelworks
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« on: November 20, 2009, 11:20:14 PM »

Earlier this week in Hauk's "Another Sawmill" thread I posted some comments on wood joint design and gluing methods, specifically the Ambroid/Acetone Glue Method. I made reference to an article on the subject I published twelve years ago in the Narrow Gauge & Industrial Railway Modelling Review. Prompted by the interest, I have updated the article with new illustrations and information and published it on the Roughboy blog. It's a lengthy article, so rather than post it here, I've just included a couple of teaser illustrations. I plan on adding a couple of more dovetail joint photographs from the cabinet-makers' bench I built and will do so once the bench has been returned by our swine former business partner, hopefully within the next 10 days or so if the settlement continues to progress as planned.





Paul
« Last Edit: November 20, 2009, 11:22:06 PM by Roughboy » Logged
Hauk
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« Reply #1 on: November 21, 2009, 02:42:13 AM »

Earlier this week in Hauk's "Another Sawmill" thread I posted some comments on wood joint design and gluing methods, specifically the Ambroid/Acetone Glue Method. I made reference to an article on the subject I published twelve years ago in the Narrow Gauge & Industrial Railway Modelling Review. Prompted by the interest, I have updated the article with new illustrations and information and published it on the Roughboy blog. It's a lengthy article, so rather than post it here, I've just included a couple of teaser illustrations. I plan on adding a couple of more dovetail joint photographs from the cabinet-makers' bench I built and will do so once the bench has been returned by our swine former business partner, hopefully within the next 10 days or so if the settlement continues to progress as planned.


Thanks for posting the article, much appreciated! A very interesting read.

I definetively are going to try the Ambroid method.
As Ambroid cement is not available locally, I am looking into alternatives.
My first try will be the Humbrol balsa and soft wood cement.

If that fails, I have read that some people make their own glue by dissolving acetate/celluloid in acetone. Could this work?
But where do you find a reliable source of acetate/celluloid in a world that refeeers to any non-wood, non-metal material as "plastic"?

Regards, Håvard H

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Regards, Hauk
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RoughboyModelworks
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« Reply #2 on: November 21, 2009, 10:17:54 AM »

Thanks Hauk, I'm glad you found it of interest.

I'm not familiar with the Humbrol Balsa Cement, but it's probably worth a try. A few simple experiments with it will tell you whether it will work or not. Certainly be easier than melting a bunch of plastic spoons or film strips in Acetone.... Wink

Other potential sources for Ambroid or perhaps a similar alternative, are outdoor stores or shops that sell canoes. Ambroid was originally developed around 1900 as an adhesive for making field repairs on birch bark and canvas canoes. (It apparently also makes a good fire starter!) Evidently the formula for the glue has remained the same with the exception that they now use recycled cellulose and an amber dye to retain the original amber colour. Traditionalists in the canoe community still use it. Northwoods Canoe Co.

Paul
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« Reply #3 on: November 21, 2009, 10:36:04 AM »

Beautiful diagrams!  Wish I could do graphics like that.

For miniature woodworking techniques, I don't think there is any finer reference than Harry Smith's "The Art of Making Furniture in Miniature".   He explains very simple techniques for accurately duplicating the common woodworking joints, plus a lot of other extremely useful info and superb eye candy.   He works in 1/12 but the ideas can be rescaled to suit. Amazing book. 

Dave

   
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RoughboyModelworks
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« Reply #4 on: November 21, 2009, 11:50:28 AM »

Thanks Dave. I'm not familiar with the Harry Smith book... I'm going to have to look that one up. I trained as an apprentice in traditional cabinet-making many years ago with Wendell Castle & Stephen Proctor. I learned to cut all these joints perfectly by hand before we were introduced to such wonders as table saws, band saws, shapers, morticing machines and so on. As I recall we used an excellent book by C.H. Hayward called Woodwork Joints as our primary reference source. Eventually though I had to give up building furniture as I am allergic to sawdust... Sad Angry - it aggravates my asthma something fierce. Even now, when I'm cutting scale lumber and working on wood models I have to wear a mask.

Paul
« Last Edit: November 21, 2009, 11:54:21 AM by Roughboy » Logged
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« Reply #5 on: November 22, 2009, 01:42:27 PM »


I'm not familiar with the Humbrol Balsa Cement, but it's probably worth a try. A few simple experiments with it will tell you whether it will work or not. Certainly be easier than melting a bunch of plastic spoons or film strips in Acetone.... Wink


The Humbrol balsa cement dissolved just fine in Acetone. So it is probably the real McCoy.

But the technique did not work very well for me.  I am not sure where the problem lies, because I did a reference glue joint with full strength balsa cement on two pieces of basswood. But I got a far weaker joint than I can get with white glue.

So neither a joint made with Pauls technique or an conventional glue joint worked.

I´m in fact quite puzzled, you should be able to glue basswood with balsa cement, right?

Reards, Håvard H
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« Reply #6 on: November 22, 2009, 01:53:27 PM »


But the technique did not work very well for me.  I am not sure where the problem lies, because I did a reference glue joint with full strength balsa cement on two pieces of basswood. But I got a far weaker joint than I can get with white glue.

So neither a joint made with Pauls technique or an conventional glue joint worked.

I´m in fact quite puzzled, you should be able to glue basswood with balsa cement, right?

Reards, Håvard H


I have glued basswood with balsa cement before successfully, however it is as has been mentioned before important if gluing on the end grain that you pre-seal the end grain with one thin coat of glue , let this dry and the n apply cement again .. I apply very thin coat to both surfaces .
Would agree that a glue joint like this will never be very strong unless you form some form of joint or add some form of reinforcement like a brass pin, etc.p
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Gordon
RoughboyModelworks
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« Reply #7 on: November 22, 2009, 05:41:29 PM »

Havard:

Since I haven't experimented with Humbrol Balsa cement, I can't offer a specific solution. Balsa cement is not known as being an overly strong product. It could be that diluting it with Acetone weakens it even more. A couple of model airplane enthusiasts I know switched to Ambroid early on because it is a much stronger and more tenacious adhesive than the standard balsa cement. Ambroid is quite strong for a cellulose cement, afterall it was developed and is still used for repairing leaks in canoes, not a task you'd want to trust to a weak adhesive.

The important point to remember is that end-grain joints, regardless of glue type or wood type, are inherently weak because end grain has no glue strength. Any form of butt joint is going to be stronger if it includes some form of mechanical connection.

Paul
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Frederic Testard
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« Reply #8 on: November 23, 2009, 12:59:40 AM »

Paul
Apart from the glueing aspect, this topic is interesting as it presents various ways to make better joining surfaces on wood (dadoed butt joint, half lap, and others on your blog page). I was wondering if you used specific tools to accurately cut the wood. I suspect if I had to do this, I would mark the places to be cut and use files, but it might not be as precise as required.
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Frederic Testard
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« Reply #9 on: November 23, 2009, 08:35:17 AM »

Paul

Your article mentioning CA glues decaying over the years made me go check on some plastic models I built back in the early to mid 1980s.  After I discovered Zap a Gap CA, I used it for gluing and gap filling nearly everything where I formerly used liquid cement and auto putty. 

Only where I used baking soda for additional filler material, or where I used CA to fill grain on wood is there any sign of oxidation or decay.  The wood has surface cracking that shows through the paint, the baking soda has a sort of sticky brown residue on it.   I recall both those effects started showing up a year or so after application, part of why they ended up unfinished in storage.   

I'm glad to report all other models, including an unfinished one with large areas gap filled with CA show no sign of any change.  I was able to check the CA glue surface very carefully on that one, still shows the grain from the fine sand paper I used, with no deterioration at all.   Models were stored in normal room conditions.   

I'm not advocating the stuff or doubting that it can be unstable, but I think stability may differ with the brand and addititives, probably storage conditions too.   I would not use baking soda again, or an additive like Zip Kicker.    These days I use mostly Elmer's white glue for wood and paper.   As you said, there is no substitute for making parts that fit properly! 

Dave
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RoughboyModelworks
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« Reply #10 on: November 23, 2009, 08:34:27 PM »

Frederic:
I use the Preac][url=http://www.preac.com/table_saw.htm/]Preac[/url] Micro-Precision Table Saw to cut all my wood. I use a range of precision slitting blades, 2" in dia. and various thicknesses: .016", .020", .028", .032", .040" & .052" depending upon the width of cut I need or amount of material to be removed. I generally use a variety of simple stops and fixtures in combination with a miniature table saw "sled" which greatly simplifies the process of cutting joints in scale lumber. I'm building a new sled now for the saw and plan to document that in an upcoming article on the blog (will also post a link here). A sled is simply a sliding top for the table saw.

I also rarely use Basswood as it is a little too soft and coarse-grained for really precise joint work. It also has what we call a high "mulge factor." This is not a scientific term, but rather was, during my apprentice days, the term we used to describe the level of sponginess in wood. Basswood has a high mulge factor, which means it compresses or squishes when machined, which makes it nearly impossible to do absolutely precise work. The woods I prefer are much harder and more dense, Swiss Pear and Boxwood, both of which machine much like brass or aluminum, very clean, very precise as long as you are using sharp blades.

Paul
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RoughboyModelworks
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« Reply #11 on: November 23, 2009, 08:48:30 PM »

Dave:

I'm surprised, but pleased to hear that the CA you were using has not deteriorated over time. There are so many different brands and formulations now in CA adhesives, it's entirely possible that one or more manufacturers have addressed the archival issue. It's no surprise that the CA bulked up with baking soda (sodium bicarbonate) has deteriorated. Though a fairly simple chemical in itself, sodium bicarbonate has many and various reactions when mixed with other chemicals, so I expect you essentially have what is colloquially known as a "science project." Generally an alkaline used to reduce acidity, it can, in combination with certain elements, produce an acid. Whatever the chemical outcome, it's not good for making a clean glue joint.

And yes, there is no substitute for making parts that fit properly. A tried and true basic test of craftsmanship is the precision or lack thereof in joint assembly, what my instructors used to refer to as "Gaposis."

Paul
« Last Edit: November 25, 2009, 10:17:17 AM by Roughboy » Logged
Frederic Testard
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« Reply #12 on: November 24, 2009, 02:46:10 AM »

Thanks for the detailed explanations, Paul.
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Frederic Testard
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« Reply #13 on: November 24, 2009, 04:42:42 AM »

Great info Paul. Thanks!


MR
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Philip Smith
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« Reply #14 on: November 25, 2009, 07:45:10 PM »

Nice read Paul.

I finish trim houses.

Gaposis ..good one! 



Philip 
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