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Post by jonathan on Sept 18, 2013 2:42:38 GMT -5
Since many question the strength of the traditional dowel. Here's some footage of some tests made by the people that make the DowelMax. Take away from it what you like.
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Post by 7 on Sept 18, 2013 21:04:42 GMT -5
Impressive. I wonder what just glue would have done. would be interesting to see a bunch of the same video comparing different joints. I'm sure it exists somewhere on the web.
Don't post anymore information on the DD40, I don't want to end up "needing" this tool too.
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Post by fidelfs on Sept 18, 2013 21:24:09 GMT -5
I think it is too late for me. I need that tool too!
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Post by GhostFist on Sept 18, 2013 23:35:59 GMT -5
I think standard white wood glue is rated at 100lbs per square inch, wood would fail before the glue does. What's interesting in these videos is the added strength of the deeper penetration. What's the maximum depth od plunge on the dd40?
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Post by jonathan on Sept 19, 2013 0:40:02 GMT -5
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luketheduke
New Member
www.lignumcarpentry.co.uk
Posts: 36
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Post by luketheduke on Jan 30, 2014 17:41:47 GMT -5
Dowel strength seems to be the only thing in my way of buying a doweller vs dominos, a lot of people say they loosen up over time, and since Ive no experience with it i have no idea if that is true, however ive found a similar video to Jonathan in which a biscuit joint, pocket joiner, dominos and dowels where all tested.
heres the link:http://www.dowelmax.com/jointstrength.html
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Post by wrightwoodwork on Jan 30, 2014 18:57:15 GMT -5
To improve the tightness of a dowel joint can simply by simply storing the dowels in a really dry place even put in an oven at a low temp and reduce the moisture content the dowel. Then as you insert the dowel into a glue hole it takes up moisture from the glue and the higher moisture content of the wood being glued causing the dowel to swell and lock tight
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Post by jalvis on Jan 30, 2014 22:24:23 GMT -5
To improve the tightness of a dowel joint can simply by simply storing the dowels in a really dry place even put in an oven at a low temp and reduce the moisture content the dowel. Then as you insert the dowel into a glue hole it takes up moisture from the glue and the higher moisture content of the wood being glued causing the dowel to swell and lock tight I think that technique would only apply if the dowel was larger than the hole and then dried to fit. Say an 8.2 mm dried to fit an 8 mm hole. Although I'm still convinced that compressed dowels will be better suited for longterm holding.
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Post by wrightwoodwork on Jan 31, 2014 2:51:20 GMT -5
Yep same principle I think it's a technique used in Japanese joinery. There was a house built in scotland using dowels to join the timber panels together need to find the article. When it comes to strength need to think of tension, sheer and compression
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Post by nucone on Feb 15, 2014 8:40:04 GMT -5
Dowel strength seems to be the only thing in my way of buying a doweller vs dominos, a lot of people say they loosen up over time, and since Ive no experience with it i have no idea if that is true, however ive found a similar video to Jonathan in which a biscuit joint, pocket joiner, dominos and dowels where all tested. heres the link:http://www.dowelmax.com/jointstrength.html I always take information from someone trying to sell me something with a grain (sometimes a block) of salt. Usually, information is presented in a fashion most favorable to the product they are hawking. Real world user input and experience is much more reliable. I have been woodworking for 35 years and have used dowels, traditional M&T, biscuits, dominos, and pocket screws in my joinery. During that period, the only joints I have ever made that failed in service were the dowel joints and it wasn't the dowel that broke, the glue joints failed. These failures occurred in joints stressed with a moment acting to pull the dowels from their holes and the failures occurred within 2 years of being placed in service. My application for this was a quilt stand however, I have also seen these failures quite often in factory made chairs. While there are certain applications that dowel joints are more than adequate, IMO it doesn't include any high stress joint subject to a bending moment. About the time this thread began, I was considering the DD40 for frameless cabinet construction and drilling 32mm system holes. I did some of my own testing of a simulated upper cabinet bottom shelf using 8mm dowels (drilled using doweling attachment to a slot mortiser), 5x30mm dominos, and #20 biscuits. I applied a shear force right at the corner joint using 365 lbs of weight and all joints withstood that force. I then jumped on the joint and the dowel joints quickly blew out the bottom shelf. It was the plywood that failed and not the dowels. I then jumped on the domino joint and it also failed by blowing out the plywood in the side panel but required more force to do so. Next came the biscuit joint and it withstood more force but failed by the bottom shelf de-laminatiing. Based on this testing and some shop space limitations, I elected to go with the Lamello Zeta P for cabinet construction. I still may go with the DD40 for drilling system holes but I don't need to make that decision yet. This is the closeup of the failed joints from the testing;
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Post by jalvis on Feb 15, 2014 11:03:46 GMT -5
Thats a good real world test for cabinets. The truth is most Euro cabinets are made from Particle cores and Confirmated together. I'm surprised to see you using ply cores.
One thing to remember about strength testing is that some joints don't have to be the "strongest." Just strong enough for the intended purpose. I think longevity is really important but thats even harder to test.
Thanks for sharing.
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Post by wrightwoodwork on Feb 15, 2014 13:10:50 GMT -5
Good video as jalvis says some joints do t need to be the strongest they just have to be fit for purpose
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Post by nucone on Feb 15, 2014 14:33:53 GMT -5
The reason I used plywood is that for uppers, I nearly always use pre-finished maple veneer ply for asthetic reasons. I even do this when the edgebanding and doors that are a different species. For lowers I use PB core melamine and support is provided for the side/bottom shelf/side interface via Blum leveling feet so the joint strength issue is less important to me there. I pretty much concluded that any of the joining methods were good for that application. It was just an information thing that I did to make the best choice for me. Since my laydown and storage area for my shop is limited, the knockdown fastening capability of the Zeta P was an easy choice to make.
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Post by wrightwoodwork on Feb 15, 2014 14:53:07 GMT -5
I take it you have a zeta p. What do you think of it? Looks a good system
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Post by nucone on Feb 15, 2014 17:50:56 GMT -5
I have had the Zeta P for a little over a month. I have only cut some test joints and it rocks! The drilling jig works well but does add a little extra time to the process. The advantage is countered by being able to store cabinets flat and save me considerable space which is at premium in my shop.
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