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Glue Joints #1: Spring vs. Straight

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Blog entry by Bruce posted 12-13-2010 01:05 PM 3502 reads 0 times favorited 16 comments Add to Favorites Watch
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Greetings. I have been watching Norm for 25 years or so. He always jointed board edges to get a perfectly straight glue joint. Marc Spagnuolo (sp?) on The Wood Whisperer seems to do the same. I have not had any problems with my straight joints. Recently, I have been watching Tommy Macdonald due to the new show Rough Cuts. He uses something called a spring joint where, after the boards are jointed straight, he uses a hand plane to create a slight dip in both boards. When this joint is clamped in the center the ends are brought tightly together. I have a couple of questions regarding the joint between boards. First, which one is actually best? Are there any publications on this subject? On the spring joint, can it be used on panels with more than two boards/1 joint?

-- I think of Jack Nicholson as the Joker in Batman when he says "Where does he get those wonderful toys" and ask WHERE DO U GUYS GET ALL THAT WONDERFUL WOOD?



16 comments so far

View Chip's profile

Chip

1904 posts in 2837 days


#1 posted 12-13-2010 01:13 PM

I noticed that too Bruce. I assumed it was to prevent any separation at the ends of the boards over time. I’ll be curious to see what the pros here have to say…

-- Better to say nothing and be thought the fool... then to speak and erase all doubt!

View tenontim's profile

tenontim

2131 posts in 2489 days


#2 posted 12-13-2010 02:01 PM

Bruce, I will normally shoot for straight joints on small tables, but will let a gap form when doing large, dinning table size tops. Like Chip said, it will make the ends tighter, with less chance of a separation at the ends with seasonal wood movement. I get my gap just by shifting pressure to the infeed table side of the jointer when I’m jointing the boards for the top.

View rance's profile

rance

4147 posts in 1905 days


#3 posted 12-13-2010 02:14 PM

Bruce, I’ve done many glueups for smaller projects, not huge tables. In my opinion, there is no reason to introduce any amount of stress in a glueup by making a spring joint. I see it similar to the color of fishing lures. It is mostly for the fisherman, not the fish. It could possibly make the glueup easier to clamp, but only slightly. Again, this is merely my opinion. It is quite possible that a sicientific study could prove me wrong. I’ve never see a ‘scientific study’ on this subject though…...... yet. :)

BTW, I also am not a proponent that all glue joints must be edge jointed on a jointer. Unless your TS blade is dull or gummed up or your TS is out of alignment, then the TS cut is just fine. I never make it a point to edge joint a board before glueup and I’ve never had a problem. In fact I’ll go as far as to say that if you make it too smooth, then the glue won’t adhere as well. Yeah, I’m pretty radical. YMMV. And no, I’m not a pro either. :)

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View Todd A. Clippinger's profile

Todd A. Clippinger

8791 posts in 2844 days


#4 posted 12-13-2010 03:39 PM

I have not made any large dining tables but have glued up many a panels through my remodel and (later) fine woodworking career. Here is what I have witnessed over the years and it has been from studying my work and the work of others.

Large panels do not tend to come apart at the joints if properly glued, they check elsewhere as the wood shrinks.

The technique you are asking about is a time-honored one that I feel was more important in the past for a few reasons: #1. when the craftsman could not rely on the integrity of the glue #2. the wood was possibly not as stable as the material we get kiln dried (this can bring on a debate in itself) #3. another issue for long term stability is the way we keep our houses conditioned for comfort also is easier on the furniture as the environment is more stable.

I respect the lesson that Tommy Mac has shared but I do not exercise the technique myself and to date have had no issues. I also know of other professional furniture makers that have a lifetime of work out there and they do not do it either without any issues.

But only time will tell;)

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View PeteMoss's profile

PeteMoss

207 posts in 2214 days


#5 posted 12-13-2010 03:41 PM

Disclaimer: I am not in any way an authority on this subject. This is just what I do and my thinking behind it.

When glueing up panels I will run the edges over my jointer. Then I will take the two pieces and fold them like a book and shoot the edge of both at the same time with a handplane. I do try to put a little bit of a spring in the joint just because it does make it easier for me to keep everything flat and lined up during glue-up. I personally feel that I am able to get a much more invisible seam from the handplanes than straight from the jointer. I also do like to have an extremely smooth surface to glue. I think that having some “tooth” for the glue to grab onto is only valid if you are using an epoxy. PVA glues, as I understand it, soak into the wood and then work chemically at the molecular level. So, the more contact between the surfaces, without any roughness, the better.

-- "Never measure......cut as many times as necessary." - PeteMoss

View Todd A. Clippinger's profile

Todd A. Clippinger

8791 posts in 2844 days


#6 posted 12-13-2010 03:43 PM

One more thing, I agree with Rance that the tablesaw can produce a good glue joint.

I use a GlueJoint blade from Freud that produces a super smooth and accurate cut for glue joints without any further work on the jointer. But the tablesaw must be tuned for it to be effective.

I love that blade.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Bruce's profile

Bruce

187 posts in 2519 days


#7 posted 12-13-2010 04:44 PM

Great info guys, Thanks.

-- I think of Jack Nicholson as the Joker in Batman when he says "Where does he get those wonderful toys" and ask WHERE DO U GUYS GET ALL THAT WONDERFUL WOOD?

View hokieman's profile

hokieman

166 posts in 2498 days


#8 posted 12-14-2010 04:16 AM

I have edge jointed for 25 years and never had a joint fail on me. While I sort of see the logic behind the spring joint, I think it is not necessary.

View cpollock's profile

cpollock

34 posts in 2158 days


#9 posted 12-14-2010 04:52 AM

I made a maple trestle table 26 years ago, it was my first real project. I used my brand-new table saw to rip the maple, and I glued it up with Titebond. I still eat breakfast on that table everyday, but there are dark lines on each end where the boards are starting to separate.
I think Tommy is an incredible resource of useful knowledge. He’s studied old classic furniture that was made by craftsmen 2 centuries ago, and he has seen what happens when wood ages. His advice is based on the experience of real craftsmen. Hopefully your joints will never shrink, but it might take 20 years to determine this. To be honest, I have not had this problem with anything else, so maybe it was an inadequately dried batch of maple, or a rookies mistake. Regardless, the spring joint won’t hurt anything, and it might prevent a problem. But here is the big point, its fun to do! Nothing beats using a sharp handplane on a nice edge of wood. That’s why I like woodworking.
My 2 cents.
Clif

View Todd A. Clippinger's profile

Todd A. Clippinger

8791 posts in 2844 days


#10 posted 12-20-2010 02:29 PM

I was thinking about Sam Maloof last night and a lecture he gave at one of the furniture conferences I attended.

He did not feel it necessary to run material across the jointer if using a good blade on a properly tuned saw. He ran material on the tablesaw then went straight to glue-up. Making a spring joint was not part of his process.

The conversation at this point had been revolving around the construction of conference & dining tables.

A video I have from Taunton shows Sam dispensing the same information. I think this must have been the normal workflow for him because I saw him in more recent years and the video was done well before that.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View MedicKen's profile

MedicKen

1602 posts in 2206 days


#11 posted 12-20-2010 03:07 PM

I have not used a spring joint nor will I. I understand the concept but I am not in agreement. If the joint is tight from the saw and or jointer why add stress to the joint? When you make the joint, as I understand it, there is a slight gap along the length of the joint in the middle, and as the boards are clamped the joint closes putting pressure on the ends to keep them tight. Now, if there is a gap before gluing and clamping wont the boards want to naturally want to return to their position before gluing? If that is so, I think the spring joint may in fact cause the board to check near the joint resulting in a ruined board. If there is an unseen defect in a board close to the joint I feel the spring joint will make that defect appear.

-- My job is to give my kids things to discuss with their therapist....medic20447@gmail.com

View Bruce's profile

Bruce

187 posts in 2519 days


#12 posted 12-20-2010 04:03 PM

You guys have given me a lot to think about and I appreciate your input. After watching ALL of Tommy (T-Chisel)MacDonald’s videos I can see that he is a rare talent. I will probably not use a spring joint, but will keep this knowledge in the back of my mind in case a stuation might warrant its use. I can see where the micro-gap and resulting outward pressure would help in aligning the ends of the boards, but folks back then didnt have bicuits n gravey like we do today. GROOVY!

-- I think of Jack Nicholson as the Joker in Batman when he says "Where does he get those wonderful toys" and ask WHERE DO U GUYS GET ALL THAT WONDERFUL WOOD?

View Todd A. Clippinger's profile

Todd A. Clippinger

8791 posts in 2844 days


#13 posted 12-20-2010 06:39 PM

It is interesting to consider the talent that I have encountered and the varying viewpoints on a given subject.

Setting aside any fame that Tommy or Sam has, I know plenty of guys that are as talented as them and work professionally in the shop. To me, their opinions are valid and carry just as much weight as anybody that is on tv, the internet, or published.

I am of the mindset that I keep an open mind and understand the various viewpoints.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Bruce's profile

Bruce

187 posts in 2519 days


#14 posted 12-21-2010 05:40 AM

Certainly, Todd. Didn’t mean to discount anyone else. Thanks.

-- I think of Jack Nicholson as the Joker in Batman when he says "Where does he get those wonderful toys" and ask WHERE DO U GUYS GET ALL THAT WONDERFUL WOOD?

View Todd A. Clippinger's profile

Todd A. Clippinger

8791 posts in 2844 days


#15 posted 12-21-2010 03:37 PM

Oops – sorry on my part.

Sometimes much can be lost in emotionally sterile text. I was kind of rolling through the rolodex of people I know, their opinions on the matter, and my respect for the varying view points. It was a bit of thinking out loud.

This was all to set up that I consider the various opinions and try to understand the principles at work.

Hope you did not think I was putting you in “check.”

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

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