for people who do spring joints at times

[Warren Lake]

if you buy good material trim the end 1" whatever throw it on the concrete floor if it breaks there is a crack you didnt see, then trim some more do the same, if it doesnt crack you are good to go. Once or twice found shakes a foot in but they were boards that were bad and had issues.

[Mel Fulks]

After I cut at least 2 inches ,I take that piece and use it to hit the saw table. If it easily breaks , I try again and take close
look. Then sometimes I can see the end of flaw. Not gonna glue up a panel that includes a board with a crack. Yes , I
waste a few seconds that some would use to adjust their radio or check email and web news.

[Joe Calhoon]

Warren,
here is what Diehl says about it.
https://diehlmachines.com/straight-and-hollow-cut/
Their gap is pretty slight. Sounds similar to what I get off the Martin jointer in spring joint setting. I have a small import SLR but have never been happy with the glue joint I get off that. It’s great for breaking down material for the moulder or further processing though.

[Brian Holcombe]

Springing compresses the ends of the board. The ends of the board lose moisture sooner than the centers and therefore are more likely to shrink and split. This compression helps avoid that, it also makes for better looking glue lines.

A plainly visible glue line is weaker than a truly invisible glue line and therefore the effort required to make the invisible glue joint (springing) is not wasted effort.

[Will Blick]

> Will whats your background? 30 years in this? Manufacturing? supplier to shops, custom shop??? one man shop? Hobby guy with 400.00 hand planes ?

Hi Warren... I thought this thread was about the use of spring joints? What is the relevance of all these personal questions as it relates to the use of a joint that has been around for 300+ years? In case you did not read all my posts, I was quoting other articles on this subject who are authorities in the field. Why not pose these questions to the author of those articles? Do u remember the old adage...

Attack the message...
NOT the messenger!

Very applicable in here...

[Warren Lake]

your tone to one of the most experienced guys here, enough of them have left. Guess you answered the question.

[Will Blick]

Just trying to learn Warren...
I thought that is one of the benefits of these forums?
Possibly I am not understanding the purpose of these forums?
I offer contributions, and appreciate constructive feedback from other members.
Sorry if my style does not concur with yours.
Regardless, I will remain civil and not redirect the discussion against any member personally, including you. That is NOT my style. I realize you feel differently and desire to turn ww issues personal against fellow members.
Now, back to the 300 yr old spring joint??

[andrew whicker]

I have never heard of this jointing technique until I read this thread earlier this week. It's an interesting idea, but I'm also confused by the necessity.

I have a few questions in the form of comments:

- It seems we are assuming the internal stresses created by this joint will stop the end of the boards from changing size. I don't understand why this would help. In all the cases of material movement I have dealt with (I'm coming from a metal machining / fabrication background), the correct design is to allow movement. Constraining movement doesn't work. I read Brian's comment that it 'squishes' the ends (my words, not his). How much does hand pressure compress wood?

- It seems that for some reason 'hand pressure' is the right amount of internal stress. No one seems to have any other type of explanation of what the proper stress is. Hand pressure is very low internal stress.

- I'm not sure how we would ever collect enough data on this subject to know the reasons behind cracks unless it's very obvious. A humidifier on one end of a big table top. A table that has one side finished, the other not finished. Etc. Do we know how this 300 yr old furniture was stored, lived, used, etc? Did anyone collect data on the moisture content along the length of the boards as they were building and kept taking data as the years went by? Were the pieces re-finished? Was the board's MC balanced when it was built? How did furniture builders 300 yrs ago decide the lumber was dry enough, etc?

- How does anyone's personal experience help me make a decision in this discussion? Even if you have 40 years of experience, wouldn't that mean we could only judge your first few years of work? Certainly work made in 2020 won't tell me anything about cracking 40 to 50+ years down the road.

- Why would I assume I could make a perfect ellipse along a 4 ft board with a low point of .005"? What about the local highs and lows? .005" is specification, but the local .008" or .003" isn't a concern?

- Overall, how do we know the reasons for failures (and, conversely, the reasons for success) of a piece that's been handled over 100 years?

Anyway, I think it's an interesting concept and I enjoy the topic and enjoyed thinking about it for the past days. It seems more or less like a belt and suspenders route than a necessary technique. I'm interested in giving it a shot, the articles I read also suggest it's a pretty easy technique to add to your building process. I'm sure I spent more time thinking about it than it would take to just try it and move on. I can definitely see it producing invisible glue lines, which I'm a fan of.

[Will Blick]

nice post Andrew, fully agreed with all your queries.
I also find the topic interesting.
As the link I posted previously.
Table top manufacturers IMO are the ultimate test to this methodology.
They make hundreds of thousands of table top glue ups, with automated rip saws moving directly into the automated glue machines then automated clamp system. With this volume of glue up tops over 50+ yrs, common sense suggest, they know better than any single woodworker that has built a few hundred panels in his life. If anyone has tested this scientifically, it would be these manufacturers, as they have the most to loose if their tops crack. Hence why I put credence in the authors position regarding table top manufacturers. I would think these manufacturers have run a lot of testing over the years. Unfortunately, any testing they do, would never become public knowledge as they want to maintain a competitive edge. Again, this addresses panel glue ups for primarily indoor conditions.
I also agree that adding less than 5 thou gap is not problematic with the incredibly powerful clamps we use today...heck, just normal jointing of boards will often have gaps like this, but prob. not centered.

[andrew whicker]

Thanks

but I do disagree with using capitalism as a metric for success. Capitalism learns the lowest cost way to provide the customer with the lowest bar of acceptable quality. I don't rely on our economic system to create high quality.

[Warren Lake]

Ill stick with the old guys, they told me enough ive never seen anywhere. Simple example was posting to not machine after sanding, post it here and told im wrong. Thankless. Old guys paid their dues and a lifetime and never steereed me wrong. They were about what they were taught and why, passed down from someone serious to someone else serious then add in the time spent running big stuff after a proper apprenticeship and production at mass level and more is learned. When you are running a shop with 12 stickers you are in the big leagues. When you send two boats to burma to buy teak to do city hall and have 36 other jobs on the go you will have some serious knowledge.

On the sanding I followed up after being told I was wrong (me not doubting the old guy) talked to two big companies. The first one my long time guy gone the new replacement copied and pasted something, hence my parrot statement. Checked with Hermes and answered by a pro. Happy there are still people still left in the industry that know what they are talking about. I once asked a wood expert how much material he has run on machines. He didnt answer. In school we had teachers who had degrees. We had some old europeans, they didnt spell well and had grammar issues though I should not talk. I was quick to realize someone with proper training in a top place at a top time to do an apprenticeship (after a town was bombed) knew massive stuff the education never taught.


I've done enough time to get stuff Mel and Joe and others have said that you will not find in books or the net teachers.

[Will Blick]

Well, I sort of agree...
its a balancing act with capitalism...
quality falls off so bad, Sales fall, which is the kiss of death for any business.
Also, warranty replacement is costly, and can sink a business if bad enough...
so quality must be high enough to prevent financial losses...
But in this case, its my guess, end cracks would take many years to appear, possibly way after warranty.

I was just looking at some bases I built from 1" maple almost 20yrs ago... quick jointed, sloppy glue up (its a machine base with wheels below, not furniture grade!), one layer of latex paint, peeled off in many areas, or nicked off.... never repainted them...not a single end crack in any of them. And they get exposed to all kinds of stresses a kitchen table top would never experience, in addition to changing levels of humidity constantly.
Like u pointed out, I am not drawing any conclusions from this, but nonetheless, shows how impressive glues are, specially thicker boards which offer more surface area.

[Mel Fulks]

Will ,the biggest stress is out doors, not the kitchen of a home with modern "climate control".
I would love to hear about and see stuff kept outdoors all the time. Wooden stuff ....not the charcoal grill.

[Mel Fulks]

Thanks

but I do disagree with using capitalism as a metric for success. Capitalism learns the lowest cost way to provide the customer with the lowest bar of acceptable quality. I don't rely on our economic system to create high quality.

If you live in USA you are getting higher quality and more choices. I think that translates to relying on Capitalism.
Unless you are ordering free stuff from 3rd World delivered by carrier pigeons.

[Will Blick]

> Ill stick with the old guys,

I am an old guy! But I will take info from anyone who has it.
I am an equal opportunity information "taker"!
If they are old, I don't assume they are right.
if they are young, I don't assume they are wrong.
I have seen it go both ways, in every field, not just ww.
In my field of engineering, I see old guys with wisdom as well as some highly outdated thinking and techniques which have long been superseded. I see some young guys with great innovative methods and systems and sometimes wisdom as well. Some are clueless.
I take every situation and evaluate it based on the facts and merits.
No "one size fits all" for me.
There is room for both of our methods of evaluation.