Picture(s) thanks: 0
Results 16 to 27 of 27
Thread: 10 years ago
-
1st August 2019, 10:00 AM #16
Wongo, I can't remember if it was in that thread or another that I related my story of demonstrating glue-strength to the members of a woodies club. I prepared several examples of side to side & straight end-to end joints from the same wood using 4 different glues, and let them cure thoroughly. So I fronted up on the night & proceeded to demonstrate the relative strengths by ripping them apart. The side to side joints all failed under similar (extreme) loads with 80% plus wood failure. The end-to end joints were easy, just a sharp rap on the bench & they popped apart cleanly. That is, until I came to the epoxy example. I picked it up saying "and even epoxy won't work in this situation...." as I whacked it on the bench. The joint remained intact. I gave it as hard a whack as I could - still nothing! The other blokes reckoned the look on my face was worth a year's subscription & were still chuckling about it years later. I put it in a vise & whacked it with a mallet and it gave up & broke - very cleanly across the glue-line.
So in some situations, with some woods, it seems you can indeed get a pretty strong end to end joint with epoxy glues. In a non load-bearing situation an epoxy joint may be as durable as needed, but my lifetime's experience has been that just about any glue fails, eventually, so any joint relying on glue alone, whatever the glue, is probably not a good idea & better avoided if possible.
Cheers,IW
-
1st August 2019 10:00 AM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Age
- 2010
- Posts
- Many
-
1st August 2019, 10:30 AM #17
-
1st August 2019, 12:15 PM #18GOLD MEMBER
- Join Date
- Jun 2005
- Location
- Helensburgh
- Posts
- 7,696
When are you going to test it, thousands are waiting to see what happens.
CHRIS
-
1st August 2019, 12:28 PM #19
-
1st August 2019, 01:08 PM #20SENIOR MEMBER
- Join Date
- May 2013
- Location
- Auckland, New Zealand
- Posts
- 997
10 years ago this month I started my solo bicycle tour from Beijing to Istanbul via the Stans and Iran!
P1040184.jpg
photo taken at Bukhara, Uzbekistan. near Turkmenistan
just a little more interesting than some glue/timber joint lolSCM L'Invincibile si X, SCM L'Invincibile S7, SCM TI 145EP, SCM Sandya Win 630, Masterwood OMB1V, Meber 600, Delta RJ42, Nederman S750, Chicago Pneumatics CPRS10500, Ceccato CDX12
-
1st August 2019, 02:34 PM #21
-
1st August 2019, 06:42 PM #22GOLD MEMBER
- Join Date
- Aug 2016
- Location
- Brisbane
- Age
- 57
- Posts
- 1,315
10 years ago my shed was mostly just used to store junk. Half of it belonging to other people.
Now it's completely different.
Now I can hardly squeeze myself in there. ... oh wait.My YouTube channel: https://youtu.be/2_KPRN6I9SE
-
2nd August 2019, 10:48 PM #23
I glued a piece of wood 35cm long on either side. Placed a 9kg weight in the middle.
IMG_7098.JPG
IMG_7099.JPG
IMG_7100.JPG
Next I put a piece of Spotted gum (160cm X 20cm X 5 cm). It is probably 25 to 30 kg.
IMG_7101.JPG
IMG_7102.JPG
IMG_7103.JPG
Finally I tried to stand on it. It broke with just one foot on it and it broke easily.
IMG_7104.JPG
Once again I am not trying to prove that it is a strong joint because it is not. In fact it is very weak which we all know. What I am proving is without any load it won't just fall apart, not after 10 years anyway.Visit my website at www.myFineWoodWork.com
-
3rd August 2019, 11:20 AM #24
I'm reviewing my opinion of modern glues. In 2004 I made a pair of stools from Tas. myrtle. The glue used was supposedly good quality PVA. One of these stools is used every day; the other, less often.
Kitchen stools - Tasmanian myrtle 1.jpg
Recently I noticed that the back supports, rear legs and the front-to rear stretcher have become loose. When I say loose, I mean the joints move slightly: the glue has failed, but I cannot pull them apart.
IMG_2815.jpg IMG_2816.jpg
The back supports to legs joints are finger joints which were a gentle fit to each other and to the seat. They have plenty of edge-to-edge surface area and no large gaps. The stretcher joint is a short double tenon - not as much surface area, but it should not have as much load, either.
I can't think of any obvious reason for the glue to fail. It wasn't old, and the temperature was > 20C. Although there is more load on the back supports, the joint should have been strong enough.
-
3rd August 2019, 06:12 PM #25
Coupla quick points Alex: 1), as I said above, you should build expecting all glues will eventually fail, and with chairs it tends to be sooner rather than later, given the sorts of stresses they are commonly put under.
2). PVA glues are not good choices for chairs, they tend to remain at least slightly plastic, and moreso at high ambient temperatures, so creep & letting-go are always on the cards.
3). When I use 'stretchers' on chairs, they are used for stretching, i.e., pushing the legs apart, and really don't need glueing. It often takes a lot of effort & some very carefully-planned assembly steps to get the chair together (& even more to get it apart if something goes wrong!), & if I do use glue on these joints, it's more for lubricating the bits so they slide together more easily..
Cheers,IW
-
3rd August 2019, 10:27 PM #26
-
9th August 2019, 08:20 PM #27Novice
- Join Date
- Aug 2019
- Location
- Palmerston North
- Age
- 63
- Posts
- 10
Is it though?
I admit it’s a little more interesting than Auckland / North Harbour derbies, but it’s much more interesting .to you than are glue joints, to me.
Ten years on a bike - where did you get? See, kinda interested, but data on wood joints will hold my attention longer.
Similar Threads
-
49 years
By powderpost in forum Hatches, Matches & Dispatches. Birthday greetings and other Touchie-feelie stuff.Replies: 12Last Post: 31st July 2015, 01:12 PM -
16 Years
By rrich in forum Hatches, Matches & Dispatches. Birthday greetings and other Touchie-feelie stuff.Replies: 4Last Post: 28th May 2015, 10:25 PM -
In All the Years
By Dalboy in forum WOODTURNING - GENERALReplies: 13Last Post: 5th August 2014, 10:26 AM -
10 years
By Barry Hicks in forum WOODIES JOKESReplies: 2Last Post: 16th August 2007, 04:09 PM -
50 years
By Ray from Toronto in forum WOODIES JOKESReplies: 0Last Post: 9th November 2002, 09:11 AM