20 April 2017 at 9:18 am #311323
I’m planning on glueing up a Japanese twisted dovetail joinery and I’m a bit antsy from my past experience with its glueup.
Basically the problem I have is that the joinery is so tight — as it must be tight–that the glue doesn’t allow me to seat the dovetails properly.
Please keep in mind that these dovetails are married together from the corners — quite unusual compared to our regular dovetails. So two corners will need to be glued up seprately and then joined together as a whole.
So, is there a better way to thin the glue to slow down the drying process or I have no other option but to work at 10000rpms?
You must be logged in to access attached files.20 April 2017 at 11:56 am #311327Brett aka PheasantwwParticipant
I don’t think there is a way to slow down PVA. Your better option for a complicated glue up, and one that I use is a liquid hyde glue. Lots of advantages that have been discussed previously but a great option is Old Brown Glue. Very good “open” time. Easy clean up….
Located in Honeoye Falls NY USA. The Finger Lakes region of Western NY.
"If you give me 6 hours to fell a tree, I will take the first 4 to sharpen my axe" Abe Lincoln20 April 2017 at 12:55 pm #311328EdParticipant
Is this really an issue of drying speed? Binding is not occurring because the glue sets up so much as because the moisture in the glue swells the joint. Of course, as the joint gets tight from the swelling, this makes the sticky (but not dry) glue grab even more. Another reason for getting stuck is hydraulics, where you get a pool of incompressible glue in a tight joint that keeps the joint from closing up….more an issue with M&T than with dovetails.20 April 2017 at 1:06 pm #311329EdmundParticipant
Tony Konovalov, a professional woodworker and disciple of Jim Knenov, has this tidbit on his website:
…brings to mind something I saw while I was at school. Jim Krenov was gluing up something and working like a madman to get it done and I thought great, I am not the only one who semi-panics during a glue up. Then I thought, crap, he has been doing this for over 40 years and glue up is still a panic…
Anyways, try Brett’s suggestion of something with longer open time. Hyde glue works great. Matt Cremona uses epoxy when he needs more open time, and it’s not difficult to get 30-40 minutes of open time from a good epoxy if you buy a quality product and keep it in small quantites (don’t mix a big batch in a single cup and expect long open time, mix a batch and separate it into many small cups or pour it out onto a tray). Titebond 3 claims is can be thinned 5% with no problems, but they don’t say if that increases the open time.20 April 2017 at 5:17 pm #311331
Thanks Brett for the tip! I think it makes sense to use the hide glue. I’ll give it a try today.
Ed, that’s very true—that is the hydraulic pressure. I may have put “too much” glue (but had a feeling it wasn’t too much at all.)
Ed, I just realized how mad I become during a glueup. I begin to cuss and surprisingly it helps. (Just a myth I guess lol)
Jake20 April 2017 at 6:40 pm #311332Larry GeibParticipant
Maybe somebody mentioned it, but a quick scan didn’t jump out at me, but Titebond makes a slow set PVA.
The Orange box store list the product number as 1414.20 April 2017 at 8:42 pm #311336
I’ll give it a try. Right now I have the animal hide glue and it’s reversibility brings my stress level down 🙂 but of course, I should be confident that it’ll be fine and I won’t need to take it apart.
Jake20 April 2017 at 9:31 pm #311337Steve GilesParticipant
I just made a mirror frame with tenon and mortise joints and it started me thinking about joinery, glue etc.
It occurred to me that the discipline of joinery was invented before modern glues were available, and the whole point of joints such as dovetails, tenon and mortise, etc was to facilitate a strong structure without the need for the yet-to-be-invented glues such as PVA and epoxy.
My next thought was that the panic of getting a joint to fit before the glue grabs is a result of taking an unnecessary ‘belt and braces’ approach (ie modern glue used on a joint that doesn’t really require it).
I ended up dowelling my mirror frame’s tenon and mortise joints and not using glue at all. If I was making my workbench over again I wouldn’t use glue on the T&M joints. IMO, dovetails need some glue, but maybe not as much as I have been using.
I’m beginning to believe that the strength should come from the joint itself, and the glue’s function (if used at all) is just to stop the joint from slipping apart. In short, if PVA is used, save some time and just use a butt-joint instead.
I’d be interested to hear others’ opinions.
Steve21 April 2017 at 6:40 pm #311352
I agree that wood can hold wood with counter forces that we can create by offsetting the dowel holes. So I agree with you.
But then, can we really educate each and every person in this world?
I’ve people who contact me for woodworking and don’t know the difference between IKEA and me.
Many years ago I was a carpentry licensed contractor in CA and I remember how I passed the trade exam in short time and how I failed the law exam the first time.
Basically these days everything is directly associated with the law. Glue is a standard requirement by law 🙂 so 😉 we don’t bother with it in my town.
It’s also unbelievable how some bureaucrats decide how we should make things. I’ll give an example of a job we did many years ago. It was a historical house, so it had huge board of historians who would command us what to use and when they required us to use Resorsinol glue (which had been discontinued after the World War 2) I started to panic until the moment when the general contractors lawyers counseled with us.
Anyhow, it will be very difficult to convince the general consumer that glue isn’t necessary, but since we are afraid that you’ll sue us if there’s a movement in the wood and if something becomes loose, we will use the glue with 10 year warranty period.22 April 2017 at 3:17 am #311356
Good evening. The glueup with the hide glue you mentioned went very well for me. I just had one burts out only because I was alone and my helper was hiding in the office and someone had to hold the shim between the clamps. Other than that I felt that in 10 minutes or so the glue was becoming sticky inside the joints, but clamping really set everything in place.
Thanks for the advice!
Jake22 April 2017 at 1:16 pm #311361Hugo NottiParticipant
If you heat the wood before using hide glue, the glue will stay liquid for a longer time. And if that is still too fast, simply re-heat. A hair dryer is hot enough, so you don’t need to be afraid to burn the wood. And don’t be afraid to use much glue, because you can wipe off the excess easily with hot water, even after years – hide glue doesn’t cure.
You can also re-activate PVA (within a time frame of perhaps 20 minutes) with heat. For example, you can coat a piece of veneer with PVA and then iron it on.
For very long drying times, I would use epoxy. Depending on type and mixture, you have up to one hour for readjustments.
For delicate glue-ups, I really like hide-glue, because you can put on as much as you like and wipe off the excess with hot water, even the next day.
Dieter22 April 2017 at 4:52 pm #311367
Good morning! Thanks for the tips. I love the reversibility of the hide glue.
I think that not curing isn’t an issue for the twisted dovetails since they don’t come apart from from either side. Specially that I have a drawer divider that will keep the box from moving on the corners. And by adding the base and top frames it won’t move at all.
You must be logged in to access attached files.
- You must be logged in to reply to this topic.