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Large glueup help

Gerald Lawrence

Gerald Lawrence

Joined
Feb 6, 2010
Messages
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Location
Brandon, MS
Website
threeringswoodshop.square.site
Had a call from a painting contractor couple months ago looking for someone to turn new finial to top metal stair finials. These will be about 10" wide and 16" long. He found someone else to do these and the glue up blew up on this turner after he did three. So now contractor is looking for someone to complete the project.

I know that wood glue inside large glueup takes a long time to cure. Contractor special ordered kiln dried treated lumber (didn't know this existed). Now I am thinking screws to hold this together, only in the central part of blank. Any ideas or am I thinking in the right direction?
 
One thing I have seen woodworkers/turners do is over-clamp glue ups. If too much clamp pressure is applied, there is not enough glue left to adequately hold things to together. As well - why not use epoxy instead of hide glue? Prime the surfaces to be glued up by thinning down a coat of epoxy, allow it to really tack up then apply a full coat of epoxy, then clamp with reasonable, adequate pressure.
Thanks would be my trial piece - before using screws.
 
I used Gorilla glue to build a fence gate that had a hardware clothe window so the Yorkies could argue with the neighbors dogs. The fence panels and 2x4s were all treated and when I replaced the fence years later the gate was still strong without sags. It is a water activated glue that apparently the moisture/ products in the new treated lumber did not affect the bond, would make a test piece and test it though before making something to turn. Would for sure wear breathing protection when turning treated wood. Another option would be to use #1 redwood, cedar, or cypress.
 
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Gerald Lawrence said:
Had a call from a painting contractor couple months ago looking for someone to turn new finial to top metal stair finials. These will be about 10" wide and 16" long. He found someone else to do these and the glue up blew up on this turner after he did three. So now contractor is looking for someone to complete the project.

I know that wood glue inside large glueup takes a long time to cure. Contractor special ordered kiln dried treated lumber (didn't know this existed). Now I am thinking screws to hold this together, only in the central part of blank. Any ideas or am I thinking in the right direction?
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Are you talking about pressure treated lumber? Authoritative advice is hard to come by but I would trust this professor of wood technology gluing pt lumber. The gist is that any common wood adhesive will bond clean, dry pt lumber. "Kiln dried" is a term of art in the lumber trade; kd construction lumber is usually dried down to about 19% and can move around a lot before it gets down to equilibrium moisture content.

Pva wood glue cures as it releases moisture into the surrounding wood. If the wood is wet the cure will take longer, be weaker, otherwise thick glueups should not be a problem. You could use mechanical fasteners or splines to strengthen the joint but basically the best thing is to use dry wood. For wet wood you may have better luck with polyurethane glue or construction adhesive, but there is still the risk of distortion after drying. Do you have a moisture meter?
 
Kevin Jenness said:
Are you talking about pressure treated lumber? Authoritative advice is hard to come by but I would trust this professor of wood technology gluing pt lumber. The gist is that any common wood adhesive will bond clean, dry pt lumber. "Kiln dried" is a term of art in the lumber trade; kd construction lumber is usually dried down to about 19% and can move around a lot before it gets down to equilibrium moisture content.

Pva wood glue cures as it releases moisture into the surrounding wood. If the wood is wet the cure will take longer, be weaker, otherwise thick glueups should not be a problem. You could use mechanical fasteners or splines to strengthen the joint but basically the best thing is to use dry wood. For wet wood you may have better luck with polyurethane glue or construction adhesive, but there is still the risk of distortion after drying. Do you have a moisture meter?
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Yes I do have a meter and you bring up some good points. Besides that I would want the lumber to acclimate in my shop a few days. Besides this thinking IF I get the job to add two or three screws in each layer , centered so will not be in the line of cut.
 
A couple of suggestions.
If possible use biscuits to strengthen the joints.
Screws will add strength. Also dull tools if you don’t measure twice.

Nylon strapping tape placed on unturned parts then moved to the turned parts will give you a few more seconds to get out of the way and turn off the lathe should things come apart and it may hold everything on the lathe until it stops.
Heavy duty zip ties will work too.

I know you understand heavy metal poisoning. It is cumulative and the body gets rid of it slowly if at all.
Trick is not to breathe the particle that tips the scale.
 
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Sanding both surfaces will provide "teeth" on both smooth surfaces of the wood to bond to each other with the glue.
A smooth un-sanded surface is more likely to break its glue bond.
 
You’ve already got terrific advice. I’d also suggest epoxy. Generally with epoxy you want to be careful, as Tim said, to not clamp too tightly and starve the joint. With epoxy, apply a coat of straight mixed epoxy to each surface, then thickened epoxy using cotton fibers to make a strong joint. https://www.westsystem.com/403-microfibers/.
 
Gerald Lawrence said:
He found someone else to do these and the glue up blew up on this turner after he did three. So now contractor is looking for someone to complete the project.

Contractor special ordered kiln dried treated lumber (didn't know this existed).
Click to expand...
I'd pass for two reasons. Contractor has demonstrated sub-standard work on his glue up. Screws to hold things together is rinky dink. Treated lumber dust is nasty and dangerous. Tyvek suit and good respirator would be appropriate but you still have the dust in your shop.

This was a glue up for a similar size finial on a covered porch for a historic mansion. It was a rush job (like next day). I had air dried white oak which is fairly decay resistant and also in equilibrium with the outside environment in stock. Made my glue up using Titebond 3. If time had allowed, I would have ordered resorcinol or epoxy glue which would have been good for total submersion.

IMG_4892.JPG
 
Glue doesnt take any longer to cure on the inside. The problem is the chemicals and surface of the wood. I would plane it to get a fresh flat surface and then use epoxy or polyeurethane glue like the original Gorilla glue. I made some spheres for a guy years ago. They were outdoors and eventually cracked but not at the glue joints. Pretty sure used Gorilla glue back then. I now use epoxy because it's easier to clean off my hands.
 
For exterior painted work accoya is a highly rot-resistant and stable non-toxic choice, though it may be hard to find. It can be glued with epoxy, polyurethane and resorcinol. Spanish cedar, African mahogany and white oak are some alternatives.
 
Well, before the glue up, I would run pieces through the planer, and then run them through the drum sander. You want dead flat surfaces for any kind of glue up. The Gorilla glue is 'water proof' but the container says some thing like 'not to be used for things under water'. I would go with titebond 3 so you have a little longer open time. Species of wood can make a huge difference in how long the piece lasts. Since it will be outdoors, I would apply a couple of very thin coats of marine type finish first so it penetrates in, especially on end grain, even to the point of soaking it, submerged, in a vat of finish. The piece will need to be refinished every couple of years. Sun and weather are hard on any outdoor wood. Even teak and ipe.

robo hippy
 
I made these out of cypress and treated wood, glued with Gorilla glue and finished with exterior water based semi-gloss paint. They stay in an outside storage area and have been used on the porch at Halloween, a couple of outside weddings. Though I hate working with this glue, it is my go to glue where moisture could be a problem, have to wear gloves and deal with the expansion after it is dry but it will expand into every crack and void...
IMG_1269.jpg
 
The main ingredients for a successful glue up is flat clean surfaces and a quality glue like Titbond III, which should yield joints stronger then the wood itself. The problem that no one has addressed is a 10" by 10" mass of any species will not allow for the movement that will occur due to changes in moisture therefore the result is checking. The only possible solution is to hollow out the inside or make the glue up with internal voids. Another better solution would be to contact one of the companies that make synthetic outdoor architectural components.
 
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Just incase you think I don't know what I am talking about this is a walnut glue up for a table base. The first picture is the beginning turning and the second & third pictures are after it came back for repairs. Note that it is hollowed out from the bottom to relieve the stress then I had to mount it on the Bridgeport mill to machine out the checks to repair them. This project was done in December of 2018 and when picked up on one day then it was brought into a lake cabin for the night and by the next day the checks had already appeared so it came back. The final repair apparently worked out since I haven't heard any complaints since it made it to Minneapolis and was installed at the customers home.
 
robo hippy said:
Well, before the glue up, I would run pieces through the planer, and then run them through the drum sander. You want dead flat surfaces for any kind of glue up. The Gorilla glue is 'water proof' but the container says some thing like 'not to be used for things under water'. I would go with titebond 3 so you have a little longer open time. Species of wood can make a huge difference in how long the piece lasts. Since it will be outdoors, I would apply a couple of very thin coats of marine type finish first so it penetrates in, especially on end grain, even to the point of soaking it, submerged, in a vat of finish. The piece will need to be refinished every couple of years. Sun and weather are hard on any outdoor wood. Even teak and ipe.

robo hippy
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Titebond 3 also says not for use underwater...I thought we were talking about outdoor stairs, didn't realize the stairs were under water...Most epoxies need dry wood, you need to dampen lumber to glue it with Gorilla Glue. That's my only point..it glues damp wood. Treated damp wood. I use epoxies and wood glue all the time, much more than Gorilla glue...
 
If you glue up some thing with the Gorilla/urethane resin type glues, it can delaminate if you ship by air, because of the air bubbles. Had a friend who sent expresso tampers to Japan and found that out the hard way...

robo hippy
 
If I ever do ship something glued together with Gorilla glue, hope I can remember to include reassembly instructions...:rolleyes: who would have thought of that?
 
I second the opinon that you should take a pass on the project. Last one that touches it, owns it. If it is building construction, regulated by the building code and the thing fails, you might be legally liable for property damage at minimum just by having touched it. I am not an expert on the building code (nobody is, except the inspector that is doing the inspection, right at that moment), but I don't think that wood glue is approved for use on pressure-treated lumber. PT lumber doesn't take glue well at all, nor much of anything else aside from penetrating oils or solvents. It gets better as it ages and dries out, but it is still iffy.

I know you don't have a choice in what material you get, but white oak (for rot resistance) laminated with an exterior grade glue would have been a far better choice for that application. Your contractor "should have" known that, but that's a somewhat arrogant and ignorant thing for me to say from way over here in NC. It's hard to know everything, and he might be God's gift to framing and roofing for all I know.

Having a piece de-lam on the lathe is not something I would risk in any case, and PT really makes bad odds.
 
Another possibility is to turn the piece from untreated wood and have it treated after, which is what I did with 2 barber poles. The poles were made from 8 X 8 X 60" white pine that had been run thru the kiln about 4 times. The PT cost under $20.00 but it did require a trip of 75 miles each way. The first picture is the poles crated for PT and the second is the finished and painted pole. The poles had to be run thru the kiln after the PT before the painting was done.
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