Thread: wax to stop glue sticking?

I use Techniglue epoxy for bent laminations for rockers and back slats. It should give you at least half an hour of working time, unless it is very hot weather - say, more than 30 C. Do not use PVA glues, which will creep under stress. Carbatec stock Techniglue.

I am a bit dubious as to whether WR cedar will be strong enough for your purpose. I would prefer to use a strong hardwood like blackwood or jarrah.

Rocker

I've never done bent laminations myself but i have looked into it a little as i plan to build a rocking chair with laminated rockers. For the rockers i have bought some Titebond long open time. Its rated for a 15 - 20min open time & is recomended by a top rocker builder. However your curve is pretty damn tight, it looks to me like a perfect job for steam bending. I visited a local artist a few months back who specialized in steam bent timber. He uses a polyurethane glue for all his lamination. His reasoning behind the poly glue is that while the glue isn't as strong as other glues when it comes to joints 'pulling apart', laminations tend to pull along their length or slide apart & this is where poly glues are especially good. I've seen heaps of his work, both indoor & outdoor & have never seen any sign of failure. Poly glues also have a good open time.
Good luck with the project, i love anything with sweeping curves in it & this should be a really nice project when finished.

Thanks guys!

MJ - I'll be sure to get some photos on the weekend when im back in the shop, then post them up. I appreciate you taking the time to check it out! I also agree with the bondcrete, having looked into it myself. And it doesn't have the working time it claims - it took me 10 minutes tops from start to finish!

Rocker - thanks for the heads up! ill look into it... half an hour sounds plenty! and I understand your concern with the cedar, i had similar concerns, so last week i quickly glued up lams to make a thin bend (total of 15mm thickness) and it seemed strong enough - put two side by side and it should be plenty... but time will tell - i also have 2 lengths of Oak ready to go, but thought the cedar might be an easier timber to work while i get the hang of it. Pine was just nasty to work with!

Rattrap - thanks for the info as well, ill check out both these glues. They both sound like they are what i need. Good luck with your work as well... sounds like you have done plenty of the research!

My next challenge is to get my bandsaw tuned better than it is. I spent most of the weekend aligning, squaring off and balancing... I think i have the wrong blade for the job though!

Thanks again guys! post piccies shortly.

T

T ,
check out this page for the Western Red Cedar Wood Properties by Connected Lines

Originally Posted by Manuka Jock

T ,
check out this page for the Western Red Cedar Wood Properties by Connected Lines

Hey thanks!

Originally Posted by Rocker

I use Techniglue epoxy for bent laminations for rockers and back slats. It should give you at least half an hour of working time, unless it is very hot weather - say, more than 30 C. Do not use PVA glues, which will creep under stress. Carbatec stock Techniglue.

I am a bit dubious as to whether WR cedar will be strong enough for your purpose. I would prefer to use a strong hardwood like blackwood or jarrah.

Rocker

Rocker/MJ

What do you use to cut your laminations? Bandsaw or Table saw?

Would you expect to get a clean cut from your bandsaw? to the point where you could go straight into glue up without putting your lams through a thicknesser or drum sander?

If not, what other methods would be available to clean up the cut if you didn't own a thicknesser or drum sander? would a simple sanding block and sand paper suffice?

T

Ecks,
For my rocker laminations I used a table saw followed by a thicknesser. I think that, if you use a band saw, you would need to clean up the laminations; if you don't have a thicknesser, you could probably do the job with a jack plane. However, it would probably be better to use laminations thicker than just 2.5 mm, if you are going to plane them. I used 6mm laminations for my rockers, but they didn't have nearly such tight curves as your project.

Rattrap,
I would be very wary of using Titebond for bent laminations. As a PVA glue, it is liable to creep, and your bent lamination might delaminate in hot, humid weather. I have built a number of rockers using Techniglue, and found it ideal for the job.

Rocker

WRC has its place and the best one is in the tree.

I would suggest using a hardwood and there are may that would do the job very well.

Your plan to cut the laminations on a bandsaw is a good one & if you can't get a good cut from your machine then you can always dress the surface a little with a handplane by clamping one end and planing away from the clamp to keep the wood in tension. I am assuming that after each cut on the bandsaw you will be dressing the timber before cutting the next lamination.

I have used both Titebond PVA and Techniglue epoxy for laminating. I much prefer the former as it is cheaper, is a lot easier to clean up, and you don't have to contend with the fumes.

Using PVA you have to get the glue on & the pieces onto the former as quickly as possible and things that can assist are

Lay out all your pieces and apply glue with a small roller
Use as few laminations as possible
Glue a limited number of laminations at a time.

I would suggest revisiting your project as 9 x 2.5 laminations is 22.5 mm thick & will be very stiff and very strong. There are many commercial chairs available similar to the design you have shown, & I suggest you have a look at those & how they are constructed. Obviously the welfare of baby needs to take priority here, but I think you can safely reduce the number of the laminations and make the project a lot simpler.

Regards

Thanks guys!

Both very useful comments and feedback. I think my biggest mistakes where, glue & timber selection, and trusting the bandsaw could give me a clean enough cut to go straight into clamping.

Basilg - I didn't dress the timber each time before cutting the next lamination, i will try that, i need to invest in a good hand planer - since i don't have the space for a jointer. any suggestions? one that will help me keep a square edge?

I do have a festool router table, the i can offset one side of the fence - i assume this could act as a planer in a similar way? - won't help me for each lam, but will help me prep before each cut?

regarding glue, i'd prefer to use one which is safer for the little fella - so will look into which is non-toxic etc. but obviously has the strength required.

Cheers guys - ill keep chipping away with all the suggestions. I've also found further ways to fine tune the bandsaw for a cleaner cut.

T

quick update: Had someone at the shop un-clamp and put the cedar lams under strain... apparently stiff as a board and holds up great... although as Basilg pointed out, requires too many lams and is not practical. also, long term use may show differently.
Nice to know it would have worked though...

T,
I use the machinery at the club . Ripped with a bench saw and then thickness them.
I ran a few thru the bandsaw and found that it took a few more passes to thickness them . That may be due to the state of the bandsaw that does more circle cutting of lathe blanks than anything else.

T

It is a bit difficult providing advice when I don't know a great deal about your experience or what tools you have. However I will assume minimum for both. On the handplane topic I would suggest starting with a fore plane which is a very versatile plane and capable of doing the majority of what you would require. There are many options ranging over a large price range one that is good quality and around the middle price range is the Lee Valley plane if you are close to a Carbatec store you could also look and purchase from them With the favourable exchange rate there would be a price advantage buying direct from LV. I would also recommend you buy one with an O1 steel blade which is easier to sharpen and IMO gives a better cut than A2.

Lee Valley Tools - Important Announcement

There is a lot of information available on Bandsaws setting them up and their use, and this can be found in books, magazines and on the net. one source of this info and much much more is Fine Woodworking magazine. Michael Fortune is one guy that has written a fair bit on the subject. You can get a subscription to the magazine and or the online system or run a trial for a few weeks for free.

Fine Woodworking - Search: michael fortune bandsaw

regards

Thanks Basilg,

My experience is certainly limited, something i have not done in 12 years and just getting back into things.

I appreciate your advice and comments, they have been very helpful. I also got myself a subscription to fine woodworking, where i found a link to a [ame="http://www.youtube.com/watch?v=JowHmdihl-Q"]youtube video[/ame]. I might look for more from Michael like you've suggested.

In thinking about it, i also decided i may be able to use my router table as a Jointer for cleaning up the edges after each bandsaw cut, then change the setup to make the router table a thicknesser - using a straight cut bit - to run the 2mm lams through.

Im off to check out Lee Valley - thanks again!

T

Bondcrete is essentailly a masonary glue as previously suggested, primarily used where you need to bond a skim of concrete to an existing cured slab, e.g laying slate or tiles in a mortar bed. Very good at this type of work, or as a waterproof seal coat over cement.

It is also very good for providing a very water resistant bond for woodworking, providing that you can cope with a few limitations. The first, as you discovered, is limited drying time. This can be extended considerably (doubled) by thinning the glue to about 4 parts glue and 1 part water, at the expense of also doubling the cure time. A reduced bond like this will not be as strong as a full strength bond, but would be still be as strong as the parent timber.

The second limitation is that it reacts with tanins to produce a dark stain through the penetration zone, which cannot be sanded or planed out to hide the seams. A third limitation is that the glue is rather heavy in the cured state, and a forth is that is promotes rust in any steel that it contacts in cured or uncured state.

When I was a kid my father built his third boat , a 22foot speedboat with twin Ford V8 flatheads. This was planked in 8inch x 1/2 inch Mahogany screwed and glued with Bondcrete as it was the most accessable water resistant glue available to him at the time. When the boat was about 15 years old, the boat was partially dismantled to convert to stern drives.

This involved shifting the motors to the rear, replacing the transom with a substantually thicker unit and reforming the hull over the last four hull frames to add about 12 inches to the transom width at the waterline to better support the increased stern weight. It proved impossible to mechanically seperate the planks from the frames and stringers after removing all of the screws in the area, with all attempts splitting the planks almost midway through their thickness. This gives some indication of the penetration and bond strength achievable with Bondcrete. The task was eventually completed by cutting out the planks and stringers and taking about 3/16inch off the frames where they had been in contact with the planks.

Originally Posted by ecks79

In thinking about it, i also decided i may be able to use my router table as a Jointer for cleaning up the edges after each bandsaw cut, then change the setup to make the router table a thicknesser - using a straight cut bit - to run the 2mm lams through.

It is relatively easy to set a reasonable router table for jointing the laminations, but to truly thickness them you would have to the laminations pass between the bit and the fence, which is generally considered as unsafe.