How much glue do you guys use during glue up?

[Kopper1013]

Just curious...

Finished glueing one up and for what ever reason when I inflated my hose you should have seen how much glue uzzzed out, should have taken a pic, let's just say there shouldn't be any glue starved joints. I figure glue is cheaper than a breaking bow, thought I had a very thin layer but..... Took forever to clean her up. I use a cheap 1.5" wide puddy knife to apply my glue.

So, how much glue do you apply and what is your chosen method of application?

[Bowjunkie]

Depends on the bow. For a longbow with 6 lams including glass, I mix up enough Smooth On to fill a tuna fish can.

I apply it with a .040" thick piece of Bo-Tuff about 8" long.

To help judge thickness of glue during application, get a lam wet all over with glue and on your final pass, with just a little pressure, the applicator should glide over the glue without dragging on the lam. If I feel it drag/scrape in any one area, I add a little glue and try it again. With a little practice, you'll know how much glue is needed, how much pressure to use, and know by feel that you're right in the ballpark. Adequate glue, minimal wasted.

You want SOME squeeze-out when pressure is applied.

[Robertfishes]

I usually mix too much...For one piece longbows and recurves I was using two plastic 3 oz bathroom cups of each part of smooth on.. Now I use one 3oz and one 1.65 oz cup of each part(9.30 oz total).. For the ILF takedown limbs I have been building lately I have been using plastic Shot glasses from the grocery store. They are 1.65oz each for a total of 3.30 oz.. I'm still using auto body bondo squegees cut in half for applying smooth on, I buy them at Harbor Freight in 10 or 12? Packs

[Mad Max]

I use a putty knife like this one, i file a v notch (not very deep) every 1/8"/3/16" across it.

vvvvvvvvvvv kind of like that, if too much glue comes out , I sand the end a little bit so the v notches are not so deep.

works for me    

 www.amazon.com/Red-Devil-4251-Painters-6-In-1-Tool/dp/B00002N6IT/ref=sr_1_9?ie=UTF8&qid=1428003347&sr=8-9&keywords=putty+knife

[Mark R]

Both parts of smooth on fill a bathroom cup, I believe its the 3 oz. kind, I use a wall paper roller after applying with a putty knife or such. Play with it, you just want to apply enough to wet both surfaces.Should be at least room temp, a little warmer helps the flow ,but I don't heat mine as others do.

[Krasus]

I myself broke about 4 bows being to conservative with my glue. Now I probably use way to much but haven't had any break now.  Make sure you'butter' both sides. Who cares if you have extra glue spooging out.  A easy tip to avoid a big clean up is just use some shrink wrap over top of your jig to catch the extra glue.  Works great for me.

[LittleBen]

I think I had figured I'd get 6-8 bows out of a pint smooth on, which is actually a pint of each ... So 32oz. Which works out to 4-5oz per bow. That's making tri-lam bows and definately not worrying about being stingy. I think if I wiped it real thin I could use 30%less, but at $30/6-8 bows ... I'm not gonna risk it in order to save $1.50 on a bow that takes 20hrs of work to complete.

The real problem with smooth-on is that it's awesome, and I've found it has many uses outside of bow building .... Anything you ,ugh wanna glue together would probably benefit from being glued wth smooth on. That's when it starts getting costly.

[mikkekeswick]

I've only been getting 4 bows out of  the pint cans.
66 inch long, 1.5 wide and 2 glass,2 veneers,a taper and a parallel.
I weigh mine and use 220 gram total.

[Bowjunkie]

Ben, I concur. I've used Smooth On for a wide range of repairs... home, automotive, footwear, flytying, knife making, and more.

I too often use the 3 oz bathroom cups for measuring... fill one with each part to glue up a 6 piece glass/wood longbow, and about 3/4 full each for trilams.

[Al Dean]

As long as both surfaces appear wet I'm good.  When I watch is when temperatures get in the 80s and glue becomes very runny.  Easy to get to light then.

[Wolftrail]

If she is ooozing out ya got enough, if you tighten the clamps to much you could starve the joint.

[JamesV]

I use plastic spoons to measure my glue. One for each can. 1 1/2 heaping spoons of each for a kid's bow and 2 heaping spoons each for an adult bow with 4 lams. My wife saves the little yogurt cups for me to mix in. About half a cup per bow.

James

[BigJim]

I weigh mine and usually glue up 3-5 bows at a time. some use a little more and some less depending on model and length, but I would say the average is a combined 9 oz. so that is what I mix for every bow...a little extra goes on the next bow.
I put each part in it's own separate cup and then down in the hot box while I'm gluing. My shop stays at a controlled 72 degrees and the glue is a little firm at that temp so heating it makes it much easier to ensure proper mix.

I have used wood scraps and bondo scrapers in the past but have settled on a wide painting knife  (1-1/2" wide)and have been using the same knife for many years...until my brother threw it away  :(  oh well, I always keep a back up or two on hand. You can pick them up from a hobby shop for about $7-10. Probably have done over a thousand with one knife.

If you sand laminates with 60g (probably 80g too but I don't know), and you spread enough glue on both sides of every piece, all the pressure your hose can handle won't starve a joint.

Glue starving surely happens, but every time a bow fails, it gets the "glue starve" blame. It ain't happening that often and especially not with a bowyer with any experience.
If you take a pocket knife and start at the tip of a bow, you can peel one pretty quickly and easily and it will usually happen on a glue line.

These lines look somewhat dry to the untrained eye. What do you expect to see? big layers of glue? There will only be what will fill the depth of the sanding ridges of either side. Our glue dries clear.

Be safe, use coarser grit paper. I use 60g exclusively(unless staining veneers). No you can't see the sanding line. I used 40g for years and with one exception could never see the lines then. Again, I would expect that 80g is fine...this is what glass is sanded to.

My personal observations and suggestions. If you don't agree, than do what makes you feel comfortable.

BigJim

[mikkekeswick]

9oz is 255 grammes so it looks like i'm in the ballpark.
A full yet concise answer Jim - thanks.

[talkingcabbage]

Not trying to hijack a thread here, but a question for BigJim.  Talking about starved joints and failures, what would you attribute a failure to where the glass separates on the belly side at the fades?  I had one do that recently and didn't think I starved the joints since I usually use too much glue and have a ton of squeeze-out.  This bow was actually strung up and hanging on a rack when it happened.  Could the glass fail and split to look like a delam or starved joint?

Sorry again, don't mean to hijack, just thought it followed the thread with glue joints and starving/failing.

Thanks all.

[BigJim]

The problem with bow building is that too often the cause can't be Identified.

Certain things can cause adhesion issues such as burnishing/burning the wood when sanding, moisture in the laminant, Moisture in the glue, Unforeseen contaminant.

There is just too many possibilities, including not dragging the fades out far enough...but I've seen risers that looked like they should have caused a failure but hadn't over many years.

I wish I had more answers and might if I had seen the delamed bow...but more than likely not so we will just call it glue starved.

BigJim

[MikeWinVA]

I haven't built many bows, but I have done lots of laminated lay ups for boats and bicycles.

Unless you are using prepreg materials or materials where the resin completely saturates the laminate, such as cloth or matt, too much clamping force is a bad thing. With wood, the resin remains on the surface for the most part.  Too much clamping pressure will result in glue starved unions.  

When I try my next bow,  I may try a vacuum bag with peel ply.

[Wolftrail]

I know with wood bows that I'm getting sometimes to much bend in the fades and thats where she breaks.  My tiller defect. And sometimes its the grain. Knock on wood I have never had any belly frets or chrysalis happen.