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I've decided to switch to hot hide glue for neck and bridge attachment.
Can you tell me what strength of hide glue you prefer for these particular procedures?
Also how thick (water/granule ratio?) do you usually make it?

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Formerly know as Mandodiddle.

have used both 192 and 215
they are both plenty strong enough.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I like the 192 stuff from LMI. Not sure what the exact water proportion is. I err on the low side to start, and then add more water until it's just right. Put out a drop of glue and let it cool, and then press on it with the back of your thumb nail to feel how firm the gel is. If it springs back to shape even with a fair amount of pressure, it's too dry. If it squashes with minimal pressure, it's too wet.

I just use 192 gram strength, and it works great. I normally use a 1.6 water to 1.0 dry glue ratio, measured by weight, not by volume. If I need it to be runnier than that, I add more water. I rarely need it to be thicker than 1.6 to 1.0.

Leaving aside the question of strength for a moment, the higher gram strength glues gel much faster than the lower gram strength glues. So, whatever gains in strength come from using a higher gram strength glue, you have to move faster during joint assembly. Not good or bad; just something to be aware of.

I suspect John may have meant 315g, rather than 215g. I couldn’t find any 315 when I was stocking the shelf, I use 260g on bridges, 192g for everything else.


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315 for bridges, vacuum clamped. 192 clear for everything else.

1.9:1 water/glue by weight.

meant 251 strength

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I have been using 192 for just about everything. Recently got some 315 from a discussion on Torrified tops and bridges as per Woody's suggestion to use 315.

For a dovetail neck joint I would think 192 would be best.

I use 192 for everything except bridges on torrefied spruce, for that application I use 315.

_________________
Steve Smith
"Music is what feelings sound like"

192 for neck sets, bridges, headstock repairs and anywhere else that HHG makes sense.

192 is plenty strong enough for bridges that are properly fitted and the patch is properly prepared and the rest of the box is in order meaning no loose braces or bridge plate "tenting" that will lead to the bridge lifting again.

I'll add that it's more important than what gram strength that one uses for one to have the chops, knowledge, dry runs (the verb not the malady...) and an understanding of HHG to meet the short open time requirements. If you cannot have things in place and snugged down fast enough other glues may be a better choice for you.

Me thinks that the whole point of HHG was the original KISS thing, keep it simple stupid..... We tend to make this overly complex when we discuss HHG here but the open time requirements is real, important and will bite ya if you ignore it.

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Ann Arbor Guitars

So what kind of open times do folks feel like they are working with?

_________________
Formerly know as Mandodiddle.

Trick question! Personally, I try really hard to not bump up against whatever the pre-gel time limit is. I plan out gluing operations that allow me to spread the glue and get the parts clamped in less than half a minute. If it will take longer than that (which for me tends to only be the case for gluing plates to rims), I preheat the parts and add a smidge of urea to the glue, just to avoid the dreaded gelling. For everything else, if you can’t plan it out to get it done in less than half a minute, there is some dawdling going on. Just my opinion.

I’ve never had a bridge pop off in service using 192. When I was first starting to use HHG on my own builds I lost one due to poor process - not getting the clamps on in time. Now I have no problem getting the budge on and clamped in 10-15 seconds. I preheat parts with a hair dryer for a few seconds and work in a warm room.

Caveat here is I don’t deal with much torrefied wood - if you search you’ll see posts from Woodie outlining her process for using higher strength glue for these.

One (of the many) things I like about HHG for bridges is that failures tend to manifest quickly when stress is applied to the joint. So if you screwed up you will know about it shortly after installing the strings

That means if something goes wrong you have the opportunity to fix your mistake (easily and quickly, thanks to the forgiving nature of HHG) before the instrument leaves the shop.

192 for everything. 315 for repairs.

We shoot for ten seconds or less with 192, 15 seconds is fine too we just always are trying to do better than last time.

We have a unique way of doing bridges where we preposition the clamps in the exactly location that they need to be so that all I have to do is slap the bridge down in a pocket made of masking tape and snug the clamp(s). I can usually have my bridge clamp in place and snugged in only several seconds with this technique.

We've never had any need to use any other gram strength HHG than 192, no bridge lifts (except for the fish glue bridges I speak of here when it comes up).

It should be mentioned even though all I use is 192 that other gram strengths have a different open time, the more the gram strength the less the workable open time. One of our attractions to 192 only is we don't want any less open time as it is 15 seconds is fast for some repairs anyway.

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Ann Arbor Guitars

The higher the gram strength the less viscosity you have. Hot Hide Glue 192 is plenty strong and you will have the most open time with this.
I also suggest to warm the area to gain as much open time as you can. When I tried higher gram strengths I have a few failures due to the clamping issues.
They are easy to reglue but I now use almost all 192 and 215

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I just jointed two torrified red spruce tops with 315. I use wedges to clamp the two halves together and what I found was that there was not enough time to get it clamped before it gelled up. But once it was in clamps and I hit it with a heat gun the joint closes up and after sanding them the joint is totally invisible.

I know a lot of luthiers just do simple rub joints but I tried that last week on these tops and there was a visible line so I sawed it through and redid it with clamps.

For those who use 315, or any others for that matter, what is your ratios when mixing? I have 192 from LMI and they recommend 1.8 water to 1 glue by weight so that is what I use. For the 315 I used 1:2 glue:water.

If you build using the peones the 315 is fantastic as you just hold it there for a couple seconds and it's stuck.

I mix 315 just like any other HHG, I don't measure anything. I put granules in a 1 oz bottle and then add distilled water till it just covers the top.

_________________
Steve Smith
"Music is what feelings sound like"