Loar Specs

[c3hammer]

That's very intersting that the mando in question was refinished.

Today I had a go at Gary Vessel's one year old F5 with a Hacklinger gauge. #It came out almost identical to the print I posted earlier! #Probably a couple of tenths thicker, particularly as you moved toward the neck in the center of the top. #Gary said that he made that one from a particularly hard piece of red spuce. #

I think it is one of the best sounding mandolins I've ever heard. #It's definitely loud

Number 2 is comeing together as we speak and it's top is significantly thicker than #1. #Some where in the low 5mm range in the center of the top as opposed to 4.4mm or so. #The recurve area is about 3.3mm as opposed to 2.7mm on his #1.

Maybe the type of spruce has a lot more to do with it than I would have guessed.

Cheers,
Pete

[Michael Lewis]

Regarding the tone bars, you will find variations in how tall , how long, and placement. But in general I have found in the 5 Loars I have measured that the treble bar runs just inside the treble adjuster of the bridge almost paralell to the edge of the fingerboard, and the bass bar splays out much wider. They have been in the same places on the ones I saw, but the lengths varied. Some stopped at the recurve area and some went all the way to the lining, often one bar is long and the other is shorter in the same instrument. John Reischman's '24 and David Grisman's '23 are like this. So far I haven't measured a top that was thicker than 4.4mm in the bridge area, they are usually a bit less, around 4.0mm - 4.2mm.

[Nick Gellie]

I am resurrecting this old thread as it has some interesting observations about Gibson Loar's back and top graduations. It seems that the top graduations in some of the modern mandolins are heading towards 0.18" at centre depending on wood density. The back seems to be 0.16" at centre to compensate for the higher density of maple over Spruce.

I am interested as I am graduating the back of an F5 mandolin Arches kit and he suggests 0.18" at centre for the top and 0.16" at centre for the back. I have left out the other measurements at it seems that at the recurve typically 0.1" is the target figure. My mandolin back is at 0.25" at the centre and 0.2" around the recurve. It seems I may have to remove 0.08-0.09" thickness to get close to Loar specifications.

Any thoughts from builders since this thread is now eleven years old.

[fscotte]

Yup. Make em thinner than you'd expect. I've seen tops as thin as .145 in the center. And backs even thinner.

[Jim Hilburn]

Wow, I had some learning to do back in '04.

[Nick Gellie]

Thanks Jim and Fscotte. I am aiming for Chris Baird's graduations as a target. If I happen to go a bit thinner than his specs I won't be too worried about top and bottom stability as you are suggesting that I could go a bit thinner if I have to depending on wood density and deflection characteristics.

[Jim Hilburn]

The wood being used is still a big factor and judging that can be a challenge in the beginning.
I'd also say to be careful with the string line. Leave it thicker at the tailpiece and under the FB in the recurve area.

[Nick Gellie]

Yes I agree Jim wood is a big factor. You have that many more years' experience than I do judging how much to take off. I have noted leaving it thicker at the tailpiece and under the FB. Chris Baird mentions that in his graduations template for both top and back plates.

[robert.najlis]

Hans Brentrup always talks about the Loar's being built heavy, and I know he built that way.
I don't know anything about it personally, not being a builder, and never having played a Loar. But I do like his mandolins
I believe he has the graduations he uses in his book, but I have not really looked at them or compared them to any other graduations.

[Jim Hilburn]

Loars were not built heavy. Based on Crusher grads anyway.

[Hendrik Ahrend]

Some Loars may, indeed, be built heavy. Others don't seem to: These hac charts have been published at least once over the past years here on the mc by some friendly members. (I hope it's okay to reload them here):

I believe fellow café member Adrian (HoGo) based his drawings (among others) on Loar #75307:

Here is #74003, the Griffith Loar A5:

This chart is said to be from the Ted Davis drawings. But I'm not sure about that, since LMI sells it as from "Loar #73992", which is Darryl Wolfe's, who again said that those charts were taken from a refinished Loar. So I don't know which one it is:

[robert.najlis]

interesting! It would be interesting to hear heavy and light built Loars compared.

[HoGo]

interesting! It would be interesting to hear heavy and light built Loars compared.

I would like to see a heavy built Loar. I've seen at least dozen graduation maps from Loars and they tend to be on the thin side (sometimes scary thin in areas). My plans (from version 3 up) are mostly based on 73008 (the details of graduation and archings, neck, etc.). The basic outlines are merged from five or six Loars and original body form.
Generally the tops are around 4.0-4.1mm at the center and around 3.0 mm (sometimes down to 2.7mm) in the recurve. That is thinner than the original specs. The backs are usually around 4.0mm at the center and 2.6-2.7mm at recurve which is thicker than suggested thickness in the original specs sheet, probably because heavy final sanding/scraping removed spruce wood faster than maple.
I've seen more than one mandolin with Loar style graduations of top collapse under tension so my opinion is thay are just on the line - from my experience when coupled with CORRECT arch shape they are strong enough. All the collapsed tops had different arch shapes and that was their sentence of death. I think the arches kit has good archings and will work well with grads close to typical Loar if the wood is not extremely weak. Some players might even prefer slightly thicker tops (couple 10ths of mm) and thinner backs as they deliver more cutting power when played really hard (heavy picking hand) and more woof on the chop IMO.

[Jim Hilburn]

Crusher has pretty severe top deformation, bulging behind the bridge. But still hanging in at 93 years.

[ellisppi]

Wow, I had forgotten about this thread, while I should have made another post back then, let me say now that the drawing of thickness measurements from Ted Davis' plans that is attributed to me was taken from a smashed loar that was in 100 pieces. I played the mandolin the previous year (late 70's) at Winfield and the mandolin was pristine and 100% original, not refinished, and the owner won Winfield with it, and yes it was intentionally destroyed. My measurements were taken with a dial caliper and are VERY accurate for that mandolin. the plates were symmetrical enough that the drawing shows top on 1 half and back on the other. You should redraw it into 2 drawings, make small adjustments and draw contour lines. As far as I know, this mandolin still remains unknown. And yes the top was thinner under the bridge than it was behind it.

[fscotte]

The thickness being only half the story, since the braces offer the most support. I tend to think of the top as the floor in your house. You make that floor really thick and strong, thereby not needing as heavy floor joists, or you can make it thinner and use stronger joists. In a house it's mostly about cost. But in a mandolin it's about the mass. Make the top thick and you'll need smaller braces, but your top will be heavier thus needing strong input from the strings, perhaps less responsive in the end. Make it super duper thin, and it will deform under pressure, but nice strong braces will support the pressure. Each will have varying tone.

I know for a fact that some Macrostie vintage models are on the edge of that black hole. But Don being a master builder knows how to build em without collapsing. That little thing called arching is oh so important.