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Steve Hinde
Feb-05-2004, 8:29pm
I am starting a Stewmac kit. I would like to know how close Don's thickness specs are to the Loars'? How can I get the specs for the Loars?

Steve

Chris Baird
Feb-05-2004, 9:16pm
What are Don's specs? #The best bet for getting Loar specs are to either measure a Loar or possibly even better measure a new Gibson master model. #I think if anyone knows Loar specs it's Derrington and the master models are probably more consistent than the Loars were. #I've heard a wide range of numbers when it comes to loars. #Your best bet it to get an exact copy of the arching and the thicknesses for that arch. #Different arches will have different grads. #Siminoff is suppossed to have a "definitive" set of plans out but they are way off from what I've got. #I haven't seen his archings though so maybe his loar measurements are for a different arch than the ones I've seen. #Any experts care to talk about differences in Loars and their published specs?

Jim Hilburn
Feb-05-2004, 10:07pm
If your building your first mandolin ,I suggest using the numbers on the Stew- Mac print as a guide and don't expect to duplicate a Loar the first go round. It's a real challenge just to get it put together ,maybe you can build a perfect Loar copy on the second attempt. The recurve thicknesses are actually quite thin on that print ,and you may want to stay at around 3mm unless you have a very stiff piece of spruce.

rose#1
Feb-05-2004, 10:55pm
decent specs:

recurve 3mm-3.1mm

inner recurve 3.5-3.7 mm

center 4.5-5.0mm
try and make a nice flowing dish shape for your first one use stew macs tone bars and you should have a nice sounding mando.

Darby

Fretbear
Feb-05-2004, 10:58pm
Good advice from Mr. Hilburn. You definitely do not want to go any thinner on the recurve than what is stated on the Stew-Mac/Macrostie plan, and the thickest centre graduation thickness can stand to go a very small amount thinner. Don't worry about Loar's; Don's plan will make a great mandolin, and as Jim has stated in previous posts, if you were to go any thinner than the graduations stated on Don's plans (or even if you don't), you will start to get the tone bars "witnessing" or showing through the top after stringing, which means you are approaching the outer limits of what you can expect #a poor (or good!) piece of spruce to withstand. A mandolin built to those specs will still require a substantial "break-in" period, so be patient, before and after building.

Yonkle
Feb-06-2004, 12:45am
If you get Siminoffs "New" book it has the Loar specs. I have done 2 Stewmacs and I am doing a Siminoff right now.
The main difference I see in the two plans are.
1 The neck angle (which you can't change now)
2. The Location of the tone bars. (which are way different) Siminoffs look to be in the same location as Dudenbostels, McRostie has them inward a bit more and a lot more on the treble side.
As far a graduations, I did not check, because Siminoff graduated the top and back for me. Thats the part I screwed up on my Stewmacs, I got them too thick (my fault, not the plans) http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

Steve Stahl
Feb-06-2004, 1:00pm
From the original specification sheet for F5s (GAL Journal):

Backs: The carving graduations at center 3/16". Fin. 5/32"
at 7/8" from sides and tail end 1/8" Fin. 1/10"

Tops: The carving graduations at center 7/32". Fin. 11/64"
at 7/8" from sides and tail end 5/32" Fin. 1/8"

So converting this to decimals and metric, backs are 0.156" (4.0 mm) at the center and 0.1" (2.5 mm) at the recurve. Tops are 0.17" (4.4 mm) at the center and 0.125" (3.2 mm) at the recurve.

This only provides a very rough measure of the graduations, but it is a good starting point.

Darryl Wolfe
Feb-06-2004, 2:30pm
Mr Stahl's interpretation of the original spec sheet is very good, and Loars were done very closely to it. The problem is that they need a couple more statements to clarify that the recurve specs do not apply everywhere.

One must know that the top has some elliptical symmetry to the carving in that it gets thinner again under the fingerboard extention similar to the tailpiece end...but the back does not. It essentially gets thicker and thicker as you go north along the center line. The thinnest part of the back is an elliptical "U" shape. Most builders apply some symmetry to the back by taking way too much meat out of the inside in the upper bout area.

Feb-06-2004, 4:47pm
Hey Darryl.. On my Paganonni I used to have I noticed what was kinda unusual that the back of the mandolin near the button had more meat than any other mandolin I have ever seen on the outside of it. What I mean is at the back button the thinkness was raised Were all the Pags like that and were they any loars like that?

Steve Hinde
Feb-07-2004, 1:44am
Hey thanks. This gives me some things to consider and some thoughts on variation of the kit. Just looking for a great sounding instrument when it's done. Not too worried about the assembly or finish out, but the graduations are a new adventure. I'll let you know how it goes.


Steve

John Bertotti
Feb-07-2004, 1:39pm
After reading Steve Stahl's post and reading F5journl's reply I have revised a comment/question and deleted it from another post and here we are now. I see that the center and the recurve are the recorded measurments. I was wondering if the Loars used a common rate of graduation from center to recurve? A problem with this train of thought is if the center and recurve are fairly consistent to the center and recurve thickness's than a common rate of graduation must be out of the question because the tops had to be tuned. With a set center and recurve thickness you would have to play with the rate of graduation to get the proper sound from your top. I may be right or wrong or possibly stating the obvious but please let me know if I'm on the right train of thought. It wouldn't be the first time I hopped the wrong train. Thanks all John http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif

Chris Baird
Feb-07-2004, 4:29pm
According to Charlie Derrington Loars were not tap tuned as free plates but were just carved to spec.

HoGo
Feb-09-2004, 7:58am
Chris, I agree that the Siminoff plans are off or at least suspicious. I do not have the plans but from what can be seen here (http://siminoff.net/Media/roger_dwg_collage.JPG) (bottom left). There are three lines in the graduation map (of back), representing three different thicknesses, that meet the outer edge! That's most certainly not kosher. No one will argue that the edge is 3/16" thick all around the plate except the part of the scroll. I assume that the outermost line that connects smoothly on the edge is the 3/16" line. That suggests that the back is quite a bit thicker in the center (bridge center) than the thicknesses stated by Mr. Stahl.
I used to own the Stew-Mac plan and I am sure those archings and graduations were not taken from a Loar. The single evidence of this is the ridge on the back. This is certainly not a feature of a Loar mandolin. Howewer, there is a Loar with a ridge, but with a very subtle one. The ridge on the plans is maybe more pronounced than the ridge of most old mandolins with a "ridged" back.

Darryl Wolfe
Feb-09-2004, 9:22am
It'd kiinda tough to explain but most all Loars have a flat button 3/16' high. The binding on the adjacent sides is also 3/16" high...all the way into the scroll area and the point area on the other side. But the profile starts rising almost immediately fron the binding. Along the centerline headed to the flat button..the back smoothly adjusts profile to return to 3/16" high at the button

c3hammer
Feb-09-2004, 2:16pm
Here's a jpg of the grads that I was sent last year. I don't recall if these were from one of the books or someones personal copy.

Cheers,
Pete

Jim Hilburn
Feb-09-2004, 4:02pm
I've never seen a copy of Ted's prints before, but assuming it is correct ,I would conclude that Loar's were inconsistent at best, and that they may not have been all that carefully graduated. How else would you explain a 4.2 reading at the bridge while it was 4.5 a couple of inches out toward the rim. Also, 4.5 seems very thin to me. While 6.35 on McRosties may be a little stout ,I personally have scrapped tops that I got below 5.5, worrying about the structural integrity. 4.5 is what I'm looking for around the inside f-hole point. And I've made some pretty thin-topped mandolins in the past. They will start to distort.

Darryl Wolfe
Feb-10-2004, 10:31am
Those graduations were taken from a refinished Loar..use your own judgement on how it got that way

ellisppi
Feb-10-2004, 11:47am
Darryl, Please elaborate on your comment that those numbers were from a refinished loar. I'd like to hear more detailed information about that mandolin, its history and what became of it.

Jim Hilburn
Feb-10-2004, 2:14pm
That could certainly explain what looks like rather less than uniform instrument.

Christopher Standridge
Feb-10-2004, 4:25pm
I was told by Tom Ellis, who Davis acknowledges on the print, that those numbers came from a mandolin that was brought in to him for repair. The story went that someone had to prove his love for his wife over the love for his Loar by smashing it onto the driveway. It was the wife who contacted Tom and remorsefully inquired of him to do the repair. Tom took it in and said that it was way beyond repair, but that he was able to take measurements off of it. It must have been refinished prior to that. If any of you are not aware of who Tom is, he has built a few great sounding mandolins in his day and I trust that he took the most accurate of measuremnts off of that one example. Who knows, maybe it wasn't the first time that Loar had been sacrificed to prove true love.
What do you think Daryl??

Darryl Wolfe
Feb-11-2004, 11:20am
I don't know much about it other than it had been refinned. I only heard that Ellis took the measurements. The best way to arrive at loar specs its to do a composite of all available info on graduations..from there you can see the consistency of measurement. There are about 5 or 6 "maps" that people have done

MarkG
Feb-11-2004, 12:50pm
There seems to be quite a bit of information about Loar plate thicknesses and graduations available, but I've not seen anything on tone bar size for Loars. Darryl, do you have any information on this?
My feeling is that the tone bars on the MacRostie plan are taller than on a Loar, and they stop at the recurve rather than continuing out to the lining, also the placement is slightly different than on a Loar.

Thanks,
-mark

Darryl Wolfe
Feb-11-2004, 1:27pm
The Loars go to the lining. #I dont have my tone bar info handy..but memory says they are 1/4" wide with one being 5/16 high and the other 1/4 high. #They are rounded slightly triangular. #The bass tone bar parallels the f-hole about 1/2" in from the edge of the f-hole "holes" while the treble one is in about an inch from the upper end of the f-hole and about 1-1/2-1-3/4 at the lower end. #Essentially the treble bar runs straighter up and down and is further in. #I can just barely touch the treble tone bar with my little finger..whereas you can see the bass one

Darryl Wolfe
Feb-11-2004, 1:33pm
One of the best pictures ever on the subject is one from the Bluegrass Unlimited article on the C. Derrington fix of Monroes Loar.....showing the inside of the top with the back off. Monroes mando seem to have a peculiar placement of the tone bars..possibly contributing some to the sound. I'll try to scan and post it

rose#1
Feb-11-2004, 4:56pm
I have seen that pic of Monroe's mando I actually made a templete from that pic by blowing it up to the exact size of a mando top and taking the tone bar placement from it.

c3hammer
Feb-11-2004, 5:29pm
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 http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

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
Feb-12-2004, 2:37am
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
Dec-21-2015, 5:54pm
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
Dec-21-2015, 8:27pm
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
Dec-21-2015, 8:37pm
Wow, I had some learning to do back in '04.

Nick Gellie
Dec-22-2015, 7:05am
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
Dec-22-2015, 9:21am
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
Dec-22-2015, 4:35pm
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
Dec-22-2015, 4:42pm
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
Dec-22-2015, 5:08pm
Loars were not built heavy. Based on Crusher grads anyway.

Hendrik Ahrend
Dec-22-2015, 5:12pm
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 #75307:142017142018

Here is #74003, the Griffith Loar A5:142019142020

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:142021

robert.najlis
Dec-22-2015, 5:25pm
interesting! It would be interesting to hear heavy and light built Loars compared.

HoGo
Dec-22-2015, 5:56pm
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
Dec-22-2015, 6:48pm
Crusher has pretty severe top deformation, bulging behind the bridge. But still hanging in at 93 years.

ellisppi
Dec-22-2015, 6:56pm
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
Dec-22-2015, 8:16pm
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.