Loar era F-5 Graduations compared to F-4 graduations

[carleshicks]

I bought a 1924 F-4 Top from Ken waltham here a few yeas back, I am in the process of building an F-5 from adrians prints and was comparing the graduations of the f-4 to the f-5 grauations on the print and they are dead on with in .005", except in the minimum area under the recurve. on the f-4 it goes all the way down to .099" . is this also the way the Loar f-5's were. Adrian's lowest dimension is only.126" ?

[D.E.Williams]

Who is Adrian, and where does one get his plans? I'm finding the Siminoff plans to be lacking in detail and consistency from one drawing to the next, and they don't really address the scroll detail at all.
Are there any other books out there on building an F5 that are more comprehensive?

[Jim Hilburn]

With an oval in my future I've been looking at what's the same and what's different.
Your in a good position to compare since you have an F-4 top to measure.
The big difference is what happens forward of the bridge and obviously where the bridge is positioned. Since an F-4 has to have the fingerboard attached to the top instead of elevated like an F-5 it makes for a flatter arch looking at it from the side. An F-5 has more of a domed arch which is naturally stronger than the partial arch of the F-4. This plus the fact there's no hole right in the string line makes it possible to thin the arch in front of the bridge as well as behind and this is just a more efficient design.
I'm not sure where to get Adrian Minarov's (Hogo) print. i thought Elderly had them but I couldn't find them there. But this is the print I refer to most.

[grandmainger]

Who is Adrian, and where does one get his plans? I'm finding the Siminoff plans to be lacking in detail and consistency from one drawing to the next, and they don't really address the scroll detail at all.
Are there any other books out there on building an F5 that are more comprehensive?

Adrian Minarovic (mandolincafe name: Hogo). Plans based on a 1923 Loar. I think they are regarded as being the best availble for accuracy. They're available through Elderly for $50: http://www.elderly.com/books/items/656-1.htm

Germain

[buddyellis]

These things varied more than many would probably like to admit, from what I can tell. Depending on the wood, I believe I've seen almost everything from a minimum (in places, not constantly) .95 to .130 in the various measurements from different sources. They are generally uneven and thinner/thicker in random spots. According to Adrian's study (and he's had his hands on and measured quite a few of them, from what I understand) he came up with a 'blended average' of .125 for the tops and .100 for the backs.

The original spec sheet for the F5 was something like this:

Backs: Center 5/32"
minimum area, at 7/8" edge (excluding the neck end) 1/10"

Tops: Center. 11/64"
minimum area, at 7/8" from edge 1/8" (fairly symmetrical all the way around, even toward the neck end)

Adrian's plan shows 4.3MM in the center (.169) and .126 for the minimum for the top, with more or less symmetrical graduation. The backs are a whole different ball of wax, with the center being around 4mm, and getting thicker toward the neck up to about 7mm near the button, with the rest of the back being more or less symmetrical, and the minimum being about 2.5mm.

[D.E.Williams]

Adrian Minarovic (mandolincafe name: Hogo). Plans based on a 1923 Loar. I think they are regarded as being the best availble for accuracy. They're available through Elderly for $50: http://www.elderly.com/books/items/656-1.htm

Germain

They're apparently out of stock, and Adrian is working on new plans.
Elderly's doesn't know when the new ones will be available and said it could be more than a year.

I'm trying to piece as much together as I can from the plans I have. They are mostly very good, but some of the contours don't quite mach the down-the-center cross section, and there are a few other minor issues similarly with the neck drawings. One can certainly appreciate the effort of all the different drawings that Mr. Siminoff did though. That took a lot of effort and work to collect the data and draw. I've talked with him on the phone, and he's a heck of a nice guy.

[HoGo]

Hello,
Yes I'm working hard to release the new version ASAP. Basicly, the drawing work is done. I need to decide on layout and sheets size (probably smaller format but more pages).
Re the OP: I showed moro or less the thicknesses from original Loar specs sheet. Actual Loars may be down to 2.2mm (and even less) in the recurve of tops. I'll show a grad map from a '23 Loar with such thin spots in the new version of plans. The backs can be even thinner in places (down to 1.9mm). But 3.1mm and 2.5mm was what Gibson wanted to use.
I hope this helps.

[Rick Turner]

If you read up on the history of violin makers trying to reproduce Strads, then you'll see that blind (or deaf) adherence to sets of measurements rarely gets the desired results because each piece of wood is different. If you go for Loar graduation on an Englemann top, for instance, you're likely to get very different results than the same graduations on a Sitka or Adirondack top...and here I'm just assuming that we're dealing with "typical" versions of those woods. Yes, I know there's tremendous overlap of stiffness and density, but the averages are a bit different. This is where deflection measurements are helpful. If I had that old F4 top, I'd be at least as concerned about it's deflection specs and the density as the actual graduation measurements.

[UncleNorm]

Making a comparison of F5 plans (any) with a real F4 top is probably more for interest than to copy. For starters, the F4 has an oval sound hole, and a single horizontal brace. The F5 has "F" sound holes and parallel bar bracing, never mind different curvatures caused by the floating (vs. attached in F4's) fingerboard. As has already been said, wood varieties will impact on "how thick" to carve. Then there is brace/bar tuning which unlikely comes into play for F4's.

[HoGo]

I measured '21 F4 and it was very close to average Loar grads. (except near the f/b).
Each mandolin is different, lots of hand sanding/scraping took place...

[carleshicks]

The reason I bought the F-4 top was to see how the graduations blended over the whole top. I was having a hard time visualizing the graduations just from the print. I thought that the F-4 would be completely diferent thickness in graduation so I was suprised to see that it was pretty parrelel. I can see that the arching is different, and the recurve is not very pronounced on the F-4. I have seen a few F-5's Loars that the Recurve was very visible and others that it just kind of arched up from the flats on the edge. i guess that is what makes it so much fun to copy these, they where all different.

[Michael Cameron]

If you read up on the history of violin makers trying to reproduce Strads, then you'll see that blind (or deaf) adherence to sets of measurements rarely gets the desired results because each piece of wood is different. If you go for Loar graduation on an Englemann top, for instance, you're likely to get very different results than the same graduations on a Sitka or Adirondack top...and here I'm just assuming that we're dealing with "typical" versions of those woods. Yes, I know there's tremendous overlap of stiffness and density, but the averages are a bit different. This is where deflection measurements are helpful. If I had that old F4 top, I'd be at least as concerned about it's deflection specs and the density as the actual graduation measurements.

I remember seeing Don MacRostie's(Red Diamond) device for measuring deflection of tops and backs(about 12 years ago). I think he tested them both before gluing them up.

Just wondering how many builders use a device like that or measure deflection of different woods?