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Thread: another contour map question

  1. #1
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    Default another contour map question

    Hi everyone, I'm still yet to start my first build but doing a lot of reading,watching YT, preparing molds , woods etc. I am starting an A5 first with the help of the Stewmac plans.
    To keep this simple, is the arching for the A5 similar to the F5?
    I.e. could I use for example the Mowry F5 contour maps for the A5 as a starting point to rough out the outsides of the A5 plates?( obviously excluding the scroll area)

    There is a lot of stuff out there regarding F5 carving graduations, but not so much about A5.

    Thanks in advance, Mike.

  2. #2
    Adrian Minarovic
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    Default Re: another contour map question

    Each maker has his own style of arching (albeit mostly based upon the Loar style). Basicly the A or F style have the same arching except the scroll area. Some carve the recurve all around top (including under f-b extension) but Loars didn't have it that way.
    There are two rules that I would suggest sticking to.
    First, make sure the highest spot of top arch will be where bridge sits.
    Second, let the recurve vanish towards neck (1" from sides of f-b there should be no trace of dip in the arch).
    Keep the transition from recurve to top of arch as smooth as possible. On back the typical arch is moved slightly forward so the area near heel is not too flat and that arch also makes it a bit thicker towards neck block.
    Adrian

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    Default Re: another contour map question

    Many thanks Adrian, that's just the kind of information I was hoping for. I was wondering where to start but now I can think about using the Mowry maps and then I have a direction.
    Mike.

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    Registered User Steve Sorensen's Avatar
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    Default Re: another contour map question

    After building an F5 copy with Siminoff's graduation drawings (minus about 10% from his suggested thicknesses), I used HoGo's plans drawn from Loar Era F5s to further refine my plans, with Andrew's drawings as a great reference.

    Steve

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    Default Re: another contour map question

    Quote Originally Posted by Steve Sorensen View Post
    After building an F5 copy with Siminoff's graduation drawings (minus about 10% from his suggested thicknesses), I used HoGo's plans drawn from Loar Era F5s to further refine my plans, with Andrew's drawings as a great reference.

    Steve
    Steve, thanks for the added input. Mike

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    Default Re: another contour map question

    After more studying and searching the archives looking at thickness maps, there is even more confusion. Most of all the maps posted here relate to Loar graduations, and they're all different, and far from symmetrical. Are they meant to be asymmetrical, or is it just they they were carved with the intention of being symmetrical? I suspect some effort is made to tune the plates and this is the end result. As these will be my first mandolin builds(A5 and F5), I'm not so hung up on striving for a Loar tone. I don't play mandolin(yet) but would like at least for them to sound like a mandolin when finished.
    So I'm looking for a more simplistic approach to carving the plates. I intend to start with the Mowry maps to shape the outer domes, then use the drill press method to leave a thickness of approximately 5mm all over. Once this is achieved , I can then refer to graduation maps to refine further.
    Any thoughts would be appreciated. Thanks Mike.

  8. #7
    Adrian Minarovic
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    Default Re: another contour map question

    Quote Originally Posted by mikeyb2 View Post
    After more studying and searching the archives looking at thickness maps, there is even more confusion. Most of all the maps posted here relate to Loar graduations, and they're all different, and far from symmetrical. Are they meant to be asymmetrical, or is it just they they were carved with the intention of being symmetrical? I suspect some effort is made to tune the plates and this is the end result. As these will be my first mandolin builds(A5 and F5), I'm not so hung up on striving for a Loar tone. I don't play mandolin(yet) but would like at least for them to sound like a mandolin when finished.
    So I'm looking for a more simplistic approach to carving the plates. I intend to start with the Mowry maps to shape the outer domes, then use the drill press method to leave a thickness of approximately 5mm all over. Once this is achieved , I can then refer to graduation maps to refine further.
    Any thoughts would be appreciated. Thanks Mike.
    Loars were made in factory that made many many mandolins a week. The plates were carved on duplicating machines and final graduations or archings were not reworked too precisely. From CT scans I have some Loars definately show off center carving of inside and outside each to different direction which results in asymmetric arch and graduation. Most likely that is result of imprecise alignment of plate in the carving machine - if you drill a hole for alignemnt pin shifted to one side from centerline the error will be exactly like I described above. On the CT there is also noticeable dip in areas that can be over-sanded (next to fingerboard) on assembled instrument.
    Just don't take the maps you see as gospel. They are thicknesses of mandolins that work well (or even great) and are good starting point for your build. Just stay close to those numbers and judge stifnesses and resulting tone and after few instruments you'll start seeing what works.
    Adrian

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  10. #8
    Mandolin tragic Graham McDonald's Avatar
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    Default Re: another contour map question

    Mike, keeping it as simple as possible, once you have the 5mm all-over thickness, aim for around 4.5mm in the centre under the bridge, and gradually thinning out to around 3mm in the recurve except in front of the tailpiece where it should stay no thinner than 4mm. That should work for a reasonable piece of spruce. The three Loar graduation maps that I have tend to be a little thinner in the middle and maybe a little thicker in the recurve (though they are a bit vague in that area) but 4.5-3mm should result in a good sounding mandolin without getting too stressed about it.
    Cheers

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    Default Re: another contour map question

    Adrian and Graham, many thanks for your advice above. I'm beginning now to have a clearer picture of where I'm going with this(I think). I'm not far away now from the carving, with both sets of plates prepared, and Safe T planer sharpened and ready to go. I'll be using the STP just for the perimeter as on the Mowry maps.
    Mike

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    Registered User amowry's Avatar
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    Default Re: another contour map question

    One tip for doing the perimeter with the Safe-T-Planer that helps avoid tearout is to make a small climb cut all around the edge before going back and making a deeper cut in the conventional direction. I still taper the back of headstocks that way. The same warning applies as with making climb cuts with a router, i.e. hold the stock firmly, keep your hands away from the cutter, and take only a light pass. The name "Safe-T-Planer" always seemed to me like an invitation for a lawsuit, but in practice the worst I ever did was trim a fingernail one time.

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    Default Re: another contour map question

    Quote Originally Posted by amowry View Post
    One tip for doing the perimeter with the Safe-T-Planer that helps avoid tearout is to make a small climb cut all around the edge before going back and making a deeper cut in the conventional direction. I still taper the back of headstocks that way. The same warning applies as with making climb cuts with a router, i.e. hold the stock firmly, keep your hands away from the cutter, and take only a light pass. The name "Safe-T-Planer" always seemed to me like an invitation for a lawsuit, but in practice the worst I ever did was trim a fingernail one time.
    Thanks Andrew, I agree the STP seems anything but safe. I've never really used it much but I'll have a few practice runs on scrap first. Having routed binding channels on around 10 instruments, I'm familiar with the climb cut process, although never using the STP. On Guitars I usually give the area to be cut a couple of coats of shellac to prevent tear out, but not sure whether this works with the STP. Like I say, I'll practice and thanks again for the advice.
    Mike

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