Completely traditional looking Hauser style classical guitar

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Sat Sep 24, 2016 2:44 am

Thanks guys,

I got the pureflex a while ago from Petros's website for a rosette. Now he sells it from http://purflex.net/. I am like you most intrigued but I usually do not use anything as fussy as that.

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Tue Sep 27, 2016 9:13 am

I have the guitar pore filled and about three wipes of shellac for a seal. I also started the bridge by laminating three from a BRW blank together with a CF fabric.

I used zpoxy for the back sides and necks. Ultimately I will french polish the top with shellac, and pad on Royal-lac for the rest of the guitar.


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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Tue Sep 27, 2016 9:46 am

John,

Have you drilled the string holes on that bridge yet? I ask because I had a Gore style Tas blackwood bridge fail on me a week ago. I'm pretty sure I'd built the bridge as per the book with the string holes going horizontally through the tieblock below the lower CF layer. This means you have to rout the trench between the tieblock and saddle ramp to below same CF layer. The trench then becomes a zone of weakness and in my case the tie block was taking all the string tension and the bridge folded neatly in half along the trench. I ended up re-topping the guitar and have put on a conventional bridge with string holes drilled at an upward angle from back of the tie block. I'd recommend doing the same on your CF sandwich bridge so there's a bit more wood plus the lower CF layer left at the bottom of the saddle ramp/tieblock trench.
IMG_2387.jpg
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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Tue Sep 27, 2016 10:22 am

Good idea Martin, Thank you, Sorry that happened to your bridge. I had been thinking of tilting the holes as I found that it was difficult to get the strings into the holes. I solved that issue on my last two by using some sanding string to bevel inside of end of the hole. It seems that I have another reason to tilt the holes past the CF.

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Fri Sep 30, 2016 11:10 am

I got to play with my little mini mill. I used it to help make a template for classical string holes and I used it to do a bunch of the carving on the bridge.

First off I forgot this picture in my last post but it is a pre-layup photo for the bridge blank
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The first thing I did with mill was to drill a series of 1/16 holes in a drill template for classical guitar strings. It was fun to play with the mill I learned to square the vise and deal with backlash in the x and y table. Also I had to learn how to use the various clamps. Once set up it was fun to not mark the holes, rather to just dial in each string space and moving the x-axis. When I was finished the last hole was spot on, closer than my ability to measure and mark.
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I used the mill to separate the saddle block from the tie block, I cut the rebates for the bone strips in the tie block and I cute the saddle slot. I used a luthier's friend to make the wings.

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I think I have enough royal lac on the back and sides and neck. I will start the top tomorrow.

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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Fri Sep 30, 2016 1:35 pm

What make and model is the mini-mill John?
Martin

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Trevor Gore
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Re: Completely traditional looking Hauser style classical guitar

Post by Trevor Gore » Fri Sep 30, 2016 1:58 pm

kiwigeo wrote:...I ask because I had a Gore style Tas blackwood bridge fail on me a week ago...
Interesting failure, Martin, though very unfortunate. Is the photo representative of how it failed, because it looks like the whole of the back of the bridge wasn't glued down.

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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Fri Sep 30, 2016 2:51 pm

Trevor Gore wrote:
kiwigeo wrote:...I ask because I had a Gore style Tas blackwood bridge fail on me a week ago...
Interesting failure, Martin, though very unfortunate. Is the photo representative of how it failed, because it looks like the whole of the back of the bridge wasn't glued down.
Hi Trevor,

The tieblock came away leaving the frot part of the bridge intact. The underside of the tieblock looked ok far as integrity of the glue joint...a fair bit of top wood came off with same bridge and I ended up having to re-top the guitar. I definitely think not routing the saddle ramp/tieblock trough through the lower CF layer and drilling the string holes at an angle so they exit above the lower CF layer is an idea worth considering.
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Re: Completely traditional looking Hauser style classical guitar

Post by Trevor Gore » Fri Sep 30, 2016 8:02 pm

kiwigeo wrote: I definitely think not routing the saddle ramp/tieblock trough through the lower CF layer....
Certainly, the depth of that cut will affect the strength of the bridge, especially if it is done as a full width cut that extends into the wings (which it looks like yours did). I tend to stop shorter than that because if you carry on through to the wings, it tends to define the thickness of the wings. I have run over the wings, though, and never had a problem.

The pic below shows a recent bridge, which shows how the wings taper and also the extra support the tie block gets if you shorten that first routing cut. This one is stained walnut and weighs in at ~13 gms.
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...and here's a blackwood one where it's easier to see the carbon.
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And finally, here's a through-cut one (stained walnut again) from around 10 years ago.
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...with apologies to John for hijacking his thread! Sorry, John!

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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Fri Sep 30, 2016 8:15 pm

Thanks for the pics Trevor. Maybe Im seeing it wrong but on the first two bridge the string holes must be angled up as they appear to exit in the trough above the lower CF level. The third bridge looks pretty similar to mine in regards to thickness of wood at bottom of the saddle/tieblock trough.

Apologies also from me to John for thread hijack.
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Re: Completely traditional looking Hauser style classical guitar

Post by Trevor Gore » Fri Sep 30, 2016 9:15 pm

kiwigeo wrote: Maybe Im seeing it wrong but on the first two bridge the string holes must be angled up as they appear to exit in the trough above the lower CF level. ...
In all cases the holes are parallel to, and below, the lower CF layer. I'm not sure you'd be able to drill through the CF at such a shallow angle, even if you wanted to. If you want to strengthen up the bridge, probably the best thing is to shorten the first cut so that the tie block has some "tilt" support at the ends, as per the first two pics.

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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Fri Sep 30, 2016 9:45 pm

Trevor Gore wrote:
kiwigeo wrote: Maybe Im seeing it wrong but on the first two bridge the string holes must be angled up as they appear to exit in the trough above the lower CF level. ...
In all cases the holes are parallel to, and below, the lower CF layer. I'm not sure you'd be able to drill through the CF at such a shallow angle, even if you wanted to. If you want to strengthen up the bridge, probably the best thing is to shorten the first cut so that the tie block has some "tilt" support at the ends, as per the first two pics.
Ok I see now what youre talking about. Thanks for explaining Trevor..
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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Fri Sep 30, 2016 10:17 pm

Thanks for the discussion of the bridge. I have three installed bridges cut through at the string hole, 1 padauk and one BRW 6 string. I also made an 8 string that way with BRW. The one I just made I also cut through. I like the idea of ramping up at the ends. I was surprised to see Martin's lift the way it did. On another forum I saw a simulation that show the main stress on a tied bridge at the trailing edge of the bridge. I do not remember seeing a bunch of stress 10 mm in where the break happened. It seems that the trailing edge of the bridge would have needed to lift first before the bridge snapped the way it did.

The mill that I have is a little machine shop version of the SIEG SX1P Micro Mill. So far I am finding it usable. I did not really need it but it is a fun toy I have wanted for awhile.

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Sat Oct 08, 2016 7:40 am

The guitar is all strung up. I still have to really set it up, and do a final sand and polish in another couple of weeks.

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From the last post I finished the french polish of the top with shellac and Royal-Lac on the neck, back and sides.

After a couple of day, I decided to glue on the bridge. I re-located the bridge and drilled a couple of holes to pin it in place. I had a undersized tape mask in the bridge location to make it easier to clear the finish. Not shown in the pictures, with the bridge pinned in place I used a fresh scalpel to trace the outline of the bridge in the shellac. With the tape removed I had about 1/8" inch wide strip of finish all around. It was really easy to peel that strip off using a very sharp chisel from the cleared area inside of the bridge outline to the line I cut with the scalpel. I used my vacuum clamp to glue the bridge down, remembering to clear the squeeze out after about 4 minutes.

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Today I fretted the guitar with some EVO fret wire made a nut and string it up.

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My top resonance target,T(1,1)2, is 190 Hz, At this point I am at 194 Hz strung up. The back is high at 159 Hz, and it does not really have that big of a peak. I will start shaving the back braces, until I either hit 4 semitones above the top or the top hits 190 Hz.

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A lot went right on this build, My neck angle was spot on, the bass action is 4 mm with the string 11 mm over the sound board at the saddle, right on target. So my initial setup of the saddle and the nut both built to spec off of the guitar are really close to being spot on.

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Thu Sep 07, 2017 11:01 am

kiwigeo wrote:
Tue Sep 27, 2016 9:46 am
John,

Have you drilled the string holes on that bridge yet? I ask because I had a Gore style Tas blackwood bridge fail on me a week ago. I'm pretty sure I'd built the bridge as per the book with the string holes going horizontally through the tieblock below the lower CF layer. This means you have to rout the trench between the tieblock and saddle ramp to below same CF layer. The trench then becomes a zone of weakness and in my case the tie block was taking all the string tension and the bridge folded neatly in half along the trench. I ended up re-topping the guitar and have put on a conventional bridge with string holes drilled at an upward angle from back of the tie block. I'd recommend doing the same on your CF sandwich bridge so there's a bit more wood plus the lower CF layer left at the bottom of the saddle ramp/tieblock trench.

IMG_2387.jpg
Well it a little while later .... I had a nice glue joint there is good wood all the way across the tie block. The slot I cut still left the bottom of the holes visible. I think I will tilt the holes as Martin suggested leaving the a bit more wood in place. It was such a clean break it looks all of the stress was one the tie block and the slot was too deep for the rest of the bridge's foot print to count.
split bridge.jpg
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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Thu Sep 07, 2017 12:31 pm

Jezuz John......that's a bummer. Looks like the back of the bridge didnt take too much of the top with it. I ended up replacing the whole top.
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Re: Completely traditional looking Hauser style classical guitar

Post by Jim watts » Fri Sep 08, 2017 2:48 pm

Ouch, hopefully a new bridge is all that's required.
Sorry to see that John.

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Re: Completely traditional looking Hauser style classical guitar

Post by Trevor Gore » Fri Sep 08, 2017 6:28 pm

Some pretty scary pictures here. Sorry to hear this, John.

It's hard from here to postulate on failure modes. Usually, this sort of thing stems from a peel failure from the rear edge, but John's explanation of the centre slot being too deep for the rest of the bridge to count, implying a shear failure, may be true, too.

So far, I've not had one fail on me, and I've probably done more than anyone else, so perhaps I'm doing something different. Here's a few things that I do that may not be obvious to a casual observer:

1) The top curvature in the bridge location has to be kept under control to help avoid a peel type failure, which means having enough bracing under there to prevent local distortions

2) Buttressing the tie block by not routing straight across is something I've nearly always done (as per most of the pics I posted higher up this thread). Here's another pic of what I mean. The centre slot at the ends is only as deep as the tie block trim.
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3) The bridge wings have a taper up to the tie block, which you may be able to make out in this pic:
DSCF0211s.jpg
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This bridge has no CF because it's on a Fleta style build, so no CF anywhere. The wood is EIR. The tapering is done on this jig which is just pushed into a drum sander in the usual way...
DSCF0212s.jpg
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...but the bridge on it is a very early one with "parallel" wings. That bridge, by the way, was one I tried to re-use when I re-topped one of my experimental guitars. But even with a lot of heat and moisture, I couldn't get it off cleanly and broke a wing. Here's the underside:
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American black walnut bridge glued with Titebond onto Euro spruce. There was no way that bridge was going to come off accidentally.

[As an aside, if you need to take a well-glued bridge off for any reason, and save the top, I've found it best to rout most of the bridge off then apply heat and moisture to the ~1mm thickness that's left. That will give a completely clean detachment and won't compromise the panel's centre joint]

4) So far, I've not drilled holes in the tie block angled upwards. An approach I've used is to bush the tie holes as per the pic:
DSCF8425s.jpg
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If you do this, you don't have to rely on the CF to guard against string hole wear, so the CF could be placed lower in the bridge and not be routed through.

5) I sand the curvature onto the bottom of the bridge (matching the top curvature) literally JUST before the bridge is glued down and just after I've scraped the finish off the top. The best glue joints are made with new surfaces, as they have the highest surface energy. I never mask over the bridge area. Masking tape tends to leave a greasy residue, even though the surface looks clean.

Let's hope we don't get any more unplanned detachments!

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Re: Completely traditional looking Hauser style classical guitar

Post by kiwigeo » Fri Sep 08, 2017 6:42 pm

Thanks for your valuable input into this discussion Trevor. I'm still digesting all the info from my experiences, those of John and also your comments. On my build that had the bridge failure I ended up replacing the top and making up a conventional bridge using some Brazilian Rosewood blanks I found hidden away on my shelves. The guitar is currently packed away with the rest of my workshop while I build my new house.
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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Fri Sep 08, 2017 10:52 pm

Thanks for the posts. The bridge came off cleanly no issue with saving the top, I will plane the remaining part down and use heat to remove it completely. Trevor, looking at your pictures I do see the structural advantage of not going all the way across. I will change the way I route the slot. I also will carefully check this failed bridge for where I am drilling the holes. Although eyeballing the break it looks like I had about 3 mms of wood left.

One last thought, I use a scalpel to score the finish. I ended up with such a thin clean layer of spruce across the tie block that maybe I scored the spruce allowing it to peal.

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Re: Completely traditional looking Hauser style classical guitar

Post by johnparchem » Sat Sep 09, 2017 5:08 am

I looked it over and I think this one was most likely a peel from the tail bass corner of the bridge. My guess is that there was a small corner of finish that left the an area on the back of the tail block with a poor joint.

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