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Ash's acoustic rabbit hole


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5 minutes ago, ADFinlayson said:

Thanks Mike, but save your congrats for the day I strum a chord without the body imploding :) 

I think at some point I'm going to ease into this sort of thing with a 335 or similar first... "your balls... they are very large balls"

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Thanks for the tips @Andyjr1515, I followed the dimensions on the plans for the ned block  not considering that but I'll see if  I can take a forsnter bit to the centre of the end block. I have tentatively agreed that a friend can have this guitar if it comes off and he asked me to put a Fishman preamp in it although I said I would build the guitar then retrofit the fishman if it's a success (I don't want to put £200 in it of it's going to implode), so you may have saved the day with the tip on end block thickness :)   

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More acoustic shenanigans! my ebay fibreglass rods showed up a couple of days ago, 5x 3 metre lengths meant I got 30x 500mm rods out of them, however the rods actually tuned out to be 3010mm in total length, so the last one of each rod, instead of cutting the last of each rod down to 500mm I left them at 510mm, the rationale behind that is that if I precarve any of the braces (where the finger braces meet the x braces for example), I can use the slightly longer ones to give more clamping pressure on the carved areas - we'll see how that goes...

Did a dry clamp, they work really well, very impressed!

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and brace yourself... first brace glued on :D Now you probably can't see from the photo but the grain direction of the brace is apparently supposed to be perpendicular to the grain direction of the back. I haven't done that because I don't have any wood that is wide enough, however the joint on the back is very good, I've also got the maple binding strip on the other side so I think this area "should" be strong enough... we'll see.

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I'm expecting the radius dishes to arrive by the end of the week, so that's when I'll be working on the curved braces. So exciting :D 

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Glue up went well and I got got the brace carved with a thumb plane and a scraper

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Once I got the other braces cut out, I marked round them with a scalpel then used a razor saw to cut away the waist material on the bigger two, but I managed to lightly scuff the back in a couple of places with the saw to I switch to chisels and got on much better

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I've marked a centre line and where the carving will start on each of the braces.

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Then I offered up the sides to I could mark where I needed to cut the long brace short, scored it a few times with a scalpel then managed to work a big chisel underneath and carefully popped it off fairly cleanly.

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And I found a razor blade works really well for getting rid of the excess glue 

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Fits quite nicely :) 

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Still waiting for kerfed linings, but radius dish is coming tomorrow so I can start on shaping the braces and perhaps get them glued on.

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2 minutes ago, komodo said:

This is amazing. You’re not going to want to give it up.

I'll definitely be making another one, I've invested too much time and money into tools/jigs. Hopefully it will be acoustic #2 and not a remake of this one when it implodes under string tension :P 

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Huzzah! braces are in. The radius dishes were both slightly warped, cupping in at the edges which was a bit annoying as that will have been reducing the radius, so I glued and clamped them back to back which will hopefully stabilise them, if not it certainly wont help my case for a return. Anyway, I put the braces in the dish and used a pencil to make the radius on them, roughed them out on the band saw and sanded them in the dish and go them glued up. 30 go bars felt a lot more when I cut them, only 4 left after sticking those braces down.

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I finally got wood today - Spare walnut sides (now obsolete), a cheep ebony back and and sides (on the off chance this build is successful) and a couple of B grade spruce tops.

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I steered the bus to put the 15 feet radius on the back of the sides, there is a spot at the very end of the heel block that I didn't get, but it's a very small area so I'm thinking I'm just going to leave it instead of making the sides too thin.

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and I've carved the back braces. I wish I took a page out of your book @Andyjr1515 and rough shaped them prior to glue up because it was a lot of effort to carve them with chisels in situ. Tapering them was easy though, I just used thumb planes and they happily rode over the the centre bar without scuffing anything they shouldn't

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I need to start thinking about rosette mate, I'm struggling to come to terms with prospect of paying for the stumac dremel base and rosette cutter as it's a lot of money. So I made this crude offering out of odds and sods in the garage - it does work at marking out the circles but it's a bit shit to be honest. So I need a better solution.

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If you have small trim router, you can make a base out of plywood or plexi but make one side really long. Then drill a bunch of holes down the center for your locating pin. I did this for cutting out circles for speakers. Use a small downcut spiral bit for clean edges. I’ve got the bits used in Rotozip tools. But I’ve never cut rosettes though so ...

Kinda like this.

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On 7/11/2020 at 4:47 AM, komodo said:

If you have small trim router, you can make a base out of plywood or plexi but make one side really long. Then drill a bunch of holes down the center for your locating pin. I did this for cutting out circles for speakers. Use a small downcut spiral bit for clean edges. I’ve got the bits used in Rotozip tools. But I’ve never cut rosettes though so ...

Kinda like this.

Thanks Jeff, I was thinking about something like that, but it feels like overkill and potentially harder to control for such a small circle like a rosette. I've now got the little dremel circle cutter that Andy recommended and will be having a go with that soon. 

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So I got myself the dremel circle cutter as recommended by @Andyjr1515 which I'm looking forward to trying out. I also got myself some new bits for the dremel which should give me some options on the rosette design, I also got them as a quick and easy way to clean out/deepen bound fret slots which was something Christopher at Crimson did when I was doing a refret course there last year.

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I've got my kerfed linings in, still need to do a bit of sanding between them and glue clean up. You will notice a couple of small gaps - Areas where the kerfed lining didn't want to bend without breaking, I decided to pre break them prior to glueing. 

I can't remember if I mentioned before but I sanded the back on the 15' radius dish prior to glueing on the linings, glued the linings just proud of the side and blocks, then sanded again until everything was flush. I followed the same process with the front just with the 28' side of the dish, and I know I've become massively unfit over the last couple of years, but steering the bus on the radius dish is a serious ab workout :P 

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And some context :) I've taken a 25mm forstner bit to the end block to make sure I can 

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Now a small issue I have here - my plans states the width of braces B3 and B4 should be 19mm wide, but doesn't include height. I was advised that those braces are normally 14-18mm high so I went in the middle at 16mm high and 18mm wide. But they seem massive, did some more digging and it looks like old martin braces are much lower more like 8mm high so I need to carve them down a bit.

I got this absolute beastie of a Record No8 on Sunday, with a few other planes from the same workshop clearance that the Bestcombi came from. Completely covered in rust as it hand't been used for years, but I scrubbed base and sides, blade and chipper with wirewool and salt and vinegar and got 99% of the rust off, gave the screws etc some oil, honed the blade and buffed it all with machine wax 

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My god it's a good plane, jointing that spruce took 4 strokes.

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 I know nothing about spruce, but that whiter strip on the outside of each piece, looks to me like sap wood so I decided to glue that up on the waste side. ACtC-3fQkMfdluDtcbOTCrzbdMc5Ckho3GMeVV1x

Now that the top is all glued up, I shall be having a go with the dremel circle cutter and attempting to make a rosette. I was going to go for walnut but when I was rummaging around in the offcuts, I found some of that golden pheobe leftover from Snuffy's bass, so I'm tempted to use pheobe for the rosette and inlays as a nice touch, and it has nothing to do with the fact that all my walnut offcuts are 1-2" thick and the pheobe is 4mm. 

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2 hours ago, Andyjr1515 said:

Did your radius dishes come with the sanding disc circle, @ADFinlayson ?  I must investigate!

Yes - the wide braces at the rear are often rounded and 8 - 10mm at their highest.

Thanks Andy, I will get those braces trimmed down before glueing it all together. Those sanding discs aren't included but G&W sell them too 

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On 7/14/2020 at 1:08 PM, Crusader said:

This expresses my thoughts exactly!

 

By the way, what are the spaghetti rods for?

The rods are an easy way of glueing down the braces that are otherwise awkward to clamp, the gobar deck has a floor and a ceiling, the gobars (rods) are wedged between the work and the ceiling to create clamping pressure, each rod creates a few pounds of pressure so the combination of lots of rods creates even pressure along the braces. I'm tempted tp try this when glueing down the top on the next solid body electric because it's a much nicer way to glue that scewing down a load of clamps.

So this is the rosette finished, getting there was a pain in the arse

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the golden phoebe I mentioned above wasn't large enough to make a rossete (on the figured area) so I went with some walnut. I routed out a couple of circles using the dremel and circle cutter, then roughed it out on the bandsaw

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then I ran it through the drum sander to reveal my rosette. 

Then after lots of measuring I carefully place and scored around it and used the dremel to route out the area 

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Then even after carefully routing in quadrants I had a nice fitting hole but with a shit-tone of tearout :(

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So I used a combination of maple and bog oak veneers to make some purfling strips and made the cavity slightly larger. I had to cut the walnut to get it to fit with the purfling but wedged everything in place and flooded it with fine super glue.

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After all the router tearout I decided to have a go with my DIY circle cutter and I'm not sure wtf happened with that because the circle just isn't circular. Trouble here is the centre pin for my circle cutter is 1/4" and the dremel circle cutter is 1/8" so I drilled the centre hole larger and the dremel was no longer an option. At this point I should have walked away, but I decided to get fast and loose withe a forstner bit, then thought "what have you done you moron"

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Then after sleeping on it I carefully shaped the sound hole on the bobbin sander and it seems to be successful. I need to fill a couple of gaps with walnut dust and glue, I also still have a small amount of tearout in the spruce which I hope I can fix with spruce dust and glue, 

I guess I need to potentially tape over the sound hole when routing or ceil with it some shellac to help prevent tearout because I don't think I could have been any more careful when routing :( 

Anyways, on to bracing the top!

 

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7 hours ago, ADFinlayson said:

I guess I need to potentially tape over the sound hole when routing or ceil with it some shellac to help prevent tearout because I don't think I could have been any more careful when routing

I wonder how some plain water would have done. Guess shellac is a better option, though.

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Good save and yes, rosettes are indeed PITA, but a shame about the tearout.

I'm not convinced shellac or tape would help.  My guess would be it's the Dremel bits themselves, or the speed or the speed and/or direction of the travel.

It's worth trying to bottom it if you have some top wood offcuts.  The bits I always use are from Small Wonder inlay supplier, I tend to use (from memory) a 1.6mm router bit and run it at around 17000 rpm and I go slow round the circle but their other sizes are all pretty good too.

How are you planning to do your purfling/binding cuts?

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2 hours ago, Andyjr1515 said:

Good save and yes, rosettes are indeed PITA, but a shame about the tearout.

I'm not convinced shellac or tape would help.  My guess would be it's the Dremel bits themselves, or the speed or the speed and/or direction of the travel.

It's worth trying to bottom it if you have some top wood offcuts.  The bits I always use are from Small Wonder inlay supplier, I tend to use (from memory) a 1.6mm router bit and run it at around 17000 rpm and I go slow round the circle but their other sizes are all pretty good too.

How are you planning to do your purfling/binding cuts?

I'm not convinced it was the cut direction because I cut in quadrants as the pic above. Could well be the bits - When I was cutting the rosette I used a couple of very fine, 0.8mm (ish) down cut bits and they cut beautifully but I managed to break them both, so I switched to the larger bit that the dremel circle cutter came with and did the rest of the rosette and the spruce with that. 
I may very well have tried to take too much depth in each cut, I ended up cutting 2mm deep because that circle cutter was very awkward to set depth and the set screw seemed to force the dremel off square and kept taking nicks out of the circle. I found that out when I was taking initial cuts in the centre of the cavity so got to full depth and started taking tiny parses at full depth to gradually increase the width of the cavity. The outer cut was absolutely fine, it was just that inner cut that kept tearing out. 

This is it after some dust and glue to fill some seams and tearout, a bit of 120 sanding to clean up the filler and wiped with some thinners. i can see a bit of discolouration where the tearout was filled that became visible with the thinners, doesn't look as bad as I thought though.

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For the binding channels I was planning to use the trim router and I've got the Radian rebate cutter set which has excellent quality blades, obviously I still have the same risk on the end-grain that I had here. I was planning to use a flush trim bit to route the excess to get the top and the back flush with the sides first and see how it behaves before attempting the binding cut.

In terms of the dremel cutting speed, I'm not sure what speeds it works at - there is no reference to speed, just notches 1 - 5. I'm assuming 17,000rpm is as fast as it goes? 

 

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That looks a pretty good result!

I'm not sure which Dremel you have - mine shows the rpm up to 25000.

Some of my bits have criss-cross cutting edges that therefore cut on both sides of the slot.  I'll check when I get a moment whether the size I used for the rosette was one of those.

Andy

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