Andyjr1515

Final couple of jobs ready for starting the carve on the back over the weekend, MrsAndyjr1515 permitting. I've glued a couple of sycamore fillets either side of the tuner block wedge and routed the back of the neck ready for the coils access cover: The stripy cover will be flush with the stripy neck, and the body rebates will be carved down to the neck level as part of creating the concave curve at the back.

One of the jobs to be done while the back is still flat is the holes for the magnetic pickup coils: The other is the rout to flush fit the hatch at the back that will cover those holes - which will be a longer version of this...

[quote name='TheGreek' timestamp='1495191845' post='3301992'] It's all Greek to me!! [/quote]

[quote name='samhay' timestamp='1495185667' post='3301909'] ^That all makes sense. Why that's not on the website escapes me. John's potentiometer suggestions of 5k blend, 25k volume seem quite sensible, so that's what I would use. You may find it easier to get hold of 4.7k and 22k pots. These will work fine too. [/quote] Great - thanks

[quote name='Jabba_the_gut' timestamp='1495179414' post='3301823'] E-mailed you the drawings Andy. Cheers [/quote] Brilliant! In addition to a couple of more technical drawings explaining the shunt options, this is the one that, for me, clarifies the basic wiring options and is pretty much what samhay says above: Now I don't reckon many of us would have been able to work that out without the diagram! Many thanks samhay and Jabba_the_gut Andy

[quote name='samhay' timestamp='1495183857' post='3301884'] Indeed, the MPM01 'detailed' information sheet is pretty poor. I would expect input and output impedance and some suggested wiring schemes at a minimum. (John - if you are listening...). Sound like you may have this covered now though. The MPM01 page confirms that 'Outputs can be mixed with the addition of a simple single gang blend pot.' I assume that both the mixer and piezo outputs are low-impedance. The pictures of the unit show an 8 pin IC, which I assume is a dual op-amp, which would almost certainly be configured this way. I would try a small-ish value pot - maybe try 10k - wired with lug 1 to the mixer output, lug 3 to the piezo output (or vice versa) and lug 2 connect to lug 3 of the volume pot. I would then use a 100k pot for the volume. You could scale these values up, but the key is to keep the mix pot much smaller resistance that the volume pot. The problem you will have is that the tone control won't work very well if wired as for a passive bass - i.e from lug 3 (or 2) of volume pot. However, if you don't have room for a tone control anyway, then that problem is solved. [/quote] That's great info, samhay. I've just read Jez's mail which pretty much confirms what you say - I'll post the pics that John East did for Jez...and drop John a mail suggesting he just adds this to his website to replace the out of date one that's there at the moment! Thanks Andy

[quote name='Si600' timestamp='1495183187' post='3301870'] Why haven't you finished carving the front before starting the control cavity? [/quote] It's a bit iterative. It's only the lower bout that's critical but where I've got to so far on that is the minimum curve I would be happy with: I then need to work out how deep my chamber can go without breaking through the top, and how deep it needs to go to accommodate the components, the cover and the scoop at the back. If it's generous, then I will go back to the top and increase the curve a tad. If it's tight, it will stay where it is. Also, what I do with the rest of the top carve will depend on what I've done to the back carve. So the sequence will be: [list] [*]Sort the back carve [*]Review the top carve of the lower bout [*]Finish the top carve [/list] ...if that make any sense whatsoever! Once I have the final top curve sorted of this boutcurve

Well, this looks almost artistic... ...which is probably more than the carve itself is The carved chamber's essential kit:[list=1] [*]Thickness gauge [*]Chisel [*]Deepest item you're going to need to fit under a flush cover [/list] I'm at another "Sit and THINK, Andyjr1515, before even touching anything that is going to remove wood". It is a great temptation to get out the pullshave and start the back curved carve - but I mustn't...yet Factors include:[list] [*]I need to preserve the present flat surfaces until I'm sure all and any routing has been completed. It is extremely difficult to rout on a scooped surface - ask me how I know! The one thing that probably will be routed is the covered shallow chamber the pickup coils will sit under [*]I probably should finish the reference point roundover along the back edge [*]I need to add the two small sycamore fillets at either side of the tuner block support [*]I need to work out just how much depth will be lost from the control chamber when I scoop - and where. Almost certainly I will need to go deeper (and therefore thinner) with the control chamber carve if I want to have a flush cover [/list] So I'm going to spend much of the day just sitting on my hands, looking at it

[quote name='Jabba_the_gut' timestamp='1495179414' post='3301823'] E-mailed you the drawings Andy. Cheers [/quote] Great - thanks, Jez Andy

Of all the 'go carefully' jobs, this is the one... It needs to be deep enough, but the remaining top needs to be thick enough. I know carved-archtop makers do this all the time but I'm going very carefully. I will check the thickness with some calipers this evening but I reckon there's another 3mm to come out of this. A job for tomorrow.... You can see here in the top left of the chamber the pickup cable rail breaking through. Phew - right place

[quote name='bartelby' timestamp='1495115901' post='3301404'] Nice to see you're making things easy for yourself... [/quote]

This afternoon is the carve of the main controls chamber. For those of you who are paying attention ( ), you will remember that the back is also going to be scooped out. So the control chamber cover will also need carving...

[quote name='Jabba_the_gut' timestamp='1495113198' post='3301367'] Andy, I got a couple of drawings from John East - will send you a copy when I get home. Cheers [/quote] Great - thanks, Jez

While I work out exactly what type of pots I will be using with the pre-amp mixer, the fact remains that there will be only room for two of them The access chamber has now been forstner-drilled and chiselled out. Here you see it: ...and here you don't:

[quote name='samhay' timestamp='1495106871' post='3301295'] With the MPM01, you shouldn't need a dual-gang pot for the mix/blend control. [/quote] Oh...that's interesting, samhay. How do you get the blend? I assumed you would blend between the piezo pre output and the mixer output. Is it just a single pot off the mixer output? The PDF on the web site isn't overly clear....

Now I know broadly where the body surface is going to be, the next task is sorting the control chamber. This is the basic idea: Basically the controls will be accessible from the back but hidden from the front - a bit like Gelfin's Smoothhound on his Mouradian style: From the back it will look something like (without the sharp wing-tip): Basically it will have, as a minimum:[list] [*]Onboard mixing pre-amp [*]9v battery (18 v if it will fit) [*]Piezo / Magnetic blend control [*]Master Volume [*]Jack [/list] I think somewhere I've seen a mini stacked pot. If I'm right I may even be able to incorporate a master tone...time will tell on that one. If not, I'll probably pop a piezo tone trim pot under the cover just in case it's a bit too jangly After talking to Jez at the Basschat Bash, I've opted for the John East MPM01 preamp which should be with me early next week. I looked at a number of mixing preamp, including Fishman, L R Baggs Bartolini, Cafe Walter and John East. The John East has the advantage of having trims on both the piezo and the magnetic pickups so it should be possible to dial in the right balance for starters and then have the full live playing spectrum on the blend knob. I will hog out the chambers with a forstner but will probably use chisels to do the final shaping - I've got to get pretty close to breakthrough and simply too much can go wrong with routers.... I'll let you know how I get on

[quote name='Norris' timestamp='1495047043' post='3300888'] I had to buy her a new one for domestic duties [/quote]

[quote name='LukeFRC' timestamp='1495043217' post='3300837'] It's like if Ned steinberger took acid [/quote] Ooooh - that sounds even better than tea and biscuits!

[quote name='TheGreek' timestamp='1495036584' post='3300755'] "[color=#282828][font=helvetica, arial, sans-serif]I'm pleased with today's progress [/font][/color] [color=#282828][font=helvetica, arial, sans-serif] "[/font][/color] [color=#282828][font=helvetica, arial, sans-serif]Me too....sit down, put your feet up, have a cup of tea and a biscuit.[/font][/color] [/quote] Actually, I might just do that!

[quote name='Bigwan' timestamp='1495032489' post='3300704'] Looking awesome! [/quote] Thanks! Probably done enough for one day. Best to leave it and review it in the morning. This isn't the final roundover (and isn't all the way round anyway) but it gives me a lot more idea how close the carve is getting: It's pretty much there in terms of planing - before I then go onto sanding - for the lower large bout, but this view shows that I still have a 'hump' on the upper large bout relative to the fretboard: I'm pleased with today's progress

The carve is a softly-softly job. I started by using a generous round over router bit on the back to give myself a datum to carve towards: At the moment I'm just using a couple of hand planes. With a super-sharp blade, I'm taking off a thickness per stroke thin enough to read news-print through. This is a slow, careful job. Next job was to mark the fretboard-mating edge with soft pencil so that it doesn't get inadvertently planed and end up no longer flush...: The freshly planed surface shows the figuring very well: Here, the larger bout of the lower body half is starting to get there and the upper half is about halfway: In the meantime, I've been speaking to Martin at Herricks to firm up the custom coils he's doing for us. This is where the positions will be underneath the fretboard. The cable channel, already cut, is in the centre of the lower body half join: OK - that's the cup of tea done. Now it's time to hone the plane blades and continue carving

Yes - it's an old picture....

OK - spent the evening sharpening the planes, spokeshaves and scrapers so everything is ready to go. It will be a long job, removing tenths of a mm at a time. The profile obviously varies depending on the width at each cross section, but the slimmest it will get will be where the two bouts are at their widest, here: The cross section here will be something like this (this is full size): The minimum radius at the edges will be 12-15mm at these two extremes and larger where the body is narrower

Just to illustrate how much wood is going to disappear - this is the carve so far: ...and this is where it's heading: That's why it may take me most of tomorrow. And that's just the top

[quote name='stearstree1304' timestamp='1494948709' post='3299882'] Hi-tech display unit that Andy - My wife has a couple of these - can you believe she hangs clothes from them??? [/quote] That's quite shocking... I can't believe that MrsNorris would do such a thing. And anyway, Norris tells me she's much too preoccupied trying to work out where on earth her clothes rack went to worry about trivia like that