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Step 2: The Mould

In order to make the bass' body a mould has to be used to give it it's shape. There are three shapes that I know of. The Gamba, Violin, and the Busetto. They are all very interesting and nothing short of beautiful and as my photo shows, I decided to make the violin style bass. In order to make the mould however, I had to draw it out on the 3/4 sheet of plywood using a grid. I had to be very careful with the placement of the corner blocks, neck block, and end pin block. Once it was drawn out, I proceeded to cut it out with the jigsaw. After it was cut out, I traced it over the sheet of plywood and cut it out again. These two mould layers were then separated in the middle with scrap wood. Finally, when the mould was cut out, I drilled a series of holes along the sides of the mould in order for the clamps to have something to grab on to.

In order to make the neck block, I assembled one out of 6 pieces that I cut out of the 2 x 10 x 12 and glued together(the last piece to be glued was thinned down by about 1/4 of an inch). I used the mitre saw to perform a dado cut on each neck block piece, I found it to be much more precise than cutting out the slot on top with a jigsaw. As for the corner blocks, I cut out four pieces measuring 8-3/4" long out of the 2 x 2 x 8. The end pin block was simply a piece of 2 x 6 that was cut to 8-3/4" in length.
<p>Hi buildingupbob,</p><p>Many thanks for sharing this project, and congratulations with the successful completion!</p><p>You may get quite a few followers, and therefore some comments.</p><p>1. Tuners.</p><p>I believe you have installed these tuners oriented the correct way. In situations where the peg is supported on both sides (like Double Bass = DB, Spanish guitar), the force of the string in combination with wear will cause the sprocket to go towards the tension, over time, so into the worm. In situations where the peg is supported on only one side (like electric guitar, bass guitar), the tension will cantilever the peg and wear will cause the sprocket to go away from the tension. In those cases the worm should be above the sprocket. Tuners made for mounting that way also have the gears cut in the other direction: a counter clockwise rotation of the flapper (as seen from the flapper side) normally causes the string to tighten.</p><p>I do however not recommend to drill the holes for the pegs perpendicular to the central axis of the neck, as you did with a column drill. In order for the tuners to fit properly on all sides, and without gaps, those holes should be drilled purely perpendicular to the outside of the pegbox they are mounted on. So if the 2 sides are not parallel, like here, the pegs cannot be parallel either. This is particularly important with pegs supported on both sides, and even more so with conventional DB plate-type tuners.</p><p>2. Instrument tension &amp; bracing</p><p>One of the aspects in which your DB differs from a conventional DB, is that it has a flat top. The top is normally curved outwards, and one of the reasons for that is that the curved geometry, in combination with the longitudinal forces on it by the neck and the end nut, provides an upwards force in the centre. That upwards force helps to carry the bridge, at least on the E-side (with the G-side being largely carried by the sound post). The bridge pushes down onto the top with 2T.sin(90&deg;-&szlig;/2) (T = total tension of the strings, &szlig; = the break-over angle, i.e. the angle the strings make when bending over the bridge), and that can be quite a significant force. Furthermore, with the bass bar below the top, the geometrical force is also downwards. So even though the strings you used are ultra low tension, I fear the top might be subsiding over time.</p><p>In a situation with a flat top like this, it should be considered to install the bass bar on the outside, i.e. between the bridge &amp; top. It looks a bit silly, but that way you at least get some geometrical lifting capacity. Not quite enough, but it helps.</p><p>For completeness, the bracing on the back should stay on the inside, as you did. Conventional flatbacks have their bracing running sideways, but with a ply back longitudinal (as you did) is probably preferred.</p><p>3. Glue</p><p>My 2 cents as follows:</p><p>A perfect joint done with hide glue is amongst the strongest available, does not creep, lasts forever, is invisible, and hide glue has the advantage that the joint can be un-done by heating. But hide glue requires skill, diligence &amp; patience, and without that very few joints are perfect. If it doesn't fit right, the water in the glue dissipates and you get air pockets (so 0 adhesion there), and if you didn't get the temperature right, the adhesion is poor (is why blades separate from ribs so frequently). Nevertheless, if you make a high value instrument, expect it to live for centuries, and it needs to be maintained: for such there is no alternative to hide glue.</p><p>But if you are not dealing with a high-value instrument, or if the joint you make is not supposed to ever be taken apart, or if your fit is not so perfect, or if you're in a hurry, you're probably better off with a modern glue:</p><p>- a foaming PU glue: can be reasonably quick &amp; fill gaps. If a gap is filled with foam, it is not very strong - but probably strongest available for that poor fit. With a good fit, PU is sufficiently strong for most instrument applications, and lasts a long time too (certainly decades). Requires brute force to be taken apart, but can be repaired with new PU.</p><p>- epoxy: quick epoxies are generally lousy glues, weaker than marginally foamed PU. But they fill the gap, and you're done in 15 minutes. Again, some force to undo, and temperature helps too. Repair w/ epoxy.</p><p>Ultra slow epoxies can compete with hide glue for strength, but also require a good fit (though not necessarily as good as for hide glue), and final setting times in the order of months. Expensive too. Can be considered for a structural joint (or repair) never to be taken apart. In instruments, that's structural repairs only.</p><p>- PVA (white glue, carpenters glue): can be quick, can be strong, have some gap-filling capacity. But they creep, are highly visible, and are a dead-end street. Repairs are difficult to do well: nothing sticks well to set PVA, and it is difficult to remove. But it is easiest to work with, hence probably the best choice for projects like this.</p><p>4. Sound post (SP)</p><p>The exact placement of the SP makes quite a difference to the sound &amp; character of the instrument. It is normally placed a bit south of the G-foot, and the optimal place is found by trial &amp; error. If you don't have a setting tool, you can easily make something by bending thick wire in shape. After setting it at the approximate location, tap the SP to the desired place by means of some suitable tools (like an old-style soldering iron (= not electric, but the ones you heat-up with a flame), suitably bent). Of course set without string tension, and move after taking sufficient tension off the strings. Best not glue the SP in place.</p><p>In spite of all my comments: congrats with a job well done &amp; many thanks for sharing it!</p>
<p>Hello, sorry for a really late reply and thank you to you too for the all of the wonderful information. I can tell you know your way around a double bass. If I ever do make another one (which I hope I do) I'll be sure to keep all of this in mind as you've given me and everyone wanting to make one a lot to think about :)</p>
<p>If the string length (the sounding part = scale) is anywhere near 42&quot;, it is a 3/4 bass.</p><p>On the exterior bracing of the flat top, it's not something I thought of, I saw it from a guy who experimented w/ balsa violins. Physically (wrt carrying capacity of the bass bar) it makes perfect sense, and practically it allows you to 'tune' your instrument. When installing, you make the bracing a bit heavier than you think is required. And when all is assembled, you can thin it down to your liking, while being able to play the instrument &amp; perceive the effect. Downside is that it doesn't look so hot. Bit industrial. (As bracing I would suggest a longitudinal bass bar below the E-leg, and 2 transversal braces at the widest part parts.)</p><p>More importantly: do you still play the instrument?</p>
Sorry, but what size is it? I've been looking up basses and found that some are 4/4, 3/4, 1/2, and so on.
<p>Hello, I am incredibly sorry for being so late to reply but to answer your question I don't really know. It was supposed to be 3/4 at first but I ended up making it a good bit wider. </p>
<p>Hi</p><p>i would like to thank you for your instructable. it was kind of giving me the last impulse to start an upright bass project by myself.</p><p>During my research the most i could find were comments like: just by a cheap one.</p><p>when i did finally find your instructable i thought okay just go for it.</p><p>I did several things different, but i am finally done.</p><p>so thanks</p>
<p>Hello, sorry for replying so late but you're very welcome I'm very glad I could help :) and I love the way your bass turned out, it's beautiful in every sense of the word. You are incredibly talented!</p>
<p>Great post and a good looking instrument. Please check out this link for discount bass parts http://www.janika.co.uk/Contrabass_Parts.php</p>
Hi, I'm just wondering why you didn't use hide glue? I'm looking at fixing a busted (REALLY busted) bass and considering hide glue vs. other types of glue for the repair, what do you think?
Hello, I didn't use hide glue because I couldn't find any locally where I live and I was afraid it wouldn't hold as I had never used it before. The major setback with me not using it is that the glue I used doesn't dissolve with water so if it breaks, I can't really do much :/ but then again I made the bass for fun and didn't really keep this in mind.
Thank you :) I'm suspicious of the odds because I fixed a smaller instrument (The neck of a guitar) with gorilla glue and it has held up in abhorrent climate extremes for almost a decade. That said a bass is a high tension instrument and probably actually needs the hide glue for a repair (instead of ground up construction)
Yes! We want a video.
lol just uploaded one , I hope you like it.
Thanks! Sounds great. Rich deep sound. It would be interesting to have a practiced bass player put it though its paces. With your construction gift, you should invent some new instruments!
That *looks* really cool, but can we hear it?
Yup, I just uploaded a sample video I hope you like it.
You need to change the settings on your video - it tells me it is private.
Sorry, I tried deleting my Google+ account but it messed up my entire YouTube channel, I fixed it now though, enjoy :)
Awesome!
+1
I want to hear it too! It looks like an amazing project, and congratulations on the ribbon!
Thank you :) I just uploaded a little video I hope you like it.
Structurally it's a far cry from a traditional bass, but it's very creative and well made. I think you could take those skills and make a real carved or molded top bass one day.
Thank you, hopefully I can get to work on one in the near future.
How does it sound? I would love to see a video of someone playing it. Good job!!
Thank you and I just uploaded a little video to show how it sounds
That magnum gator line you used for strings?
No, they're Slap Happy weedwackers. Not the best strings but they got the job done.
I've been whining for years that I'll never afford a double bass; this has inspired me to make one! <br> <br>One question, what are the approximate dimensions for the back/front? Unless I missed it in the Instructable? Is it made from a 4 x 8' sheet of plywood?
Yup the sheet was a 4 x 8 I bought at lowes, it wasn't that expensive. Good luck on making one! <br> I got the dimensions of the bass from gollihur's website, here's the link: <br>http://www.gollihurmusic.com/faq/2-SIZES_DOUBLE_BASS_SIZING_FAQ.html
Congratulations on building such a difficult and beautiful piece. While I was not near as good as you in high school, my shop teacher made a great impression on my and now my hobby of wood working still continues. <br> <br>Good luck with your future pursuits
Thank you and good luck with your future pursuits too.
Wow! That is so cool!
Thank you!
your bass is remarkable; but even more remarkable is your incredible level of craftsmanship. those pieces could have been factory produced! that level of skill is rare. <br>don't abandon this type of work. you are one of a kind.
Thank you very much, that really made my day :)
how does it sound?&nbsp;<br> ive been a bass player since 2nd grade, and playing in the orchestra throughout my whole time at school. I used to have an upright but now I only have a couple electric basses and a few electric guitars, and an acoustic guitar (need an acoustic bass badly)...&nbsp;&nbsp;<br> &nbsp;<br> I badly want a upright again. I'm also a carpenter with a full wood shop and I might take what you did and make it my own, just curious how it sounds with your choice of wood, and if you would change anything (like the type of wood used for individual parts).
To me it sounds great but I think I would make a few changes. I would make the neck and tailpiece out of oak I don't know what it is about oak but I love it and I would definitely use bendyply rather than the one I used. Aside from that, I don't think I would change anything else.
Great project now I want to build one! <br> <br>One point I noticed is you seem to have installed your machine heads backwards. They should always be installed with the worm towards the back and the gear in front i.e. sound box side so that the gear is pushed into the worm.
Thank you and yeah I kind of rushed putting the gears together. I didn't realize it until after I was putting it on display at the competition xD

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Bio: In short I like anything that has to do with clay, chickens, pokemon, sonic and wood :P
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