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Been a while since I've done a build thread. I had actually come to the point where I had more guitars than I had room for and managed to sell a bunch off to free up space and reduce the collection to something more managable. I've still got a couple more I'd like to move on. However, extra space on the wall can only mean one thing - time to fill it up again!

I've actually had the parts for this build for some time now, but as mentioned above I didn't want to start it until I'd made some room for it. And it will need some room when it's finished...

In true curtisa fashion, this build will once again be a new thing for me and completely outlandish to boot. So...

Target specs:

  • 7 string fretless bass (you read that right, 7 strings!)
  • Blackwood body with figured brushbox top
  • 5-piece blackwood/sassafras neck with gidgee fretboard, 34" scale
  • Hipshot A-type bridge in black
  • Gotoh compact tuners, 4x3 configuration in black
  • 2x Bartolini slim soapbar pickups
  • Bartolini active preamp with 3-band EQ.
  • Added risk/complexity - the body will be largely cut on the CNC (what could possibly go wrong? 🙄)

The blackwood body blank actually has a little bit of fiddleback figure and some sapwood which will remain when the outline has been cut, which will be a nice touch when it's all assembled and finished:

20180522_141239.jpg

The rough locations of the cutaways has been removed from the brushbox top, which will help minimise the number of clamps required to glue it to the body blank. The offcut will then be re-used as the headplate when the time comes:

20180522_141256.jpg

A couple of brads to help locate the top to the body while it glues up:

20180522_141756.jpg

And then clamp forest (plus curved clamping caul through the middle and a couple of breeze blocks for good measure). The reason I'm gluing the top early is because I want to mill the entire body in one go on the CNC, rather than mill the top and body separately and try and line them up afterwards. Could be a recipe for disaster, but I'm willing to take a punt:

20180522_143933.jpg

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7 string fretless bass? 

what are you trying to do give me a stroke? 

the man from down under with a build thread- and one to get me drooling. watching with interest. 

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15 hours ago, Andyjr1515 said:

Wow...

...just...Wow

I say. Steady on, dear boy. I haven't built anything yet. There's plenty of scope for it to be an unmitigated disaster.

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15 hours ago, pan_kara said:

this is gonna be fun 👍

As long as that statement doesn't include, 'fun to watch this build crash and burn in a most amusing fashion' I'll be happy ;)

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11 hours ago, ScottR said:

Yep, I'm looking forward to this.

SR

Well, your current rate of builds was making me feel like I was dragging my feet. I'm only throwing this bass together to steal back some of your thunder! :P

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11 hours ago, Mr Natural said:

7 string fretless bass? 

what are you trying to do give me a stroke? 

the man from down under with a build thread- and one to get me drooling. watching with interest. 

I reckon I'm going to give myself RSI trying to play this thing once it's done. The fretboard is nearly 2.5" at the nut and 3.75" at the 24th. 

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yeah- I have to admit- I have been playing the 6 string I built a few ago and sitting and getting in first position on the low b absolutely sucks. not comfortable at all. and standing isnt much better-so- you know- I am building another one. derp

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Updates are slow at the moment as I'm waiting on some parts to arrive for the CNC to allow the milling of the body to commence, but things are still crawling along behind the scenes. Unfortunately things will slow down again fairly shortly as I'm having underpinning and restumping work performed on the house and workshop. This afternoon I've dismantled all the dust collection ducts and moved a lot of the machinery around to allow the builders access to the foundations. I'm sure @MiKro can sympathise.

So the trick with milling a complex shape on the CNC where features exist on both sides of the object (control cavities, neck pocket, pickup cavities, bridge mounting holes, string-thru holes etc) is to devise some way of flipping the workpiece to allow the machine to precisely align both halves of the milling operation. First order of the day is to make such a method doable.

The easiest method I can come up with (and perhaps the preferred method for all you CNC ninjas out there) is to strategically install some dowels in the spoilboard and drill corresponding holes in the body blank that allow the job to be flipped front-to-back so that each half precisely aligns with the other.

Step 1. chuck up a 6mm twist drill in the mill and add four holes to the spoilboard. For obvious reasons these need to fall outside the edges of the intended body shape. Please ignore the sooty skidmark in the middle of the spoilboard. That was from a previous experiment that we no longer mention in public for fear of looking like a bit of a twat (hint: wood on wood at 18000RPM heats things up fast).:

20180526_125426.jpg20180526_125747.jpg

20180526_125950.jpg

 

Step 2: line up the body blank with the centreline on the spoilboard and drill 4x corresponding holes that occupy the same coordinates as the four we just added in the spoilboard:

20180526_131645.jpg20180526_131654.jpg

 

Step 3: Install 4x 6mm dowels in the spoilboard, flip the body blank over, 'plug' the body blank into the pins and drill the same 4 holes again on the back of the body blank:

20180526_132622.jpg20180526_133027.jpg

 

Which now gives me the ability to flip the workpiece over and mill all features on both faces of the body.

Oh, and first look at the neck laminations. This is going to be a monster neck when complete. It's currently gluing up and currently clocks in at about 4 inches wide. God help me:

20180610_123836.jpg

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Looking good there Curtisa. :) yes I know that pain of the house. LOL!!

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Very exciting.  That looks a nice-sized CNC you have there :)

My CNC is of the 240 volt manual router type - Completely Nutter Controlled

 

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never heard of brushbox before but it's very pretty.  Nice work picking something more unusual.  7 strings?  you crazy... I can hardly play 4!

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5 hours ago, Andyjr1515 said:

Very exciting.  That looks a nice-sized CNC you have there :)

My CNC is of the 240 volt manual router type - Completely Nutter Controlled

 

I often have days where I'm not sure whether the person using the tool is a bigger tool than the tool he's using :rolleyes:

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2 hours ago, mistermikev said:

never heard of brushbox before but it's very pretty.  Nice work picking something more unusual.  7 strings?  you crazy... I can hardly play 4!

This the first time I've used brushbox myself (Australian native timber). It's actually surprisingly dense stuff, very tight grain. Under the handplane it almost comes away as a fine dust rather than long strings of curly timber.

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I know I've said this one or six times, but you always find the nicest timbers.

SR

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On 5/22/2018 at 9:12 AM, Mr Natural said:

7 string fretless bass? 

what are you trying to do give me a stroke? 

the man from down under with a build thread- and one to get me drooling. watching with interest. 

 

4 hours ago, Prostheta said:

Zoinks! 7-string fretless?

How have you missed this one Carl?

You must have been distracted lately.

SR

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Yes, what with union action and being unemploydinated or whatever the technical term is. I'm not an expert in these matters.

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You know me, Carl. I'm not a happy builder unless I'm trying something completely ridonculous.

At least it will incorporate an easy element for a change - no fret levelling and intonation to worry about. Playing the bugger when it's finished, however...

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You'll find it surprisingly easy. Your methods of moving around shapes will adapt very quickly.

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Well, the builders have been and gone, I have a house that will now stand upright for the rest of my life (fingers crossed), and a severely wounded bank balance. Workshop is still in a state of partial disassembly, but I can at least focus my attention on the CNC  for a bit.

Time to bite the bullet and commit endmill to timber, starting with the interior features located on the front of the body. Pickup cavities:

20180706_142922.jpg

20180706_143928.jpg

 

Control holes for pots:

20180706_143957.jpg

 

Neck pocket:

20180706_144331.jpg

 

You may wonder why I'm only milling the outlines of these cavities rather than milling the full profile. There are a few reasons why I've personally decided to do this:

  1. The endmill cutters are quite a bit more expensive than your typical 1/4" router bit. I don't want to prematurely wear them down if I don't have to. Using one 1/4" endmill to do an entire cavity is quite inefficient. Lots of chips and dust to deal with. By just cutting the profile on the CNC I can come back later with a forstener drill bit to remove the excess and then tidy up the rest of a cavity using the hand router with a template bit while still retaining the accuracy of the outer edges afforded by the CNC.
  2. The CNC might be convenient at making this all as easy as possible with minimal hands-on, but it takes a fair bit of time to make large cavities. By reducing the cavities down to just the outlines and doing the hogging-out by hand later on, I can reduce the milling time down from 2 hours to about 30 minutes.
  3. I need to retain some level of hand-made quality to this thing :rolleyes:

Top face milling complete:

20180706_150927.jpg

 

Switch to a 1/8" endmill and do the bridge mounting and string-thru body holes. It's also possoble to see how tight I made the body blank fit the CNC'ed profile. There's less than a mm of timber left at the tail end of the body here, and about the same at the tip of the upper horn at the other end of the blank - there was absolutely no way I could afford to let this slip:

20180706_154634.jpg

 

Flip the body over and start the profiles on the rear. The battery compartment is only small so I elected to ignore my cut-profile-only rule and mill the whole thing in one go. Control cavity cover recess is also milled complete but the cavity itself will be hogged out and cleaned up by hand later on:

20180706_155716.jpg

 

Rear mounting of the string-thru ferrules, including milling the shouders to sit flush once installed:

20180706_160300.jpg20180706_160353.jpg

 

Rear milling complete:

20180706_161609.jpg

 

The next trick (once the workshop is back in some kind of functioning order) is to take it to the bandsaw and trace around the profile cut to extract it from the blank. There's a 1mm lip of timber left holding the body inside the blank after milling the body shape from both sides, plus some deliberate 'tabs' of wood strategically placed for added strength. That'll also be the point where I see exacly how successfully I've managed to align the front and back milling operations together.

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Boy, you cannot deny the clean looking accuracy of the CNC milling. You need to add some sort of minor imperfection somewhere to lend it that personal touch.:D

SR

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Like a perfectly planned error, executed flawlessly? Is that what all CNC errors are? User mistakes executed with the precision and unthinking accuracy that only a machine can manage?

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