JZ-6 to Bass VI conversion project

One week ago, I don't even think I was aware of the Bass VI. I maybe saw the tommycarlos thread about building one in an apartment, maybe I saw one peripherally in a video from the late 60's or something.

But last week, I was made aware and I became obsessed. I am, at heart, a bass player. In the recent years I've been playing a lot more guitar, and recording music on my home computer using guitar and bass. September 2020, while trapped in my apartment, I began making guitars.
So when I was (re)introduced to the Bass VI, I knew I had to build one.
I poked around for a day or two, and eventually landed on the JZ-6 baritone kit. And, seeing as how it's been done before, I figured "What the hell, worth a try"

So I've got the JZ-6 on the way, should be here within a week or so, and I am beyond excited.
So excited that I'm already starting this build diary thread.
I just want to kind of organize my thoughts, maybe catch the interest of some of the wizards who lurk around these parts.

I know some modifications need to be made to turn this kit from a baritone to a Bass VI. I know the nut slots need to be widened to accommodate the larger strings. Also, I've read that the holes for the strings on the bridge need to be widened as well.
I know the stock tuners might not be able to handle the bass strings, so slotted tuners are probably the way to go.
Also, research indicates I need to step up the string gauge to at least a 100 on the Low E. I am planning on organizing my own custom set from bass and guitar strings, hopefully the scale length works out.

I haven't *really* thought about color scheme yet. I'm a sucker for black hardware on matte white, but unlike other kits I've made in the past, I think I'm going to get the kit here before I go off and order a ton of hardware that might not work for the project. Same with the electronics.
I know the Squier and Fender models had some fancy schmancy single coils especially made for the Bass VI, but I don't think I'll go in that direction. I love Warman pickups, so I might poke around there once my ideas solidify a little more.

Anyways. Just starting this thread to take the community's temp on this project, also to keep myself accountable as I would like to document this build because I anticipate it being a blast.

Thanks for reading this long, meandering nonsense!

So! Good news and bad news!
First, the good news...the kit already arrived! Way in advance of when I anticipated, which is great. Secondly, the wood is really gorgeous!
Attachment 42989
I was planning on matte white...or some sort of very, very dark charcoal grey or something like that, but I have to at least attempt to give this thing a natural finish. I think I will be sticking with my trademark black hardware where I can (I will attempt to fabricate a pick guard, get black tuners, swap knobs) The knob plate, bridge, and tailpiece are a maybe-down-the-road-swap type situation. Right now I will stick with the chrome. I think that will look good with the natural finish and black accessories anyways.

Then there's the bad news. Well....not bad news.
There's work to be done to get this thing playable. But that's what we are here for right!?! RIGHT!?!?
Attachment 42990
Something seriously funky (not the good kind) is going on with this neck pocket.
Pictured here, you see how high the heel sits above the pick guard. I mean..you can see quite a lot of neck under the fretboard, I don't know. That stuck out to me.

And...yeah
Attachment 42992
Then I threw a string on there just to see what was happening there (regular guitar strings are definitely not fitting on this 30" scale but you all probably knew that already and were just waiting for me to figure it out)

but the 6th string reached the tuner so I tensioned it up and raised and raised and raised the bridge to get it off the neck and....whoops!
Attachment 42991
That's not supposed to be like that!
So
I think the next move is to....deepen the neck pocket? Which is something, even after 9 other builds I have yet to do...so. Wish me luck? Give me some pointers? It's back to the research stage it seems.
All in good fun. I haven't given up on this just yet, there's still some fight left in me. I mean come on. It's night 1

I ordered a modified JZ-6 quite awhile ago with the same idea. My order had no hardware or routing other than the neck pocket. I like hardtails so my idea was to put in place a hardtail bridge with through body strings. This matched with a Jazzmaster blank pickguard, as I like to keep things simple. Pickup wise I was going for some P90's with similar values to the original single coils but was only going for twin pickups rather than triple. I also thought about a single Kent Armstrong dual/power blade as I have used one before and it can be setup as a single coil or humbucker. I have a set of Ernie Ball Slinky strings that range from 20-90 but that is where I hit my first problem.

The strings are slimmer at the headstock so they would fit through a normal tuner but seeing as they are made for the Fender Bass vi they are considerably longer due to the original having a tremolo whereas my setup is considerably shorter and the thinner part of the string goes past the tuner and so I am trying to fit a thicker string through a much smaller hole.

I thought about the slotted headed tuners but the way most of them are set up the spacing between the holes in the head have to be correct due to the tuners being butted to each other and sharing a common screw between the tuners. I then thought about using a Jazz style tailpiece with a roller bridge but that is to be sorted out some where in the future as funding is a little bit short due to the other 4 guitars that are ahead of the bass vi copy. I even considered replacing the pillars of the tuners with some stainless steel and making my own to suit the strings which maybe the way I will go. I can polish the stainless to look like Chrome and if I use some 316 it wont tarnish.

But of course the problem with your neck was going to be a problem I would face due to how low the bridge will be with a hardtail setup, but obviously yours is the opposite. What I was going to do is make up a little jig to use with one of my routers to flatten the angle on the bottom of the neck so the angle would be as close to zero as possible and reduce the height down to match the bridge. As for your problem I would say the only way to fix it would be to deepen the pocket but when you do make sure the screws don't bust through the finger board. If you have any other similar style of guitar just measure the neck angle, if it has an angle, how much of the neck sits above the body and compare the body thickness and depth of the pocket with the thickness of the neck and that will give you a starting to point to head towards but just creep up on it a little at a time.

As for colour I was going to tint my neck using some diluted Feast Watson Golden Teak stain, as I have used on all of my bolt in necks and use some, maybe, Walnut stain as I have used it on a couple of guitars and find it a colour I like but may go without a colour as the wood may look OK with just some poly on it. Or I may stain with the same stain as my neck, or undiluted, and sand back to just highlight and then cover in poly. To be determined down the road.

On a side note this is the second JZ-6 I have ordered as the first one had a standard length neck as I was in the middle of making a simplified Jazzmaster. I was using some Jazzmaster style pickups but going simple on the controls. Unfortunately during a move I have misplaced the pickups and I am waiting to see if I can find them or may have to order another set. Also lost a set of P-90's I had bought for a Strat I was putting them in. I told the missus if I buy some more and I find the others it just means I have to buy some more guitars, which she agreed to which maybe another way to expand my collection via stealth.

Unfortunately I got the pickups from Guitar Fetish, as I have used their gear on other guitars and their prices and quality were reasonable, but it seems they don't deliver to Australia any more. I had an order I was going to place and when I had a look at the shipping it had gone up from the normal $25ish to over $75, which was more than the price of the pickups I was ordering. I didn't place the order and they contacted me about leaving the order in the cart. I replied that when the shipping goes back down then I may order some more gear. Next time I looked at the shipping, Australia has been removed from the list of countries they deliver to. Their loss.

Firstly, allow me to thank you for such an in-depth and informative response. It's great to know I'm not the only lunatic who's attempting this right now.
Secondly, your ideas for the finish sounds wonderful! I would love to see pictures when you get back into it after the funds come through for this project (same boat, buddy. This happens to be the one on the front burner right now)

Lastly, all the advice re: neck. Thank you, very helpful. You know what's crazy? You kept mentioning Jazzmaster ... Jazzmaster ... Jassmaster. Wait.. I own a Jazzmaster! (bona fide Fender, a real-live factory build)
So I took it off the wall and compared. It honestly was a relief to see how similar the neck pocket shapes are.
Attachment 42999
The neck even has a similar amount exposed under the fretboard.
The picture angle is a little deceiving, the amount of body wood behind the neck pocket is actually very similar.
Sitting looking at the two bodies, I realize that I have to trim from the neck-ward side of the pocket, not the seemingly more difficult body-ward side.

So this revelation that the body is essentially identical to the Jazzmaster is great. Ground-breaking. It clears up a lot of my fears. In the research portion of this project, I couldn't find anywhere that the body of the average Bass VI is that of a Jazzmaster.
Your experiments on thru-body strings, hardtail bridge are very intriguing too. I definitely thought baout going that route, but now that you've told your hardships with trying that, maybe I will stick with the trem, though I hardly intend to use it. Might prove to be fun.
Anyways. Thanks again!

Back at the Jazzmaster...
I removed the neck to measure various things.
The necks were an exact match. 21mm of neck from end to fretboard

Attachment 43004

But about 2mm extra thickness on that fretboard!
Also, whilst daydreaming today I realized that I did indeed have to dig into the body-ward, more difficult end of the neck pocket in order to remedy the crazy-a$$ situation I had going with the gap between pick guard and string. Again, you all probably realized this and were just waiting for me to figure it out.
After measuring it appeared as though I had about 3mm of pocket to remove (not including the extra thickness on fretboard...we will see where I net out)
...in as exact as an angle as I could eyeball without a protractor, using my rudimentary basement tools.
So I got to chiseling and rasping and filing and measuring and chiseling and rasping and filing and measuring....etc.

Attachment 43003

It was hard to be patient and work slow, that is not my rock-n-roll MO.
But it turned out well

Attachment 43005

Much more appropriate. And that bridge is flat on the body, with the faux-string resting on the fretboard, so I have some room to mess with.

Life happened a bit tonight, so that was basically all I had time to do
But I did want to try out my nifty new nut files. So, although this looks god awful, it was mainly a proof of concept to see if filing would get the gauges to where they needed to be

Attachment 43006

I am going to upgrade to a bone nut before the end of this build
Next time I attack a nut with the files I will have some sort of jig set up to make sure the files go straight down the neck, and stay at the right angle.

All for now! back for more in the next couple days.

A quick note about strings.
There's a lot of discourse about Bass VI strings, like what gauge gives the least flop, which brands make the best sets, it seems like a lot.
When I started this project I thought, "What the hell, its just gauges, I can assemble my own set from a set of bass strings and a set of guitar strings"

Also, I've been using DR Black Beauties on my basses for a couple years. Something about the blackness of the strings is definitely badass, but I just love the thick tone they produce.
I think they are going to look great (and hopefully sounds great) on the project I'm working on so I ordered a 100, 80, 60, 40 set of bass strings and a corresponding guitar set containing a 32 and a 24

I measured the lengths this morning and the B and e strings are baaaaaaarely too short. They won't work with the current orientation of tuning pegs

BUT, and I'm just thinking through things out loud here, the tuners need to be replaced anyways as the bass strings won't fit through the holes.
So maybe I will toy with the idea of drilling assymetrical tuning peg holes? Like 4 on the top, 2 on the bottom? Just spitballin'.

I didn't expect to get much done this weekend, as most of the pieces for this project are current en route to my place.
But my grain filler showed up like 4 days early! Huzzah! That was one thing that was holding up any work I was going to do on the body.

I got some of stuff called Gork's GoodFilla, and thus far it's been great. (Buy straight from the manufacturer if possible, no need to cut Bezos in on this)

Here's the body slathered in black goop

Attachment 43015

Then sanded back

Attachment 43016

And finally with the first coat of stain on it.

Attachment 43017

I was really hoping for a yellower stain color. Something really 70's.
I have a couple instruments in a reddish / dark brown kind of finish. But this turned out very pretty in it's own way.

The other nonsense I got up to was some neck work.
I thought "what the hell" and leveled, crowned, and polished the frets (at least a first pass, they seem good at least thus far without strings)
Also, I'm moving forward with the crazy-ass idea of filling the original tuning peg holes, drilling in slotted bass tuners and putting 4 on the bass side and 2 on the treble side.

Attachment 43018

I will have to abandon the classic "Fender" style headstock design in this case.
I sketched up something rudimentary, at least to see if it was feasible without looking too dumb.

Attachment 43019

I was worried about the strings fanning out above the nut, break angle, etc. Typical design worries.
I was worried that what I think is called the "deflection angle" being too great, and the string popping out of the nut slot.
In a reddit post I found while researching, someone said something that totally blew my mind ( Link to give credit where credit is due )

"It's a little counterintuitive, but there's still only a single bend over the nut. If you look down the neck (from the headstock end) of a guitar that isn't straight pull you'll find that if you rotate the guitar about the axis of the neck, there is an angle for each string where it appears to be straight."

Wild. Anyways. The sketch appears at least grounded in this reality so I'm moving forward with the idea. Also, contingency, I found some baritone conversion necks for sale on eBay if everything goes pear-shaped.

You’ll need a set of 4+2 tuners if you go that route. You can’t just rotate two tuners from a standard set and hope it will work well. You want the string tension to pull the round tuner gear against the worm gear, and if you rotate a standard tuner the tension pulls the gears apart, not together. The effect is more immediately noticeable on smaller diameter guitar tuners than good quality bass tuners which have a much wider post, but engineering-wise, the correct way is far better in the long term as the incorrect-way tuners will wear out far faster than the tuners with the correct orientation.

You should still be able to arrange the tuners for a straight string pull if you play about with paper and pencil. Given the relative thickness of bass strings to guitar strings, you’ll find that to get equal distance between the outside edge of each string, there’s a noticeable offset between the centres of the nut slots on a bass. You can’t just draw the centres of the slots an equal distance apart.

It is better if you can get the strings pulling in the line of the strings along the neck as much as possible. That way you only get the string pulling against the bottom of the nut slot, not the bottom and side. You need to consider the 3D force vectors. You get less overall friction, and less is better for tuning stability. A well cut nut slot can minimise friction, so you can get away with some splaying of the strings. But if the slot isn’t smooth, excess splay angle will exacerbate this, and you could find it hard to get the string in tune to start with, and then find it’s more prone to slipping out of tune when playing.

This is going to look great

Thanks John! Yeah I'm excited. Tru-oil coats going on now. The body is starting to look really great.

Simon - That's really interesting about the tuners. I did not know about the internal construction and the fact that you shouldn't just flip 'em around.
Luckily I already have a set of 4+2 on the way. StewMac was having a sale and I thought i should at least try and do it right.
As for the nut, any tips on filing it right? I haven't seen any pre-fab replacements online really. One company has some pretty nifty looking brass ones, but i think the gauges on that are off anyways. So I think I will have to fabricate
I have a 42mm bone nut coming from graph-tec. I was thinking of rigging something to at least file more straightly. I think if i just go down the middle of the existing channel I have at least a good chance of getting them spaced right.

StewMac do nut spacing rulers, though you can get similar on Amazon for slightly less or often a more local supply if you aren’t in the US. A few videos on how to use them on the web. Always start cutting the slots with a thin saw or file to get a shallow mark, and then switch to the larger ones.

So I've built and unbuilt and rebuilt and re-unbuilt it a few times trying out different things. I drilled holes for the bass tuners and....rushed it. In typical fashion.
Looks sweet. It even held the strings and stayed in tune until I replaced the nut.

Attachment 43092

But the angle that the strings jut off into is causing a lot of problems. I was sure, against the advice of Simon, that the *one bend* in the path of the string would not cause issues.
But when there are 6 strings, high tension bass strings, tuggin' on that nut all in the same direction, well. It ain't great.

Attachment 43093

In better news, I also received the Warman pickups I ordered for it and they are great. Really, really great. Pick guard looks BAAF (not sure about swearing on this forum, I typically speak like a sailor) and I'm very happy with everything happening on the body right now.

Attachment 43094

Neck and up, not so much.
I am thoroughly disheartened that it's not working the way I had hoped, and disappointed in myself for rushing the process of making the head.
I ordered a paddle-top baritone neck on eBay and I'm going to try a different approach in a few weeks when it arrives. 3+3 on the tuners...actual math involved in sketching out the tuner placement. I will spend more time crafting the new nut.
And heck, maybe even in that time i will find a way to eliminate the trem bridge, because I don't really see myself using it. Might go with a LP style so I can go black. :p

Anyways. I'll post a pic of the pick guard when I get back to the workshop.

Looks very nice.
In terms of the trem, I picked up a rejected custom order on the specials page. It had the same trem as the JZ-6 - https://www.buildyourownguitar.com.a...t=11585&page=2
Problem was there was a fault with the trem and it would not return properly when used, jamming and throwing the tuning out. Being a lefty I could not find a replacement at the time. I finished up fitting a fixed tail plate. Found it on eBay when I searched for "Jazzmaster/Jaguar Hardtail Conversion Plate". Don't know if it would hold bass strings but might be worth a look if you don't want to use the trem. I don't use the trem so it worked well for me and gave me stable tuning and a lot more sustain.
Probably easier for you to get hold of in the US as well.

Most of the issues with nuts is that they are badly cut or still far too rough. The nut slot should slope back from the fretboard side of the nut to ensure the fulcrum point is o the front edge of the nut, and I'd rub the slot with P400 and P800 grit paper to smooth it off as much as possible. Graphite in the slots also helps. My Flying V nut has quite severe splayed string angles on the two E strings and that stays in tune happily. Splayed string angles can exacerbate bad nut slots, but unless extreme, they shouldn't be an issue if the slot is correctly cut and smooth.

Your main issue looks to be that all the strings are pulling the nut out of its slot towards the treble side, so it's going to need to be firmly glued in. Which is an issue as you'll probably want to remove it as some time in the future, so you don't want it too firmly glued in, or you'll never get it out again!

If it's not already in, I'd stick it in with Titebond without the strings fitted and let it dry well and see how that goes.

I have another tune-o-matic bridge en route to me right now, black. If I don't use it for this project, It'll get used, no doubts about that.
While I wait the 3 or so weeks for my Bass VI Neck Mk II to arrive, I've gone with the sacrilegious option

Attachment 43095

It ain't pretty, but at least the nut doesn't go flying off.
Simon - my thoughts exactly. I didnt want to glob the glue on, so I lightly super glued like I usually do and the tring tension pulling to the treble side ripped it off when I tried to adjust the tuning.
Gotta say, the ripping, cracking sound that happened when I tightened the E string was...not something I want to hear again. Thank the bass gods it was only the nut coming unglued. I thought perhaps my shoot-from-the-hip headstock was protesting it's very existence.

She looks good though

Attachment 43096

I'm proud I got the fender headstock style, not something that will easilty be reproducible with the 3-3 setup I'm planning. But maybe I will spend the next couple weeks thinking about that

Pickguard:
Proud of my wiring

Attachment 43097

Going very bare bones. I know the Warman G-rail hybrid I have in the neck position is a tremendously powerful and versatile pickup, but the way I'm wiring it is just straight into the 3-way switch so that position 1 will be full-bore neck, position 2 will be both, and position 3 will be full-bore bridge, which is the twin loco from Warman as well.
One master tone, one master volume.
And a heart-shaped thumbtack to plug the last hole.

Attachment 43098

I got a black control plate, so that'll get switched out...and then It's just waiting for the other neck I guess!

Wow. That's a pretty different approach than mine :) Especially with those tuning machines! Looking forward to hearing how it all goes once you get the new neck...

Finally got the new neck after tracking it all over Asia. Looks to be in good shape! I opted for the paddle type headstock so I could go a 3+3 orientation without stuffing it into a Fender style headstock area.
Bonus, this actually has a break angle at the nut! Which will solve another issue I was having.
I sketched out a better string path and made my holes. Already lookin good

Here's where I run into issues...

Obviously, the neck is not designed specifically for this kit.
So it is about 2.75mm thicker at the heel, and the shape of the heel does not quite match the pocket on the body.

I know what I want to do, but I thought I'd take the temp of the community to see.
Would you either:
1) trim the neck to fit the pocket
-or-
2) trim the pocket to fit the new neck

ps in the intervening weeks I purchased a router (big boy stuff I know) so with a combination of router, rasp, file, and sandpaper I would prefer to trim the heel of the neck.

‘It depends’ would be my answer. I’d really want to see it to get an idea of how it’s likely to fit together.

Firstly, what type of neck have you bought?

There are ‘true’ baritone necks with the same number of frets as the original guitar, to fit bodies where the bridge and pickups have been moved back compared to the standard guitar, so the extra scale length is shared between the neck and the body. That’s what the kit has.

Then there are ‘conversion’ necks designed to fit standard guitar bodies where all the extra length is in the neck. These normally have one or two extra frets compared to normal. If you try to fit that sort of neck on a baritone body, then the scale length won’t be correct; it will be too long and it won’t play in tune except on the open strings.