5 string neck graft or not?

[Mike Weems]

Hello I have a 3/4 Czech bass most likely made in the 30's that at some point was converted from a 4 to 5 string. I wish the leave it as a 5 string but the neck width at the nut is 42mm. Should I graft this scroll to a new neck and if so what is the optimum neck width at the nut and end?

Thank you in advance for any help.

[Ken Smith]

Originally Posted by Mike Weems

Hello I have a 3/4 Czech bass most likely made in the 30's that at some point was converted from a 4 to 5 string. I wish the leave it as a 5 string but the neck width at the nut is 42mm. Should I graft this scroll to a new neck and if so what is the optimum neck width at the nut and end?

Thank you in advance for any help.

When was this converted? Can we see some pics of the bass? Is the bassbar beefed up for 5-strings?

You can put a wide fingerboard on that neck and fan it outwards to be wider than a 4. Also, you have to be careful cutting the Nut slots and angling them into the Pegbox without rubbing the insides of the cheeks.

This is strung for Orchestra with a Low B?

[Mike Weems]

Ok sorry for the lack of info. I asked this question last night after a long day. I should have let you know that I am a professional luthier. I have been so for 29 years. I have made violins, violas, and guitars in addition to fretted and bowed instrument restoration. The extent of double bass repair that I have done has been mostly school basses and lost of Kay basses for the area blue grass people. I purchased this bass and an old flat back from friend a month ago. The top was off and there were no fittings aside from the tuners. The bass in question is fairly healthy overall.
1. The bass bar was a monolithic type.
2. The conversion date is not known
3. All the maple has air brushed enhanced figure
4. The bass bar will of course have to be replaced
5. The top grads are 9mm at the post area to 5.5mm at most of the flanks.
6. The back is roughly the same 9mm along the center joint to 5.5-6mm at flanks.
7. The neck width measures 42mm at the nut to 68mm at the end.
8. The neck is a dove tail type joint.
9. A low “B” is what has been suggested.
I am doing this to perform repairs that I do not feel comfortable doning for customers but mainly for the love of the trade. I will try to post some pics but this is new to me so bear with me.
Questions
1. Should I leave the top and back thickness as is?
2. Should I go thru a scroll graft to increase width and change to mortis type neck joint?
I should also say that I have done cello scroll grafts so I am not afraid to do this.

[Ken Smith]

5-string?

From looking at the few pictures you are showing me and without any actual measurements of the bass other than the 3/4 size, I can't see why you would pursue this as a 5-string when the neck is a 4-string size.

With comfortable measurements for playing, the strings at the Nut should be spaced from 9-10 mm on average center to center. I have seen basses at 11 and 12mm as well but that is what I called wide. I think 42 mm across is about average without actually measuring anything. I will however measure MY 5-string Hofner that was made AS a 5-string with a wide neck and fingerboard.

Now, bass wise, in USA 5s are rare, very rare. The vast majority of players going low use a C-extension of one type or another. In Europe, 5s are more popular but to the up and coming players, the C-extension is becoming more and more accepted over the 5-string bass.

So, why take a 3/4 bass or minimal construction and re-work it into a 5 string that might not be big enough to carry that low string.

Can we see the Top inside and outside as well as all the other angles of the bass in and out?

[Arnold Schnitzer]

I'm in agreement with Ken, plus this: your bass appears to have inadequate overstand for modern playing. If you do decide to make it a 5-string, you may want to do so in a reversible way. Installing a wide fingerboard would be my first choice (after re-setting the neck).

[Mike Weems]

Wow thank you for all the great suggestions. I really appreciate you helping me think through this problem. After reading the last 2 posts it sounds like I should restore this bass to its original four string status. As I said in my last post I acquired this instrument in its current state. I am not wedded to the 5 string status. Your idea to install a “C” extension sounds quite good. Here are some dimensions that may be helpful.


1. Nominal body length 1103mm
2. The string length is roughly 41.5inchs(1054.10mm)
3. Width of upper bout 508mm
4. Width @ C bout 363mm
5. Width @ lower bout 637mm
6. Rib depth @ end block 197mm
7. Rib depth @ back cut 187mm
8. Rib depth @ neck block 157mm
9. F-stop 585mm
10. Chin of neck to heel 370mm
11. Neck length from frnt edge of nut to end 442mm