I dont know how well it can be seen from this picture, but the string spacing seems a bit off to me. Do you all prefer strings to be equidistant from the perimiter of the strings, or equidistant in terms of the centerline of the string? It makes an even larger difference on these huge strings than on a guitar.
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Double Bass 3/4 Thomann Upright Overhaul
- Thread starter j-stylez
- Start date
To me the distance difference between strings appears so miniscule I would not think it would have much effect on playing.
Greg Clinkingbeard
Commercial User
I've now sanded the bottom of the bridge Post so that they evenly touch the top, which was not the case before.
Then I marked how much lower I wanted to get the action (with a safety margin) on the bridge. I cut off a few mm of the top edge, keeping the same arc so that it would leave me enough meat to file in the string notches. Then I carefully made new notches, so that I would not lose the marks. Then planed some material off the curved side of the bridge, towards the notched, because it was now too thick after lowering the whole top by a few mm.
Then I installed it, so that I can now lower the notches slowly by feel until I like the action.
This instrument no longer has much left in common with the first double bass I ever touched a week ago
It feels and plays completely differently. More to come...
Then I marked how much lower I wanted to get the action (with a safety margin) on the bridge. I cut off a few mm of the top edge, keeping the same arc so that it would leave me enough meat to file in the string notches. Then I carefully made new notches, so that I would not lose the marks. Then planed some material off the curved side of the bridge, towards the notched, because it was now too thick after lowering the whole top by a few mm.
Then I installed it, so that I can now lower the notches slowly by feel until I like the action.
This instrument no longer has much left in common with the first double bass I ever touched a week ago
It feels and plays completely differently. More to come...After doing more reading on bridges and what to look out for when fitting them, I understood that I have to go another round with the bridge. The flat side (towards the tailpiece) is not fully flat, possibly a slight warp or just a cheap and unsquare bridge from the start. I've still got enough material on the bridge to make some corrections, so that's what I'll do.
First I'll fully plane the south side of the bridge. Then I'll reshape the rounded (north) side, so that it still has uniform thickness at the top with a smooth taper. That's currently not the case, because I cut off part of the top to lower the Action.
Then I'll also go another round on fitting the bridge perfectly perpendicular to the top on the south side, as well as make Sure the feet Touch the top uniformly. I will use a carving knife and some crayon to do the fitting this time. One of my Problems are rounded edges from relying on sanding to do the fit in the first try, which I want to avoid this time.
I might also add some more nicely carved edges, which I saw on other high end bridges. If I mess this one up, no harm done. But it seems like it will do fine for me if I work carefully.
By the way, I played the bass for a while this morning after another test assembly. Oh my, it plays like a dream compared to when I bought it. I havent the slightest idea how someone could have enjoyed playing that in its original state. Then again, maybe that's why the previous owned sold it to me
First I'll fully plane the south side of the bridge. Then I'll reshape the rounded (north) side, so that it still has uniform thickness at the top with a smooth taper. That's currently not the case, because I cut off part of the top to lower the Action.
Then I'll also go another round on fitting the bridge perfectly perpendicular to the top on the south side, as well as make Sure the feet Touch the top uniformly. I will use a carving knife and some crayon to do the fitting this time. One of my Problems are rounded edges from relying on sanding to do the fit in the first try, which I want to avoid this time.
I might also add some more nicely carved edges, which I saw on other high end bridges. If I mess this one up, no harm done. But it seems like it will do fine for me if I work carefully.
By the way, I played the bass for a while this morning after another test assembly. Oh my, it plays like a dream compared to when I bought it. I havent the slightest idea how someone could have enjoyed playing that in its original state. Then again, maybe that's why the previous owned sold it to me
Do I understand correctly that the bridge should be set to be aligned this way?
Right angle should be on the tailpiece side? I started by making that side truely flat. Next I would carefully carve the bottom of the feet to make that right angle. Then some finishing touches on the rather rough bridge. I like the look of slanted edges and sharpened my carving knife already.
Right angle should be on the tailpiece side? I started by making that side truely flat. Next I would carefully carve the bottom of the feet to make that right angle. Then some finishing touches on the rather rough bridge. I like the look of slanted edges and sharpened my carving knife already.
To my understanding, yes, that's the correct direction. The overturning force is towards the nut as the strings are tuned, so that's where the support is needed.
Non-flatness is common with time - the bridge may well have been dead flat the day it was installed. The newly flattened bridge may well become not flat again after some months or years at tension.
Non-flatness is common with time - the bridge may well have been dead flat the day it was installed. The newly flattened bridge may well become not flat again after some months or years at tension.
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I *do* hope you are talking about at the nut, and not the bridge.
Suggestion (maybe too late):
"Final fitting for the bridge is done by taping a piece of sandpaper onto the top of the instrument and pushing the bridge back and forth to sand the bottoms of the feet so they mate with the top. I like to keep the exposed part of the sandpaper just a little wider than the span of the feet."
"Final fitting for the bridge is done by taping a piece of sandpaper onto the top of the instrument and pushing the bridge back and forth to sand the bottoms of the feet so they mate with the top. I like to keep the exposed part of the sandpaper just a little wider than the span of the feet."
I tried it like that in the first Attempt, but it's quite difficult to get just right it seems. Maybe I could carefully do that for the final fit, I'm very close now with plane&scrape. What I dont like about the sandpaper is that it seems to round my edges quickly (i dont have or want to build a roller-jig).
Okay, thanks for the hint. I'm switching back to sandpaper, but this time small movements, only one direction, and a fairly coarse grit (80). Let the paper do the Rest of the work while I focus on steady one directional movement. This looks much better already.
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I've got the action low enough for my taste now, which lets me identify a couple of spots where I have to adjust the fingerboard plane. I get slight buzzing ("mwaaaaah") on the G string when fingering the B and B# region. The fingerboard is almost dead flat under the g string, less than 1mm scoop. I need to carefully lower the Region in the middle a tiny bit, probably just a little sanding around the C, D Region to give it a tiny bit more space there.
Good work so far. One thing I learned about planing boards when I apprenticed with my local luthier -- it's counterintuitive -- use a shorter straight edge, like 12", to evaluate your scoop and find bumps easier. Moving from the nut to the end of the FB you should have a consistent (razor thin) clearance under your straight edge. Bumps may even cause your straight efge to rock.
Thanks, this is advice is very much appreciated! Checking that Region with a 20cm straight edge, I could immediately identify a very slight local "upwards bump" across that exact region. So then it's clear what is causing my buzz. I could find the same local bump on the E string, around the G. Moving around there, I can find one buzzy Spot that coincides with the upward bump.
I wonder how I'll deal with these two Spots. I think sanding, but gotta make Sure I hit the exact Spot. Scraping is more Controlled in terms of the precision, but I'm afraid to take off toi much material. Besides, if I sand with a short straight edge, it might be easier to get it even.
Maybe I first try to put a piece of masking tape just above and below the high spot. Then sand across that, with the high area inbetween. Should prevent me from sanding a crooked angle, if you get what I mean?
Use a china marker (AKA grease pencil), or simple soft lead pencil to mark where the high spots are. Just like the hashes you are putting on the bottom of your bridge feet. And yes, use a scraper. Matthew Tucker, at 2019 ISB build-a-bass workshop showed me how to make a sharp scraper with broken window glass. That's what I'd use for the high spots. Alternately, a sharp block plane might be better.