tall_martin Posted February 10, 2015 Share Posted February 10, 2015 Hi, I have bought my self a Harley Benton fretless acoustic bass. Its lovely, it was cheap (for a reason). It has an iffy neck. I could send it back, get it fixed but I'm going to fi it my self. The neck is not flat. It came with the trusrod fully wound on tight a super low action. There were huge buzzes everywhere. I have slackened off the trussrod and now the buzz is between the 10th and 15th frets. There is a bump/ lump around here. Before I take some 400 grit sand paper and block to it does anyone have any advice? Thanks for any help Martin Quote Link to comment Share on other sites More sharing options...
Manton Customs Posted February 10, 2015 Share Posted February 10, 2015 You should be fine but here are a couple of pointers . Before starting, make damn sure there is definitely a bump there, do this by checking with a straight edge (as I'm sure you already did) and adjusting the truss rod to get it as flat as possible. Then, buying a radius block of the correct radius would be a good idea. If it's a noticeable bump you may want to start a bit lower than 400 (240 or something) before working your way up to 400 and beyond. Keep an eye on your progress with a straight edge. Hope none of that was too obvious . Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted February 10, 2015 Share Posted February 10, 2015 (edited) I'd try some "bark rubbing" tricks to try to find the low or high spots. With frets I've used felt tipped markers to show low areas of frets - while filing flat it can let you take the bare minimum material off. With fretless I'm less certain how it would work - without staining the wood. Perhaps a sheet of special paper - thin and uncreased like tissue paper - That plus painted / dusted straight edge could an accurate evenness detector make. By applying the paper smoothly to the fingerboard, and pencil "lead" or other ink etc. to the flat surface - it should give a pattern revealing high and low spots on the paper. That's just in my head though - there could be much easier and more accurate methods out there. Destructively planing or sanding flat is always an option if there's plenty of fingerboard to work with. Manton Customs is totally right. 400 grit is quite high to start with. If it's a big hump, start at around 120... but be careful. anything around 80 - 180 grit removes [u]a lot[/u] of material fast - depending on the material and pressure used. The lower grit you start with, the faster you go in general, but the more work is needed to take out sanding marks. You may need to go from 120 to 180 to 240 to 320 to 400 to 600 to 1,000 etc. rather than just 240 to 320 to 400 etc. if you start with 240 grit sandpaper. Try to assess the extent of the hump before you begin sanding. Oh and recheck often. EDIT: I just realized I repeated a lot of the previous comment. Whoops, my mistake. In any case good luck with the project and I hope you get what you want out of it. Edited February 10, 2015 by PlungerModerno Quote Link to comment Share on other sites More sharing options...
tall_martin Posted February 10, 2015 Author Share Posted February 10, 2015 Thank for the tips. It seems there is more of a dip in the middle than a bump at the end. Would raising the bridge have the same effect? I'll try that first with some bits of card or something. Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted February 10, 2015 Share Posted February 10, 2015 [quote name='tall_martin' timestamp='1423591575' post='2686781'] Thank for the tips. It seems there is more of a dip in the middle than a bump at the end. Would raising the bridge have the same effect? I'll try that first with some bits of card or something. [/quote] It could - a shim under the saddle could allow for greater imperfections in the fingerboard. As a reversible tweak it'd be a good option to try anyway. It may be down to a compromise of string height / playability and dealing with too much buzz. If the buzzing issues persist . . . I'd start from scratch with a setup & fingerboard leveling. Quick question - I assume you've followed Manton Customs advice "[i]adjusting the truss rod to get it as flat as possible[/i]" and checking it with a straight edge - that way you can be sure the buzzing is coming from an unevenness in the fingerboard as opposed to a setup issue. If there is a slight dip in the middle of the fingerboard that runs over a good few frets - you may need to try getting the neck straighter before assessing high or low areas. Quote Link to comment Share on other sites More sharing options...
tall_martin Posted February 12, 2015 Author Share Posted February 12, 2015 Cheers for the advice. I had not got the neck straight, so your advice has sacred me significant amounts of swearing. I started on 320 grit, then went to 70 when I realised how much there was to remove! After a lot of sanding, strings back on checking and repeating it's now lovely. Not perfect but I've stopped and will go back to it if it still bothers me. A happy ending :-) Quote Link to comment Share on other sites More sharing options...
Manton Customs Posted February 12, 2015 Share Posted February 12, 2015 Yay! . Get yourself some Micro Mesh to finish it off and give a shine it would have never had from the factory. 0000 steel wool is also an alternative which will give a similar level of shine (not quite though), but tape off anywhere you wouldn't want steel wool fragments to get if you do this. Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted February 12, 2015 Share Posted February 12, 2015 Quote Link to comment Share on other sites More sharing options...
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