markdavid Posted February 12, 2008 Share Posted February 12, 2008 Hi , was wondering if anyone would be able to help , I have aquired a new p bass , have lowered the bridge saddles as low as they will go but action is still quite high. Do I need to tighten or loosen truss rod to correct this ? Quote Link to comment Share on other sites More sharing options...
bremen Posted February 12, 2008 Share Posted February 12, 2008 [quote name='markdavid' post='138815' date='Feb 12 2008, 01:01 PM']Hi , was wondering if anyone would be able to help , I have aquired a new p bass , have lowered the bridge saddles as low as they will go but action is still quite high. Do I need to tighten or loosen truss rod to correct this ?[/quote] It sounds like you have to tighten it, to counterbalance the strings. Be careful though, it could just be that the neck is perfectly straight but is too low in the pocket. I've seen this a few times. If this is the case you'll need to shim the neck (or mutilate the bridge saddles). There should be a sticky somewhere here on setup and truss rod adjustment. Basically if you fret (simultaneously) at the 1st and 21st frets, is the gap between the string and the 10th fret excessive? If it's less than the thickness of a business card don't try and tighten the truss any further. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted February 12, 2008 Share Posted February 12, 2008 You need to shim the neck. Take the neck off and cut a piece of thin plastic (I used the plastic from the blister pack from a set a of TI strings - it doesn't need to be very thick) the width of the neck pocket and about one third to half the depth (the smaller the shim depth the greater the angle). Fit this at the body end of the neck pocket and re-attach the neck. It may take a couple of tries to get the right combination of length and thickness and you'll be surprised just how much difference such a small amount of "padding" makes. The truss rod should be used to set the relief of the neck only. Quote Link to comment Share on other sites More sharing options...
bremen Posted February 12, 2008 Share Posted February 12, 2008 [quote name='BigRedX' post='138824' date='Feb 12 2008, 01:13 PM']You need to shim the neck. Take the neck off and cut a piece of thin plastic (I used the plastic from the blister pack from a set a of TI strings - it doesn't need to be very thick) the width of the neck pocket and about one third to half the depth (the smaller the shim depth the greater the angle). Fit this at the body end of the neck pocket and re-attach the neck. It may take a couple of tries to get the right combination of length and thickness and you'll be surprised just how much difference such a small amount of "padding" makes. The truss rod should be used to set the relief of the neck only.[/quote] Is my advice wrong then? I'm not suggesting that adjusting the truss rod is necessarily the solution, but surely if it's too loose then the relief should be adjusted first, then when that's right get onto shimming if necessary. Quote Link to comment Share on other sites More sharing options...
BOD2 Posted February 12, 2008 Share Posted February 12, 2008 Adjusting the truss rod is used to set the correct amount of "relief" in the neck. The relief is a small amount of "bowing" along the length of the neck that allows fretted notes to vibrate freely without striking adjacent frets. It will have a small effect on the action, but only if the truss rod is currently very badly adjusted. Truss rod adjustment is not normally seen as an adjustment for the action. More info [url="http://www.garywillis.com/pages/bass/bassmanual/trussrod.html"]garwillis.com[/url] [url="http://www.tunemybass.com/bass_setup/adjusting_neck_relief.html"]tunemybass.com[/url] Shimming the neck changes the angle between the neck and the body. If you tilt the headstock back then this allows the action to be raised more. If you tilt the headstock forward then this allows the action to be lowered more. It sounds like the neck here needs to be tilted forwards - this would lower the action and allow you to raise the bridge saddles up a bit to get you into the correct adjustment range. BigRedX - if the action is already too high, wouldn't the shim need to be placed at the neck end of the neck pocket in order to lower it ? (or if there is already a shim in place - just remove the shim) ? I can't get my head round this today Some Fender basses have "micro-tilt" necks which allow for neck adjustment without shimming. Check the 4-bolt plate at the back of the neck. If there is a small hole in the plate then this if for neck adjustment. Loosen the strings off, then loosen each of the 4 neck screws slightly (you don't have to take them out). Now put a correct sized allen key in the hole. Turn clockwise to move the headstock back, or anticlockwise to allow it to move forwards. Tighten the 4 screws to complete the adjustment. [url="http://www.fender.co.uk/support/basses.php"]Fender[/url] Quote Link to comment Share on other sites More sharing options...
BigRedX Posted February 12, 2008 Share Posted February 12, 2008 I've done a diagram to show the when to shim and when to adjust the truss-rod. You should check the relief of the neck first, but in my experience when I've run out of bridge adjustment the it's been the neck/body angle that needs adjusting not the relief of the neck (except once when both needed adjusting!). The tilt the neck back to lower the action the shim needs to got at the body end of the pocket. Hopefully the diagram makes all this clear. Quote Link to comment Share on other sites More sharing options...
bremen Posted February 12, 2008 Share Posted February 12, 2008 [quote name='BigRedX' post='138864' date='Feb 12 2008, 02:09 PM']I've done a diagram to show the when to shim and when to adjust the truss-rod. You should check the relief of the neck first, but in my experience when I've run out of bridge adjustment the it's been the neck/body angle that needs adjusting not the relief of the neck (except once when both needed adjusting!). The tilt the neck back to lower the action the shim needs to got at the body end of the pocket. Hopefully the diagram makes all this clear.[/quote] pictures worth 1000+ words. Gold star! Quote Link to comment Share on other sites More sharing options...
Hamster Posted February 12, 2008 Share Posted February 12, 2008 The contact the neck makes with the body makes a difference in tone - the more contact the better. When I shim a neck I use several layers of very thin shielding tape to make more of a 'wedge' shape to optimise the contact, a bit like this: ______ __________ ______________ __________________ A professional luthier I'm not - but it seems to make sense Hamster Quote Link to comment Share on other sites More sharing options...
simon1964 Posted February 12, 2008 Share Posted February 12, 2008 All good advice on shimming the neck. Here's a link to Fender's own set up guide, which has some useful info on setting up your bass (including their advice on how to shim the neck - about 3/4 way down) [url="http://www.fender.co.uk/support/basses.php"]http://www.fender.co.uk/support/basses.php[/url] Quote Link to comment Share on other sites More sharing options...
Thunderthumbs Posted February 12, 2008 Share Posted February 12, 2008 [quote name='bremen' post='138873' date='Feb 12 2008, 02:26 PM']pictures worth 1000+ words. Gold star![/quote] Too right. +1 for that. Quote Link to comment Share on other sites More sharing options...
BOD2 Posted February 12, 2008 Share Posted February 12, 2008 [quote name='Hamster' post='138939' date='Feb 12 2008, 04:02 PM']The contact the neck makes with the body makes a difference in tone - the more contact the better. When I shim a neck I use several layers of very thin shielding tape to make more of a 'wedge' shape to optimise the contact, a bit like this: ______ __________ ______________ __________________ A professional luthier I'm not - but it seems to make sense Hamster[/quote] While I totally agree with the logic behind this, it appears that things are not quite as simple as they seem. The Fender "micro-tilt" neck worked by embedding a small circular metal plate (about the size of a 10p but thicker) into the heel of the neck. A small allen screw and threaded holder were then fitted into the neck route on the body. If adjusted to pull the headstock back, the allen screw would push the heel of the neck away, such that the heel of the neck would not be touching the body at all ! I've seen other people recommend exotic wood shims whereas many make do with business cards. Amazingly it doesn't seem to make any difference ! I don't understand it really, I'm just making an observation. Quote Link to comment Share on other sites More sharing options...
bnt Posted February 12, 2008 Share Posted February 12, 2008 A while ago I put a temporary shim (1mm plectrum) in my Tune TWB-43, and I've just tried the stacked shim idea that Hamster suggested, using Gaffa tape. Seems OK so far, but the screws nearest the bridge have further to travel, and have dug their washers a few mm in to the body from the rear. I'm a bit annoyed that I've had to do this to a new bass, but that's what I get for buying a bargain off the 'Net from Germany, I suppose. My preferred solution would be to lower the bridge, of course. My other two basses are neck-through headless basses... good thing this doesn't happen to them. Quote Link to comment Share on other sites More sharing options...
GreeneKing Posted February 12, 2008 Share Posted February 12, 2008 Excellent bit of explanation BigRedX. This needs to be preserved somewhere Quote Link to comment Share on other sites More sharing options...
markdavid Posted February 15, 2008 Author Share Posted February 15, 2008 thanks for the info guys , can I use cardboard to shim the neck (eg. the carboard that the rotosound string packs are made of) , this would be ideal if I can as it would be easy to cut to fit , however im concerned that humidity/changes in humidity/weather might affect the shim if made of cardboard , forgive me if this sounds dumb, im not very bright were these kind of things are concerned Quote Link to comment Share on other sites More sharing options...
Kev Posted February 15, 2008 Share Posted February 15, 2008 i imagine that would be fine, give it a go! Quote Link to comment Share on other sites More sharing options...
Muppet Posted February 15, 2008 Share Posted February 15, 2008 I use a piece of plastic cut from the back cover of those flexible A4 document folders. It's a perfect thickness. I cut mine the width of the neck pocket and about 1/4" deep which more or less replicates the size of a Fender factory shim. Quote Link to comment Share on other sites More sharing options...
robert43 Posted February 16, 2008 Share Posted February 16, 2008 Some people use sand paper the logic is that 1 side which has the grit ( + you can try diffrent grit for the thickness) which bites into the wood thus wont move. I have also here of people using gyprock( thats what we call it in Australia plaster for wall Yanks call it drywall) sanding sheet it works like the sand paper but has both sides with grit to bite both body & neck Quote Link to comment Share on other sites More sharing options...
BOD2 Posted February 16, 2008 Share Posted February 16, 2008 [quote name='markdavid' post='141394' date='Feb 15 2008, 10:09 PM']thanks for the info guys , can I use cardboard to shim the neck (eg. the carboard that the rotosound string packs are made of) , this would be ideal if I can as it would be easy to cut to fit , however im concerned that humidity/changes in humidity/weather might affect the shim if made of cardboard , forgive me if this sounds dumb, im not very bright were these kind of things are concerned[/quote] From what I've read in various places you can use just about anything ! It seems to make no difference at all. Once the neck is screwed back down tight humidity won't be able to reach it. I can see the logic of sandpaper but if your neck moves enough in the neck pocket to make the sandpaper bite in then I would think that shimming the neck is that last of your worries Quote Link to comment Share on other sites More sharing options...
BigRedX Posted February 16, 2008 Share Posted February 16, 2008 You'll be surprised how little material you need to add to the neck pocket to significantly change the neck angle. On my Lightwave Sabre A thin piece of plastic cut from the blister pack of a set a TI strings approximately 60mm long in a neck pocket 130mm deep was enough to give me the couple of mm extra hieght adjustment I needed at the bridge. Quote Link to comment Share on other sites More sharing options...
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