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HSlash

Many Qs: Neck angle, PU cavities & neck pocket

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Hi everyone, I am planning on building my 1st PRS-style guitar. Aside from its standard shape, its going to be a bit of a Frankenstein:

Body: swamp ash, flat top with bevelled edges and belly/arm grooves (like a Strat)
Template: https://i.pinimg.com/originals/d8/eb/11/d8eb11db7cf99a4d81ee42af260219c1.jpg
Neck: TBC (preferably maple, but mahogany is more available where I live), one-piece bolt-on, ~20mm
Fretboard: indian rosewood, 24 frets, 635mm (25") scale length, 43 -> 56 taper, 12 radius, ~5mm (hence entire neck 25mm before sanding down)


Headstock angle: ??? 11 degrees? debating whether to do Gibson-style or Strat-style (parallel to top)
Neck angle: when I insert my specs into https://www.tundraman.com/Guitars/NeckAngle/index.php it gives me an angle of 1.9... But for some reason I thought flat tops and low bridges (see below) did not need a neck angle?
Neck pocket: assuming only 2 frets will overlay the body, it will join at the 22rd fret so I will trace the tapered fretboard from frets 22-24 on the body. However, how deep shall I go? I may go for a Strat-like heel for simplicity
Pick up cavities:  70 x 38mm for both bridge & neck, not sure what depth... Any opinions? 


Truss rod: low-profile 2-way 18-1/8" (Stewmac)
Nut: slotted unbleached bone for Gibson, standard string spread (Stewmac)
Bridge: Gotoh hardtail (GTC-102? Stewmac), ferrules
Electronics: Gibson Classic 57s (with legs), Stewmac standard Les Paul wiring kit

I would appreciate any insight you guys have, especially with regards to the things in bold. I appreciate this is a lot to ask, and so if you've made it this far down - thanks for reading!

51572969_2334987403399673_7526273133553123328_n.thumb.jpg.6f0d965a31a1322f2bceca8b7258bcfc.jpg51590778_691432864692801_208869074262818816_n.thumb.jpg.aa2a512befa5e82dc37b0f3525abac4e.jpg

 

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5 hours ago, HSlash said:

Headstock angle:

The headstock angle only needs to be enough to keep the string firmly in the nut when under high attack. Anything from 7 degrees and up has been used. If your angle is too low, just add a string tree like Fender does.

5 hours ago, HSlash said:

Neck angle:

The neck angle is purely an element of design. It is based upon the height of the bridge saddles at the lowest setting and the height of the fretboard over the body at the neck join. If your fretboard is the same height (or just a hair lower) as the bridge saddles, no angle is required. If it is lower, neck angle is used to line the stings up with the saddles.

5 hours ago, HSlash said:

Neck pocket

The depth is determined by the thickness of the neck at the heel and how much clearance is require to line the strings up with the bridge saddles.

5 hours ago, HSlash said:

Pick up cavities:

Wait till you have your pickups in hand. Measure them from top to bottom to determine how much depth is require to mount them in proper relationship to the fretboard and string height.

SR

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Thanks SR for helping clear a lot of that up!

I think I am good with headstock angle now :)

I will do more research on neck angle... My bridge is 11mm at its highest point and you mentioned it depends on the fretboard height. If I have a fretboard that is flush with the body, I imagine that will be 5mm (due to the width of the fretboard) - so isn't that quite a large discrepancy?

I understand that that the heel will determine the neck pocket, but as I plan to make the neck from scratch I haven't got any set measurements for either. For simplicity sake, I may go for a fender-style neck and use these dimensions:

HeelDimensions.jpg

 

HeelDimensions.jpg 

Is there any particular reason that there is a 3mm gap between the fretboard and body though? Perhaps its for the truss rod... But mine will be adjustable from the headstock

I already have my pick-ups, but I'm still curious as to what depth to use, aka how much of the pickup should stick up out of the guitar. Also, shouldn't that differ in the neck and bridge positions?

Thanks for your help!!!

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I've also read that:
The depth of the neck pocket depends on the bridge used: when the saddles on the bridge are set to their lowest position the strings should touch the fingerboard. The pocket depth is therefore "thickness of neck plus fingerboard (25mm or 1") minus lowest possible saddle height".
http://buildyourguitar.com/resources/pocket/index.htm


So I guess I'll need to measure the saddle of my gotoh hardtail bridge when it arrives (unless anyone has that handy haha). This method makes sense to me, but I want to be sure of it before progressing with the build - so can somebody also verify?

Sorry for double posting, I'm new here (as you can tell) and still working out how to use these forums

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I've made a few guitars with 10º headstock angle and it's fine, but the last few guitars have been 11º which I think is the perfect balance of string tension vs strength whilst not requiring insanely thick neck blanks.

This is how I do neck angle. The actual angle doesn't matter a jot, just get a block of wood that is the hight of the bridge + 2mm - height of fretboard and frets, stick it at the position of the scale line and plane down the front. Then when you want to route your neck pocket, leave the block there and stick the template down. The floor of your neck pocket will sit at the correct angle and you wont have to angle your neck tenon. But I've found that my break angles usually end up at about 2º when I'm using PRS style wrapround bridges.

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If you're building a PRS style guitar, the tenon extends under the neck pickup (deepset tenon) and you need to cut am L shape into the tenon for the pickup to fit, so a strat style neck heel will not do, you need a deeper neck pocket and a thicker heel so you've still got plenty to glue/bolt - I only leave about 10mm under the tenon when the body is 47mm thick in the middle. 

The depth of the pickup route doesn't matter hugely either, it's only the posts of the pickups that require the most depth, you can do that will a drill if you want. I tend to let the weight of the wood dictate how deep I'm making pickup cavities.

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On 2/10/2019 at 3:29 AM, HSlash said:

Is there any particular reason that there is a 3mm gap between the fretboard and body though? Perhaps its for the truss rod... But mine will be adjustable from the headstock

Leo Fender designed his guitars to be economically made from readily available materials. Necks come from 1" thick blanks. That's why there is no neck angle and no headstock angle, just a half inch drop and string trees. The 3mm gap comes from height of the bridge and the fact of zero neck angle. That is how high the strings need to be be playable with that bridge. The fretboard has to sit 3mm proud of the body to achieve that proper string height. It could also be achieved with the addition of some neck angle....but Fenders are flat.

SR

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21 minutes ago, ScottR said:

Leo Fender designed his guitars to be economically made from readily available materials. Necks come from 1" thick blanks. That's why there is no neck angle and no headstock angle, just a half inch drop and string trees. The 3mm gap comes from height of the bridge and the fact of zero neck angle. That is how high the strings need to be be playable with that bridge. The fretboard has to sit 3mm proud of the body to achieve that proper string height. It could also be achieved with the addition of some neck angle....but Fenders are flat.

SR

The fretboard is also very thin on most fenders so it sits a little higher - as above, fretboard wood is much more expensive than neck wood so they would be able to get more fretboards out of a billet by saving 2mm on each fretboard. If you look at Les pauls, the fretboard is at least 2mm thicker and sits flush on the body. 

But I would always make the heel oversized if you can, it's much easier to fettle it down to the right height with a plane than it is to stick another piece on because it's too short.

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Thanks everyone for the informative replies!

 

ADFinlayson:
I thought PRS only used a 10 degree angle because they use a tremolo bridge? If anything I'm now thinking to increase the angle to say 12 or so (I have a hardtail bridge) and do a 'cut and flip' technique. But I guess it doesn't matter that much :)

I'm a little lost when you said bridge + 2mm for fretboard & frets: my bridge is 11mm at its highest point, the fretboard is ~5mm thick, and my frets are ~1mm hammered in (so = 6mm if level with the top). How does that work out? Also its worth mentioning that I have no templates to stick down and I don't have the neck pocket dimensions. This is all going off what I find online! After looking into it, you're right - I need an extra tenon to make the joint stable. Do you recommend any particular measurements on that? From a quick CAD drawing I did, and assuming it joints the body at the start of the 23rd fret, it will overlap by 27mm, 4mm for the pickup ring (black rectangle), 38 for the pickup, another 4... = tenon that is ~73mm into the body? Hopefully thats the right way of thinking about it. Gosh then theres the heel to consider haha

SR & ADFinlayson
Ah I see, thats super interesting... I guess I'll be going with an angle then, would much prefer it to sit flush if I can!

Screenshot 2019-02-11 at 21.42.42.png

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Yeah so your bridge is 11mm + 2mm for a bit of adjustment:

13mm - 6mm = 7mm block of wood at the bidge (scale line) position, then just plane down the front of the body with a jointer plane and the will angle the front of the guitar. 

I think this pic demonstrates the concept better

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The other thing you could do is us a potractor rule (I think that's what they're called, a protractor with a rule attached to it), offer that up to the block of wood and that will tell you how many degrees you need and you could then put that into the neck heel and keep the top totally flat, the downside of that is that your fretboard won't be parallel with the top of the body and might look weird.

Edited by ADFinlayson

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14 minutes ago, ADFinlayson said:

I think this pic demonstrates the concept better

Oh that makes perfect sense, the picture really helps! I'll go with the first method to angle the top. Do you prefer to angle your neck pocket/heel/use a shim to get the same neck angle (to make it flush)? I'm just trying to get a feel for the best method :)

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You need to make/buy a template for your neck and neck pocket, then stick the template to the top once you've done your angle into the top, Then when you route the pocket, the bottom of the pocket will be parallel with top and you break angle is done.

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Neck angle and tenon tick, headstock angle tick... Thanks a lot for helping me clear these up!

A few more Qs if you don't mind:


Where does a heel usually start on a PRS? and how thick should it be?
- I know it varies and thicker = more stable, but I just want to get a feel for the 'norm'. My current thinking is to start it around the 19th fret (as it joins at start of 23rd) and make it ~20mm (so full thickness, 20 neck, +5 fretboard, + another 20 for stacked heel). This also means my tenon will be 20.

Pickup cavities... I'm still not 100% clear (I've overthought it).
How much do pickups normally 'stick out' the body? I know the bridge is usually much higher, but is this due to cavity depth of just adjustment? Also, do the cavities need to follow the angle of the top for it not to look weird?

Thanks again

 

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I've got a 24 fret Mira and a 22 fret Paul's guitar, which I stare at regularly when trying to figure this stuff out. Both the Mira and the Paul's start curving up to the heel at fret 17 and the taper finishes at fret 19, which means the heel on the 22 models are longer in comparison to the neck. This is potentially just design thing but people do say that the bigger/longer the tenon, the better the sustain and tuning stability. 

But on this one I made earlier. The heel taper starts at the 19th and finishes at the 21st (actually down to a whoopsie with the band saw) but it sustains just fine and is more accessible at the dusty end.  So I don't really think it matters  :D

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This isn't the best pic in the world but it does show you how high the fretboard/pickup is from the body, there isn't a huge amount of room here.

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4 hours ago, HSlash said:

Pickup cavities... I'm still not 100% clear (I've overthought it).
How much do pickups normally 'stick out' the body? I know the bridge is usually much higher, but is this due to cavity depth of just adjustment?

The bridge is higher because of the neck angle and the bridge height combine to make the strings higher above the body in that area. For a no neck angle Fender you'll find the pickups at roughly the same height. How far the pickups stick out of the body is more a function of bringing them up closer to the strings. Somewhere between the base of the fretboard and the top edge is most common. You then adjust them higher or lower during or after the setup, whilst plugged in, to find the sweet spot--the height where they sound the best to your ear. Also, it is common these days for neck and bridge pickups to have different outputs. If one is noticeable louder than the other, they can be balanced a bit by lowering the loud one and raising the other one closer to the strings.

SR

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Thank you AD, you've been really helpful (your guitar is gorgeous) & thanks SR

I think I've run into a new problem whilst modelling the neck pocket (see image).

 

I'm not sure I have enough 'bite' in the body to keep it stable with my measurements...
Also, I wanted this to be a bolt-on but I'm not sure theres enough wood either.

The fretboard is 5mm, neck is 18mm and 'stack' of the heel is 12mm. The guitar body is only 44.5mm thick 😕
I haven't yet added the neck angle, but that will be taken out of the pocket, so make it even deeper

Any advice?

Screenshot 2019-02-15 at 20.15.47.png

Edited by HSlash

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If your body is 44.5mm and your neck is 30mm (12+18) you can afford to add another 4mm to the tenon leaving 10.5mm under the tenon. 

I would recommend glueing the neck because a good glue joint is always going to be stronger than a bold on. Consider that drilling holes removed wood therefore removes strength but a glue joint is stronger than the wood itself so 2 pieces of wood become one stronger piece. 

All that being said, your 3D work is a lot more precise than I’m used to, I normally just make it up as i go really, I make the neck first with an oversized heal, then I make the body and route a pocket and shave the heel down to get the right fit. But just to confirm, there is plenty there in your design for a good glue joint on a set neck 👍

Edited by ADFinlayson

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I guess I'm just a little worried about messing it up and the neck being stuck in there... Plus PRS's are usually bolt-on anyways. But you're right, a set neck would be stronger.

How comes you route a pocket, and then fit the neck - rather than the opposite? (make a neck then route the pocket)
Do you have standard neck pocket dimensions you like to use?

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You have that wrong, most prs even the basses have set necks, it’s only they bolt on range or CE that arent. 

No I do make the neck first, then I make the body and neck pocket. That way the neck is ready to test fit as soon as I’ve routed the pocket. 

If you are making a prs style guitar, my advice would be to just get some prs templates and some cheap wood and have a go. You will learn a lot more from your hands than 3D software can ever teach you 

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I hear you, I've bought some spare wood and I spent yesterday practising routing the cavities and headstock angles etc

I've also marked up (most of) my real wood now

New Q: pick-up placement
So the neck goes right up against the fretboard, but what about the bridge? Searching online just confused me with harmonic overtones and nodes 

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I normally put the bridge pup 20-25mm from the bridge/scale line but it is subjective, don’t forget to take pickup rings into account if you’re using them, you should place the neck pickup cavity a few mm away from the end of the neck tenon 

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Me again! I've started actual work on my materials, and I have a question about the truss rod (its probably stupid)...

I'm using https://www.stewmac.com/Materials_and_Supplies/Truss_Rods/StewMac_Red_Low_Profile_Truss_Rod.html

And I was wondering which way to insert the truss rod? Should the circular bit at the top be facing up towards the fretboard, or facing down away from it? I'm not sure whether it would matter at all, as its dual action.

 

Also, how long do people usually make the access slot :) ?

I've attached a picture with it in the upward position52819611_2306478586278893_6701139684686299136_n.thumb.jpg.b18b9f79bec15033cb04345a74ffb6f3.jpg

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28 minutes ago, HSlash said:

Me again! I've started actual work on my materials, and I have a question about the truss rod (its probably stupid)...

I'm using https://www.stewmac.com/Materials_and_Supplies/Truss_Rods/StewMac_Red_Low_Profile_Truss_Rod.html

And I was wondering which way to insert the truss rod? Should the circular bit at the top be facing up towards the fretboard, or facing down away from it? I'm not sure whether it would matter at all, as its dual action.

 

Also, how long do people usually make the access slot :) ?

I've attached a picture with it in the upward position52819611_2306478586278893_6701139684686299136_n.thumb.jpg.b18b9f79bec15033cb04345a74ffb6f3.jpg

I normally place the truss rod so the roundover is facing down and the flat is facing up, that way the nut itself is recessed and not flush with the top of the headstock. The size of the access hole depends on the design of headstock you are doing, if you're doing a strat style headstock where there is no angle then I don't think it really matters as you will remove the material almost up to the nut anyway but if you're doing an angled headstock, you need to make sure there is enough room to get your allen wrench in there. But I tend not to make access at this stage, I just drill through to the truss rod with a hss bit once my headstock angle is done

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Useful, thank you! But would it matter if I had the truss rod with the flat facing down? It seems to be a more snug fit that way, without any rattle. I'll think about access later :)

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1 hour ago, HSlash said:

Useful, thank you! But would it matter if I had the truss rod with the flat facing down? It seems to be a more snug fit that way, without any rattle. I'll think about access later :)

I've never done this but it is fairly common on strats to do this so that the nut sits higher and is accessible without cutting so deep into the headstock... the issue is going to be that now it will act in reverse afa tighten/loosen.  if that's not a problem for you then sure.  afa rattle... I cut my channel using a 1/4" bull nose bit and then chisel out the areas where it needs to be flat.  this results in a fit that is so tight it doesn't seem to be as prone to rattle... that said I still throw some silicon in there to prevent it in extreme cases.  hope that helps!

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1 hour ago, HSlash said:

Useful, thank you! But would it matter if I had the truss rod with the flat facing down? It seems to be a more snug fit that way, without any rattle. I'll think about access later :)

Honestly I don't know, but whenever I've had a loose fitting truss rod before, I've put a strip of veneer down the side of it (not even glued) and that's solved the problem. It's always handy to have a roll on veneer hanging around!

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