problem flattening surface

axisus

Bit of a newb question. So I have my separate neck and fretboard mostly sorted. The problem is that the flat surface that I am going to glue the fretboard onto isn't flat. I imagine that lazy working on my part is the problem - it's mostly flat but curves down a fraction at the sides, so it's slightly convex. Does that make sense? I've tried sanding it flatter (probably caused the initial problem!), tried planing a bit but my plane isn't good enough. The problem is I don't have much room to make things right with truss rod installed.

Best approach?

WezV

When you say sanding it, was that with a handheld block? 

If so, try a long strip of abrasive stuck on a flat surface instead.  Decent paper too... don't cheap out.

octatonic

As above^.
Next time leave installing the truss rod until the same day as putting the fingerboard on.
Oh and I would usually fix it with a block plane- get a good one- I like the Veritas one.
And keep it sharp.

I actually make the fingerboard gluing surface slightly concave- a very tiny amount, less than a fag paper difference between the outer edges and the centre.
It can help stop the edges lifting.

axisus

Thanks people. 

Andyjr1515

It's very easy to end up with a slight concavity and very hard to sort without making it worse.  

Personally, I would use a rectangular cabinet scraper (cost just a few £'s from Internet or decent DIY stores). Scribble zig zags along the top of the neck with a soft pencil and then draw the scraper along the length of the neck towards you with both hands holding it level with the neck surface and angled at about 30 degrees to vertical to engage the cutting burr.  Aim to gently scrape the hump off, watching the pencil marks to tell you if you are straying from the middle 'hump'

axisus

Andyjr1515 said:

Personally, I would use a rectangular cabinet scraper (cost just a few £'s from Internet or decent DIY stores). Scribble zig zags along the top of the neck with a soft pencil and then draw the scraper along the length of the neck towards you with both hands holding it level with the neck surface and angled at about 30 degrees to vertical to engage the cutting burr.  Aim to gently scrape the hump off, watching the pencil marks to tell you if you are straying from the middle 'hump'

That sounds good. I'll try and get one tomorrow. Ta

Andyjr1515 said:

It's very easy to end up with a slight concavity and very hard to sort without making it worse.  

Yes! that is my problem!

octatonic

axisus said:

Andyjr1515 said:

Personally, I would use a rectangular cabinet scraper (cost just a few £'s from Internet or decent DIY stores). Scribble zig zags along the top of the neck with a soft pencil and then draw the scraper along the length of the neck towards you with both hands holding it level with the neck surface and angled at about 30 degrees to vertical to engage the cutting burr.  Aim to gently scrape the hump off, watching the pencil marks to tell you if you are straying from the middle 'hump'

That sounds good. I'll try and get one tomorrow. Ta

Andyjr1515 said:

It's very easy to end up with a slight concavity and very hard to sort without making it worse.  

Yes! that is my problem!

Is the neck attached to a body yet?
Might be worth making another one if not- chalk it up as a learning experience.
I've done this before if it helps.

Corvus

If it's true lengthwise, pushing along sandpaper on a flat surface will do it. If not so true I'd clamp or make supports for the neck, and sand down onto it. Long board/block. I have a long piece of ally square tube 3mm wall for things like this, bought dirt cheap from the offcuts bin at the local metal shop.

A plane would be ideal though. You can get Stanley/Bailey #4 and such for small money on ebay, get a new iron or sort out what it comes with. Clean up, tighten up, flatten the base (sandpaper) etc, an hour or so. Then iron & cap to sort out. New life in pretty short order.

axisus

octatonic said:

Is the neck attached to a body yet?
Might be worth making another one if not- chalk it up as a learning experience.
I've done this before if it helps.

Worst case scenario and I may well do that, but I'm hoping to save it! I'll see how it goes today

octatonic

It depends on how much you've sanded down the edges.
I actually rebuilt mine with layers of veneer, enough so I could get a block plane over it to make it flat, then glued.
It is pretty much invisible but took me 2 days to fix IIRC.