Finding the High Points

[Bwalker15]

Hi all,
This is a fairly basic beginners question I think- I'm just starting to assemble the neck to the body via a mortise & tenon joint on my guitar build & I need some means of determining high points in the joint. Online info seems to use "chalk" for this purpose but it seems to me that since the joint cannot be rubbed or moved very much the indication from chalk would not be great. Is it just normal blackboard chalk that is used or is there some other more sophisticated product that is more suitable.
Thanks,
Colin

[kiwigeo]

Grab a stick of chalk and rub it over inside of the mortise. Fit the tenon and the chalk will transfer to the high points on same.

[johnparchem]

Yup normal blackboard chalk.

[lamanoditrento]

Hi all,
This is a fairly basic beginners question I think- I'm just starting to assemble the neck to the body via a mortise & tenon joint on my guitar build & I need some means of determining high points in the joint. Online info seems to use "chalk" for this purpose but it seems to me that since the joint cannot be rubbed or moved very much the indication from chalk would not be great. Is it just normal blackboard chalk that is used or is there some other more sophisticated product that is more suitable.
Thanks,
Colin

Hey Colin, welcome to the forum. Are you using bolts with this mortise & tenon? Normally there is no problem with a small bit of play in an m+t joint that is being bolted on. The only time I would normally worry about a tight fit that needed chalk is a dovetail joint.

[Allen]

If you need to adjust the left / right alignment of the neck then the M/T will more than likely need a little bit of play, or there will be pretty much no chance on getting that adjustment dialed in.

[kiwigeo]

I usually chalk up the mortise when fine tuning for for a bolt on/bolt down neck. That way I know after taking anything off the cheeks if the tenon is hitting the side of the mortise.

[Bwalker15]

Thanks all,
I'll now find some chalk. Yes I am doing a bolt on M&T connection, with screwed in female thread inserts in the neck & M6 socket head screws. I'm sure that I will need to adjust the left/right alignment of the neck & also slight adjustment of the depth of the M to ensure the fret board sits firmly against the body.
Just as a side issue, I decided to use the flush thread inserts so that they could sit slightly below the surface of the tenon, after drilling the recommended size hole, I screwed the insert in using an allen key & the female drive hexagon sheared off when the insert was about 2/3 in. I managed to get the insert out again with minimum damage & then inserted a flanged insert (which has a lot more metal around the driving area) fully in, then unscrewed it & fitted the flush insert- another learning exercise.
Cheers all,
Colin

[Mark McLean]

Good luck with it Colin, and let us all know if you hit any trouble. The left/right adjustment of the neck alignment is made by fine adjustments of the cheeks of the heel, bearing against the exterior of the guitar body - not by adjusting the tenon. That is what Trent and Allen meant when they said that the M&T joint can afford to have a little bit of play in it.

[johnparchem]

One other option to chalk is sand paper to mark the high spots on the cheeks. I insert a strip of sandpaper under the cheeks and pull once. The sandpaper will mark the high spots. I use a chisel to remove the high spots. This is not "flossing" as I am not trying to change the neck angle, just mark the high spots.

[Bwalker15]

Thanks Mark & John,
I hope to start on this stage this week.