Anyone know how to make wedges for archtops?

Rabs

As the title says... I have been asked if we can provide some wedges for an archtop type build.. Anyone know how they are done apart from with a hand plane? (8-25mm taper)

greggreg66

Had to google that.... is it the angled bookmatched top? How about a sled to carry them through the thicknesser?

Rabs

Yes thats right.  Putting it on a sled was what I thought too but have never done it before... Surprisingly little info out there about this.

GSPBASSES

David Dyke Luther supplies. 

Rabs

GSPBASSES said:

David Dyke Luther supplies. 

Ha.. Well I am meant to be the luthier supplier here    

WezV

Search for violin family techniques.  I think many just draw it on and guide it through by hand... But I bet there are some clever jigs out there.

Be aware of your final dimensions.  If your top needs to be 25mm at the centre, your wedge will need to be thicker than that... Probably 25mm thick at a point 50mm from the join

WezV

http://www.rocheviolins.com/html/violin_plate_tuning.html

Some clues there

edit, although it should be noted that the wedge method used there is for getting perfectly quartered spruce... not a perfect bookmatch. 

for a perfect bookmatch i would just cut it normally at 25mm thick, and plane the slope into it by running through the thicknesser shimmed up on the thin edge, leave the center section flat at the thickness requested.... it feels like a wasteful way of cutting wood either way. That's the nature of a carved plate and usually reflected in the price


I asked for some wood for a small archtop recently.  The guy asked if i wanted wedges and i said yes.  TBh i wasn't that bothered for the size, and should have made it clearer. We ended up going with a flat set after he killed a nice billet trying to figure out the best way to do it

let us know how you get on, as i could really do with a couple of other back/side archtop sets at some point 

 

GSPBASSES

Sorry I didn't mean for you to buy from him, but give him a call and he tell you how he does it, he's a very helpful guy. I'm going out there later today, if he's cutting wedges I'll take a photo of him cutting them, I do know it is done on a bandsaw.

greggreg66

Rabs said:

Yes thats right.  Putting it on a sled was what I thought too but have never done it before... Surprisingly little info out there about this.

It'd be quite straightforward I reckon. Looks like a 17mm height diff. I'd start by planing a strip of timber 17mm thick and pin it to a piece of MDF that the wood rests with one side 17mm higher than the other. You'll want to know the thickness of the substrate (say 18mm) so you can workout the correct height to thickness the whole lot to.

Ideally you'll want a lip at the back edge to stop it slipping backwards as it goes through the planer. Depending on the overall width you might want a second piece underneath as the thicknesser rollers can distort it a little if unsupported over wide pieces. 

Another option is to cut some wedges on the table saw and pin these to the MDF board so the timber panel has more support across the whole width.

Planer sleds are really satisfying as you get a nice shaped piece coming out the other end!

WezV

you can definitely get there with a planer, but you need to consider wastage.   

here is a quick sketch on how i think it would need to be sawn from a billet for minimal wastage.  I'm not saying the cuts are easy  
https://imgur.com/YQmwh47

Left is a rough idea of the cuts from a larger billet in order.   Right is making sure the bookmatched face is on the right surface 

greggreg66

I'd accept the wastage with the planer than risk a wonky cut on the bandsaw and stuff it up ha!

WezV

greggreg66 said:

I'd accept the wastage with the planer than risk a wonky cut on the bandsaw and stuff it up ha!

 totally, it does depend on the wood available too.  I will be planing down the back set i already have here for an archtop.. its currently a consistent 1" thick..

   The billets of spruce used for tops are already wedge shaped, split from the log rather than sawn.   its then a case of truing that up and splitting it down the middle... as shown in the link i posted earlier (actually, that is is maple)

I'm honestly not sure how they normally do it from bigger billets and planks, but i would doubt most commercial ventures accept the extra effort and waste of planing when they could just sell them at a consistent thickness instead


edit: for context, the rough sawn spruce wedges i have here are roughly 1 3/4" thick at one edge, and 1/2" at the other... you can see why wastage would be a concern if cut from a rectangular blank

Rabs

Wow.. Ok stuff to look in to here..   Thanks very much for all of that info @WezV.

Yeah my boss said just to stick it through the bandsaw, and while I am okish at it, I cant see it coming out that well..  When ever I do a straight bookmatched top through the bandsaw I have to allow at least 5mm of re-thicknessing to get them flat again.

Wastage is something we just have to do sometimes to get the piece that the customer wants.. They pay for the full thickness board though so its up to the customer. 

Ok, some reading up to do before I attempt this. But I will post my results when I do it   

Rabs

GSPBASSES said:

Sorry I didn't mean for you to buy from him, but give him a call and he tell you how he does it, he's a very helpful guy. I'm going out there later today, if he's cutting wedges I'll take a photo of him cutting them, I do know it is done on a bandsaw.

Ok thanks.. That will be cool. Cheers.

Rabs

One of the things about all of this is this is a sample I have been asked to make up for an instrument maker..  They actually want the wedges for an archtop mandolin and have asked for acoustic back and sides (which is easy enough)...

BUT if they like it and want more I will need an economical and reliable way of doing this or it wont be worth our while when they ask for 50 or 100 sets which is why doing it manually with a hand plane is out.

more

Originally soundboards  were split by hand , from a log . It is still still done but the set are expensive ,   For you to do it you would need to be buying logs . Most soundboards are cut with a band saw. I don't know what your business is . I have imported soundboards from German suppliers that supplied  wedges for classic instruments . I don't believe it would be viable  to buy big block  of wood and  saw  them  into a wedge 

Rabs

more said:

Originally soundboards  were split by hand , from a log . It is still still done but the set are expensive ,   For you to do it you would need to be buying logs . Most soundboards are cut with a band saw. I don't know what your business is . I have imported soundboards from German suppliers that supplied  wedges for classic instruments . I don't believe it would be viable  to buy big block  of wood and  saw  them  into a wedge 

I work with a timber suppler..  We have loads of logs (mostly from in and around London) which we mill, air and kiln dry.. Then we are part of a shared workshop which is where the main business is based and we mainly supply joinery timber and we sell stuff on ebay...  So I am not starting from scratch here   Ive just never been aske for wedges before ..

greggreg66

It's possible to split the logs accurately with a froe.... but you have to be pretty good I reckon! (not saying you're not! : )

Make a sled for the bandsaw and then another for the thicknesser

Revolting1

I wonder if they've ever been steamed?

WezV

Revolting1 said:

I wonder if they've ever been steamed?

Archtops, yeah.  Some have definitely been steamed from thinner wood.  Many more laminated instead 

Neither sounds like a fully carved plate, and neither can be carved as gracefully

Rabs

greggreg66 said:

It's possible to split the logs accurately with a froe.... but you have to be pretty good I reckon! (not saying you're not! : )

Make a sled for the bandsaw and then another for the thicknesser

Well I had to look up what a froe was if that tells you anything    We have a saw mill that we hire in.. They do all of that, I just sell it and cut it in to smaller bits... I am going to the farm this week though as I need to fill the kiln up and grab some more stock..