need to cut scarf's on thin material

[giantbeat]

appreciate the replys everyone, I'm going to pick up a toothing plane to try but i think we need a more mechanical production way, so will also continue my drum sander jig idea & see what stacks up as being the best solution.

Been making ply wood shells for 15 years but i make them the modern way, I'm tasked with better replicating the vintage constructions, which is a different story, i have loads of info, books, original sketches & descriptions from the times, so i know my tooling & methods for everything will work, but no where shows or describes what they used to taper the boards, i suspect they just had a stack of lads planing them down as we have found similar groove patterns inside shells.

 

[bugbear]

... as we have found similar groove patterns inside shells.

I don't know how precious old drums are. But. IF you could get a broken old drum and IF they didn't use non reversible glues, you could carefully delaminate (I'm guessing you have a steamer) an old drum and see what you see.

BugBear

 

[Neil S]

Just trying to get my head around whether it would work but could you not just glue it together as an overlap joint first. Then sand back each side tapering from 0 to full thickness over the length of the overlap. Hope I've explained that well enough.

-Neil

 

[giantbeat]

... as we have found similar groove patterns inside shells.

I don't know how precious old drums are. But. IF you could get a broken old drum and IF they didn't use non reversible glues, you could carefully delaminate (I'm guessing you have a steamer) an old drum and see what you see.

BugBear

thats exactly what i have done before i got to this stage, well to be fair i have been dissecting drums for decades for research in my job, some drums have the grooves, some dont, the specific type of drum I'm working on all have the lap/scarf type joints through them.

 

[giantbeat]

Just trying to get my head around whether it would work but could you not just glue it together as an overlap joint first. Then sand back each side tapering from 0 to full thickness over the length of the overlap. Hope I've explained that well enough.

-Neil

tried it, its ok, but its not great, would need a lot more automation and jig setups to be able to trim them back consistently, this is not a one off... and there will be more than one layer of this veneer in each drum.... the conclusion was it would take more specialist equipment (something im not alien to making) & more time than scarf/tapering the ends in the first place before we mould.

 

[giantbeat]

decided to put jobs to one side for an hour & play with my drum sander idea.

20min putting together using scraps of MDF from next doors kitchen fitters waste bin & i had a quick test setup.

I'm convinced its the way to go for production, taper/scarf took less than 1 min to do using this and 120 grit paper, will build a proper version next.

 

[novocaine]

as has been mentioned, cut with a knife but would this not work for you?
https://www.google.co.uk/shopping/produ ... RQQAvD_BwE

 

[bugbear]

decided to put jobs to one side for an hour & play with my drum sander idea.

20min putting together using scraps of MDF from next doors kitchen fitters waste bin & i had a quick test setup.

I'm convinced its the way to go for production, taper/scarf took less than 1 min to do using this and 120 grit paper, will build a proper version next.

You're power sanding across the grain - I am astounded it didn't tear the veneer to shreds at the "zero thickness" end.

BugBear

 

[rafezetter]

A friend's father does vintage aircraft repair, and super-shallow scarf joints are used on the very thin plywood he uses.

He just freehand planes them.

I did teach him how to sharpen though...

BugBear

I was going to suggest wood aircraft repairs - I've seen them do this many times on shows about vintage aircraft renovation.

If the veneer is so thin can it not just be sanded?

 

[iNewbie]

If you don't have any pics are there any online for us to view of the shells construction method. Curious to know the manufacturer, too.