sash windows, scribed joints

[dexteria]

Hi all,

I'm currently making a sash window from some Ash that I have.

I made a prototype in pine using the scribe/profile cutters that I have but without tennons.

I had planned to use tennons in the final version but the scribed joints seem very strong. I tried without success to break the joints in the prototype.

Has anyone built sash windows without using tennon joints. Could you rely on the scibed joint only? Other options I had thought of were to dowel or screw & plug. Any advice appreciated.

Each sash is 920mm * 600mm * 44mm

TIA

Mark

 

[mailee]

I have only built windows for outbuildings before and did use the scribe joints but I also used tennons for the main frame as I didn't trust the scribe joint alone. Maybe someone with more experience of window making can help.

 

[CHJ]

First frames I ever made (1962/3, a 40ft run of them) were tenoned throughout, the last lot I made were scribed and glued then doweled after assembly, I know which way I would do it again, the first are still sound in the building last time I passed but the latter will also be around after I depart this playground.

 

[Scrit]

Gut instinct tells me that a scribed joint can fail or creep over time. I've not made sash windows, but I've replaced quite a few kitchen doors and some front/back house doors where the scribed-only joints have begun to show signs of creep and I wouldn't make a door or window like that unless I could at least put a couple of dowels through each joint to secure the joint. Remember if you are going to use screws in oak you'll need to use either brass, bronze or decent quality stainless steel to avoid them rotting out and potentially causing staining. Personally I'd prefer to do it the traditional way with mortices and tenons, but I have the luxury of a single-end tenoner and a morticer, so it's a bit easier for me.

We have at least one contributor who builds/repairs sash windows regularly, so hopefully you'll get some more constructive comments soon

Scrit

 

[lugo35]

re subject to the weather they will need more than just glue.if they were inside you could probably get away with it.
dispite how good glue is these days, the wood will move and the joint will break. best tenon them or dowell.

 

[jasonB]

Another way to do the joints without a scribe bit is to masons mitre the moulded section then you just have plain M&T joints, I've done casements this way. Would not be too happy with just a glued scribe joint once the weather gets at it.

Jason

 

[dexteria]

Thanks all for the advice. I'll have to think a bit longer about what I'm going to do but looking like scribed and doweled.

Cheers

Mark

 

[Anonymous]

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[Steve Maskery]

This is a timely and interesting topic for me. I've just taken delivery of more Unsorted than I care to think about. My neighbour and friend, Brian, has decided to replace all the sashes in his 1930's mock-Tudor house, to accommodate DG sealed units, and we have a Little Project between us, which isn't so little. A couple of years ago Brian helped me to lay a patio. I wouldn't have managed it without him, and I think this is payback time!

A few of the sashes will be opening lights, but most will be fixed, so we have decided to go with open bridle joints which gives loads of gluing area, and can be done easily with a small bandsaw (which he has) and a chisel. We'll probably mitre the sticking (although I tried to persuade him of the advantages of scribing). It was all delivered at 1pm on Friday, and by 5pm yesterday we had cut it all into manageable sizes (the boards were 5.2m long) and all the components planed and edged.

We were expecting to finish thicknessing tomorrow, but he has fallen off a ladder this afternoon and is a bit shaken and bruised. It might set us back a day or two. Or a fortnight.

Perhaps we should compare notes?

Cheers
Steve

 

[JFC]

Ive made quite a few box sashes and casement windows and always used haunched M&T and wedge them .
In fact im fitting one ive made tomorrow .
Windows get alot of abuse from weather and people and i dont think a scribe joint would hold up to that abuse over time .
If your putting double glazing in think about the size of the weights your going to need , you could have a nasty shock when you cant find them or fit larger ones in the pockets as i found out

 

[dexteria]

I chose ash as I didn't want a painted finish and was advised at the hardwood store that either this or oak would be good. I was planning on using danish oil for the finish which would be tended to on a yearly basis.

The scribed joint is a Ovolo and matching cope not a plain square butt.

I will be installing 4mm DG units with 6mm air gap (14mm overall) and have spring balances in leu of the sash weights.

I was reluctand about the M&T joints as my mortice cutter is... (well lets say not very good). Maybee I should just bite the bullet and invest in a new one.

Cheers

Mark

 

[JFC]

I use a Record bench top morticer and clean up with a chisel .
I don't have the room for anything bigger and don't see the point as there is always a little chisel work to do on a mortice , even if its cutting back for wedges .
If i need to cut a mortice on site i use a 3D drill bit and a sharp chisel .

 

[Scrit]

I just came across the best reason not to use dowels (well, beech dowels, the generally available sort) in exterior joinery here

Scrit