sash window

by **stevep** » Sun Jun 13, 2010 10:07 pm

The first complete one I've made to take dgu's, though I've done a few replacement sashes. This is part of the unsorted I bought last week, which looked a bit rubbish when I got it back to the workshop, but with a bit of careful cutting it turned out ok. I was left with a 1.2 of 50x50 that was unuseable, out of 4.8m of 50x225. Very sticky though - I had to take the bandsaw blade off and clean it, and the wheels, with acetone after ripping it down.

Extra deep rebates for the dgu. Ellis says that only the best quality work had horns on the inside and outside sashes, so I went for plenty of horn.

Dummy glazing bar, scribed then glued and screwed through the rails with epoxy. All the other joints were done with PU - really crappy make I haven't used before called Lumberjack. Absolute bugger to clean off, as you can guess from the middle picture.

Mouldings on the sashes were done with a set of Wealden narrow sash cutters here Really good cutters and not too expensive, as usual - don't go anywhere else for router cutters now. Cunning plan for hanging the wagtails - a bit of 6mm steel, 2 bits of plastic tube:

by **mr clewlow** » Mon Jun 14, 2010 7:39 pm

look's good. 1 thing though. the box frame should be notched over the cill? it look's like you have cut the face of the cill back to the line of the box.

nice looking window though.

by **mr clewlow** » Mon Jun 14, 2010 7:43 pm

sorry 2 things. the box frame should run into the head. and where the head meets the stile of the frame there should be a half mitered joint.

by **stevep** » Mon Jun 14, 2010 9:23 pm

There was a bit in George Ellis that I didn't really understand - I thought the inside lining should be taken right down, with the sill notched out to take it, at least thats what the drawing shows in his book.

The pulley stiles are tongue and grooved into the head - copied from the original one in the next room. I see what you mean about the mitre - it makes a much neater finish. My original didn't have mitres, the linings were just nailed to blocks with huge cut nails

Obviously the originals were made on the cheap - no wagtails and the pockets were just ordinary mitres cut in from the side of the pulley stile as far as the groove for the parting bead - I put proper ones in. I also used ply for the backs which is definitely not traditional - gave it a soak with cuprinol yesterday. Won't be seen by many people once its installed!
Thanks for the tips - the next one will be better now.

by **thatsnotafestool** » Mon Jun 14, 2010 10:57 pm

stevep wrote:There was a bit in George Ellis that I didn't really understand - I thought the inside lining should be taken right down, with the sill notched out to take it, at least thats what the drawing shows in his book.

.....

Yes, it's quite clear that both linings go into 'sinkings' that take them right down to the bottom of the cill.

Did you rebate the pulley stile into the linings?

In Ellis's book, it's only the sash lining that is mitred and not the head/outer lining.

My reading also suggested that the reason for horns was so they didn't need to bother with dovetail or other complicated joints on the bottom rail of the sash. Certainly the earlier sashes didn't have horns.

by **jfc** » Tue Jun 15, 2010 7:59 am

Looks good to me

by **stevep** » Tue Jun 15, 2010 8:26 am

thatsnotafestool wrote:Yes, it's quite clear that both linings go into 'sinkings' that take them right down to the bottom of the cill.

Did you rebate the pulley stile into the linings?

In Ellis's book, it's only the sash lining that is mitred and not the head/outer lining.

My reading also suggested that the reason for horns was so they didn't need to bother with dovetail or other complicated joints on the bottom rail of the sash. Certainly the earlier sashes didn't have horns.

This is my sketchup version of one of the drawings in the book:

Presumably with the joint cut like that any water has a chance of draining right down and dripping off the bottom?? maybe...
The pulley stiles are tongue and grooved into the linings as well as the head.
No mitres anywhere - the original didn't have any, and after re-reading the book several times I'm more confused where these mitres are supposed to go. When you say 'sash lining' do you mean the inner lining? I'd have thought it would be better to mitre the outer lining where they overhang the face of the pulley stile.
And yes, I put the horns on the inside sash to make the joint stronger - I think it's important with the weight of double glazing.

One thing I did learn was how useful Sketchup is - if all the components fit together on the screen then it will be right in real life. I'd still use a rod as well though.
Anyway, time to get some work done...

by **thatsnotafestool** » Tue Jun 15, 2010 9:07 am

Man after my own heart, Steve! I'm just about finished on my detailed SU drawing for a box sash. I agree with you - if it fits in SU then it (should) fit in real-life. Not quite there yet though, in my case.

Mitred sash lining is on p 198 and you can also see it Fig 1 on page 194. Great book. Volume One of McKay is even better for window plans/construction. McKay also shows the cill cut back for the inner lining.

Like your wagtail support. Brilliant!

by **mr clewlow** » Tue Jun 15, 2010 7:57 pm

steve. the detail on sketchup for the cill is correct. i meant the outside face of the box lining? i have never seen one that is chopped into the cill?

as for the mitre detail it goes where the side meets the head? a bit complicated to explain realy. i think the box frame you have done looks good.

i am doing a 3 section one next week so maybe i will post a few pics up. it might make things easier to understand.

by **stevep** » Wed Jun 16, 2010 9:30 pm

We really need to be standing in front of it and pointing fingers at all these bits! I've attached a zip file of my two SU drawings of the box frame - both the same drawing except one is assembled and the other one is exploded. Had to be a zip file as the forum software doesn't like .skp files. Done on a Mac, but I'm pretty sure they open just the same in the windows SU version.

boxframe.zip: (64.79 KiB) Downloaded 30 times

by **jonnyd** » Wed Jun 16, 2010 10:25 pm

In your sketchup picture of the cill you have cut the outer lining cutout too far it should be level with the inner one and pulley stile groove. If your not having any moulding on the outer lining i dont suppose it matters but if youve got a staff bead moulding this needs to stop at the cill so you chop back the outer lining to be in line with the pulley stile allowing the moulding to finish at the cill.

cheers

jon

by **thatsnotafestool** » Wed Jun 16, 2010 10:39 pm

This is a fascinating thread ...seeing as how I'm in the process of making my first box sash. I'll take some pictures of mine tomorrow.

These box frame sashes have so many 'gotchas'. I nearly got caught by one..and think that Steve..looking at your SU diagram ..you may have missed it. Parting bead groove in the head ? I dry-assembled my box frame this afternoon and must have stood there for at least five minutes with my mouth open as it all fitted together...properly. Only one cock-up.

Ellis talks about cutting away the 'bead' on the outer lining at the bottom to allow water to run away freely. Think that's what Jon was alluding to.

I think that there is an inherent weakness in the SU diagram/Ellis design...and I have the same problem. There's a sopping great hole at the bottom of the pulley stile ...where the groove for the parting bead has been run all the way down. I know that the parting bead will cover the hole but in the fullness of time, any paint seal is going to fail and so let in water to rot the cill. Would be even worse if they were going to unpainted hardwood. I intend to fill my hole with silicon. Just re-read that last sentence.... :oops:

by **stevep** » Wed Jun 16, 2010 11:58 pm

Right, getting clearer now - thanks Jon, know what you mean now that you mention a moulding on the outer lining. And I did forget the parting bead groove in the head on the SU drawing - I realised when I was taking the photos the other night, but I didn't mention it in case everyone thought I was an idiot. I have taken the frame apart to bring it down to the site, so I can run the groove in the head on a router table before I finally stick it all back together.
I'm not sure about the parting bead groove at the cill either - I suppose with the right size chisel it would be possible to chop out the sinking with a morticer and leave a sort of haunch to fill the groove. Probably easier to just glue a small piece of timber in there as its assembled. I'm pretty sure the Victorians just relied on a good draught in the cavity, along with breathable lime mortar and plaster, to keep the joinery relatively free of damp. And Mr Grim reckons that the backs weren't painted on purpose so the wood could breathe.

by **thatsnotafestool** » Thu Jun 17, 2010 9:31 am

I had a quick look at the old sash windows in my house to see where they had rotted. Many had rotted where I'd have expected them to...ie around the bottom of the parting bead. A few had rotted in the cill behind the parting bead and staff bead which suggests to me that the parting bead should also be cut short at the bottom to allow water to flow away freely and not pool behind the parting bead. Which makes sealing that channel even more critical.

by **jfc** » Thu Jun 17, 2010 8:06 pm

I think mastic has a five , maybe ten year life span . How old are your sash windows Rog ?

by **thatsnotafestool** » Thu Jun 17, 2010 11:13 pm

Not sure I follow you, mate. Bit too cryptic. Even for me !

by **jfc** » Fri Jun 18, 2010 10:01 am

How old are the sash windows with the rotton cill ?

by **thatsnotafestool** » Fri Jun 18, 2010 11:53 am

30-40 years maybe. Could be longer.

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