Need a "how to" on making wood window sashes

[Tom Hammond]

Hi guys.

I've got an old farmhouse property I'm looking to fix up and move into in a couple years. It's got close to 40 sets of standard ol' double hung windows, almost all 6 over 1, approximately 36 x 60, 32 x 60 and 26 x 60. The jambs are in reasonably good shape, with sills that are solid and without too much rotting, checking or splits. However, the sashes themselves are in deplorable condition. Many are literally falling into pieces. Some have been previously "repaired" with drywall screws. Most have no hardware and all have tons and tons of old, curled up and split lead paint on them. A good deal of the glazing is gone, and what is there is hard, curled, split or in pieces.

I considered removing each, stripping, sanding, properly repairing, reglazing and then staining/varnishing them. If I do one each week for 40 weeks a year (not in the winter) I can be done in two years. But, then, I remembered that I have a significant stack of beautiful poplar S4S in my storage... and thought "Hmmm... wouldn't it be easier just to replace them, and wouldn't it be fun to make them myself?" I was able to sell my wife on it because the poplar costs me nothing for this job, I have the tools and the skills... and I've already budgeted the time. Plus, I save all that money on paint stripper and lead abatement. And, since this is not a "historical" property of any significant value, replacement now seems the best option... but I do still want to "do it right" and keep the original look. I found ALL of the original storm windows and screens (EVERY SINGLE ONE!!) in the barn and they are all in excellent shape considering their age (I will have to replace the screen itself but, otherwise, they are totally fine. They're the kind that hang from hooks at the top of the window and then are held in place by rotating little clips on each side. So, since the storm windows will be in place almost all the time for almost all the windows, I don't think using the poplar will be an issue after finishing.

The only problem is... I've never made or installed a muntin in my life. I can make the sash if it's a single pane, like all the lower sashes... but the 40 upper sashes need muntins to divide the glass. So, any advice on a resource to learn how to make the sashes with the muntins is greatly appreciated, and any advice on how to properly measure these things so that the top and bottom sash fit together beautifully when closed would also be appreciated!

Thanks in advance!!

[Jim Galvin]

Tom


Take a look at this website http://historichomeworks.com/forum/viewforum.php?f=16. I just got done doing some old casements windows and transoms over 160 pieces of glass was removed and reglazed and I stripped the frames and repainted. Building windows is alot of work and poplar is not a wood I would use recommend for windows since it does not have the weather resistance.

Jim

[Walter Plummer]

Modern Practical Joinery by George Ellis has a lot of information on sash building. http://www.amazon.com/Modern-Practical-Joinery-George-Ellis/dp/0941936082/ref=sr_1_1?s=books&ie=UTF8&qid=1322315064&sr=1-1 It is a very interesting book and well worth the price. The PATINA tool collectors had a demonstration/show once and the gentleman who collected sash makers tools was making one. I think it was 6 lights. With all the tools it went very quickly and he made it look easy.;)

[David Keller NC]

Probably the best resource for way historic sashes were made is the various episodes of Roy Underhill's Woodwright's Shop. He also covers this topic in some of his books.

Watch the 3 episodes of the Corner Cupboard. In it, he shows one alternative to making muntins (You can watch these free on-line):

http://www.pbs.org/woodwrightsshop/

I'll have to do a bit of searching to figure out which one of his books has the description of historic sash-making. Even if you choose to do this with a router table, mortising machine and a table saw, the construction details are well worth reviewing.

[Mike Hollingsworth]

I considered removing each, stripping, sanding, properly repairing, reglazing and then staining/varnishing them. If I do one each week for 40 weeks a year (not in the winter) I can be done in two years.


That would be like painting the Golden Gate Bridge. You will NEVER be done. You'll need to start all over again.
Best idea is new sash.

[Tom Hammond]

Building windows is alot of work and poplar is not a wood I would use recommend for windows since it does not have the weather resistance.

Jim: What do you think instead? Fir? I don't want to ever have to mess with these again. Thanks for the help!

[lowell holmes]

You might consider quartersawn whiteoak. Its straight and has good weathering characteristics.

I've never made muntons either. You might look into a shaper or molding machine.

[Jim Galvin]

My windows that I repaired were pine
I believe pondorosa pine

Jim

[Patrick Tipton]

I have a similar situation with a 200 year old house and 6 over 6 windows. I have built some, repaired some and had a guy make me some. All my original windows are pine. I built four sashes using poplar and I think it is a fine choice as long as you keep them painted. The process of making and installing the muntins is pretty straightforward - it is past my bedtime, but I will post more manana.

Regards, Patrick

[greg Forster]

Tom,

...having repaired/replicated over 1000 window sash (usually with some NPS review), I would really,really,really consider repairing your exsisting sash- just
from an amount of work aspect; repairing is a lot easier.
I'm guessing your windows are from the late 1800s to early 1900s?; and maybe Yellow Pine- even in Ohio. I've used Yellow Pine in the Carolinas and Virginia ( even from the big box stores- very selectively) and was able to source good Cypress on a Texas job; Poplar, even for free, would not be on my list.

[David Keller NC]

Jim: What do you think instead? Fir? I don't want to ever have to mess with these again. Thanks for the help!

Fir would be a big no-no. It will rot exceptionally quickly, and the kind of fir one can easily obtain isn't stable or hard enough to make sashes out of (though clear Douglas Fir would be OK, though expensive).

What you have to decide is whether you want the sashes to be highly weather resistant in and of themselves, or whether you'll depend on coatings and storm windows to prevent weathering problems.

For high-end sashes, the wood of choice is (used to be) South American Mahogany. It is easy to work with power and hand tools, sufficiently hard to be resistant to everyday use, and will not rot - ever. But since Brazil banned its export, it is very expensive - around $12 a b.f., though you could get it cheaper (perhaps $8 a b.f.) if you are looking to buy a large amount and in narrow sizes.

The industry for high-end sashes has switched to cedrela odorata (cigar-box cedar), sometimes called "Spanish Cedar". Despite its name, it is a species related to the true mahoganies, and is highly weather resistant, and has similar working properties. It's in the $4-$7 a b.f. range, which is similar to white oak in many parts of the country.

For work-a-day sashes, the ultimate wood to build these out of is the heart of loblolly pine - typically sold as "heart pine". It will not rot, ever, even if the paint has been gone for 20 years. Again, however, it's difficult to get heart pine unless you are willing to troll the salvage lumber dealers for some heart pine beams that were removed from an old factory. These are hotly coveted for re-sawing into yuppie flooring, though, so you might have to look around for a good deal.

White oak, if obtained from trees that grew in a forest rather than fields/farms/yards so that it is largely free from knots, is highly weather resistant and is very hard, so it resists day to day use and wear. However, I would not recommend building sashes out of it unless you use the counter-weight design. White oak is quite dense, and sashes built from it will be heavy.

[Tom Hammond]

HOLY COW!! QS White Oak??? Mahogany??? Cypress??? The windows would end up being the nicest furniture in the house!

This an old Ohio farmhouse built around 1900. The current sashes look to be pine and are very soft material. I'm sure the Amish guys at my local lumberyard have something to replicate the material. I will rethink my poplar consideration. But, back to my original question... if I do indeed make replacements, I need a how-to on the muntins. I've got the tools and the skills, I just have no experience with this joinery. All your help is greatly appreciated.

[greg Forster]

If you are determined to build all replacement sash,in decreasing terms of effort: 1) you can cope/tenon the muntins at the intersection- heavy duty window sash; 2)just cope/half-lap the muntins; or 3)just run the long muntins thru, then cope/butt the short muntins and glue and pinnail in place- this isn't as strong, but if you fix the top sash in place (non-operating), once the glass is puttied in place , it is good enough.
In all cases tenon the muntins into the stiles.

[lowell holmes]

My reasoning is it is straight, strong, and rot resistant. I use it for entrance door frames because it is all of the above and also is more difficult to kick in.

I can't see putting the effort in making a door or window replacement and using poplar or white pine.

I have used fir in a sash replacement. It had no divided lites though.

[Peter J Lee]

Old paint and glazing are just part of old windows and not that hard to deal with. Don't be put off too much by those. Save the ones you can. My experience with salvage houses has been they're expensive but maybe you can find one near you that has some replacements. In the 20s working class house where I live, the workmanship is often impressive. I can't imagine reproducing the windows without a shaper. There is a steady stream of them being replaced. You used to see sashes and doors now and then in the alleys that yours truly would scavenge for wood, but I think the city got down on contractors and they likely go to the dump from the contractor's place.:(

I can offer some tips and experiences if you go the rehab route.

[David Keller NC]

HOLY COW!! QS White Oak??? Mahogany??? Cypress??? The windows would end up being the nicest furniture in the house!

This an old Ohio farmhouse built around 1900. The current sashes look to be pine and are very soft material. I'm sure the Amish guys at my local lumberyard have something to replicate the material. I will rethink my poplar consideration. But, back to my original question... if I do indeed make replacements, I need a how-to on the muntins. I've got the tools and the skills, I just have no experience with this joinery. All your help is greatly appreciated.

It's not impossible for them to be eastern white pine. In many areas of the country, joiners would use whatever was at hand, regardless of the consequences for the product's longevity. In many cases, what we view as "luxury material" was very inexpensive at the time that the woodwork was created. S.A. Mahogany is a good example - in the late 1990's and early 2000's, large sizes of mahogany could be had for as little as $3.50 per b.f. Given that a sash has little wood in it (mostly labor and glass), one could understand why S.A. Mahogany was the wood of choice for exterior sash work in the late 20th century.

Cypress, by the way, would be another alternative. It is highly rot resistant, and in this part of the country (East Coast), it is very cheap indeed. It's still a little soft for my tastes, though.

[Tom Hammond]

Hmmm.. I certainly have a lot to think about. All the input so far is why I am asking now and not waiting until spring. GREATLY appreciated.

I do have a Delta shaper... have had for 10 years, and have been looking for an excuse to use it... for the FIRST TIME EVER!!! I have a set of stile/rail router bits I use to make small cabinet doors and mirror frames, etc. So, I can probably transfer the router table skills to the shaper once I get a set of bits, if I decide in the end to replace. I still need to do more investigation on available and proper material for the job though.

If I decide to strip these, repair them and stain/varnish them... I'd like to get some input on a technique I saw a while back where steam is used in the process to remove the paint and glazing:
http://www.youtube.com/watch?v=I1bjOENLTQA


I've done a little steam bending, but have never used the technique for paint removal. It looks incredibly effective... almost "too good to be true." So, any comments are welcome.

[Aleks Hunter]

Gotta second you on the QS white oak. And add very well dried. Beside the excellent weather resistance, the oak is significantly stronger and I think poplar sashes would be prone to flexing, yes even windows move. regardless of what wood you use sash weights would be a good idea There are stringent standards for new construction and replacement windows regarding water migration under different windloads. And yes a molder or a shaper over a router table. A cut optimizer program might not hurt either. You are going to need almost a thousand linear feet for the frames and almost 700 linear feet for the muntins, which will need to pe profiled on 2 sides for 1400 LF to be fed through. Human life span is only about 80 years!

The really good news is that after you make eighty sashes, you're going to be able to crank out some righteous cabinet doors:D

[Nicholas Carey]

You might head over to http://www.historichomeworks.com/hhw/index.htm. John Leeke, who runs the site, wrote the book [literally] on restoring old windows: http://www.historichomeworks.com/hhw/reports/reports.htm#Windows

Here's a source of traditional window hardware: http://www.smithrestorationsash.com/

This gentleman has written a couple of what seem to be good articles on building traditional wooden sash:

http://awwm.files.wordpress.com/2009/10/window-and-door-making1.pdf
http://awwm.wordpress.com/making-wood-window-sash/
Fine Homebuilding has published several articles that are pertinent:


Making Window Sash: How To Do a Custom Job With Ordinary Shop Tools And a Router (http://www.finehomebuilding.com/how-to/articles/making-window-sash.aspx?nterms=63742&ac=ts&ra=fp), by John Leeke. Fine Homebuilding #18 (January 1984). pp 72-77.
Shop-Built Window Frames: Simple Joinery, #2 Pine and Stock Sash Make Inexpensive Custom Windows (http://www.finehomebuilding.com/how-to/articles/shop-built-window-frames.aspx?nterms=63742&ac=ts&ra=fp), by Joseph Beals III. Fine Homebuilding #84 (November 1993). pp 76-79.
Building a Divided Light Storm Sash: Changing the Setup of Router Bits Is the Key To Quick Window Construction (http://www.finehomebuilding.com/how-to/articles/building-divided-lite-storm-sash.aspx?nterms=63742&ac=ts&ra=fp), by T.H. Richards. Fine Homebuilding #182 (November 2006). pp 82-85.
Restoring Window Sashes: Yes, They're Worth Fixing. Those Old Windows Were Built Better (and From Better Wood) Than Anything You Can Buy Today (http://www.finehomebuilding.com/how-to/articles/restoring-window-sashes.aspx?nterms=63742), by David Gibney. Fine Homebuilding #161 (March 2004). pp 84.89.
Making Storm Windows: Wood Storm Windows Look Better and Seal Tighter Than Mass-Produced Aluminum and Vinyl Units (http://www.finehomebuilding.com/how-to/articles/making-storm-windows.aspx?nterms=63742&ac=ts&ra=fp), by Rex Alexander. Fine Homebuilding #112 (November 1997). pp 104-107.

Two of the above articles are available as PDFs from the Gifford Park Association (http://www.gifford-park-assoc.org/), Elgin, Illinois: John Leeke's Making Window Sash (http://www.gifford-park-assoc.org/MakingwindowsashFHBLeke.pdf), and T.H. Richards' Building a Divided-Light Storm Sash (http://www.gifford-park-assoc.org/Buildingadivdedlightstormsash.pdf).

There's also George Ellis' 1908 Modern Practical Joinery: A Treatise on the Practice of Joiner's Work by Hand and Machine, for the Use of Workmen, Architects, Builders, and Machinists (http://www.cambiumbooks.com/books/finish_carpentry-joinery/0-941936-08-2/).

For weatherstripping/weather seals, take a look at the high-tech silicone stuff that Conservation Technologies has to offer: http://www.conservationtechnology.com/building_weatherseals_components.html. More types of weather seals for windows detailed at http://historichomeworks.com/forum/viewtopic.php?t=1444

Don't forget the sash weights: if your new sash differs significantly in weight from the original sash, the windows won't operate properly. You can get new sash weights from a number of places...for a price :eek:, cast or otherwise fabricate your own, or find appropriately sized weights at an architectural salvage store.

That's what I know. Good luck!

[Peter J Lee]

That does seem pretty impressive. On a job the scale of what you might get into, making a cabinet might make sense. I almost always do them one at a time when I'm working on an area where the window is at. I've done my share of furniture stripping and dislike the chemicals and the mess so I go with a heat gun. The challenge is to keep from cracking the glass and to keep fresh air on me as I'm basically baking lead paint.

To protect the glass, I use a piece of cardboard with aluminum fail wrapped around it a couple times. It doesn't take long for the heat gun to soften the glazing. I use the 2 part epoxy that is like a tootsie roll to fill defects. There is probably a better bulk choice. The only major repair I've done is replacing a corner and with my limited equipment and skills, I cut a corner out of a spare and used lap joints to splice it in. I guess you could say, "glue, epoxy and paint make a window fixer what he ain't" or something like that. It was really solid though.

[Tom Hammond]

Don't forget the sash weights: if your new sash differs significantly in weight from the original sash, the windows won't operate properly. You can get new sash weights from a number of places...for a price :eek:, cast or otherwise fabricate your own, or find appropriately sized weights at an architectural salvage store.

That's what I know. Good luck!

Thanks for all the info. I saved the PDFs for later. Oddly enough, I have found about 100 sash weights hanging in the basement. Amazing they were saved... there are plenty more than enough. What I need now is a Boy Scout to teach me how to tie the right knots!!

Thansk again.

[Peter Quinn]

I'd save the poplar for another use, it will rot faster than you can believe. I'd skip the QSWO too. It will not rot, but have you ever seen a window sash made from WO? Boats, wine barrels, floors, the doors to the castle, yes, but a double hung has to be lifted, it might take three sash weights and two people to lift a QSWO sash! Ok, maybe not, but its not typical for good reason. Good fir could fly, but its a big pain to mill, and no longer cheap. The problem is that ALL the good cheap sash wood is GONE. Oh, there is good wood still to be had, but not cheap. And there is cheap wood to be had, but its not great for sash work. Yes, there is a good reason your average home owner of average income has some form of vinyl or aluminum clad finger jointed unit....they are affordable, good wooden sash are very expensive in terms of both time and labor. That is why all the clamor to save everything you possibly can of the old stuff. I have restored as many of the sash in my 100 year old home as possible, and thats most of them. I use an infa red paint stripper, proper technique for lead abatement, a little glue or epoxy putty as needed, almost nothing cant be restored easier than remade. Those great old trees are gone, but their legacy lives on. Preserve it.

For new sash work presently I use African mahogany, but I have to be real real picky about selecting the stuff for grain, not all of it even in vertical grain pattern grade is appropriate. Even 7 years ago we were using South American, but the price is through the roof. Pine was a great choice 100 years ago, and can be a reasonable choice if kept well coated and covered by storms during severe winter weather.

Anyway, how to make them? Well, the two hardest parts are the meeting rail and getting the bars the correct length. Shaping delicate bars falls just behind that. You need to make full scale working drawings for each size you want to build, include all three views. Pay particular attention to the meeting rail. It would take me days of typing to tell you everything I know, and I don't know everything on the subject by far, so it may be better to go to the literature. But it starts with proper wood selection for sure.

Here is one good old resource somebody recently showed me. http://vintagemachinery.org/pubs/detail.aspx?id=1497 Read that as a primer of the joinery involved and a good use of your shaper with the right tooling. Vintage but accurate.

I included a guide to using router bits from CMT. Amana, Freud, and the Cheyenne Sales web site (http://www.cheyennesales.com/wsashref.htm) all have good intro's to making sash with a router table, you can use the same basic ideas on a shaper assuming you know how to set up a shaper. Don't assume it is just a big router.

There is a book called Make your Own Hand crafted Doors and Windows by John Birchard. There were a few variations published, its out of print now but I bought a copy used from Amazon for next to nothing. He spells out several ways to make sash. There are no real shop drawings to follow per se but these other resources should help you develop those yourself. I suggest you get some cheap practice wood and make one complete sash to learn the process and work out any kinks before experimenting on more precious stock. Like a proto type. Its a seriously good investment of your time before endeavoring to make that volume of sash from a small shop. I actually made a bunch of sash out of 8/4 #2 common pine that was being sold as scaffold planks by a local saw mill. The stuff was 12" to 14" wide and dirt cheap. Air dried several years. I cut blanks from in between knots, hit and miss planed it, stickered it in my shop for 6 months, ready to go. There was plenty of straight grain material along the edges to make all my rails and stiles, I made bars from the parts in the middle. You don't necessarily need FAS or clear grade stock to make sash, but you do need knot free parts.

[Floyd Mah]

I want to share my experience recently with replacing windows. First, I think it is extremely difficult to rehabilitate an old window, especially with lead paint present and trying to preserve the existing glass. I attempted that on a couple of windows and realized that I was probably poisoning myself with the lead exposure and I still ended up with a window that was not very sturdy or cosmetically pleasing. In addition, you can probably make the windows in the same time and with less effort.

I had made eleven windows ten years ago, so I knew how to put together a window. Back then, I had just a table saw, a router, sled, and had made a horizontal router jig. That plus the correct rail and stile bit set will enable you to make as many windows as you need. For this time, I also had a bandsaw (not essential but helpful) and a Harbor Freight mortizer. I made fourteen windows this time. Each window had at least six panes, of varying sizes. If you carefully dismantle the windows you plan to replace, you will learn how to make them. As you sort through your windows, you will find that most of them are probably the similar or you might have several groups.

My cost was about $50 per window. The key to getting the right lumber is to find out where the local window makers get their stock. I could not find the lumber at the usual lumber sources. One hardware store steered in the direction of the local supplier. The important part is that they will have the lumber pre milled to the correct dimension. In my case, I found exactly the right thickness and so only had to cut them to the right width and length. As it turned, glass price quotes I got varied from as high as $7 per pane (about 10" x 10") to $1.50. Call around to get the best price. I used a clear pine that they had.

When making that many windows, it is important to be systematic. I used a digital height gage to make sure that the router bit was adjusted to the right height. Anyway, make a few prototypes to get your equipment adjustments down. Have a few extra pieces for each type of window so that you have a ready replacement when you make a bad cut. That happens occasionally.

I used polyurethane glue for the glue-up, but it's messy (foams), so probably wouldn't in the future. It is supposed to be waterproof, but may not be as strong as other glues. The only thing going for it is that it actually liquifies as you are assembling, so that you have plenty of time to do your assembly. Couldn't have put it together without an assistant. I pinned the joints with a pin nailer, then used bar clamps.

Glazing the glass was not a pleasure (over a hundred panes). The most important trick was that after you get the putty pressed in, you can clean the glass by dusting it with baby powder and brushing the oily glazing putty off. I primed and painted the windows before glazing so that I could avoid having to tape off the windows later.

Good luck. As I said above, be systematic. Because the muntins make calculating the dimensions a bit tricky, I used a spreadsheet to calculate the sizes of some pieces, after inputting a few of the basic dimensions.

As for tying the sash weights, examine the windows before taking them down. The trick to the knot is the free end of the rope is tucked in such a way that the iron weight will clamp the end with just its' weight.

[Peter Quinn]

As for tying the sash weights, examine the windows before taking them down. The trick to the knot is the free end of the rope is tucked in such a way that the iron weight will clamp the end with just its' weight.

The correct knot for the sash weight is a bowline. It will never let go in use, and can be undone in the future to make repairs or adjustments. Or you can use sash chain and be done with the problem forever.

As PS, look at http://www.conservationtechnology.com/building_weatherseals_sliding.html for weather seals that can make your old windows or the new ones you make more efficient at blocking drafts.

[kenneth fleming]

I would agree with the mahogany and cyrpress and disagree with the poplar...old grow poplar might be another discussion, but even so, not the choice here. If your going to make true windows with tenons you cannot do it on your shaper without a wide deep cutter with a 1 1/4 inch bore. The shaper spindle on normal cutters does not allow for the tenon to be made with any length. Amana sells a sash cutter in 3/4 bore but you will not have a tenon if you use that cutter. Unless you have a big shaper with that big deep cutter you will need to use a flat top cope cutter bit in your router. Amana makes a set of 3 cutters and if you buy 2 of them you can make the windows with a tenon.
As noted, it will take time and very acurate measurements as well as a few jigs to carry the thin strips back into the cutter. The mortise can be cut with a 1/4 mortising chisel and you will need to cut back in a few other places if you are going to hide the tenon...if your concerned about the tenon and fit then use something like a west system epoxy and add some gap filler fibers if necessary...If I was making the windows, I would spend the extra and use west system on the whole window...
In a nutshell, lots of setup but if you are doing that many, certainly worth the effort...
Good luck

[Ryan Mooney]

The correct knot for the sash weight is a bowline. It will never let go in use, and can be undone in the future to make repairs or adjustments.

The Ashley book actually has a specific knot for sashes "The Sash Weight Knot".
http://books.google.com/books?id=aN58gdigmy4C&pg=PA39&dq=sash+weight+knot
(I was curious as the bowline didn't seem like the optimal knot for this use case so looked it up)

I'm sure a bowline works fine and is certainly more commonly known :). I appears that the knot as shown has the small advantage over the bowline though in that its a tidier knot and is less likely to bind or get caught in the sash, especially if the tier is unfamiliar and leaves to large of a loop or tail (although I suppose the cord is always under tension so its pretty minimal difference).

[Peter Quinn]

The Ashley book actually has a specific knot for sashes "The Sash Weight Knot".http://books.google.com/books?id=aN58gdigmy4C&pg=PA39&dq=sash+weight+knot(I was curious as the bowline didn't seem like the optimal knot for this use case so looked it up)I'm sure a bowline works fine and is certainly more commonly known :). I appears that the knot as shown has the small advantage over the bowline though in that its a tidier knot and is less likely to bind or get caught in the sash, especially if the tier is unfamiliar and leaves to large of a loop or tail (although I suppose the cord is always under tension so its pretty minimal difference).Thanks form that Ryan! I've always used a bowline, but there is a better way! iit looks a lot like a bowline with an extra twist, but it is as you note a bit more compact looking. I usually cut the tail off the bowline real tight. I'm going to have to practice and learn that one.

[Myk Rian]

I made many muntins for the old Detroit Elevator building during its restoration. Not easy. Had to use multiple router bits to do it.
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[Neal Clayton]

you can always go with brass chain instead of rope, nicer look, and permanent ;).

i've built all upstairs replacements for my rotten originals. there are lots of pics on the historic homeworks site above, and some here. rncx is my username there. i use cypress.

it's not rocket science but there are a lot of 'gotchas' that must be done in a certain order. there are lots of cuts in general on each board. each muntin gets like 12 cuts apiece if you're doing them without a tenoner. the trick is to line up with scrap and a micrometer and assembly-line the part cutting as much as possible. no moving of fences/stops til you're done with one cut, then go on to the next cut. reduce it to simple math. oversize everything by 1/8 on all sides and trim to fit. it's humanly impossible to make a double hung set fit right directly after assembly, they always have to be trimmed to fit.

i use bridle joints glued, of course you can do it truly old school with proper mortises pinned/wedged if you like. either way you need joints all the way through, and leave the edges unfinished. it needs to breathe to stay stable. otherwise you'll trap water and cause rot at worst, or swell them into a bind at best.

oh and for weight replacements, don't buy actual weights, too expensive.

my weight idea....1.5x square steel stock, and weld a washer on to each end. just have to go by the weight per foot from the manual at the steel supply place in your town to figure out the correct lengths.

other good idea from a guy on historic homeworks....take a length of PVC, drill a hole, fill it with concrete and cap each end. just have to figure the weight of the concrete and make the length match up.