Window Hinge Mortising Retrofit Techniques

Detailed advice for cutting new Soss hinge mortises on custom replacement windows to match already-mortised existing window jambs. June 3, 2007

I have a job coming up where I have to replace a bunch of wooden casement windows. Only the sashes will be replaced; the jamb will remain in place. There are two soss hinges per sash. As the jambs are already mortised for the existing hinges, I need to work to that and mortise out the new windows for the hinges. Soss hinges have no means for adjustment. Anyone have experience doing this on site? I'm going to buy some hinges and try a prototype out in the shop but I'd appreciate any suggestions for getting the technique dialed in before I begin the job.

Forum Responses
From Gary Katz, forum technical advisor:
When you buy the hinges, buy the correct router template from Soss. They make two-step templates for their hinges, with removable pins which you back out before plunging in deep to cut the pocket mortise. With the pins in, you cut the shallow mortise for the shoulders of the hinge. You'll need a plunge router and a long bit. Make sure you get the right diameter bit for the template/hinge combination. Sometimes even the long bits aren't long enough and I've had to drill out a little of the pocket with spade bits. A minor hassle but not a problem.

If you set yourself up that way, you'll be a happy finish carpenter, for sure. If you don't, you'll probably be sad, for sure, unless you are good at and enjoy drilling Soss hinge mortises by hand with forstner or paddle bits.

You're right. There's no adjustment. Your hinge mortises have to be spot on. I usually go a little shallow at first, try the door, then dial the router in to move the door a tad closer to the jamb. Shimming out the hinge from a mortise that's too deep... well, you can do it, but it's not fun - and then the hinge will wiggle a lot.

Also, don't back bevel the hinge stiles (I usually do on regular doors). That really screws up Soss hinges! (I'll let you imagine how I learned this stuff...)

From contributor J:
I recently worked on a job with 9 doors hung on soss hinges, the large 218. One of those needed a pair of the 218 Invisible Closers. It was a remodel and I went frame to finish and laid out hinge locations roughly on the cripplers as I went and kept nails out of those spots. If you are hanging in existing jambs, you may want to keep the deep mortise shallow and maybe finish it with a spade bit depending on the size of the hinge and the depth required for the deep pocket. Soss 216 and 218 hinges require 1 5/8" deep pockets. Depending on the jamb thickness, you might get into the framing and hit a nail. I ordered a template from Templaco for the last job and it worked alright. I used a 2 1/2" straight bit and a bushing guide. By the end of the job, the thin strip on the inside of the mortise pocket did get a little warped, so maybe go with Gary's suggestion of the Soss template. I'll try that next time.

I had to shim out one set of hinges on the job. I used laminate samples that I cut to fit snug in the bottom of the mortises to keep the hinge from rocking.

When putting the hinges into the mortises I rubbed a little wax on them. They fit real tight and I had to get them out for the painter and didn't want to use a block and hammer to do so.

Also cut out the drywall at each hinge location, just a small square, and glue in a block of hardwood to replace it. If the window sits flush to the jamb, the outer hinge screws will have something to bite into aside from sheetrock. Casing will cover this.

With a plunge router and template, cutting these hinges isn't too bad. It's just time consuming. Double and triple check your measurements and everything works out.

From the original questioner:
I looked on-line for the soss template. It looks like a butt hinge template, but a different template is needed for each size hinge. At $180 to $250 per set (for one size), I'll make sure I get the right one.

Contributor J, the existing hinges are already mortised into the jambs. I only need to bore the new sashes. I'll keep your wood block for drywall trade in mind, if ever there is another time.

Thank you for your detailed and insightful posts. This website is truly a blessing.

From contributor J:
I found the Soss single pockets for 37.95 at That's about what I paid with shipping from Templaco.

After reading the bushing and bit requirements of the Soss templates, I see the advantage of the Templaco is that you use a 5/8" o.d. bushing and 1/2" bit which I usually leave set up in an older Porter Cable plunge router anyway for oddball and stepped mortises for hardware in homemade templates. Norfield makes a heavy duty adjustable template for a couple hundred bucks but it can be modified to do other stepped mortise applications like extension flush bolts. Unless I mortised for this type of hinge very frequently, I'd go with an inexpensive single pocket or a couple at different sizes and add to my labor price for the time spent laying out and cutting. The layout may also vary, as it frequently does, in new door/old jamb situations, so you'd end up spending a lot of extra time playing with the extension bars between a multi-pocket template. I am not aware of any hinge blocks like those made for the Bosch Butt Template for quick layout of Soss hinges to existing mortises. If they are all the same, you could make a story pole for layout or make spacer blocks with a hook on the end that registers each hinge off the top of the sash to the top of the template. That way you only have to manually lay out one. My last time out with this hardware it wasn't worth doing this, as the door sizes ranged from 9'4" to a 5' door cut and rerailed to follow the pitch of a stair and the hinge requirements per door of 2-4. Maybe I am missing something.

There is an instructional video on the Soss website that could be helpful. One other tip. Don't try and be slick and set up two routers for the different depths. Bushing guides aren't all exactly the same size. At least the Porter Cables I was using weren't. Cut yourself a spacer block at 1 5/8" or whatever the depth for the size hinge you are using requires, zero the cutter inside the pocket, lock in the router, and use the block to set the depth for the deep mortise. Do the same for the finish mortise, except use the hinge itself to set the plunge depth. I found this out the hard way the first time I used these hinges. Oops.

Gary's suggestion about leaving the mortise shallow and adjusting the depth after a fitting is a great one. I intend to use that the next time I get to play with these.

From contributor T:
Since you are replacing window sashes, you should pay close attention to how the old ones are fitting on the hinge edge. If the gap is good, you can replicate the mortise exactly with some degree of confidence. Also, pay even closer attention to the hinge backset - the distance between the edge of the window sash to the mortise of the Soss hinge. The hinge may not be centered on the sash edge and the result will be a bind.

From contributor D:
A little trick I do if I need to re-cut a hole slightly over from the existing hole. I fill the existing hole with bondo, then it just drills out like there was fresh wood there all along.