Context / X-Y problem source:

I'm trying to arrange perfect-fit blinds in a bedroom with bright South-facing windows. The blinds have runners that attach to the insides of the recessed window, to entirely seal the blind.

The tolerance on the blinds I'm ordering is +/-6mm variation in the width of the window, top to bottom.

My recessed windows are have more variation than that - the top is 13mm narrower than the bottom. Fortunately (AFAICT) all the off-square-ness is on one side. The other side of the recess is plumb.

My plan is to acquire an insert to be screwed to the off-plumb side, to create a plumb edge, that the blind's runners can then be attached to.


So ... I need to acquire a piece of wood that is a ramp (or a right-angled triangular prism) that looks like this:

enter image description here

With dimensions:

  • a = ~98mm
  • b = ~1175mm
  • c = ~13mm

Obviously constructing an object with 3 different orders of magnitude for its 3 dimensions is ... challenging :D There are websites where you can order custom shapes cut, but none that I found support dimensions this extreme.

Any ideas about how to solve this issue?

  • 3
    This is a simple job, a neighbour with a table or band saw can do it for you or your local lumber yard can do it. Your 98x13 would be a common 1x4 by 4 ft. size of lumber in north america. Using a website to order this, would cost too much, compared to local.
    – crip659
    Jul 4, 2021 at 18:09
  • 2
    What trim is around the window? Is it cased, or a drywall return? Either way, you'd be better off just putting a non-tapered board there and trimming/filling up to it. Jul 4, 2021 at 19:19
  • 1
    Please provide a photo of the window, show the recess, and indicate the plumpness problem that needs to be corrected. While the sloped plate is doable, but 13 mm slopping over 1175 mm run is not something commonly done. I think there shall be better solutions, but require more details that you have provided.
    – r13
    Jul 4, 2021 at 20:44

3 Answers 3


Forget the ramp, 13mm is easier to do with shims. Buy a strip of trim wood similar in width to the side of your window. Buy some shims (a box of small wooden wedges). Use the shims to install the strip at any angle your need. You get very fine control and this will do the job you need.

If the runners are strong enough you don't even need the trim, you can just shim the runners directly using wedges or washers, then conceal it all with caulk. OTOH if the runners are flimsy plastic, screw them to solid wood with the shimming behind it.


If you want to make that large wedge-like "ramp" you start with rectangular wood then rough-cut it with a rip-saw (eg: a table saw) and finish with a plane.

personally I would just make the wedge wide enough to support the track (or possibly two at half-width with the join hidden by the track.. that makes the cutting much easier.


Use long attachments that you can adjust.

If the ramp fits it will be great. If it is not perfect it will not be true.

Why not attach your blinds with long bolts? You can adjust the depth of the bolts until you get your blinds level. The place where you would have thick wood to build it up will instead have a long bolt. Then if you don't like the look of the different length bolts you can conceal them with a skirt of some sort.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.