Squaring wood sheet that’s un square on all sides

[Roboboyo]

Hi guys

Does anyone have tips on how to square up a sheet of ply that’s out of square on all 4 sides ?, (no bows or twists, just off square)

Cheers

 

[recipio]

I'm guessing you don't have a table saw with a nice sliding fence which is how most people would do it. You need to get two sides at right angles to start. You could plane one side back to a line and then finish the other sides with a saw. Or you could find a square piece of MDF and use it as a template to rout the edges square. It really comes down to the equipment available.

 

[ChaiLatte]

It really comes down to the equipment available.

I'll name that tune with a piece (loop) of string divided into twelve equal parts.

 

[Roboboyo]

I'm guessing you don't have a table saw with a nice sliding fence which is how most people would do it. You need to get two sides at right angles to start. You could plane one side back to a line and then finish the other sides with a saw. Or you could find a square piece of MDF and use it as a template to rout the edges square. It really comes down to the equipment available.

Thanks for the reply, I do have a table saw but how would that work against a fence if it’s off square?

 

[SLM]

Thanks for the reply, I do have a table saw but how would that work against a fence if it’s off square?

Set the mitre fence square to the blade

 

[recipio]

Thanks for the reply, I do have a table saw but how would that work against a fence if it’s off square?

The fence must be adjustable ? Use a large square like a roofing square to set it at right at angles to the blade. Most saw fences are token miter fences so it's worth adding a straight batten to the fence before squaring up.

 

[Inspector]

*Tack a straight piece of wood, ply or MDF on one edge, longer is even better to help keep stuff aligned. Run it along your fence to get the parallel edge straight.
*Remove the straight edge and put the freshly cut edge against the fence to cut the formally tacked edge straight.
*Tack the straight edge at 90º to the parallel edges and run it along the fence to cut the edge parallel to it.
*Remove the straight edge and cut the plywood edge it was on.

Now you have a squared up sheet. The wood you cut off only needed to be kissed by the blade to clean it up.

This only works if the saw is in tune, fence parallel to the blade and the saw is big enough to make the cuts. Otherwise do it with a track saw or router against the straight edge.

Pete

 

[HOJ]

Are you using the full sheet as a whole, or just squaring up to start with to re-cut into smaller pieces?

 

[Hornbeam]

Assuming it is an 8X 4 sheet (works for any size) then too big for most saws. Use a hand held circular, a batten and a tape measure/ Draw a triangle 4 ft on the side across the sheet and 3 ft along the side. The edge joining the 2 sides is 5ft, , Draw a line across the sheet and if you have measured correctly and teh 3 sides of the triangle are 3,4,5, then your line must be at right angles to the side. Clamp batten to the plywood parallel tp you line to act a st a guide for your saw ( or use a track saw). Once you have 2 sides at 90 degrees it is just measuring to set up you batten and using the saw
I have a large olld scrap pallet that I sue as a base so the saw can cut right through

 

[Sachakins]

+1 for Inspector.

 

[pe2dave]

Anyone recall the method taught at school to draw a right angle?
Basically bisecting 180 with compasses.
That would give you a true 90, not trusting any equipment to be true.

 

[BucksDad]

Anyone recall the method taught at school to draw a right angle?
Basically bisecting 180 with compasses.
That would give you a true 90, not trusting any equipment to be true.

I do now you've reminded me I often look back at schooling and think that we were taught things to pass exams, not for pleasure / life long usage / learning and it's why I never really enjoyed school and so much of what I learnt didn't seem to stick in my mind long term

 

[Spectric]

Is this not the domain of the tracksaw if you have one, else a circular saw and batten. If the edges are ok but form a parallelogram then surely just pick on one edge as a datum and then cut at 90° to this with a set square and batten / track. The last cut is to get the last edge square from one of the two previously cut edges.

 

[pe2dave]

This shows it for acute angle, same method for bisecting 180.

 

[pe2dave]

Is this not the domain of the tracksaw if you have one, else a circular saw and batten. If the edges are ok but form a parallelogram then surely just pick on one edge as a datum and then cut at 90° to this with a set square and batten / track. The last cut is to get the last edge square from one of the two previously cut edges.

Yes, but only if your measurements / your mitre fence are really accurate?
Geometry ensures the right angle is accurate. Ruler and tracksaw can then do their job.

 

[Spectric]

I suppose just applying good old Mr pythagorus and the 3 4 5 rule is another way to confirm the accuracy of your tools. I made a square using the Parf 2 system and I know that is sound, plus I can check it against my Benchdogs triangle.

This is a situation where if you had the space a decent sliding table saw comes into it's own, something I would love to own but the only space it could go is the living room and that is not happening.

 

[pe2dave]

Simple geometry overcomes any inaccuracies in jigs, is more 'portable' and is reliable @Spectric .

 

[richnfamous]

Hi guys

Does anyone have tips on how to square up a sheet of ply that’s out of square on all 4 sides ?, (no bows or twists, just off square)

Cheers

the first step is to cut a straight edge. you can do this with a circular saw and a straight batten - maybe the edge of a sheet of MDF? Clamp it in such a way that the edge of the foot plate of the circular saw runs along it and make the cut

as for the second square cut: it's good to have a nice big square but a rail to cut along is essential

after that, it's a question of accurate measuring. you could make a 'poor man's panel gauge' with a piece of ply and a batten, and tap a nail through at the correct width but that's optional

 

[Jacob]

Hi guys

Does anyone have tips on how to square up a sheet of ply that’s out of square on all 4 sides ?, (no bows or twists, just off square)

Cheers

Can only be 3 sides off, so that's a start!
What's the problem exactly? How do you know it's off square?
If you know it's off why can't you mark it up square and trim to the marks in the normal way?

 

[SLM]

Simple geometry overcomes any inaccuracies in jigs, is more 'portable' and is reliable @Spectric .

Though it is still reliant upon the accuracy with which the geometry is transferred to the material; the straightness of an edge, the thickness of a pencil line…