Squaring up a small piece of sheet goods on a table saw.

[Dan Steely]

Hi All,

I have a small DeWalt DW745 table saw which is fine for dimensioning sheet wood no bigger than about 500x500mm.

Using the table saw what it the correct way of producing a a square piece of wood with 4x 90 degree angles?

 

[baldkev]

Hi dan, i have the same saw for site use and routinely whizz down full sheets, its fab. For longer term jobs, i have a mobile / take down table which the saw sits in, and it increases the table size.

But to answer the question, i guess it depends if you are starting with square stock. If so, just run it through at the required sizes. If not square, youre saw came with a mitre guage which you can set at 90°...... the other option is to research 'sleds' and build yourself a very versatile sled, although size of workpiece is definitely limited when using the mitre guage or sled.
For bigger items you are probably best to square up 2 edges to work from and then use your saw.

Others will be along shortly with some ideas

 

[TRITON]

and routinely whizz down full sheets

Doesn't that make them smell and stain the surface

 

[Orraloon]

How big a square? On a small tabled saw I would first be breaking down a full sheet to manageable size. Factory edges of sheet goods are usually strait and square but check first. A checked square corner gives you two reference faces to run against the fence to get started. Set fence slightly more than size of required square. The two cut edges should now form 90*. Set fence to size of square and trim factory edges. If you dont have a 90* corner to start with then it's a job for a track or circular saw with strait edge.
Regards
John

 

[Dan Steely]

My problem is that I start off with bits of sheet that do not have any square (90°) corners so I start by creating a 90° corner and then spin the wood anticlockwise until I end up with a piece with 4 right angles.

But is that the right way to go about it?

 

[Orraloon]

Your method gives a 50/50 chance. It is right to start by getting a true 90* corner then the 2 sides of that right angle are the reference edges that run against the fence. Mark those 2 edges as they have to run against the fence. For a square the fence stays on the same setting for both cuts. For a rectangle there are 2 fence settings. Think what is happening. Make a cut and you have 2 parallel edges. Flip 90*(other marked edge to fence) cut and you have the other 2 parallel edges. That gives you a square. If the fence gets moved between cuts then its a rectangle.
Regards
John

 

[gmgmgm]

Have a look at the "5 cuts" method on Youtube - that's how to make sure your 90 degrees are actually 90 degrees (they probably won't be, to start with). Then do the same thing, but to the dimensions you want.

The DW745 has sliding mitre fence, which can be set at "90" degrees.

 

[Sideways]

My problem is that I start off with bits of sheet that do not have any square (90°) corners so I start by creating a 90° corner and then spin the wood anticlockwise until I end up with a piece with 4 right angles.

But is that the right way to go about it?

Personally, no.
Your saw has a small table and a modest mitre gauge. Any wobble of the mitre gauge in the table slot will create error. So will slight variations in grip holding the square against the short mitre gauge fence.

4x going round the square and errors could easily add up.

I would assume that the long rip fence can be tweaked to be more accurate than the mitre gauge.

Get one edge straight first. Check it, and if not, cut again or straighten with a plane until it's right.
Cut a second edge square to it with the mitre gauge. Check and recut or trim until as accurate as you are looking for.
Then use the rip fence to make the last two edges parallel with the first two.

If you need process bigger pieces, make a big sled with a long carefully fitted bar to fit the mitre slot, or fit the whole saw into an extended table top (or just get a tracksaw).

 

[Dan Steely]

Hi all,
Many thanks to all with your ideas, it's much appreciated.

As has been said, the DW745 has a sliding mitre fence is only usable for very small bits of material:

The picture above shows the saw with an after market mitre fence but as you can see, it's hopeless for any material that's bigger than. 300x300mm (the piece of wood in the picture is 370x300mm).

So I guess I need to use the rip fence as a point of reference not the mitre fence.

I have seen people make & use jigs for cutting tapered pieces for wedges.
If I have a piece of work that, for example, has a 'worse' corner at 92°, is there a way of making a long taper (using a jig) that will trim off the 2°?

BTW: the material In the picture is 9mm laminated birch ply and is the material I work with most of the time.

Many thanks again.

 

[Sideways]

If that's anywhere near typical work I would just make a sled that's 500 to 600mm longer than your table top. Get some "ground flat stock" in the correct width to fit snugly in the slot, 8 to 10mm thick, and as long as the whole sled. That way you will have the best possible accuracy from your mitre slot for the entire length of the cut. Make a nice big fence to fit across it and if you don't need to cut angles, fix it once you have proven it's square using the 5 cut test. You can afford to lose 10mm, even 18mm depth of cut to the sled baseboard if you mostly cut birch ply.

 

[Dan Steely]

The material is generally 9mm birch ply which starts off as 8x4 and sometimes 10x4 sheets.
1200x600 is a typical size i'm using for some of my projects.

Due to space I can't get a big table saw with a sliding mitre fence.
Short of your suggestions above, I guess I need a track saw..

 

[JSW]

The material is generally 9mm birch ply which starts off as 8x4 and sometimes 10x4 sheets.
1200x600 is a typical size i'm using for some of my projects.

Due to space I can't get a big table saw with a sliding mitre fence.
Short of your suggestions above, I guess I need a track saw..

There's the problem, the DW745 just isn't designed to be able to cross cut that kind of size, track saw would be the easiest solution, but this guy has some really nice ideas, and may well inspire you to build a variation of.

 

[Orraloon]

That does look like a great setup.
Regards
John

 

[Jacob]

My problem is that I start off with bits of sheet that do not have any square (90°) corners so I start by creating a 90° corner and then spin the wood anticlockwise until I end up with a piece with 4 right angles.

But is that the right way to go about it?

No, in theory!
You need to cut the first two right angle with reference to your starter straight edge, not to go round in sequence.
This way errors tend to cancel each other - going round in one direction amplifies them.
This is a basic and ancient fact of marking up and part of the reason for face and edge marks - you always aim to reference best face and/or best edge.
In practice things may be different.

 

[Flynnwood]

Dan - I think you will enjoy this educator from 2012:

 

[mikej460]

You can obtain a straight reference edge by making one of these
Simple Taper Jig // Jointer Jig // Woodworking // Diy Jig - YouTube
and she shows you how to use it to create a reference edge in this video
$40 Moxon Vise - Easy to build in an afternoon! - YouTube

 

[Dan Steely]

Again, thanks for all your help on this subject. I've made a simple taper jig and it's worked pretty well on smaller stock. I've also taken the plunge (no pun intended) and bought a Makita SP6000K1 track saw which is a lovely bit of kit and makes squaring up large panels simple.