Breaking down plywood - which "insulation board" to cut on?

[Midnight Man]

Thanks for any words of wisdom that folks may be able to share on this!

I'm about to start working with a lot of plywood for various things, and if you search around just the tiniest bit, you'll see folks in the USA talk about breaking down sheets of plywood on a "rigid foam insulation board". They lay this on the floor, then the plywood on top of it, and cut away on the floor.

I like this idea, as it would make the process safe, and you'd get great reach etc.

Here's just one of many examples: Using RigidFoam Board To Break Down Sheet Goos - Work Shop Tip - YouTube

You will often find the comment "Just head down to your local home centre and grab one".

Problem is, the products in the US are often not what we get over here, and I'm far from knowledgeable about insulation products.

Would anyone know what product(s) we can get here that would be suitable for this sort of thing?

Many thanks if you can offer some insight/advice on this.

[aldav]

I have used suitable sized styrofoam sheets as an underlay to cut up sheet goods, not bought though, but salvaged from skips. Waffle pods for concrete slabs would work ok. The thing I've used more often though is a large size softwood pallet, also free, I like free. Pallets work well, just make sure you align your cut to clear nails etc., you can even clamp the sheet to them.

[ian]

Thanks for any words of wisdom that folks may be able to share on this!

I'm about to start working with a lot of plywood for various things, and if you search around just the tiniest bit, you'll see folks in the USA talk about breaking down sheets of plywood on a "rigid foam insulation board". They lay this on the floor, then the plywood on top of it, and cut away on the floor.

in the US and Canada you can buy 8' x 4' sheets of rigid foam insulation in 1", 2" and 3" (and probably thicker) thicknesses for about CAD $20 (1" thick) per sheet.

In Australia, a similar sheet (well actually 4 separate 1.2 x 0.6 sheets) of rigid foam would set you back about AUD $50.



Depends on the tools you have available to you.
A track saw and MFT will allow you to do a lot of the sheet breakdown at waist height. Much gentler on the knees than the garage floor.

If you have a Bora (?) table system you can also cut at waits height.

an option possibly worth considering is to have the ply supplier cut the ply into more manageable sizes.

[Aussiephil]

I wish we could buy the isulation sheets like north america but alas neither cheap nor ready available.

My 1.2x2.4 breakdown system is a pair of old steel frame tables with a pair of 1.2m long sacrificial 90x45 pine on top spaced 500mm apart per table. set the saw to a few mm deeper than what im cutting and i don't care if cut into the pine.

I've been known to forget to change the saw depth though and slice more than i should

One pair used for full sheets and a single used for part sheets .... i used a single the other day to break down a full sheet of 12mm ply as the other one had the thicknesser bolted to it.

[Sir Stinkalot]

They must have a wider range of rigid insulation boards in the USA as it is extremely common to see them use it as a base for cutting down sheet goods. Bunnings stock FoilBoard but it’s not particularly cheap for the application.

It might be worth checking your local white goods store - fridges often have a panel of polystyrene board to protect the fridge. It’s not overly thick but would do the job.

[Beardy]

Not sure if I am missing something but why wouldn’t you just use the cheapest spare sheet of whatever you have be it ply, Mdf, particle board or fancy foam board if you have it?

[jpdv]

In all honesty, don’t bugger about. The best solution is a large table, with some cheap sacrificial pine battens on it... here’s mine, being used to cut beech, but you get the idea. Based on the Paulk workbench. I made it from a few sheets of c/d ply, so it’s the right size. When not panel breaking, it’s a great general purpose assembly/layout table.
The relief on my back, and the precision gained from not having to stoop/ bend, is worth every minute and cent of construction...The battens store on the shelf underneath when not needed.741E117D-0D18-42C9-B2F5-BB3C0445FCA6.jpeg

[havabeer69]

Yep, a few 2.4m "non structural pine" battens from the big green shed work well, can also use them to clamp the ply wood sheets to your roof racks.

If you gumtree insulation or refrigeration panels you might get what you need. That or i actually saw large foam sections at bunnings the other wek specifically designed for cutting sheet goods on. Might have been this stuff

Bastion 1200 x 600 x 30mm XPS Multi-Use Insulation Foam Board

[Bohdan]

That's what I use. Two sheets and you can cut full sheets and easy to store.

[samo]

As noted above the most readily available is Foilboard from Bunnings. It's not cheap like it is in the US but in all honesty it's only $43 for a 25mm sheet. You would get many 100's of cuts out of a sheet and the convenience of having a light weight sheet rather than a sheet of 16mm MDF is probably worth it.

Alternatively if the weight is a non issue then just ask your local timber supplier for a cover sheet that comes with any pallet of sheet goods. They will probably sell you one for $10-15. Back when I worked in a timber yard, nearly 20 years ago, we did this all the time. 16mm MDF was the most common material used as a cover sheet.

[malb]

I generally use the 25mm or so thick camping floor mats with the edges punched so that the sheets can be set up to interlock. Advantage is that a couple of sets can be arranged to break down full sheets of material, or a single mat on a benchtop is handy for smaller parts, without needing to commit a lot of space. Can also be arranged for long narrow material, broader material etc, not positively locked into a particular sized foam sheet. Generally cheap to buy on special at camping supply stores etc leading into the holiday season as well. Same sort of stuff Bernmc mentions below.

Other option is a couple of saw horses and a couple of sacrificial 70x35 lengths to bridge them and support the sheet, but more hassle than foam for single handed handling heavy sheets.

[Bernmc]

I use these: EVA 50 x 50cm Interlock Foam Mats Solid Black Pk4 | Bunnings Warehouse - note that there are four in a pack. Think I got a few packs on special, but they're only $10 a pack.

Nice things is they're easy to store as they come apart, and can be connected in variable configs - so if I'm cutting on the bench, I just do a single row. If I'm hacking up sheets on the floor with a track saw, I add a row (or two). For the big sheets, I don't usually make a full surface - just a row under the cut, and a few pieces to support the rest of the board.

[Midnight Man]

Wow, and thank you to everyone who responded to this!

All excellent information, but the jackpot may well be this product: Bastion 1200 x 600 x 30mm XPS Multi-Use Insulation Foam Board (which I searched like mad for, and my Google-Fu and Bunnings-Fu failed to find). Whilst there will be more than one required, it becomes a neat modular solution that can be taped, and folded together. I will go take a look at this, and report back!

I know others suggested to use some sacrificial MDF or ply as a base, and whilst it would work, I was considering the weight and the fact it too would need shifting about.

I had also thought of making a low table or suchlike to cut on, the problem I saw with that was the fact that cutting across a 1200mm deep sheet makes it really hard, and dangerous, to reach from one side - the advantage of being at floor level is that you can "crawl" across to make the necessary reach (or so I envisage). It also turns out that I don't have a problem getting up or down, or working around on the floor for some time - at least at this stage, though I recognise it may become a problem.

Many thanks for all the thoughts and suggestions - I will see if our local green tinted hardware place can source a few sheets of the product above, and I'll report back with information in case it helps anyone in the future!

[GraemeCook]

Last time I did this, MM, I used some thick corrugated cardboard salvaged from a very large carton used to ship a two door refrigerator. The corrugated cardboard was 10mm or so thick. And free from HN.

Before that I used a flush panel door as a sacrificial bench top and just cut into it (lightly). Damaged doors are only $10 from Bunnings and M10.

[Cgcc]

Can confirm. I use these, thrown on the garage floor.

For me I don't have enough extra space to store any additional temporary benches space as it's pretty rare for me to be sawing really big pieces, and even then, but it's nature you're only making a few big cuts.

An advantage is they are super light and obviously don't degrade (although you don't want them getting muddy as it'll transfer onto your panels). So you can throw them around, store on a wall, outside, on top of something. If they fall down they're just foam and won't hurt you or anything. I keep them behind my wheelie bins.