Cutting Celotex for stud insulation

[paul_david_thomas]

Just a quick heads up... I build a few 'offices' (Posh Sheds) and we insulate with Celotex (or similar) between and over the studs. I 'used' to cut with a large kitchen knife (sorry girlfriend) or Stanley and snap the sheet with my knee, then trim. Problems with this are the stuff goes everywhere and makes me cough a lot. You also find yourself re-trimming quite a bit.

My last build i decided to use a guide rail, VAC and TS 55. Phew... That makes things a lot quicker and a lot less mess. I just let it cut about 3-4 mm too deep - goes into next sheet.

When I build offices, I tend to build the structure (inc. roof) and walls, so it is water tight, then bring all the sheet materials in, in reverse order and stack in the middle of the office. Then cut them in situ.

I've got the plate that clips onto the TS55 - which minimizes the dust lost through where the blade it.

I've also got the new 12 teeth (old one was 14) panther blade.... I've kept it in for most of my rough work - I've even used it on the cedar cladding - lovely finish - honest !

Paul

 

[ajones]

Paul I have not tryed it, but what about those wavey jigsaw blades more like a knife than  toothed?

 

[Trumpet]

Just need the right style of knife. I picked up a very old wooden handled knife which works a treat, rectangular, thin in profile, with a sharp edge along the whole length and just over 50mm long (obviously depends on thickness of celotex for a single clean cut).  Works an absolute treat, almost zero mess and very accurate when used up againt a simple straight edge or batten. Would never even consider using a saw/reciprocating blade or anything else.

 

[jonny round boy]

I've just re-done our roof (one of the reasons I've been very quiet on here of late) and insulated it with Celtex. I would have loved to have been able to use my TS55, but the insulation was 100mm...

I toyed with the idea of cutting from both sides, but constantly having to turn the sheets over would have been such a pain. In the end I just used an old hand saw & lived with the mess (of which there was an aful lot!).

 

[JeromeM]

My last build i decided to use a guide rail, VAC and TS 55. Phew... That makes things a lot quicker and a lot less mess. I just let it cut about 3-4 mm too deep - goes into next sheet.
I've got the plate that clips onto the TS55 - which minimizes the dust lost through where the blade it.
Paul

Another thing that helps with dust collection is a little tape and as it is said a picture is worth a thousand words
[attachthumb=#]

 

[toolfest.co.uk]

Hi Paul

We were set a similar problem by a customer last year and I'm sure he won't mind me sharing our results. His application was for insulated transit cases with a 'Celotex type' material lining the cases. We needed to find a way of cutting straight lines in (I think) 80mm of material. We tried the TS 55 and had good results, although could obviously not get the depth of cut required. Next we tried the wavy jigsaw blades (493656) with our demo cordless Carvex PS 400 jigsaw and 1400mm guide rail. The results were quite frankly, as near to perfect as we could ask for. Clean straight lines without dust, as we were slicing and not cutting. Also we could cut as quickly as we liked, think hot knife and butter!

We did try with expanded polystyrene as well, but the result were wholly disappointing with excessive heat build up ruining the result.

Hope this helps

Best regards

Warren

 

[woodguy7]

Bakho make a wavy edge hand saw for just this sort of thing.  Absolutely no dust.

http://www.tool-net.co.uk/p-352865/bahco-22-profcut-insulation-saw.html?gclid=CJWZqrC3sa0CFQUOfAoddVV1tg

 

[paul_david_thomas]

MMmm... Many suggestions !

I've not used a jigsaw as it's not got an adjustable blade depth. But I can see it's merit. I've decided to not use a knife (or larger one) due to the blade not cutting at 90 degs (unless you've got a real steady hand). I like a perfect (ish) fit on the full depth of my 100mm studs - not just some of it. I want a night tight fit - oh err ! I might however sharpen my current knife up and give it another go.

Fortunately I've been cutting 50mm and 12.5mm sheets - so I've not hit the 100mm issue. I've only used 100mm on sub-floor. I do refurb work, so my roof conversions tend to be 50mm between existing 100mm joist voids, then XXXmm over the joist - as you need to leave 50mm airflow.

I am liking Jerome's suggestion of the gaffa tape. I tried this and it worked great for a while - until the sticky stuff that was exposed to the blade kept collecting too much. So, I pulled it off, and put a new bit on - however stuck some more tape (shiny side to the blade) where the hole is. Thus, no sticky surface exposed to catch stuff on !!!

However, one of the most efficient ways of solving all problems is to get one of 'your lads' to do the cutting and fitting. This way, you pile up the required materials. Go, off site. Then return. All boards fitted and area swept and cleaned

 

[Wooden Lungs]

Over the years I have tried many different ways to cut rigid insulation panels effectively and I have narrowed it down to the easiest way (in my opinion!!!).

I use a recipricating saw or in the US I was told they are called 'Saws all?' with a rigid and long demolition blade inserted. I use a chalk line to snap a line.

When marking the sheets it is difficult to use a pencil or marker so  I use the tip of the pencil to basically stab lightly to make measurement marks for my chalk line.

The 'Saws all' or recipricating saw will not make too much dust and the rigid blades give a very neat cut.

It may take a few goes to get the hang of it but you will find it works great and speeds up the whole process.

Unlike a jigsaw you can plunge cut too which is helpful for sockets etc.

Plunging with a jigsaw can sometimes bend the blades.

Obviously this methed is good for thicker sheets, say 100mm etc. For the thin stuff I use a stanley knife and cut them in a very similar way to drywall by scoring the face cracking it and then running the blade down the back.

 

[Deansocial]

wavy saw blade/knife i found to work best. and thats working with the 150mm sheet

 

[duburban]

drywall knife, sharpen it if you want to. like cutting drywall. almost 0 dust. when we cut this stuff the dust/chips will be with us forever.

 

[paul_david_thomas]

duburban,

From what I can see of a 'drywall' knife is that it's does not have a leading edge that's sharp (http://homerenovations.about.com/od/drywallsheetrock/ss/drywalltools_3.htm). Infact, unless I'm looking at the wrong thing a drywall knife looks like what you use on tapper edge to fill the hollow between two sheets. Hey, I'll give it a go next time I do an office - I'll try anything !