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Cutting Fiberglass batts.

andyb | Posted in General Discussion on March 6, 2007 11:15am

Realize nobody likes them, huge advantages using foam, cellulose etc.

Long story short, I have a lot of batts to cut and fit into stud cavities and am interested in doing the best job possible. 

What methods do you use to rip 93″ batts to needed widths?

Thanks.  Andy

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  1. User avater
    BossHog | Mar 06, 2007 11:26pm | #1

    I have a utility knife with a spring built into it for cutting batts. But I don't know the brand and can't find anything like it using google.

    I did find a coulpe of other things searching around:

    http://www.6z5.com/acme-hardware-453644990.htm

    http://www.cepcotool.com/insulknife/

    .

    The simplest method - Aside from special tools - Is to compress the batt with a 2X and run a utility knfe along the edge of it.

    Imagine me and Pamela Anderson lying next to each other on the beach - Topless [Michelle Marsh]
  2. rez | Mar 06, 2007 11:29pm | #2

    Crawl around on floor with a metal straightedge, palm and knee keeping straightedge on FG and compressed tight. 

     If faced put face down to plywood floor or sheet and keep the utilityknife's blade replaced as soon as there is any question as to it's sharpness.

     And swear to never use fiberglass batts again as soon as you have used up the last of yer stash;o)

     

    be the world can be ugly enough without adding to it with fiberglass batts

     

     

    every court needs a jester



    Edited 3/6/2007 3:32 pm ET by rez

  3. DanH | Mar 06, 2007 11:35pm | #3

    Several ways to do this.

    The standard "trick" is to lay the batt down on a piece of plywood (facing up, if faced), lay a straight-edge (narrower piece of plywood or a stiff 1x4) on top, press down HARD to compress the batt, and then cut along the straight-edge with a sharp utility knife. This is remarkably easy and effective.

    Some folks have reported good luck with various large shear-type paper cutters.

    Also, for doing "trick" cuts, if you have many of them, go to a fabric store and buy a large pair of Fiskars scissors.

    It would also be interesting to try a rolling fabric cutter (like a pizza cutter) when using the plywood trick, but I don't know that it would be any better than the utility knife.

    So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
    1. rez | Mar 07, 2007 12:14am | #4

      YOU AGAIN!!! snort :o)

      Acually I find it easier with the face down and sharp blades in that there is less opportunity for the facing to bunch up and provide an uneven cut

       and the tip of the knife always providing a clean tight cut of the face by the bedding of the blade nose while the bulk of the remaining blade slices the bare glassbatts.

      be I understand paul has devised a way to cut batts using a unique screw method involving Deckmate phillip/squaredrives  

       

      every court needs a jester

      1. DanH | Mar 07, 2007 12:44am | #6

        Yeah, no biggie. I've always done it face-up, but I haven't done that much that it was worth experimenting with.
        So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

    2. User avater
      dryhter | Mar 07, 2007 12:20am | #5

      Hopefully you are working at a house that has one of those pretend Gourmet designer kitchens.

      Ask the homeowner to barrow a German made 8 or 10 inch French chef's knife, don't forget the steel.

      If nobody is home just wash the knife when you put it back.

      Paper side up always.

      Believe it or not an electric knife works well,......that's usually in the cabinet over the fridge.

      1. mwgaines | Mar 07, 2007 12:47am | #7

        I've tried all the ways mentioned here, but found that using manual hedge cutting shears is the easiest for me. I simply measure across the batt at one end and place a mark where I want to begin the cut. I start cutting at the mark and try to keep the width of the cut consistent. It works pretty well until the blades get dull.New knowledge is priceless. 

        Used knowledge is even more valuable.

        1. TheOldCynic | Mar 07, 2007 01:25am | #9

          I've had a modicum of success using a Husky Rancher 25 -- With an 18" bar, you can do a whole bundle at once.  Keep yer shop-Vac handy, 'though

          Doc - The Ol' Cynic

  4. doodabug | Mar 07, 2007 01:00am | #8

    I cut it face down. I mark it with tape measure and knife just like I do when cutting drywall. Then I hold utility knife by the end and finish cutting through.

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