Routing instrumescent strip in existing frame for fire doors

Discussion in 'Carpenters' Talk' started by Jitender, May 16, 2018.

  1. Jitender

    Jitender Well-Known Member

    As part of the loft conversion, i have to upgrade 2x doors downstairs to fire doors.

    Don't want to put the strip in the door as feel it would ruin the.

    I have a Katsu router which would be perfect to do it but the fence supplied wont go in an further, plus it too big height-wise as will hit the architraves.

    Sample of what I want to achieve. these linings were machine for me at the timber merchants.

    Katsu router with guide.

    Base of router with guide.

    Door linings I want to route out for the strip.

    Will be removing the door stops.

    Other than making a jig is there any other way to do this. I know the router wont reach upto the corners an the bottom of the frames, so will need to finish this by hand.

    Router has 4 screws which secures the plastic base to the bod of router, thinking I could make something with ply using these fixing points?
  2. WillyEckerslike

    WillyEckerslike Well-Known Member

    Sorry if I'm being thick (highly likely) but won't the fence reach if you use the other hole?
  3. CGN

    CGN Well-Known Member

    Easiest to do door with one of these.
  4. Jitender

    Jitender Well-Known Member

    Think it might work, never used the fence and accessories for the router. The only thing it will hit the architraves, as they are set in 6-8mm from the edge of the linings.
  5. CGN

    CGN Well-Known Member

    I've done them before on my HMO's with my 1/2" router. I cut some MDF to use as a fence and popped a few screws through into the frame and used a guide bush in the router.
  6. Jitender

    Jitender Well-Known Member

    I can see that the bit you've linked to has a top bearing fitted, so will need a temporay guide fixed into the frame.

    I do have a large 1/4 router which is more accurate, but will be difficuklt holding vertical and upside down. The katsu is much lighter, but depth setting is a little crude.
  7. CGN

    CGN Well-Known Member

    Its designed to go around a door. So easy to use.

    If your door linings are perfect, then you may get away with using a fence along the frame. If not, a temporary fence is the way to go.
  8. Jitender

    Jitender Well-Known Member

    Looking to make a jig. Can use the base once unscrewed for the 4xfixing points.

    2x stops fixed to accommodate different thickness of linings.

  9. Jitender

    Jitender Well-Known Member

    Yes can see now as cutters on the side so follows around a door.
  10. Jitender

    Jitender Well-Known Member

    Going to be tomorrows project.:)
  11. Jitender

    Jitender Well-Known Member


    I've built the jig and seems to work. Ordered a 15mm wide router bit

    Will upload pictures tonight.
  12. CGN

    CGN Well-Known Member

    Practice on scrap first. You only need a bit of unevenness or 'chatter' and you'll end up with a wonky slot. :confused:
    Jitender likes this.
  13. Jitender

    Jitender Well-Known Member

    this is it.

    Only took me a small amount of time to make this using offcuts. Fixed a strip of wood on the top to act as a handle.


    Underneath. Router has had plastic base removed and screws replaced. Need 2x longer screws to order. The pine strip wood acts as the fence.

    Made the mistake of having the cord outlet positioned to the top :oops:, would have been better to the side.
    CGN likes this.
  14. GoodwithWood

    GoodwithWood Active Member

    For me if it's a reto fit then either the door gets a rebate for the intumescent strip or the lining comes out and gets replaced.

    Are you sure the lining is suitable for a fire door application? It should be at least 30mm thick and not made from materials such as Ash (no pun intended).
    kitfit1 likes this.
  15. Jitender

    Jitender Well-Known Member

    Managed to rout out one of two frames the linings are 32mm thick.

    When I came to do the lounge I messed up, so need to order a new lining for the this room. All the hardwork taking paint off and sanding gone down the drain, trying to look on the good side :oops: as can make the frame higher so avoiding having to cut anything off from the door.

    The kitchen was routed out for the instrumescent strip, a few places had to be filled where the router went offline, then tidy up with a chisel

    Takes a bit longer to do as have to finish off corners and bottom on each side. Think it was worth it as didn't want more disruption.
  16. Jitender

    Jitender Well-Known Member

    Think it would have been better to make a stop on either side of the jig, to keep it on line.
  17. kitfit1

    kitfit1 Well-Known Member

    This really Jitender. Makes no difference at all how good your work, tools or accuracy are. If the door and frame are not fire door specked, then you are completely wasting your time.
  18. CGN

    CGN Well-Known Member

    Its a pain. That's why a temporary fence screwed to the frame is better, as at least its straight. Also, holding a router over your head is no fun.
    I just router the door now.
  19. AlvyChippy

    AlvyChippy Active Member

    Trend green cutters are about £25, they'll last 10 -20 doors
    CGN likes this.
  20. CGN

    CGN Well-Known Member

    True. Nice to use and very quick.

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