# Router bit for cutting window slot in garage door



## mza1979m (May 7, 2021)

Hi,
I've searched high and low for this, and can't find what I'm looking for, even though I know it exists because they use them on window cutting machines. I've been tasked with trying to find a router bit for cutting window slots in 1-7/8" thick metal garage doors. The garage doors are comprised of polyurethane foam sandwiched between 2 layers of 27 gauge steel on either side of the insulation. The bit needs to be long enough to cut all the way through (ideally 2-1/4" minimum cutting depth with 1/2" shank). Any idea where I can find such a bit?
Thanks in advance.


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## Bob Bengal (Jul 24, 2020)

Welcome to the forum.

Router motors are used in CNC to cut metal, but I don't recall hearing of cutting metal with a hand held router. Seems like the polyurethane would melt onto the bit.

I've never done what you have in mind, my first thought is to use a jig saw, after drilling a starter hole.


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## mza1979m (May 7, 2021)

Thanks Bob. I've used a jigsaw but it was a real pain in the butt. If I found such a router bit, I was going to set up a border frame to constrain the router movement. I don't believe the heat generated by the bit would melt the polyurethane, as the garage door window cutting machine is nothing but a massive CNC machine that uses a bit in a router. And it cuts without melting. It even cuts garage doors with polystyrene, which I believe has a lower melting point. Obviously I'd have to ensure my speed is consistent without sitting in one spot too long, otherwise I risk melting. I'm speculating, I don't know any of this for a fact.


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## Bob Adams (Jul 5, 2014)

While it would terrify me to try something like this, I would probably go for a carbide spiral bit. I would contact a router bit manufacturer like Whiteside and ask before I tried. They should be able to guide you in your quest.


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## mza1979m (May 7, 2021)

Bob Adams said:


> While it would terrify me to try something like this, I would probably go for a carbide spiral bit. I would contact a router bit manufacturer like Whiteside and ask before I tried. They should be able to guide you in your quest.


Thanks, Bob. I'll check them out.


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## old55 (Aug 11, 2013)

Welcome to the forum.


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## mza1979m (May 7, 2021)

old55 said:


> Welcome to the forum.


Thanks!


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## Bob Bengal (Jul 24, 2020)

There is also DIY Home Improvement Forum that is a sibling to this forum, you might be more likely to find someone there that has done this.


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## mike 44 (Feb 6, 2021)

mza1979m said:


> Hi,
> I've searched high and low for this, and can't find what I'm looking for, even though I know it exists because they use them on window cutting machines. I've been tasked with trying to find a router bit for cutting window slots in 1-7/8" thick metal garage doors. The garage doors are comprised of polyurethane foam sandwiched between 2 layers of 27 gauge steel on either side of the insulation. The bit needs to be long enough to cut all the way through (ideally 2-1/4" minimum cutting depth with 1/2" shank). Any idea where I can find such a bit?
> Thanks in advance.


What you need is an endmill cutter. If your router accepts 1/2" shanks then for less then $10.00 you will have a cutter that will do the job and also works better than 1/2" router bits.
Do not cut thru the door all at once, cut more than half way on one side and then finish on the opposite side of the door.
Make a plywood template that will smaller than the cut by the half distance from the router base to the cut line. If you have router bushings then that would be best. Make the template to accommodate the bushing to cut line . 
Screw the template to the door with 6 screws , washers and nuts that go thru the door. Keep the holes level and straight so you can install the template on the other side after the first cut.. One on each end top and bottom and one in the middle top and bottom. 
If you carefully bore these holes in the template it won't matter if the template is upside down , end for end etc.
Screw the template to the door. Install this cutter or a similar one.
HHIP 5802 5801
1-1/2" x 4" 4 flute HSS SINGLE END CENTER CUT END MILL
You will find this on Amazon, I do not recall the price but it economical. Bore a starting hole even though the cutter mentioned is center cutting. If your router is a plunge cutter than starting hole may not be necessary , I still like a starting hole myself.
Do one side about 1-1/4" deep , Install the template on the opposite side and complete the cut.
Wear eye and hearing protection. 
mike


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## mza1979m (May 7, 2021)

mike 44 said:


> What you need is an endmill cutter. If your router accepts 1/2" shanks then for less then $10.00 you will have a cutter that will do the job and also works better than 1/2" router bits.
> Do not cut thru the door all at once, cut more than half way on one side and then finish on the opposite side of the door.
> Make a plywood template that will smaller than the cut by the half distance from the router base to the cut line. If you have router bushings then that would be best. Make the template to accommodate the bushing to cut line .
> Screw the template to the door with 6 screws , washers and nuts that go thru the door. Keep the holes level and straight so you can install the template on the other side after the first cut.. One on each end top and bottom and one in the middle top and bottom.
> ...


Thanks so much for the details instructions. After a little research I learned that endmill is probably the way to go, as they are generally designed for metal cutting, whereas router bits are for wood. However, unfortunately one of the prerequisites I require is that it cuts all the way through the door in one pass. The reason being that we will be doing dozens of doors until our window cutting machine that we ordered arrives in a few months. There's been quite a delay on it. In the meantime we need to save as much time as possible, so being able to cut in a single pass would save 50% on time. However, you have given me another great idea pertaining to the usage of the frame as a guide that I will implement. I was considering the usage of an "exterior" frame but eventually scrapped that idea due to certain constraints. But an "interior" would resolve these constraints.
Thanks again!


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## mike 44 (Feb 6, 2021)

mza1979m said:


> Thanks so much for the details instructions. After a little research I learned that endmill is probably the way to go, as they are generally designed for metal cutting, whereas router bits are for wood. However, unfortunately one of the prerequisites I require is that it cuts all the way through the door in one pass. The reason being that we will be doing dozens of doors until our window cutting machine that we ordered arrives in a few months. There's been quite a delay on it. In the meantime we need to save as much time as possible, so being able to cut in a single pass would save 50% on time. However, you have given me another great idea pertaining to the usage of the frame as a guide that I will implement. I was considering the usage of an "exterior" frame but eventually scrapped that idea due to certain constraints. But an "interior" would resolve these constraints.
> Thanks again!


I did not realize that you have many doors to cut the slots. I was under the impression this was a one time deal and thought you were a homeowner. I said cut from each side only because I thought it was safer for someone that never did this before. There are quite a few options for endmills ,check out McMaster Carr as they have end mills up to 4" long with a 1/2" shank. You probably would want a 2"+ cutter ,lots of choices here.


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## mza1979m (May 7, 2021)

mike 44 said:


> I did not realize that you have many doors to cut the slots. I was under the impression this was a one time deal and thought you were a homeowner. I said cut from each side only because I thought it was safer for someone that never did this before. There are quite a few options for endmills ,check out McMaster Carr as they have end mills up to 4" long with a 1/2" shank. You probably would want a 2"+ cutter ,lots of choices here.


Yeah, you wouldn't have know I plan to do many doors since I didn't mention it 
But I'll check out McMaster Carr. I've purchased from them before, but they never occurred to me. Thanks again!


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## daviddeli (7 mo ago)

Check 

Construction Materials 

for door lit router bits, it is what we use in our garage door glazing machine at work. Our machine is an old school pantograph that you run the head in a frame. We have no fancy CNC. We use a TJ-15-61 bit. It has a drill point and then a long flute for the milling cutter portion.

It might not be suitable for a hand held router, it has a 1/2 inch shank with a flat for a setscrew.

I was interested in how your project went or if it is still going.


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## jw2170 (Jan 24, 2008)

G;day @daviddeli , welcome to the forum.


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## old55 (Aug 11, 2013)

Welcome to the forum @daviddeli


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## bob vaughan (2 mo ago)

Google: 2" flush trim bits
That should do give you lots of choices.
Apply a template to the back side.
Drill an entrance hole for the bit
Cut out the hole.
Use a good router that doesn't have its commutator end bearing stuck in a plastic rather than metal housing. Plastic will give unacceptable flexing from the leverage. Been there.


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## calabrese55 (2 mo ago)

how about this tool they even advertise it as cutting granite


https://www.rotozip.com/en_US/home


The vid here is cutting sheet metal 







calabrese55


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