Tuesday, September 11, 2012

DIY Under the Door (MULE) Tool

There's been a lot of dust kicked up over this type of tool. It seems to be a coveted item for some reason. I don't get it personally but I saw it and I made one. I think I did a pretty solid job and it works perfectly.

I picked up a 6' rod of 3/16th's steel at my local hardware store. That sounds like a lot but I didn't have to trim any of it.
I got some string from the same store.

Total Cost: about $8

I just used a large pair of channel lock pliers and my hands to make all my bends. No special tools required.

You have to use some caution making the bends as if you make a bend too sharp you're going to have a pretty rough time getting it straightened back out.

Here it is in full glory:
The Under The Door Tool (MULE)
Here's some pictures with measurements:
From Top of the Lever Catch to the Bottom of the Curve 42"
Proof it's actually 42"
Note that the doors I tested these on have the handles at 41". That may not be the case for your locale, get a tape measure and go get some weird looks, find an average that works for you.

From shaft to handle 14"
 The hoop, I didn't have any accurate measurement on the angle I just kinda guessed knowing that I needed to keep the handle away from the door so I could operate it but also needed to make sure the angle wasn't too wide so that the top where the string attaches would actually come back into contact with the door. The about a paint can estimate from darksim905 lockpicking seems to be about right, I just shaped it by hand but it seems to have worked out.

4.5" for the handle.
I've found it's a lot more comfortable for me to actually hold the whole handle instead of trying to put my hand through it to hold it. Adjust for your hand size / comfort.

Just over 6" for the top
I would like to note here that there is a design flaw. The loop where the rope attaches to needs to have it's lowest point nearest the door so the rope stays in place. Where the string is attached now should be the lowest point in the hoop, perhaps more of a triangle design, or something to hold it there. As it stands right now the rope has too much room to travel and, as you will see in the videos below, can cause it to miss the space between the door and the handle.

End of the Rope 5'
The 5' rope is a completely arbitrary number, seems to be about right though. Maybe a little shorter would work just as well. I do need to find another material and this is already starting to show signs of wearing where it scrapes against the bottom of the door when pulling to activate the handle.

Here's 3 videos of it in use. I've included the fail videos to dispel the theory that this is magic and everyone gets it on the first try. I hate videos that only show things working, you learn nothing from things working, you learn from things not working. It's not a complicated tool, but there are some caveats.

In this video you see what happens when your rope isn't at the point closest to the door, hence the redesign needed for the loop where the rope connects to more of a triangle.

In this video you see what happens if you don't keep control of the rope. It gets wound around the tool and then you can't get it over the handle.

And finally, victory. Like I said, not an overly complicated tool, but there are some things you need to keep in mind. The reason I had such a difficult time maneuvering the tool under the door is that this particular door has about half the space that the rest of the doors have between it and the floor.


  1. Thanks for covering the dimensions, etc. One of the challenges of using the traditional Mule like the K22 is traveling with the thing. When I'm on an engagement I like/need to pack as light as possible. For $8, this is something that can be picked up from the hardware store after landing, used, and then disposed of if need be (or donated to the local toool chapter, etc).

    Have you thought about using some picture hanging wire or something instead of the normal thread? I get that string was used to show how inexpensively it can be done, but I'm willing to be the picture wire will be a bit more durable and only costs a few dollars.

    1. I had thought about that, the thing I was thinking about was using a drinking straw to cover the string where it comes into contact with the door. That keeps me within the under $10 budget. Plus drinking straws are everywhere.

      The problem with using anything other than a soft string becomes that you don't want to use anything that is abrasive in the least or there's going to be scratches on the door, which while not usually a deal breaker, is undesirable.

      You could just as easily add a drinking straw cover over the picture wire but it may cut through it.


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