Installing the Marks USA 9900 Exit Device

Today we are installing the Marks USA M990 exit device on an exterior gate. The rugged steel gate construction does bring some challenges, since we will be drilling into thick steel.

Measuring and centering the exit device itself is the first step. For aesthetics, it needs to be positioned in the center of the solid portion of this gate, and for ADA requirements, all door hardware must be mounted between 36 and 48 inches from the ground.

Next, I’m drilling holes for the latch that’s going to go into the frame side of the opening.  I like to use a step-bit process. I start off with a very small drill bit, the smallest drill bit I can find, and then step it up one or two sizes.

The other thing that makes this job unique is that this is a very heavy-duty set-up. The steel that we are drilling through is 3/8 of an inch thick. That’s also why I chose not to tap this out to ¼ by 20. I knew we would start breaking taps if we did that.

This strike (photo xx) is going to be mounted on this thick piece of steel and we’re going to use some self-tapping screws to mount it in place. Normally you would use the provided screws due to the exit device’s UL-rated listing. You want to make sure to use all the existing mounting hardware. However, that wasn’t an option for this particular installation. We would have broken tap after tap.

Photo xx shows the deadlatch, which is one of the most important parts of the installation. There’s that ¼ by 20 drill tap (photo xx). We will use it for the rest of the installation. It is a very useful tool. It just doesn’t work well on thick steel. The plate that we were mounting the deadlatch onto is quite a bit thinner and that’s why we were able to utilize it.

We did use two self-tapping screws to hold the exit device in place, then we came back and drilled out the ¼ by 20 holes to use the existing screws that come with the exit device, which is highly recommended.

Next, I’m drilling and tapping all of those holes. The four mounting holes are going to be the most important (photo xx). I found that using the extension also does help absorb impact so that it doesn’t break quite as easily. It’s very efficient and a great tool to have. But be aware that they can break. I turned the setting on my impact driver way down.

In photo xx, I’m drawing a line between the top and bottom and the four mounting screws that we just added. That will give me a center location to use an inch-and-a-half hole saw to drill a hole all the way through the gate and allow us to mount the mortise rim cylinder on the outside. You could use the template, but I’ve gotten in the habit of using this method, and it works for me.

Now I’ve got the drill and the hole saw all put together and am ready to drill into the gate. Once you have the pilot bit in the external portion, you simply drill right through to the other side for a nice, clean hole. These Milwaukee hole saws seem to do very well and stay extremely sharp for a long time. I really like the way they perform. Photo x shows the plug that will come out of the gate.

We’re going to be using a mortise rim cylinder that’s also the other part number for the Marks pull device on the outside. It gives people a handle to pull. Photo xx shows the mortise rim cylinder mounting screws. These had to be cut down. I like cutting them off with the angle grinder. There are segments or sections that are not threaded on that bolt to give you a clear line, so you know exactly where to cut.

Photo xx shows that pull mount, mounted on the outside.

Next, we’re mounting the backplate. These are the screws that hold that rim cylinder in place. I prefer to leave the whole tailpiece installed as it is from the factory and then take a measurement. It’s a lot easier to cut that once it’s installed. You don’t have to have two hands. I used the angle grinder to cut that tailpiece down to size so that it doesn’t protrude too far into the Marks M990.

Now we are going to test-fit the exit device and make sure that it’s engaging. We’re going to put the exit device back onto the gate, drilling and tapping the two holes for the self-tapping screws to hold that pull the trim plate in place.

It’s time to make final adjustments and move that plate up just a little bit and then remount the exit device on top of it. Getting the tailpiece to actually go into the exit device can be challenging in some cases. Then we install the mounting screws for the exit device itself.

I would like to address some security issues. This is what was specified for this job. I notified the customer that an exit device with an open gate like this one might not be the most secure option. However, that is what the fire department had required for this application.

Again, we’re drilling and tapping the two holes for the back mounting plate. I did have one of those taps break. It can happen and, if it does, you need to know how to fix it. We were able to tap that with a drill bit. It was able to punch right through and basically collapse it and let it fall inside the gate. Even though they sometimes break, these taps do come in handy and they are very convenient.

Now we’ve put the end cap on the device.

Here (photo xx) are the factory mounting screws, the ¼ by 20 screws that come with the M99 exit device. The back piece gets mounted on the other end of the exit device. Twp screws are mounted on each side, The strike piece is mounted on the side of the frame. You need a flat screw that doesn’t stick up at all in that middle portion so that it isn’t affected by the exit device latch.

The Marks M9900 is a fantastic exit device and I highly recommend it. It is my go-to choice. It fits on a Von Duprin 99 footprint so the holes will drill and match up the same, along with the tailpiece. Everything works extremely well. For more information, visit https://www.marksusa.com/products/exit-devices-door-closers/

 Wayne Winton is the owner of Tri-County Locksmith Services, located in Glenwood Springs, Colorado. For more information, check out Wayne’slockshop.com and lockreference.com.