Drilling 40B for Eshopps L Overflow & Threaded Bulkhead Returns

[MNtadpole]

All,

I wanted to bounce my plan of drilling my 40B off of you all. Please let me know what you think!

First, my plan is to drill my 40B from the inside of the tank out. My theory was that it would keep the watertight gaskets that are inside the tank next to the cleanest cuts of the drilling that will be made. I've seen a lot of the exit drill cuts leaving chips and what not, so I figure to leave that on the outside instead of the inside.

Second, since my 40B is plastic rimmed, I would like to aim to have the tank water level to be as close to that rim, possibly behind it if I'm lucky. To achieve this, my plan was to place the included Eshopps drill template on the inside, allowing for it to ride higher than if it was placed on the exterior, mating with the plastic rim. This reinforces the first plan of drilling from the inside of the tank.

Here's the loose idea of applying the template on the inside:

Here's a close up of the template riding higher than the plastic rim. This is for reference, it can go probably 1/4" higher.

I'm planning on drilling two 3/4" return bulkheads to the left and right of the overflow. They will have loc-line returns threaded into them. Does anyone have any suggestion as to how deep into the tank I should place them? I understand that one should place them rather high to limit the amount of syphon they allow back to the sump. At the same time, I think it might be ugly to have curved loc-line half exposed and have submerged at the waterline. Let me know what you think.

 

[MNtadpole]

Here is a photo of weir if it is pressed flush with the interior of the plastic rim, no cutting made:

 

[Fish Fan]

My thought would be that whether you drill it from the inside out or the other way around, I'd back the back-side of the cut with some blue painter's tape to help minimize chipout on either side. Go very slowly with the cutting, and especially slow when it's getting right at the end.

I don't see why you can't drill from the inside, as long as you think you can fit the drill, and keep it steady and straight doing it that way.

Good luck!

 

[MNtadpole]

My thought would be that whether you drill it from the inside out or the other way around, I'd back the back-side of the cut with some blue painter's tape to help minimize chipout on either side. Go very slowly with the cutting, and especially slow when it's getting right at the end.

I don't see why you can't drill from the inside, as long as you think you can fit the drill, and keep it steady and straight doing it that way.

Good luck!

Thanks of the input! I will be sure to use the tape!

Any thoughts or suggestions on the weir depth in relation to the plastic rim?

 

[areefer01]

My thought would be that whether you drill it from the inside out or the other way around, I'd back the back-side of the cut with some blue painter's tape to help minimize chipout on either side. Go very slowly with the cutting, and especially slow when it's getting right at the end.

I don't see why you can't drill from the inside, as long as you think you can fit the drill, and keep it steady and straight doing it that way.

Good luck!

I also secured a piece of wood on the underside with clamps. Be gentle and just enough to secure it.

OP - as @Fish Fan noted above go slow and let the drill do the work. I did not time it when I performed something similar a couple weeks back but I let the weight of my drill do the work. No pressure from me and each hole was about 5 minutes give or take.

I am using a modular marine and the instructions had me place it on both sides as their template was marked to factor in trim. Once I did that I had the hole markers at the proper location. I am not sure how your kit works.

 

[fishface NJ]

I just received my second Modular Marine overflow. They are built well.

I would tape the template to where you would like it. Then take the outside overflow box and line up the holes to the box holes. Check to make sure the plastic trim of the tank is not interfering with placement. Repeat steps with the inside box. If the box is too high it will not seal with the tank

 

[underwood]

I did something similar years ago to a 40B (different overflow). I drilled from the inside and covered the backside in painters tape, like someone else suggested. Everything went fine with the drilling part. The only issue that I had related to the bulkhead gasket, but the shop sent me a replacement and that fixed the issue.

At the time, I was traveling for work almost weekly, so I intentionally drilled mine a little low to provide buffer if something wonky happened while I was out of town and the overflow got clogged. The display could absorb the water in the return section of my sump without overflowing if the overflow was completely clogged. (Never happened, but it made me feel better at the time.)