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fridmani1

How to make a hole bigger in acrylic -

Rating: 6 votes, 5.00 average.
5 Comments
by
fridmani1
, 04-22-2011 at 10:15 PM (3553 Views)
So I decided that I wanted to use a 1.5 schedule 80 bulkhead on my new sump. These bulkheads are available at Bulk Reef Supply. These bulkheads are very heavy duty and have a very large gasket.

Compare the schedule 80 to the ABS bulkhead on the right.


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Now check out the difference in the gasket:

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The bad news is that the schedule 80 bulkheads need a slightly bigger hole than the ABS bulkheads. My sump came with a 2 3/8" hole but needs a 2 5/8" hole for the sch 80 bulkhead.

So how can I make the hole bigger without destroying the sump? Since the hole is only a little bigger it is hard to keep the drill saw from walking all over.

I don't know if there is another way but here is what I did and it worked really well.

First I cut out a 2 1/2 hole from a scape piece of acrylic then I used the piece that came out of that hole as a guide for the drilling the new hole. I used a 2 1/2" bit so that it would be a snug fit in the 2 3/8" hole. This is to make up for the difference in the width of the drill saw bit.

Then I used clear packing tape to hold the plug in place from the top and the bottom.


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This gave me the pilot hole that I needed to allow the bigger bit to stay put.


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Success! Hole is nice and neat with no scratches or cracking the sump. Here is what the sump looks like with the bulkhead installed. Notice that I put the bulkhead in "backwards" I will explain why later.

Click image for larger version Name: final bulkhead.jpg Views: 173 Size: 74.7 KB ID: 4949

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Categories
‎ Plumbing , ‎ DIY projects

Comments

  1. Midnight's Avatar
    the other way is using a jig clamped in place
  2. dahenley's Avatar
    just so you know, your gasket should be on the flange side, not the nut side of the bulkhead.

    also, i always prefer to put the threaded side on the outside of the sump. in a month or so after starting your tank, the threads will be covered in crap and salt and calcium, and you will never get it off in the future.
    you will endup having to cut it out if you ever need to change or adjust or fix a leak or something along those lines. (just thought i would share my opinion)

    looks good!
  3. melev's Avatar
    The jig that midnight is talking about is the other half of the stuff you drilled. Instead of drilling out a hole in acrylic, drill it through some 3/4" plywood, then affix it to the sump with double stick tape. Now the plywood guide will keep the hole saw bit exactly where you want it, and you can start drilling.

    I'm glad your method worked. I never would have tried that.

    Regarding the orientation of a bulkhead, do whatever works best for you. I never reuse a bulkhead; it is always replaced when the time comes. However, do put the gasket on the flange side, which in this case is the outer half -- outside the sump. Dahenley is right.
  4. fridmani1's Avatar
    I would think it would be more important to keep the gasket on the inside of the sump versus on the flange side. Why is it important to get the gasket oriented on the flange side. Trying to understand.
  5. melev's Avatar
    Because the nut needs to tighten and not bind up against the gasket and get bunched up or creased. Having it against the flange, there is zero friction - simple direct even pressure. The nut can be snugged up tightly without resistance.