HVAC chamber floor drain holes (Size?)

[txdude]

TSB 05.02.07 2007/01
TITLE: "Addition of drain holes to HVAC chamber floor"

TSB calls for a drill bit diameter of 6mm. Will a 7/32" (5.5mm diameter) bit work?

I want to do this when the weekend comes, but metric bits are not available in my state! Will I be okay with this size, or is it worth ordering online & putting off a week? I figure it's better to go smaller vs larger, but would this cause an adverse affect on the draining capabilities? Thank LT!

[TheViper]

Actually a 7/16 equals a 11mm, you want a 1/4". It's the location and depth that's important.
Michael

Originally Posted by txdude

TSB 05.02.07 2007/01
TITLE: "Addition of drain holes to HVAC chamber floor"

TSB calls for a drill bit diameter of 6mm. Will a 7/16" (5.5mm diameter) bit work?

I want to do this when the weekend comes, but metric bits are not available in my state! Will I be okay with this size, or is it worth ordering online & putting off a week? I figure it's better to go smaller vs larger, but would this cause an adverse affect on the draining capabilities? Thank LT!

[txdude]

Woops, meant 7/32 --updated first post

Thanks for the response Michael.

[TheViper]

Yep, that would work too.
Michael

Originally Posted by txdude

Woops, meant 7/32 --updated first post

Thanks for the response Michael.

[RoadDad]

Use a 1/4" bit if you have it. If you don't, that .5mm from using a 7/32" isn't going to make any difference but you can always wiggle the bit to enlarge the hole if it makes you more comfortable. Like TheViper says, it is the location and depth that you need to be concerned about. If you go too deep you'll bugger things up. The "depth to go no further than" is in the TSB.

[dwkoski]

I used 15/64" bit which is only a few thousandths off. I took a 1/2 " wood dowel about 2" shorter than the drill bit and drilled a 15/64 hole through it end to end. I then slipped it over the bit and chucked it in my hand drill allowing 10mm to project past the end of the dowel. You can use machined collars with set screws to lock in place on the bit but those are sometimes hard to find and they will scratch the coating off the aluminum when they bottom against it. The service bulletin mentions coating the raw edge of the drilled hole with some exotic stuff that is probably next to unobtainable in the US. I used a paint chip disposable brush and POR 15 (an isocyanate based paint used in auto resoration). It's great stuff, sticks to raw aluminum well, wears like iron, and is available online and at automotive stores that sell refinishing supplies...Dave

[txdude]

Special thanks to TheViper, RoadDad, & dwkoski for the help. Y'all rock!

I ended up using the 1/4" bit & a piece of wood to limit the drill length to 10mm. When marking my drill spots, I actually went out 43mm (in all directions) instead of the recommended 40mm since I was using a larger bit. After I drilled through the first layer I was hesitant to continue. I rechecked the bit length & continued through the second layer & took a step back to admire my work (I was extremely nervous).

Here's the TSB I used that Viper originally posted in a different thread...http://www.lotustalk.com/forums/atta...hvac-floor.pdf

No pics of the actual job because I forgot to take my camera, but here's a pic of the drill...