Drilling a lid for an airlock grommet

[matt.]

Advice please.
I have to fit an airlock to a plastic lid.
I have the plastic airlock and bought a black rubber grommet.
I have a measurement for the outer and inner parts of the grommet.
Should my drill be the size of the inner part of the grommet?

Also...
Any tips for drilling plastic?
Warm it up slightly?
Type of drill? Metal / wood?
Place something firm under the lid to drill into?

Thanks folks

 

[The Baron]

Hi Matt there should be a inner hole which is the diameter of a standard airlock then there is the outer measurement of the grommet but you need the measurement of the middle section of the grommet i.e that is the part inside the groove on the grommet if that makes sense. You may have to estimate that but always drill it slightly smaller as you want a tight fit and you can always enlarge it if needed.
Hope that makes sense
Place the lid n a piece of wood as you have suggested so it is firm and the drill will go through the plastic into the wood but it hold it firm against it so you get a nice clean hole

 

[The Baron]

If you are still not sure Matt always start smaller then keep going up a drill size until the grommet fits tight, I would try a drill in the inner of the grommet so it is snug then go up one drill size at a time as you need it tight so co2 does not escape once the airlock is in.
Ps they are fiddly to fit as it will be tight to be leak proof

 

[borischarlton]

A flat "spade" bit normally used for wood is my go to. 13mm Fits most but I don't know what grommet you have. Go slowly with the drill.

 

[Clint]

To easily fit the grommet put in it hot water first.

 

[Chippy_Tea]

"An airlock grommet will provide a great seal between your airlock and the hole in the fermenter lid, drill size: 12.5mm, air lock hole: 9.5mm"

 

[hoppyscotty]

Have you got a step drill? That would be best...if not drill a pilot hole first. Depends on the plastic...if brittle you want to open out really slowly because if the drill grabs then it will shatter the plastic...if a softer plastic like a bucket lid best to place it on a piece of wood and drill through that into the wood so the wood supports it, but again best to use a pilot drill first to prevent grabbing...though for a small diameter hole you'll probably get away with it.

 

[matt.]

Thanks folks
Great advice
I'll look out a step drill
Matt

 

[Twostage]

Advice please.
I have to fit an airlock to a plastic lid.

Just a sec - 'have to' ? I can understand 'want to', everyone likes watching a bubbler, but 'have to' .

Just had a thought. I wonder if you could increase the pleasure of airlock watching by 3D printing one that is more entertaining that the standard fare. I've been on Thingiverse but they are all standard ones on there.

 

[matt.]

Just a sec - 'have to' ? I can understand 'want to', everyone likes watching a bubbler, but 'have to' .

Just had a thought. I wonder if you could increase the pleasure of airlock watching by 3D printing one that is more entertaining that the standard fare. I've been on Thingiverse but they are all standard ones on there.

Well, the lid is a pretty tight fit. It kinda falls down onto the bucket lip and seals it shut. I did one fermentation in it with the lid held up slightly with a pencil. It went well but I thought it prudent to fit an air lock.

Matt

 

[peterpiper]

I've mostly given up on airlocks, and now normally use demijohn safety (pressure release) bungs instead.

My fermenters have 4 inch screw lids, with gaskets, prefilled to take a demijohn (fermenter) bung.
The plastic safety bungs doesn’t seal, the hole brilliantly, but it does with some hot melt glue.

When fermenting, (wines) I now get a slight hiss when loosening the lid, though the walls arent distorting. I'm guessing a couple of PSI, so a kind of pressure fermenter.
My beers go in buckets for primary, no airlock.

 

[Sadfield]

Just had a thought. I wonder if you could increase the pleasure of airlock watching by 3D printing one that is more entertaining that the standard fare.

Perhaps a development of this. Where you direct a stream of Co2 rather than pumping air through it. Hours of fun back in the '80s.


+1 to step drills. Invaluable for kit alteration.

 

[matt.]

" I've mostly given up on airlocks, and now normally use demijohn safety (pressure release) bungs instead."

I'm not familiar with these.
Any links/ pictures please.

 

[MashBag]

Google search "demijohn safety (pressure release) bungs"

Good things.

 

[Victor Churchill]

When fitting grommets in other situations I have found a drop of soap liquid helps. Also, when drilling the lid, I would suggest have the lid itself at a cosy room temperature to minimise chance of it cracking.

 

[matt.]

When fitting grommets in other situations I have found a drop of soap liquid helps. Also, when drilling the lid, I would suggest have the lid itself at a cosy room temperature to minimise chance of it cracking.

Thanks - good advice. I've nearly plucked up the courage to do it !

 

[MashBag]

When fitting grommets in other situations I have found a drop of soap liquid helps. Also, when drilling the lid, I would suggest have the lid itself at a cosy room temperature to minimise chance of it cracking.

Personally I wouldn't use soap anywhere here brewing equipment, but if you do rinse, rinse, rinse and make sure it's gone.

Wet the grommet, it will go in fine.

Tbh I can't believe how long we have been discussing one hole with a drill. .

 

[matt.]

Personally I wouldn't use soap anywhere here brewing equipment, but if you do rinse, rinse, rinse and make sure it's gone.

Wet the grommet, it will go in fine.

Tbh I can't believe how long we have been discussing one hole with a drill. .

Sorry to let this drag on.
State of play: the FV has 7 liters of BIB SMASH inside. The lid is propped open slightly with a wooden spatula.
As soon as the fermentation finishes, I'll make a stab (!) at drilling the hole.
All previous advice taken onboard .
I'll let folks how things progress - or otherwise.

Matt

 

[MashBag]

Does the lid not come off?

 

[matt.]

Does the lid not come off?

Yes the lid comes off. When it's sitting on top of the bucket, the seal is pretty tight. I have it slightly wedged open at the moment while it is containing my 6+ liters of beer. I thought it best to fit an air-lock, hence my questions.
Thanks