Size of Greenlee knockout punch for 1/2" barb

[gugguson]

Hello.

I need to drill a hole on my stainless lid on my pot for circulation. I need to let the hole fit for something like this:

http://morebeer.com/view_product/17421//Stainless_-_1_2"_mpt_x_1_2"_Barb

My understanding is that the hole needs to be 1/2" so I'm wondering if this would be ideal for a hole (or might it be too small?):

http://www.ebay.com/itm/NOS-Greenle...194?pt=LH_DefaultDomain_2&hash=item5aeba7acfa

Regards,
Johann

 

[adman]

I'd have to go home and check mine, but I believe you want the 13/16 knockout punch for 1/2" inner-diameter fittings. See, e.g. https://www.homebrewtalk.com/f170/what-size-greenlee-punch-weldless-ball-valve-339595/

EDIT: I see that is a conduit punch, in which case it makes a 7/8" hole, which might work.

 

[Bobby_M]

No, the hole needs to be 7/8" actual because 1/2" NPT measures about .84". That one you linked to is a radio/chassis punch which means the dimensions listed for the hole size is actual. A true conduit punch is sized for nominal pipe dimensions.

 

[gugguson]

So, this might work isn't it?

http://www.ebay.com/itm/Greenlee-72...022?pt=LH_DefaultDomain_0&hash=item4d09ce9006

No, the hole needs to be 7/8" actual because 1/2" NPT measures about .84". That one you linked to is a radio/chassis punch which means the dimensions listed for the hole size is actual. A true conduit punch is sized for nominal pipe dimensions.

 

[YankeeBrewer09]

1/2 inch knock out punch makes a 7/8 inch hole. Are you looking to make 1/2 hole? I punched a 7/8 hole for my valve and 1/2 hole for my thermometer. The knockout punch that makes the 1/2 inch hole was a ***** to find. Finally found it on amazon.

 

[gugguson]

I need a hole big enough so I can put this in: http://morebeer.com/view_product/17421//Stainless_-_1_2"_mpt_x_1_2"_Barb

1/2 inch knock out punch makes a 7/8 inch hole. Are you looking to make 1/2 hole? I punched a 7/8 hole for my valve and 1/2 hole for my thermometer. The knockout punch that makes the 1/2 inch hole was a ***** to find. Finally found it on amazon.

 

[Bobby_M]

1/2" radio/chassis punch = 1/2" hole (the OP's first link was to this)
1/2" conduit punch = 7/8" hole (the OP's second link was to this)


I like the multi-size kit for like $75

http://www.ebay.com/itm/Greenlee-72...030?pt=LH_DefaultDomain_0&hash=item3a7e9729d6

 

[gugguson]

Ok, I.bought your recommendation

1/2" radio/chassis punch = 1/2" hole (the OP's first link was to this)
1/2" conduit punch = 7/8" hole (the OP's second link was to this)


I like the multi-size kit for like $75

http://www.ebay.com/itm/Greenlee-72...030?pt=LH_DefaultDomain_0&hash=item3a7e9729d6