Which method of creating a hole in a joist

[watertight]

Guys and Girls,

Wonder if you can help.

I need to provide a 45mm (ish) hole in a joist. Wouldn't normally be a problem using a hole saw, however the only way of getting to the joist is through the external double skinned wall (this is due to the position of the other joists and the position of the hole.

I would appreciate your advice on which type of drill bit I should use, I was thinking of an expansive bit with 2 x extension bars that could pass through the external wall gaining access to the joist.

The alternative it to use a fostner bit but I am unsure as to whether extension bars are available for such bits, if they are would any of you be able to suggest a supplier on the net.

Hope it all makes sense,

Mark

 

[Thermo]

whats going through the hole?

 

[watertight]

40mm waste pipe (pushfit)

Mark

 

[Thermo]

is there any access from the other side at all?

 

[Thermo]

or use one of these

http://www.tooled-up.com/Product.asp?PID=10882&MAN=Starrett-A5-Extension-For-Arbors

one of these

http://www.tooled-up.com/Product.asp?PID=10880&MAN=Starrett-A2-Arbor-To-Suit-32mm-210mm-Holesaws

with one of these on the end

http://www.tooled-up.com/Product.asp?PID=10941&MAN=Starrett-Sh0134-Hss-Bi-Metal-Holesaw-44mm

should just about make it!

 

[watertight]

No access from the other side, I was hopiung there was so I could use a right angled drill adapter.

It may certainly be worth me looking at the arbor extensions, I presume you can't link 2 extensions together though?

The reason I was looking at other types of wood bit was because my hole saws (DeWalt Bi-metal) struggled with the other joists as the wood is pretty hard!

Mark

 

[WelshMan]

how deep is the joist ?. I beleive you should only cut/hole a joist to 1/8 of its depth otherwise you will weaken it.

 

[watertight]

I needn't worry about weakening it, just getting through it

Mark

 

[big-all]

how deep is the joist ?. I beleive you should only cut/hole a joist to 1/8 of its depth otherwise you will weaken it.

isnt it around 1/8th "notched" near the ends !!!!!!

and 25% neutral acsess[middle depth] near the ends!!!!