Do 12.5mm Spade Drill bits exist?

[Toecutter]

Hi.

I need to insert some 12.5mm plastic pipes into a cabinet and need a tight fit. I have drilled pilot holes and have general 12.5mm drill bits, but because they are so large, they don't centre perfectly and wonder off line.

I did a job in the past and used 10mm spade bit and it was far more accurate.

Can't seem to find a 12.5mm version. Old measurement 1/2 bit is 12.7mm I think and might be too loose. Don't have one to hand.

Need to do quite a few holes, so can't bodge it. Any help?

 

[morturn]

Workshop Heaven do a FAMAG 1594.075 7.5mm HSS-G Lip & Spur Drill, they are amazing good drill, I bought a couple recently and love tm.

 

[SteveF]

if you cant find metric
i would get the 1\2" and grind until u get a snug fit

Steve

 

[Chrispy]

Wot he ^ said +1

 

[Toecutter]

Thank you. The 1/2 bit will make a hole o.2mm bigger. Hopefully it will be negligible.

 

[RobinBHM]

Ive got one of these brad point sets with a 12.5mm bit.

http://www.rutlands.co.uk/sp+woodworkin ... ota+dk1318

or

http://www.ebay.co.uk/itm/Veritas-HSS-L ... xy4fVTBNrw

although I wonder if this one is actually 1/2" as its american

 

[Ttrees]

Any size spade bit exists if you've got a bigger one ! ...
Just file the sides down a bit , the cheap ones I have file very easy .
That easy you can sharpen the other end to have a backwards cutting drill bit .

Here's a tip if you want flat bottomed holes after drilling ...

To make one of these up file the hexagonal edges off the shaft to the desired shank size
You need a file ,sandpaper and a lapping surface and a marker
and try to copy the cutting profile the other side ...
You could harden it but I've used it a good few times with no bad results ..

To use this tool insert this thing in backwards through the hole you've just drilled and up into your chuck.
Thanks Frank Ford =D>
Good luck

 

[Ttrees]

Here's some more that should clear things up .
Have fun

 

[ED65]

I have drilled pilot holes and have general 12.5mm drill bits, but because they are so large, they don't centre perfectly and wonder off line.

Drill larger pilot holes. Do it in stages if necessary, each successively larger bit self-centres on the hole that precedes it.

This is how I drill all holes with standard twist bits where position is critical. It's a faff, but it's needed (even sometimes when using the drill stand, which annoys me no end).

Old measurement 1/2 bit is 12.7mm I think and might be too loose. Don't have one to hand.

If you could find one you could always pack out the holes with a strip of veneer. But honestly even paper will do it.

 

[sunnybob]

Whats in the pipes and why does it need to be that tight?
Plastic expands at a much faster rate than wood. If its hot water for example, the pipe could be weakened and crack if it was too restricted to expand. You might be better off with a small clearance and a silicone seal if you really need it.

 

[rafezetter]

That's really rather clever Ttrees - I've sometimes had issue with the dome effect of a spade bit with through bolts too for sizes where I don't have a matching forstner.