# Forum Home Renovation Fences & Screens  Post holes into sandstone

## john777

Hi,
Can anyone advise best way to dig out approx. 200mm diameter x 600mm deep holes into solid sandstone ??.......I am building a boundary fence and have 5 post holes to dig into fairly hard sandsone. 
Have tried a iron bar normally used on soil / clay.....but is hard slow work into sandstone 
Would a jackhammer with a long pointy bit and also flat end bit get down far enough........or core drill ? The core drills from the local hire shop are only 50mm diameter max. so I would need to drill several holes and still use a iron bar ........any suggestions??? 
cheers  :Doh:

----------


## phild01

Maybe contact a local fencing guy who can core drill a larger hole for you.  BTW, why so deep?  If it is fairly deep sandstone, your posts need not be so far down.

----------


## intertd6

The idea is not to dig holes in sandstone if you don't have to, a method is to use deep chemical anchors into the sandstone & angle brackets fixed to every face of the post.
regards inter

----------


## SilentButDeadly

There's no need to be bigger than 50mm diameter.  More than enough for a bit of steel to bolt a fence post to.  Failing that even threaded rod & Chemset holding an L bracket would work too.  Putting timber into a hole in sandstone is like putting a pine post into a fish tank...

----------


## phild01

Do a gal posts (inside and out) into core drilled holes, best result.

----------


## Pulse

eBay some imported core drills and use a cheap rotary hammer, I cored 110mm diameter into a concrete retaining wall, then use a structural grout ( bunnings has a lanko one) to set the posts, only need to go down 100-200mm. Use brackets like other suggested as an alternative.
cheers
Pulse

----------


## phild01

> eBay some imported core drills and use a cheap rotary hammer, I cored 110mm diameter into a concrete retaining wall, then use a structural grout ( bunnings has a lanko one) to set the posts, only need to go down 100-200mm. Use brackets like other suggested as an alternative.
> cheers
> Pulse

   I ruined two cheap rotary drills with the core drills.  Be very wary of the kick using large diameter bores.  My sandstone is very hard (ironstone)! The structural non shrink grout is worth the go.

----------


## Pulse

I killed one when I hit 12mm reo, it did cut through it though. Plenty of water and patience. You could also get someone in to core drill it, but this is a DIY forum!

----------


## phild01

Yes, keep the water up.

----------

