How to drill through soil and rock with Full Boar Core Drill?

[Graeme50]

I bought a "Full Boar 2000W Core Drill" from Bunnings.  (Unfortunately Bunnings don't sell the bits anymore so I had to get that elsewhere.  I got a 65mm bit).

I bought it to drill core holes in rock for fence posts and similar.  Our property is a mix of soil and rock, in unknown depths in different areas.  I haven't used it yet.

My question is: If I want to drill a hole in rock but there is a layer (say 300mm) of soil on top of that rock, do I need to clear away the dirt first before employing the drill or can I just drill through the soil (presumably rather quickly) until I hit the rock?  (I don't want to damage or clog the bit or the machine by using it on dirt if it is not meant to.  I also don't want to have to remove the soil each time I drill a hole if the soil is not a problem in this regard).

Nothing in the manual covers this point and I can't really find anything on point on the internet.  Any help would be appreciated.

[Jason]

Sounds like a fun toy @Graeme50. Let me tag one of our resident Bunnings D.I.Y. experts in @EricL for his thoughts, as well as experienced members @TedBear, @Tyro and @Dave-1 to kick off the discussion.

Let me extend a very warm welcome to the Bunnings Workshop community. We're so pleased to have you join us and look forward to reading all about your projects and plans. Please don't hesitate to post anytime you need a hand or have a project to share - we have members sharing helpful advice and inspiring projects on the site every day.

Jason

[Noyade]

Hi @Graeme50  and others.

My humble opinion would be to dig down to the rock - then bore.

Cheers.

Another Graeme  - but much older.

[Dave-1]

Good Morning @Graeme50 

Id be sidding with @Noyade on this one. If you want to drill into something solid to fix anchors to, then removing any "loose" material is probarly a wise point to start with. Using a 65mm drill bit is a large size and would also generate a fair amount of heat, does the drill bit brand suggest to use water or another medium to help keep it cool? Last question is how far down are you drilling into the rock?

Dave

[EricL]

Hello @Graeme50 

Thanks for sharing your question about drilling for fence posts. I'm siding with @Dave-1 and @Noyade as well regarding drilling down into the soil. Removing mixed materials out of the way of the drill means less work for the unit. It's a practical approach rather than forcing the auger to drill into mixed rock and earth.

Plus, it will avoid all those things you mentioned such as clogging and damaging the drill bit.

Here is a handy step-by-step guide: How to install posts for a picket fence

If you need further assistance, please let us know.

Eric

[Graeme50]

Thank you Graeme.

[Graeme50]

Thanks Dave.  Yes, the unit comes with a hose attachment for the flow of water.  I'm not sure at this point how far into the rock I'll be drilling.  It probably depends upon how much I'm trying to retain (ie. the weight).  It may be 200mm to 400mm.

[Graeme50]

Thank you Eric.

[Graeme50]

Thank you Jason.

[TedBear]

Hi @Graeme50   Yours is an interesting question.   Those bits are tough, so theoretically should cope with the soil, but I am wondering how practical it would be to drill a hole in soil that may continuously fall into the space.  Perhaps you could push or hammer a large (over 65mm diam) tube  -even if a strong plastic one, through the soil until you hit rock. If the soil is loose, wet it inside and out of the tube, before rocking it sideways to pack the sides of the hole before removing the tube, so that you have a clear hole. Then you can drill through the rock with minimal soil involved.

(I haven't tried this though, but if it were my situation, I would try it as there's little to lose.)

You could try putting your question directly to the manufacturer:     https://www.fullboartools.com.au/contact-us