Drill press

The bigger the hammer drill the slower it turns and the lower the BPM. I was thinking you might do better on the slow speed and then not even full speed. All of my HDs operate much slower than the Dewalt. I never tried drilling rocks, yet, but I have drilled a lot of concrete that has large agragate in it and never had trouble chewing thru those smaller rocks. The higher the BPM the smaller the impact force per blow.
 
Flyinfool said:
The bigger the hammer drill the slower it turns and the lower the BPM. I was thinking you might do better on the slow speed and then not even full speed. All of my HDs operate much slower than the Dewalt. I never tried drilling rocks, yet, but I have drilled a lot of concrete that has large agragate in it and never had trouble chewing thru those smaller rocks. The higher the BPM the smaller the impact force per blow.
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Good to know - thank you. I will be testing it out tomorrow!
 
In my experience the drills in the class of your Dewalt DW 505 are good for very occasional work only. Like lagging something down to concrete but are mainly designed to be a drill first, hammer drill second. If you are drilling many of these rocks to make many of these statues you would be much better off with a real hammer drill.

With one of the smaller SDS Max drills and a good 4 cutter tip bit I think you will find a world of difference.

SDS is a Bosch designed chuck for holding hammer drill bits so the bit can move up and down freely while having a positive engagement to spin the drill bit.

SDS was replaced by SDS plus. SDS plus drills are a huge step up from your DW 505 and are made for drilling holes in rock / concrete everyday.

SDS Max is a bigger chuck designed to hold bigger hammer drill bits to drill bigger holes with bigger drills. A SDS Max drill will be much heavier than a SDS Plus drill. The Weight of the SDS Max drill is most likely all the force you will ever need to drill those stones. You could most likely get by VERY WELL with a SDS plus drill... but it is not in my nature to think small.

The old type chuck for holding hammer drill bits is a spline drive chuck. This is what I have and it works just as well. I have never had a problem finding spline drive hammer drill bits and there are spline drive to SDS Plus and Spline drive to SDS Max adapters available to use the new model drill bits in a spline drive hammer drill. I paid $50 for my Bosch spline drive hammer drill off Craigslist including a couple hammer drill bits... which is less than I have paid to rent one in the past.

Most rental yards do rent real hammer drills with pretty beat up hammer drill bits. This might be an option to try one out without sinking a bunch of money into one.

A 4 cutter tip hammer drill bit has twice as many surfaces hammering away the rock in the hole which makes it considerably faster than a 2 cutter hammer drill bit. I have found that a 4 cutter drill bit also is less likely to split the rock you are drilling than a 2 cutter bit.

To use a drill press to drill these rocks you are going to want to use a diamond core bit (diamond hole saw) and have a constant stream of water while drilling to keep the bit from overheating. Diamond core bits have a MUCH shorter life than hammer drill bits in my experience. I think you would be best off with a true hammer drill.
 
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Choiliefan said:
Would a water bath improve cutter life?
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For a diamond core bit I consider water required. I think a stream of water would be better at washing away the debris than a stagnant water bath.

Hammer drill bits are designed to work well dry and last a very long time when used dry. I usually use a drizzle of water from a garden hose when drilling with a hammer drill to keep the dust down and also wash away the debris. I can not say if a hammer drill cuts faster or the hammer drill bit lasts longer when used with water... but that is the way I like to do it.
 
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Listen to the poster above that talks about the SDS type chuck system. That is the way to go. Any hammer drill, no matter the brand, that has the conventional jaw type chuck is a joke in a hammer drill. A good hammer drill will drill through solid concrete way easier that a normal bit will drill through pine. No pilot hole will be needed, just drill the size you want. You will be totally amazed at the difference. It will cost several hundred dollars for the drill and bits, but it will be money well spent.
 
Small diamond core bits from China are dirt cheap and should work well on shallow holes. They could be used in a drill motor or in a drill press. They need to be withdrawn frequently and the hole cleared of dust. Check out Banggood.
 
gasengin said:
Listen to the poster above that talks about the SDS type chuck system. That is the way to go. Any hammer drill, no matter the brand, that has the conventional jaw type chuck is a joke in a hammer drill. A good hammer drill will drill through solid concrete way easier that a normal bit will drill through pine. No pilot hole will be needed, just drill the size you want. You will be totally amazed at the difference. It will cost several hundred dollars for the drill and bits, but it will be money well spent.
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Some great guidance. My only quibble would be price.
Locally, I could get a <CAD $200 hand-held hammer drill(used but excellent condition) and < $CAD 50 drill bit (new).

What's that about $20 USD? :grin big:

-brino
 
gasengin said:
Listen to the poster above that talks about the SDS type chuck system. That is the way to go. Any hammer drill, no matter the brand, that has the conventional jaw type chuck is a joke in a hammer drill. A good hammer drill will drill through solid concrete way easier that a normal bit will drill through pine. No pilot hole will be needed, just drill the size you want. You will be totally amazed at the difference. It will cost several hundred dollars for the drill and bits, but it will be money well spent.
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Thank you for your input! I purchased a used Ramset dynadrill SDS plus. What a difference!! You are so right - amazed at the difference. The problem I’m having now is I seem to be blowing out the back of the stone. I have tried placing the stone on hard packed sand, and also putting the stone in a vise. Neither worked. Any advice would be greatly appreciated.
 

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When you are getting close to break thru, ease way off on the pressure, You may even need to turn off the hammer or finish the hole with your smaller hammer drill.

Supporting the back also will help a lot.

In thinking about it some more, If you could make up a fixture that after you drill most of the way thru from one side, you could use the started hole as a guide to drill in from the other side. A similar technique is used on wood to keep the back side from splintering.
 
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