What drill bit type to make small holes in thin slabs?

electrocutus
spending too much on rocks

Member since October 2020
Posts: 341

What drill bit type to make small holes in thin slabs? Apr 25, 2022 8:59:37 GMT -5

Quote

Post by electrocutus on Apr 25, 2022 8:59:37 GMT -5

Apr 23, 2022 9:55:55 GMT -5 stefan said:

Just a tip for drilling. I use a Dremel and a Dumore (Fordom on steroids!). The Dumore has a flex shaft and is easy to use (mine is from the 60's and still runs like a champ) The Dremel is ok but I found adding the flex shaft made it TONS better. I use a little duct tape on the spot I want to drill (keeps the bit from wandering when you first start). I also have a backing pad (I have a polymer pad from scrap at work, but any soft rubber will work) that I drill on. It helps hold the rock steady, and helps minimize breakout on the back when the bit passes thru. Work slow, and lift the bit often to clear the slurry. Be ready to change bits as needed (when the cutting action stops change the bit!) as the bits when worn out will heat up and the diamond coating will break off in the hole and basically force you to drill a hole in a different spot. I have used one bit to drill out several rocks, and then had to use several bit to do one rock! Some bits just seem to cut better than others. Oh and I love small core bits as they seem to have the greatest longevity (and the higher price!).

Thanks, those are great tips!
My rotary tool (Dremel-like but different brand) has a flex attachment, and I never had a use for it... until now :-)

rockjunquie Global Moderator Member since March 2012 Posts: 34,995	What drill bit type to make small holes in thin slabs? Apr 25, 2022 9:16:37 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by rockjunquie on Apr 25, 2022 9:16:37 GMT -5 I found that diamond twist bits last longer. The core bits just frustrated me, but maybe I got an off brand or something.

Rockoonz
misunderstood rock expert

Member since August 2009
Posts: 11,472
Member is Online

What drill bit type to make small holes in thin slabs? Apr 25, 2022 11:01:45 GMT -5 rockjunquie likes this

Quote

Post by Rockoonz on Apr 25, 2022 11:01:45 GMT -5

I haven't been able to find core drills under 2mm, our preferred pendant hole size. We tried the plated twist drills, and they just have a very short life compared to the solid plated rods or ball end burrs. I think the tiny core drills were coming from eastern europe, so quality was better.
rockjunquie our only issue with the core drills was clearing the cores out when they broke off, when we started adding trim saw additive to the water they came out easily.

“You preachers of equality, the tyrannomania of impotence clamors thus out of you for equality: your most secret ambitions to be tyrants thus shroud themselves in words of virtue. Aggrieved conceit, repressed envy—perhaps the conceit and envy of your fathers—erupt from you as a flame and as the frenzy of revenge.”
—Friedrich Nietzsche

victor1941
driving up their electric bill

Member since November 2011
Posts: 2,178

What drill bit type to make small holes in thin slabs? Apr 25, 2022 16:53:14 GMT -5 miket likes this

Quote

Post by victor1941 on Apr 25, 2022 16:53:14 GMT -5

Electrocutus, the new Kingsley North list the small core drills. Jade carver lists 2.5 mm core drills but were out when I checked today. I buy 8" flat laps from David and have had good service.