[Frequently Asked Questions]

You will find our most frequently asked questions in this section. These answers may answer your concern quickly. But, if you cannot find your question in the list below, try asking Fern the Driller, or send us an e-mail at info@fordia.com.

How do I choose the right bit?

A. Define rock hardness : The simplest and most reliable tool to use for rock hardness is the Mohs's hardness etcher; avoid use of a pocket knife.

Mohs's scale range

1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
6. Microcline
7. Quartz
8. Topaz
9. Corundum
10. Diamond

B. Define the degree of abrasiveness, fractures or breaks within a particular rock formation : Rock formations that are abrasive, fractured or competent will affect the bit selection and bit performance.

Rule of thumb is :

• Coarse grain rock formations (abrasive and fractured) use a low bit number (Series 1 to 5).
• Fine grain rock formations (non abrasive and competent) use a higher bit number (Series 6 to 10).
  
  

C. Type of diamond drill used: Generally harder matrices (low series of impregnated core bits) require more torque than softer matrices (high series of impregnated core bits).

Generally :

• Lower power drills – use high series of impregnated core bits.
• Higher powered drills – use low series of impregnated core bits.
• Slow rotation for deep hole drilling requires the high series of impregnated core bits.
• Slow rotation for fractured broken rock requires the low series of impregnated core bits.