Core Drilling

      1. How many holes can I drill out of one bit?

It is impossible to say how many holes you will get out of a bit.  There are several factors beyond our control that impact bit performance.  They include:

A) Quality of bit - A low cost economy bit will not give you the same life (or speed) as a high quality bit.

B) Speed – If the speed is too high the bit will glaze. If the speed is too low the job will take too long.

C) Water – Not too little and not too much. The right amount removes slurry and keeps the cut clean.

D) Steel – Slows the cutting process. Maintaining drill motor speed is important. Don't push the bit too hard! Maintain a consistent speed.

E) Bond Specs – How the diamonds are bonded to the barrel is important. A soft bond is good for concrete, and a hard bond is good for asphalt. Using the incorrect bond will greatly decrease your bit life.

F) Proper Alignment – This means the rig must be properly anchored. A rig can be anchored with concrete anchors, vacuum base or post jack. Standing on the rig is dangerous and not acceptable.

G) Operator Experience - An experienced operator knows how to get the most out of a bit!

2. Can my core bits be sharpened?

Usually when this questions comes up it is because the bit is glazed. Glazing occurs when too much heat is generated at the segments of the bit (stop pushing so hard and/or slow the speed down). When glazing has occurred your bit will "sit and spin" or drill really slow. The simple fix to this is usually drilling a hole into a cinder block. The abrasive nature of the block will clear the glazing and expose new diamonds thus "sharpening" your bit.

3. Can I use my hammer drill with your dry core bits?

You can provided you have: 1) the correct adapter and 2) a setting on your drill for spin only (the hammer action will blow the diamonds right off the bit, making it useless). 

4. Are your core bits self-centering?

The industry did offer self-centering bits for a period of time, but due to incorrect usage all of the major manufacturers have stopped making these bits. The solution to this is to take a piece of plywood and cut a hole in it the diameter of your bit. This becomes a template for you to start your hole. You can remove the template once your bit is 1/2" into the material you are drilling.

5. Can I use any drill with your core bits?

No.  Besides actual core drills, hammer drills (see question 3) and variable speed angle grinders have been used with our bits.  Most carpentry drills do not have the correct RPM's for diamond core bits.  Having the correct RPM will greatly impact the life of the bit.  Below are the recommended core drilling speeds for the most popular sizes.  Please call us if you don't see your size listed.

Bit Diameter    Min RPM   Ideal RPM   Max RPM
     1"                 2400          3200           4000
     2"                 1200          1600           2000
     3"                  800           1050          1300 
     4"                  600            800           1000  
     6"                  400            530            665
     8"                  300            400            500

6. Is the diameter of your bits id (inside diameter) or od (outside diameter)?

All of our bits are od (outside diameter). The majority of our customers are concerned with the size of the hole they have after drilling. A few of our customers are concerned about the core sample that they pull out. For those customers the general rule of thumb is subtract 1/4" from the od to get your id (ex: 6 1/4" od bit will give you about a 6" core sample). It's important to understand not all bits are made the same and there can be some variance. Please call us at 1-866-268-2600 for more specifics.

7. Why does the circuit protector on my core drill keep shutting off?

Most likely this is happening because you are using the wrong gauge extension cord. We always recommend using a 10 gauge extension cord.

8. What is the main difference between wet and dry core bits?

Core bits need something to cool them.  In the case of wet bits it is water.  With dry bits it is air.  When drilling with dry bits you should drill about a 1/2" and then pull the bit out to let it air cool (tip: dip the end of the core bit in a coffee can of water to speed up the cooling process).  



1. What are the important details in selecting a blade?

There are lots of things to be concerned with when purchasing a blade. The right blade makes a job much easier.

A) Bond Specs – How the diamonds are bonded to the blade is important. A soft bond is good for hard materials (concrete, pavers, granite, etc), and a hard bond is good for abrasive materials (asphalt, limestone green concrete, cinder block, etc). Using the incorrect bond will greatly decrease your blade life.

B) Saw Horsepower - Make sure your blade is rated for the horsepower on your saw. This detail is often overlooked. A saw that has too much horsepower will use up a blade prematurely.  

C) Cooling Technique - Will you cool the blade with water or air? We suggest water. Make sure you have enough. If you use air you must allow the blade to cool every few feet of cut by running it at full speed outside of the cut.

D) Blade Life vs Cutting Speed - Typically, there is an inverse relationship between cutting speed and blade life. If the operator makes a change, such as increasing cutting pressure to make a blade cut faster, blade life will tend to be shortened as a result. Likewise, if an operator wants to extend the blade's life, he can reduce cutting pressure and cut slower.

2.  Why don't electric walk behind saws come with cords?

There are several factors in determining the correct cord to put on an electric walk behind saw.  The two biggest factors are motor type (horsepower and phase) and length of cord.  Due to these variables, saw manufacturers do not include cords with electric saws.


More content coming soon! Please call us at 1-866-268-2600 or email us.