Power tool accessories: Countersinks
A countersink is a conical hole that is tapered at the bottom. The taper helps make the press-fit tight thus ensuring the rivet stays in place. Countersinks are generally used in one of two applications;
- The countersink is the press-fit hole that has been pressed or rolled into a hole or
- The countersink is a hole that has been drilled in preparation for assembly.
What are the advantages of a countersink?
Countersinks help makes assembly easier and assists in controlling how much the rivet head protrudes. Countersinks also help with controlling the amount of material being removed from the hole being drilled.
How do you use a countersink? First, begin by drilling the hole. The key to making this step easy is making sure your drill bit is sharp. A dull bit can tear the material being drilled. Once the hole is drilled, insert the rivet into the hole and mark the rivet s head. The mark will define the depth you have.
Types of countersinksCenter
- 1. Countersink – The centre countersink leaves a centre countersink hole in the material. The centre countersink is normally used for larger-diameter rivets.
- 2. Flat Countersink – The flat countersink leaves a flat countersink hole in the material. The flat countersink is used for smaller-diameter rivets.
- 3. Cup Countersink – The cup countersink leaves a cup countersink hole in the material. The cup countersink is used for smaller-diameter rivets.
- 4. Tapered Countersink – The tapered countersink leaves a tapered countersink hole in the material. The tapered countersink is used for larger-diameter rivets.
- 5. Conical Countersink – The conical countersink leaves a conical countersink hole in the material. The conical countersink is used for larger-diameter rivets.
- 6. Combination Countersink – The combination countersink leaves a combination countersink hole in the material. The combination countersink is used for larger-diameter rivets.
Choosing the best countersink bit
The key to using a countersink is choosing the right bit. Depending on the material being drilled, there are different qualities you should look for in your bit. Steels – In general, steels are strong enough to be drilled by high-speed steel (HSS) bits. One consideration is the hardness of the steel. The harder the steel, the slower you need to drive the bit. If you are not sure of the material, use a cobalt alloy bit. Drill speeds for steels vary between 50 and 250 rpm. Aluminium – In general, use carbide-tipped bits for aluminium.
Conclusion :
After all is said and done, using the right tools and following the right procedures is the key to drilling a perfectly countersunk hole.