Jackhammer with rotation


Jackhammer is definitely powerful tool to break rock, ice, and permafrost! The capacity for the depth will be weak point of this tool. Usually, jackhammer dig only 5-10 feet or less. However, this gas powered Swedish rotation jackhammer (Pionjar) could be drill 20 feet deep to the bedrock even granite. I soon try this to the rocky permafrost last year. Unfortunately, it did not work! This strong percussion power was absorbed by the wet silty material and melt water generated by the impact. So this jackhammer works wonderful for dry bedrock but not for frozen silty gravel! We still look for drill system for frozen gravel!

Percussion drill


Percussion drill is one of the ideal drill head for portable drill system. We try to use heavy-duty electric percussion drill to apply permafrost drilling. In general, this works better than just rotation drill. But not super great system. We will need improve in a future.

Power Head



Drill (mainly rotation) action needs power. I believe three major power sources are using for drill rig today. Maybe most easy to use but weak method is electric. Electric drill is easy and also working great for colder temperature. We use this sometimes river ice, shallow drill with silty/icy materials. Mechanical drill is probably most common method for portable drill. Because relatively light weight and strong. But it’s sometimes hard to start in the colder temperature. Last method is hydraulic. This is great method for deeper, easy handle, stronger etc. That why most of the professional driller use this way. But this is not capable for portable drill. System needs to bring massive amount of hydraulic fluid and also need warm up during cold environment.

Air Hammer!


Shock (vibration) action is very efficient for gravel or bedrock drilling. We try to employ this action in our portable drill system. We asked UAF Mechanical Engineering machine shop Ned Manning and Eric Johansen for building proto type (photo). Ned is very talented engineer to build complicated small mechanics.
At first, we try to modify commercially available air hammer putting in front of auger bit. This in-line air hammer works but not greatly. It need more strong shock at the each hammer action. I hope someday we have more money to build progress type hammer!

Swivel


Water/air swivels are great idea to remove cutting chip at the bit. These system require big amount of air compressor (>100 CFM) or high pressure water pump (2GPM), however, it works greatly with our portable drill system!! This swivel connects water or air line during rotation (drill power head). In general, actual drilling system includes three major components to digging ground, 1) rotation action, 2) high pressure forced water/air pushing action and to remove chips, 3) impact shock action. Swivel support high pressure forced water/air pushing action and to remove chips. However, once we work with permafrost, we would like to keep freezing during drilling. As a result, we need chilled (cooling) system before sending swivel. It will be minimum disturbance, when we use super cooled water or chilled air to send swivel system.

Many different bits!



We try to test many different bits for this snow machine trip. We are making artificial frozen gravel (permafrost!) and using hydraulic drill system to drill. This system can measure and control drill torque and down speed. We will estimate efficiency of each bit.

core bit VS. auger bit


I introduced auger bit last two blog. Auger bit is faster and easier to drill (e.g. making hole for temperature monitoring). However, this is difficult for gravel layer. Core bit (picture) is, in general, for core sampling but also better for gravel layer drilling. We have several different shape of the core bit using carbide or diamond.

Mole bit!


There is no potable drill can dig frozen gravel. We have to develop drill bit for gravel. Designing bit is one of the fun part of this work. You will see the picture right side with two 1960s kids TV program shots. These underground vehicles were amazingly fast to go in the ground! I ask to Jon’s machine shop to build this “mole” type bit last year. Jon Holmgran is sharp and brilliant mechanical engineer living in Fairbanks. He was helping me more than 10 years to create new drill systems. Some system was greatly works but some one goes to bad. Anyway, this nice looking mole bit is not great digger like TV but I like it.

drill bit


Drill bit is maybe one of the most important parts of drill system. If you don’t have ideal drill bit for particular materials, we cannot drill efficiently. We prepair variety of drill bits for this trip. next a few days, we will show you what kind of bits we have and how works these drill bits! You can see 4 bits in the picture. All bits are fitting for augering fright, which we do not need water or air. these bits are designed for dry rotary drilling. This works great for ice, frozen silt but not for gravel. We will start these bits first at the school!

drill rig test


We are preparing snow machine/outdoor items and also drill equipment.
Maybe 70%(by weight) of our total carrying baggage will be drill equipment including pressure pump unit, PVC pipes etc. It will be difficult to evaluate which system we should choose in this trip. Portable drill system depend on materials. If we hit boulder or icy silt bonded gravel layer, it takes long time to drill or may need to give up! Anyway, drilling experiments will help better idea to cutting efficiency. We made coarse frozen gravel (permafrost imitation) at garage and test different drill bit.