squarejig sharp

Sharpening square ground chain has just became easier.

              We have created a simple jig that repositions the chain in a universal round grinder to cut a square ground tooth. The SQUAREJIG  clamps into the vise on the grinder. The round grinder maintains all of the features it was designed to do.  Professionals and experienced enthusiasts can now enjoy the square ground performance with a clamp in attachment. No modification to the grinder is required beside turning the 1/8th wheel to straight up and down and profiling a double bevel on the grinding wheel to emulate the double bevel file.  It may be hard to believe considering how simple it is but it is the real deal. 

Made in USA

     All of our materials are precision machined and Made in the USA including the steel, cap screws, pins and knurled thumb screws, clamps, holders and bases. By manufacturing and sourcing all of our materials and workmanship here in the USA, we guarantee our customers will have the highest quality parts and customer service available. We are family owned and operated and have come up with the invention here in the Pacific Northwest. The SQUAREJIG is Patent Pending so that we can guarantee the quality of parts are made in USA for a long time to come. Our number one goal is to add value to the chainsaw community. We love how useful the chainsaw is in many aspects. Many of us depend on sharp chain in our work and know that the chain is vital to the work a saw can do. To that note it is our goal to help others achieve the smoothest and most enjoyable fast cutting chain in the world. 

      We are honored to have the opportunity to work hard for you and help you achieve the ideal cutting performance for your chain.  

Benefits

#1.  Can be installed and removed instantly without modification to the grinder.

#2. Works with 3/8 and .404 pitch chain. 

#3. Utilizes common low cost grinders and common grinding wheels.  CBN wheels are also available. 

#4. The grinding wheel spins into the teeth on left and right hand cutters. 

#5. One machine can do most all chain maintenance. 

#6. The system allows the chain teeth to be clearly visible and sharpened in a small efficient work area. 

What are people saying about the Squarejig that have used it?

         The general consensus is that it's awesome. 

Common Questions:

Will it do .325 or 3/8LP chain?

Yes, It's not designed to do smaller pitch but it can easily be done. It just requires the extra step of dressing only one side of the wheel and then flipping the wheel. This works best with the 3/8ths wheel. The profile for the wheel is more of a checkmark than a "V"

What grinders will this work for? 

The Tecomec Jolly Evo works the best. The Oregon 410-120 also works well. If you have a specific grinder in question email or give us a call and we can find out for you. There are a lot of grinders out there and some of them are not made anymore. We will test them as we find them. Generally the 10 degree tilt or front to back adjustment is required. The USG grinder we tested did not work without modification. 

Why the Oregon model 410-120  and Jolly Evo grinders?  

Primarily the accuracy is the most important part of square grinding. These grinders are very accurate. As well the spring is a key feature. The grinding wheel takes minimal pressure to move which makes for easy, intricate work. 

Why is square ground more efficient than round?

Square ground cutters have razor-sharp side plates that cut the wood fibers more efficiently.

How does chainsaw chain work? 

One chainsaw chain tooth or cutter works in the same way a wood planer works. A chainsaw chain is a bunch of small planers that take thin shavings of wood. Each chain tooth has a depth adjustment that determines how thick the shaving of wood the cutter will take. These are commonly called a depth gauges, rakers or drags. 

 Feedback from the chain while operating can provide important information about how the depth gauges are operating. If the blade is sharp enough and the shaving being removed is thin enough, the teeth can operate with ease. The thicker the shaving, the more power is required to remove material. Too thick of a shaving will become too difficult to remove the shaving and the chain will grab, chatter or bog the engine.
 

 Depth gauges. 

A common size depth gauge is set for .025" or commonly referred to as 25 thou. It is difficult to determine exact depth with the naked eye, so a gauge is a good tool for getting optimal cutting. If depth gauges vary slightly from tooth to tooth, they take more or less wood. If some teeth have a higher depth gauge, those teeth would be a missed opportunity for a cutter to take wood which translates to a slower cut. In a perfect world, all of the depth gauge heights would be the same.  A good way to do this with a machine is to cut all of the teeth the same length first and then cut all of the depth gauges the same height. One thing to note is that the top plate of the tooth slopes back at about 7-8 degrees. If the length of the tooth is different, then the height of the depth gauge will need to be adjusted accordingly. 

Why does a chain bog or slow down the engine in the cut when we add pressure?

The quick answer is that energy being consumed is nearing closer to the power that the engine is producing. Each cutter consumes energy. Less cutters in the wood will limit bogging as well as higher depth gauges. If your chain is bogging your saw engine you may have too many cutters in the cut working at the same time. Going to a full skip or semi skip can help maintain chain speed. Or going to a smaller bar can help as well.  Depth gauges may be too low. The only way to fix depth gauges that are too low is to sharpen the teeth. 

Kickback (In depth) 

By definition, kickback it is a sudden forceful recoil. What do we know about this phenomenon with chainsaws? We know it causes a good portion of saw injury to chainsaw operators, but how exactly does this happen? 

With normal chainsaw operation, pressure from the operator and depth gauges regulate the amount of wood that a tooth can take. A kickback is an event that happens over the course of milliseconds. If we were to slow down the event, the condition uses the engines force to drive the teeth and rakers deeper into the wood without the operator's consent. The top quarter of the bar is where this event happens. The teeth at the tip of the bar will send the nose up, simultaneously driving cutters on the top of the bars nose deeper into the wood like a hammer driving the cutters and depth gages deep into the wood.  As the operator, we get very used to being the one deciding how much pressure to put on the cutters. 

Just as you can hammer a nail into wood, the engines force will push the rakers and teeth into the wood deep enough that it grabs the wood with incredible force.

If this condition is just right the entire saw only needs to be pushed back toward the operator slightly for the tip of the nose to escape the wood and violently rotate toward the operator. Sometimes the saw jerks while in a plunge cut. This is also a kickback condition. But in this case it is only felt as a jerk as the bar is unable to escape and reverts back to normal operating pressure intermittently. This mitigates an out-of-control kickback event. 

How does outside top plate angle affect the cut?

This can be the most confusing angle to explain on a chainsaw tooth. Simply put, a zero degree or flat top plate is more durable and may be better for ripping and an angled top plate is less durable and faster cutting and better for cross cutting or bucking. But why? A zero degree top plate angle creates a square or flat profile at the bottom of the kerf. When cross cutting the fibers are cut but remain connected in the kerf until the next tooth can sever the wood fiber on the other side of the kerf. An angled top plate creates an upside down “V” shape at the bottom of the kerf. This tooth angle cuts the fibers off mid kerf and allows the chip to be extracted without the next cutter coming by to cut the fibers on the other side of the kerf.

To explain why this happens, as we know from sharpening the tooth, the more we cut the tooth back, the lower the cutter becomes. We know that we must lower the depth gauge as the tooth becomes lower.  

If we think about how the top plate slopes back at 7-8 degrees, the farther back we angle the top plate, the less wood the inside of the cutter will take. This makes the corner or working edge of the tooth higher than the inside corner. The more dramatic this angle, the higher the working edge will be than the inside of the cutter. If you were to look down the top of a chain with the chain on the bar the profile that the chain is cutting in the kerf will be seen. You will see a slight "V" shape looking down the top of your bar if the top plate angle is pronounced. This "V" is cut inversely in the bottom of the kerf. The lower the depth gauge, the more pronounced this angle needs to be for the cutter to overlap mid kerf and take its own chip.  In the beginning we talked about how a planer is similar to a saw chain cutter. Imagine the planer cutting a flat surface. This would be similar to a zero degree top plate cutting a flat kerf. Now imagine if you were able to angle one side of the planer blade down to cut more wood on one side. It would cut deeper on one side than the other. This is what top plate angle adjustment does. When we are cross cutting or bucking wood, the fibers of the wood run laterally, and we are cutting across the grain of the wood fiber. If a cutter cuts flat, the fibers are still connected on one side of the kerf and the next tooth is required to finish severing the fibers to extract the chip. With a 35 degree top plate angle, the fibers are cut on the outside of the kerf and also mid kerf and does not require the cutter behind it to create a chip. For ripping the fibers are cut off in the kerf and the chips break easily in the center and does not require an overlap mid kerf. A zero degree top plate allows the inside of the cutter to take more wood making a faster cut. Depth gauge height plays into this as well. The more wood that the cutter takes the steeper the top plate angle is required to create it's own chip with a cross cut. Knowing how this works is a key component in creating the exact cutter for your specific needs. 

How does the SquareJig work and what machines will it work in?

In short, the Oregon 410-120 (410-230)  and Tecomec Jolly Evo model is so far the best models to use. Other models have been found to have a very heavy spring or require modification making them less safe. 

The Squarejig is a simple jig that adds the square grinding feature to a common universal round chain grinder. No modification to the universal grinder is required. The Squarejig clamps into place by the drive link clamp and is ready to use. However, not all machines have the same features. The 10-degree adjustment is required to adjust side-plate sharpness. When too much material from the tooth is removed from the inside of the side plate it will begin to hit the tie strap and the jig needs to be moved toward the wheel by the 10-degree tilt. As well the diameter becomes smaller as the wheel is dressed and will increase how sharp the side plate is. The solid chain holders on the Squarejig ensures that top plate sharpness is uniform throughout the chain. The stationary Squarejig holder guarantees uniform cutter sharpness. 

I know a bit about chain... What now? 

Knowing what you want the cutters to look like is a good first step. There are many formulas already in place that work really well. There is no need to reinvent the wheel. However, it is possible to fine tune the cutters based on the wood being cut and the power of the saw.  

 Also, determine what size drive link width you have. We carry .050 and .058/.063 holders. 

What setting on the machine changes what attribute on the tooth?

Outside side plate. 

The point on the edge or "V" on the grinding wheel determines the slope of the outside side plate. The grinding wheel is designed to emulate a double bevel file or goofy file.  A sharper "v" slopes the side plate forward. 

Outside Top Plate

 
The dial at the bottom of the machine decides what angle the outside top plate will be.

Inside Top Plate

The angle of sharpness of the inside top plate is determined by which kit you choose (40, 45, and 50). This angle is in relation to the guide bar. 

Inside Side Plate

The 10-degree tilt or slide on the Jolly Evo adjusts the inside side plate angle. This adjusts how far or close the tooth intersects the wheel. The farther away from the wheel, the sharper the side plate. The side plate can be sharpened until it reaches the tie straps. If contact is made with the tie straps you must move the jig closer to the wheel. 

 A quick tip

Chain and machine are always opposite when deciding machine settings. For example, right hand cutters are cut on the left side of the jig with the left side of the wheel. Top plate angles are adjusted to the left side of the zero on the dial. 

Right hand cutter left side of jig.

Right hand cutter left side of wheel.

Right hand cutter left side of 0 on dial.

What does dressing the wheel do?

Dressing the wheel with a diamond file has three functions. 

1.) It removes oil and metal. 

2.) It defines a corner on the left and right side of the wheel and

 3.) It determines the angle of the chain cutters side plate. 

Firstly, removing oil and metal buildup from the porous cutting surface of the wheel is vital to the function of the aluminum oxide surface. When metal and oil loads up in the cutting surface of the wheel, cutting slows down and too much heat can be put into the tooth. Issues from heat can include burrs, melting, and tempering. Overheating to the point of tempering can result in difficult hand filing and broken teeth. To remedy overheating, simply dressing the wheel and using a short tapping technique when grinding can help send heat away from the tooth and limit the amount of time the wheel has to introduce heat. A trick is to watch the sparks. Sparks are high temperature particles being pulled away from the tooth. Less spark volume suggests the heat is going into the tooth or the cutting surface has lost some of its efficiency. If you see smoke or smell sap while cutting a tooth, it may be overheating. If the tooth has become red hot, it has definitely overheated. Color is a good indicator to how hot the tooth has become. A straw color is said to appear around 354F or 180C. It takes time and close watch on how the wheel is performing to determine when the wheel needs to be dressed.

Secondly, dressing defines the outside corner of the wheel. This corner does most of the cutting and creates the defined line that runs from the working edge of the cutter into the inside corner of the tooth. A trick is to find a good drop light or lamp to see your work as the corners line up. If the wheel is becoming rounded on the corner, it will also round the tooth profile. Wheels come in different hardness and cutting ability and deform faster or slower than others. As well, chainsaw chain tooth hardness differs from manufacturer to manufacturer. Matching the correct wheel to the chain you have can make sharpening more efficient and much more enjoyable.

The third function of dressing the wheel determines the side plate angle of your cutter. A common angle of outside side-plate angle is 85-90 degrees. In theory, the side plate angle determines some of the feeding characteristics of the chain. As the cutter rocks back in the cut it changes the side plate angle in the cut. Putting a forward slope on the side plate allows for the cutter to always be pulling into the wood vs pushing out. This can lower the amount of operator pressure required to feed the chain. 

In conclusion, a light dressing is normal and often required while square grinding chain especially when feedback from the wheel or wheel profile changes. 

Warning! 

The sides of the wheel will load up. It may be tempting to remove this by dressing the sides of the wheel. This is never an advantage and will damage your wheel. Leaving the oil and metal on the side of the wheel creates a polishing surface  that will remove minimal material. All or almost all of your cutting should be done by the front of the wheel. 

 Tooth Length

Tooth length is determined by the how far the clamp is left or right on the slide. Making sure the rivets of the chain are level will ensure all of the cutters are cut the same lenth. Once left hand cutters have been sharpened, it's time to flip the chain over to do right hand cutters. Before we cut right hand cutters, set the jig up for it first. Put the right-hand cutter on the left side of the machine. Then adjust the top plate on the exact opposite side of the zero and cut all of the left-hand cutters. When it's time to cut a right hand cutters, cut a minimal amount from the tooth and check it's length putting the teeth side plate to side plate. Using a tooth farther away from the reference tooth will allow the chain to fold up. Once the correct length is made by adjusting the left to right adjustment on the clamp of the jig we can cut the rest of the teeth. 

Finally, we have come to the end of the reading section of the site. I hope that you have enjoyed some of the ideas on tooth geometry and technique for achieving the fastest cutting chain in the world. The Squarejig is a rare and specialty tool for the forestry industry that has an abundance of benefits for sharpening and maintaining square ground chain. New ideas and better concepts are sure to be out there. However, the square ground chain is still the fastest and smoothest chains you can get.