With the Granberg File-N-Jig 106B you can achieve the fastest possible cutting speed and, with good technique, have very good overall chain maintenance time. All the precision work can be done in the field. Also, you can set the up-down file angle so you can correctly sharpen square corner chain (semi-chisel) that cuts much faster than round corner chain.
How fast is the chain? You can always improve the speed of new chain significantly with the filing jig and good technique. You can maintain that speed through the life of the chain.
It is truly satisfying to always have a torrent of fat chips coming out of the back of the saw.
You might plan to spend an hour or two learning to use the jig. I include some tips that may help, but you will be the judge of whether much faster cutting chain is worth the investment in learning time.
Comparison
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I also have a Stihl FS-3 jig (I would rate this one star if it were sold on Amazon) and an Oregon 23736A jig (rated two stars, see my Amazon review). The Granberg 106B jig gives by far the best results.
The strongest features of the Granberg 106B are its all-metal construction, a very stiff frame that resists distortion, symmetrically designed chain clamp screws, all adjustments are tool-free, and a really top quality indexed height dial. At 0.75 lb, it is the lightest and also the most compact of the three jigs I own.
I use the Granberg indexed height dial to precisely control both the file height (for hook) and the depth gauge height. I can see the index numbers clearly, even when rain is landing on the dial. Each full revolution is exactly 0.100" with marked and numbered subdivisions of 0.010", so the math is easy. By reading within the subdivisions, I can control height to about 0.002" accuracy and repeatability.
The Stihl jig has no index marks, so you are on your own to figure out file height. The Oregon jig has a very small red plastic dial that was hard to read when new and quickly became impossible to read due to normal wear and tear. The Oregon jig changes height by 0.108" for a full rotation and has twelve subdivisions of 0.009". I remember some time back working with the Oregon jig on dim Washington winter days; frequently with rain or snow falling on the dial; trying to read the tiny, worn-off, red-on-red numbers; and doing arithmetic in my head using divisions of 0.108" and subdivisions of 0.009"--not fun. I can read the Granberg dial under the same conditions, and I am just smart enough to do the math in my head with simple decimal divisions and subdivisions.
Complaints
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Amazon reviewer Bill B. complains that "the directions are just not clear" and "There are 3 or 4 important adjustments to be made each time you use the sharpener". (Even with these complaints, he does give it five stars.) A number of people on forestry forums have expressed similar complaints.
With the right technique, the adjustments are easy to make and will hold between filings; and the work will go quickly and smoothly.
Some tips
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Here are some tips, developed over many hundreds of filings, that I hope will help.
1. Start with good chain.
Start working with the jig on the best chain you have: either new chain or expertly ground chain is best.
2. Chain clamps ride on the rivet heads.
When set correctly, the chain clamps will ride securely on top of the chain rivet heads. Do not over tighten the thumb screw in the back.
If the chain clamps are properly set to ride on the top of the rivet heads, the jig will be secure. The clamps can be made to ride securely on 0.325" chain and even better on 3/8" chain because of the larger rivet heads. Adjust the two opposing clamp screws tight enough to prevent the cutters from rolling under the file motion and still loose enough to allow the chain to be advanced. When riding properly on the rivet heads, the front of the jig will not drop down due to filing activity.
The thumb screw has to be snugged just enough to keep the back of the jig from dropping down or the whole jig from kicking back when you are advancing and setting the chain or making the various jig adjustments.
If you tighten the thumb screw too much, the two sides of the jig will spread apart and the top will twist. You can feel this happen and see it occur if you look closely. The distortion of the jig will prevent you from achieving and keeping your adjustment settings. If the pivot point of the rotating head is not maintained in the middle of the chain, you will need to adjust the stop screw each time you change sides. You are also likely to not tighten the thumb screw the same amount when you start. Then you must adjust the settings again. (I believe this is the source of the complaint by reviewer Bill B. and many others.) I measured the Granberg jig to be about four times stiffer than the Oregon jig with its plastic filing frame--one of the major reasons for my low rating of the Oregon jig--but even with the Granberg jig you will want to take care to not distort the frame.
Make sure the jig is parallel to the bar. Especially do not let the back of the jig drop down or the curved heal of the chain back stop (the small floppy bent metal piece) may hang up on the cutters or depth gauges as the chain is advanced.
3. Centering the chain.
There is no specific adjustment for bar width, but assuming the thumb screw is not over tightened, which will lock in the chain position; you can use the two opposing chain screws to center the chain between the two sides by pushing a little harder on one side than the other. We want the pivot axis of the rotating head to be in the center of the chain.
First adjust the opposing clamp screws by eye to center the chain between the two sides. (I assume you are starting with expertly ground chain, so the cutters are pretty even at this point.) You can now set up the file stop screw to have the file just kissing the surface of one of the cutters on one side. Now change to the other side. If your file is not similarly kissing the cutter surface on the new side, try making up about half the error by pushing the chain sideways with the clamp screws: toward or away from the file. Make up the rest of the error with the file stop screw to move the file forward or backward. Now flip sides again and retest. Repeat as necessary until you have the same file contact for both sides. Now your chain is exactly centered under the pivot axis of the rotating file frame. You should only need to do this once for a particular type of chain and bar, although you might need to tweak one of the chain clamp screws a little from time to time.
I have been able to get the chain centered with chains ranging from 0.063" to 0.050" gauge, .325" to 3/8" pitch, and bar thicknesses ranging from about 0.160" to about 0.180".
4. Easy on, easy off with the jig.
You can take the jig off and put it back on without disturbing the chain clamp screw adjustments or the file height.
This is easiest if the chain clamps are set directly under one of the right cutters before removal or at the end of installation. This keeps the two small protrusions on the inside of the right side of the jig from hanging up on one of the right cutters.
The chain clamps should always be hanging on the tops of the rivet heads.
I put little springs on my chain clamp screws so they do not vibrate loose or get bumped out of position. See (12) below.
5. Adjust file height.
Adjust the file height screw to get the hook correct. This adjustment only needs to be reset about as often as the depth gauges are done--usually after a full day of work--to account for the slow lowering of the cutter height as the cutters wear back (due to the top plate slope of about 10 degrees).
To set the file height with accuracy and repeatability, I use the excellent Granberg indexed height dial. Raise the file and move one of the cutters as necessary to put the bottom of the file directly above the outside corner of one of the cutters (round corner chain) or the inside corner for square chain. I then move the cutter back against the stop and lower the file by about 85% of the file height (add about an additional 0.015" for square corner chain because you are using the inside corner). For 0.050" gauge, 3/8", square corner chain; I find 0.180" drop to be just right but dropping 0.185" gives too much hook. I cannot judge the difference of 0.005" by eye, but it makes a difference in performance, so I use the dial to get an accurate and repeatable setting. You will want to determine the exact height for your preference.
6. Filing into the stop.
You will not want to count strokes as with a file guide, but rather take as many strokes as you need until you feel the file lose its bite as the file frame stop bar (the rectangular bar) comes up against the file stop screw. It is easiest to stop as soon as you feel the file bite decrease. I think of this as feeling the "bottom". By always filing to the where you can feel the start of the bottom, long cutters will get more strokes and short ones fewer. The process equalizes the lengths automatically--generally to within about 0.005". Short cutters are low cutters because of the top plate slope and not do their fair share of work. Irregular cutter lengths lead to lost saw power and increased vibration, as also noted by Amazon reviewer Delfino.
When I start filing, I look carefully at the cutting surface of the first cutter, adjust the stop screw to file just a small depth, file until I start to feel the bottom, and then readjust the stop screw if necessary until I just get all the edge pitting filed away to have a perfect edge on that first cutter. Now I have the stop screw set right and file all the other cutters with this setting. With a chain in poor shape, I may find other cutters so short I am not getting the edge clean, so I have to set the stop in further and restart my cutter count.
On the next filing, I bump the stop screw in typically about 1/15 rotation to account for my average of about 0.002" of cutter length worn off (I am cutting mostly softwood) per filing. One full rotation of the stop screw corresponds to about 0.060" of cutter length, so usually a small bump is all that is required to update the stop screw position. I look closely to see if the edge is clean and adjust if necessary.
If the chain is centered per step (3) above, the stop screw should not have to be reset when switching sides and the saw should cut straight with highest efficiency.
However, for square corner chain it is necessary to change the up-down file angle between +10 and -10 degrees when switching sides. This requires loosening the thumb nut that holds the up-down file angle. Unfortunately this process jostles the stop screw so that the stop screw setting may now be off. To avoid this problem try this procedure. Let the file frame rest on the back of both hands, pinch the stop screw against the frame using your thumb on the head of the stop screw and second and third fingers of the same hand behind the frame. Using the index fingers of both hands pick the thumb nut loose. Change the up-down angle between +10 and -10 degrees by rocking the frame over with the back of your hands. Pick the thumb nut back into tight position with your index fingers. A strange procedure, but with practice it can be done in a few seconds and helps to keep the left and right cutters to the same length without readjusting the stop screw, so it saves a fair amount of time.
7. Comfortable working position.
It is not necessary to hunch over the bar as with a file guide. With the jig, I can work in a comfortable position.
I set the jig near the end of the bar just short of where the bar begins to curve strongly. I work in front of the bar and look directly back along the bar. I use one hand to move the chain and steady the bar while I pull the file frame with the other hand. Pulling the frame works just as well as pushing: the angles will remain true. When changing between left and right cutters, I just swap the holding and pulling hands.
Since I am looking directly into the face of the cutters and can lean in as close as I need to for a better view, it is easy to make sure the cutters are sharp. Of course you want to file away every bit of edge erosion, leaving a completely clean edge. For square corner chain, I look for the tiniest speck of white erosion on the cutting corner. Because I can see the edge clearly, I neither over file nor under file.
One can adjust the maximum stroke length with the frame settings. You can extend the stroke to use the full 8" of the file, but I like the approximately 6" stroke that was set at the factory better because the control of the top plate angle seemed tighter. The wrist motion seemed more comfortable as well with the approximately 6" stroke.
You can set up a bench vise or stump vise in a variety of ways to achieve a comfortable position. In fact, you can use the jig with no vise at all with just a small increase in filing time. Hold the bar with one hand while pulling the file frame with the other. If you are sitting, it helps to push the back of the saw against a log or steady it with your feet. I have sharpened a chain with no stump vise while I stood in 12" of snow by standing the saw on its end and holding the bar with one hand and pulling the file frame with the other.
8. Smooth cut file.
Once a chain is worked into good condition with a "regular cut" round file, you may want to use a "smooth cut" chainsaw file that gives a smoother and correspondingly faster cutting edge. Smooth cut files have always been recommended by experts to get the sharpest chain. These special files are available from Pferd and Woodland Pro from forestry and logging online sites. I use a smooth cut file for all routine filings, i.e. with no major dirt damage.
Even a regular cut round file will give a faster cutting surface than a grinder, but the smooth cut file gives the fastest cutting edge. For an expert discussion of the importance of edge smoothness, see Leonard Lee, Complete Guide to Sharpening.
9. Lubrication.
Bar oil can be used to lubricate the file frame slide rod, file frame stop bar, and stop screw. Now and then you can lubricate the height screw, the top plate angle holding screw, and the up-down angle holding screw to make adjustments smoother.
10. Doing depth gauges.
Using the Granberg jig, the depth gauges may be set quickly and with an excellent accuracy of about 0.002".
Caution! Never lower the depth gauges more than a couple of strokes without making test cuts. Be especially cautious when using a new, unfamiliar method such as this jig. Test with a down cut, up cut, and bore cut. The chain will become aggressive and hard to control if the depth gauges are too low.
The depth gauges must be lowered at least as fast as the cutter heights drop. If the gauges are not lowered your chips will become thin and cutting speed will fall off. Irregular depth gauge heights contribute to vibration with a corresponding loss of cutting power.
The cutter height drops at about 1/6 of the cutter length reduction. If the cutters have lost about 0.010" to 0.015" of length (about a full day's worth of chain wear for me), they have lost about 0.002" of height and it might be time to lower the depth gauges. Usually I do the depth gauges at the end of the day. With the jig, it takes me about nine minutes total to file the depth gauge heights and to hand file the slopes of the depth gauges in the usual way.
The best depth gauge file to use is the Pferd 4130, EDP 17051, 8" x 23/64" x 15/64" flat file. This is a replacement depth gauge file for the Pferd Chain Sharp file guide, but happens to work perfectly in the Granberg jig.
Adjust both the top plate angle and up-down file angle to zero. You need to have the bottom of the file parallel to the bar. Adjust the file stop and the height to get the bottom of the file to just scrape along the top of one of the depth gauges. Now raise the file with the height screw and set it down gently on one of the cutters. Note the dial indication and then lower the file by the depth gauge setting.
The depth gauge file tends to vibrate more than the round file. On some chains, the depth gauges have distinct left and right forms and you may find the file vibrates more for either the left or right depth gauges. If so, do all the depth gauges on the side that vibrates less. Then flip the file end-for-end and do the depth gauges on the other side. I use much the same hand switching method and position as for the round file (7).
Carlton, a maker of chain and related chainsaw products, has recommended a progressive method of calculating the proper depth gauge value based on the shortening of the cutter length. Carlton argues that the cutters tip up at an angle when they are cutting. They have prepared an interesting technical report and sell the File-O-Plate depth guide tool, which is claimed to accomplish the progressive method. Based on my experience, I agree with the arguments for the progressive method, but I think you can apply the progressive method better with the Granberg jig than with the File-O-Plate.
When I put on a new chain, I note the length of the cutters. For my 3/8" chains this is about 0.390" to 0.395". When I do the depth gauges, I check the current lengths of a few cutters on each side with a digital caliper. Using the methods described above, all the cutters should have the same length within about 0.005", but I like to check. I then take the amount of cutter length worn off from the original value, multiply by 10%, and add this value as a correction to the factory recommended depth gauge setting. For example, if I have worn off 0.040 of cutter length, the 10% correction factor would be 0.004". I might then add this value to the a manufacturer recommendation, let's say is 0.025", so I get 0.029" for my depth gauge setting. Using the progressive procedure, I find that I can wear the cutters down to the witness mark and keep the chain cutting at top speed throughout the whole range. Without the progressive correction, I lose chain speed and my chips get thin when the cutters get fairly short.
I keep track of chain performance and check chip thickness all the time.
The progressive method (and especially my own variation using the Granberg jig) has not been given any scientific study that I know of. Adapt the method or do not use it at all according to your own best judgment.
At the end of setting the depth gauges, I reset both angles. I also have to reset the file height, so I use the index dial according to step (5). Resetting the file height about once a day ensures that the hook shape is being maintained as the cutter heights slowly decrease.
11. Dirt damage.
For light dirt damage where I need to take off no more than about 0.005", I switch back to a regular cut file for faster metal removal and expect to spend as much as five minutes more than usual for the filing. For moderate dirt damage requiring about 0.005" to 0.015" to be filed off, I use the Granberg Grind-N-Joint (Granberg Grind-N-Joint Bar Mounted 12 Volt Chain Grinder), bar mount, grinder with a diamond bit. It mounts in the same way as the Granberg jig and gives a cutter shape very compatible with the round file used in the jig. The diamond bits keep their shape and give a cleaner surface than other bits.
With more dirt damage than I could file off with 0.015" removal, which is pretty rare for me, depending on remaining length I either pay for grinding or throw the chain away.
12. Customization.
I replaced the 10-32, 3/8" clamping screws with ones of 1/2" length. This gives better purchase for my gloved fingers. I invested $5 in a box of miscellaneous springs and found two small ones to go on the chain clamp screws. These springs keep the screws from vibrating or being jostled out of position which is particularly likely to occur when filing the depth gauges.
Particularly with the 10 degree up-down angle needed for square corner chain, you may find the file starts hitting the chain clamps when the cutters get very short. Use a regular shop file to remove material at the scored areas so your chainsaw file is not dragging on the clamps.
I replaced the Granberg wing nut used for the top plate angle adjustment with a 10-32" knurled check nut of 3/4" diameter (). The knurled nut works a little faster and locks into position more securely.
I noted that file was riding up and down just a little over the length of a full stroke (The Oregon jig was really bad in this regard. It has a plastic filing frame.) With digital calipers I measured the spacing between the file frame slide rod and a round file at both ends. I found the rod and file were slightly out of parallel. I used a round file (probably should have used a triangular file) on the triangular file seat in the frame just a little to get the rod and round file parallel. I also checked the parallelism of the rod with the depth gauge file. I used a flat file on the flat part of the file seat for the depth gauge file. Note, the two types of files have respectively triangular and flat seats.
13. 10X magnifier.
A 10X loupe magnifier (BelOMO 10x Triplet Loupe Folding Magnifier with attached plain black nylon lanyard with quick release buckle) is very useful for an occasional, very close-up check of the cutter edge and cutter surface. Using the loupe from time to time to see the edge clearly helped immensely in improving my filing skills.
Filing times.
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With all this detail you may be wondering about filing times. With the jig, I have to set each cutter against the back stop so my cutter-to-cutter time is a little slower than with a file guide. However, with a file guide that has no back stop, I need a special procedure called the "master cutter" method (look on the web for details) every so often to equalize the cutter lengths. I need to measure each cutter several times with a digital caliper and try to file to hit my mark for length. Very tedious and slow.
Let's consider the total time for eight filings and setting the depth gauges--complete maintenance for a full day's work. With the jig I can do 36 cutters in about 4.5 minutes for the very fast cutting square corner chain so I am setting the up-down file angle each time. For eight filings and adding nine minutes for depth gauge work, I have a total of 45 minutes for complete file maintenance over a full day and maintained effectively perfect chain all day.
With a file guide I can do 36 cutters in about 3.5 minutes so I gain eight minutes for the eight filings, but the master cutter method takes me 20 minutes and I take about 10 minutes to do the depth guides with a depth guide tool. So I need about 58 minutes (13 more than with the Granberg jig) for complete maintenance during a full day, I have to use the slower cutting round corner chain, and my control of angles and lengths is not nearly is good. Also, I find hunching over the saw attempting to make perfect straight strokes fatiguing.
Of course your times could be quite different.
Apology
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Sorry about the length of the review, but I hope these comments and suggestions are helpful to you in using this very interesting tool. Granberg Bar-Mount Chain Saw Sharpener, Model# G-106B - Chain Saw Sharpening Guide - Chain Saw Accessories'
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