John K Jordan
07-05-2016, 11:35 PM
I just found this article and it's so complete I thought it would be worth posting in a new thread, perhaps to make it easier to find.
Steven Russell is an expert in many things including woodturning.
I found this in my notes from 2006 after experimenting with sharpening bandsaw blades myself.
Steven wrote this in 2002, posted in 2003 on another forum; it helped me "hone" my sharpening method.
============================================
How To Easily Resharpen Dull Bandsaw Blades
Steven D. Russell -- Friday, 27 June 2003, at 8:26 a.m.
Resharpening Bandsaw Blades
I save significant amounts of money every year in my production woodturning studio by sharpening dull bandsaw blades quickly and efficiently using my "On the Bandsaw" sharpening protocol. This protocol works equally well with standard steel bandsaw blades as well as the higher quality silicon steel blades. It can be adapted for use on carbide tipped bands quite easily.
For the bulk of my studio's bandsaw work, I prefer to use high quality silicon steel blades. These blades last longer initially (as well as after being sharpened) than many of the less expensive steel blades I have used in the past. Even using high quality bandsaw blades, I can dull a new blade in two hours or less. My record for dulling a brand new band is 30 seconds, resawing Australian Dead Finish.
Typically, I will get a couple of days out of a new blade before it needs to be resharpened. With careful sharpening, I can usually sharpen each band approximately 8-10 times using abrasive cut-off wheels and 15-20 times with fine diamond wheels, before they're pitched into the rubbish bin.
The best cutting performance is achieved with the second through fifth sharpenings (abrasive wheel) and second through tenth with the diamond wheel; the sixth and later sharpenings are very dependent on the accuracy of the earlier sharpenings.
The cutting performance will degrade slightly with each sharpening, but the sharpened blade will still cut and track easily through the wood, wet or dry, if the sharpening was done with care. I should mention that this protocol will not duplicate a new factory sharpened edge quality. Nor can you duplicate a professional sharpening by using this protocol.
However, the sharpened blade will work very well for rough cuts and non-critical cutting such as gross resaw work, making turning squares, corner removal on bowl blanks, dimensional cutting, etc. I would not try to make paper-thin veneer with one of my resharpened blades, but for most of the work a woodturner demands of their bandsaw, it would be appropriate.
Why Sharpen Blades?
If you are an occasional or hobby turner cutting clean dry wood, you will no doubt get a few months or more out of your blade before it becomes dull. However, if you are using your bandsaw daily in a production environment - resawing, making bowl blanks, turning squares, pen blanks and cutting through lots of bark and buried 'goodies' typically found in yard wood (like bullets, rocks, wire fencing, horseshoes, dirt pockets, concrete etc) - you will no doubt see shorter life in your blades.
In addition, if you are resawing exotic timbers with high silica contents or very dense and hard timbers like Lignum Vitae, Desert Ironwood, or Australian Dead Finish, your blades life expectancy will be quite short, measured in a scant few minutes, or perhaps a few hours.
My sharpening protocol is quite simple and does not require a lot of time or effort. Most turners just replace the blades when they become dull. However, in a production environment, the frequent replacement of dull blades can be quite expensive.
Without sharpening my dull blades, I would use approximately 125 blades per year. At an average cost of $25.00 per blade for my 150" bands, that amounts to $3,125.00 per year - just for bandsaw blades. By sharpening the blades when they become dull instead of replacing them, I can get 15-20 additional sharpenings out of each blade. This represents a significant savings versus using a new blade every time one becomes dull.
Searching for the Answer
When I first started turning full time, I soon learned that I could dull a new bandsaw blade very quickly. Cutting wet timber and species with a high silica content (especially with the bark still attached) dulls the blade in very short order. In addition, the wet extractives from some timbers can be very destructive on a sharpened steel surface. I looked at having the blades sharpened professionally, but the cost was nearly the same as a replacement blade and required driving 45 miles one way to the sharpening shop. Not a desirable solution by any measure.
Therefore, I began to investigate ways to sharpen the blades myself. Every way I discovered required too much time, equipment, effort, or money. I wanted to find something that was fast and easy, requiring no significant monetary investment. Most of the professional sharpening shops just laughed when I said I wanted to sharpen the blade...on the saw! I think one chap is still laughing and rolling around on the floor.
Problem Solved
There is not too much room to work under the bandsaw guides and I wanted something that was quick, small, lightweight and reasonably accurate. After crashing and burning with the professional sharpening shops, I had just about given up. A few days later, I lucked into several truckloads of White Ash, Pecan and Winged Elm.
However, I only had one blade left that was still sharp and I knew it would not last long with Texas Pecan, which I affectionately refer to as -Pecan-Crete- because it seems as hard as concrete when it is dry. However, I had six blades left that were too dull to use. Yes, I could have just bought some new blades, but being born in the Chinese 'Year of the Rat' made me want to stretch a little more life out of the dull ones.
I began to scan every tool I had in the studio, looking for ideas to sharpen the blade. Then it hit me... the Dremel Moto-Tool! Its small size and lightweight, high RPM motor was just what I needed.
At first I tried to use the flat abrasive stones, which worked well, but did not last very long. Then, I tried the thin abrasive cut-off wheels and my problems were solved. They are quite durable and maintain their flat face well after repeated sharpenings.
Sharpening the Blades on the Bandsaw
First, unplug the saw and put on a full-face safety shield or safety glasses. In addition, wear an appropriate respirator or dust mask to handle any of the abrasive/metal dust that is generated. Then, set up a good strong light (100 watt) that illuminates the bandsaw blade clearly. (I use an adjustable height stool to sit on that allows me to have my eyes inline with the cutting 'zone.')
Next, whilst wearing gloves, fully rotate the blade and check for stress cracks, or other damage to the blade. If anything shows up, throw the blade out. I only sharpen blades that are free of defects for safety reasons. Some chaps weld broken blades, but I do not.
Next, mount a thin abrasive cut-off disk onto the appropriate mandrel and chuck it into the Moto-tool collet. Sharpen the blade on the bandsaw; with the tension set just enough to keep the blade straight, whilst you rotate it with your gloved free hand.
With your left hand, advance the blade down by hand as each tooth is sharpened (or vice versa if you are left handed). Use your right hand to hold and control the Moto-tool, which is set to the lowest speed (10,000 rpm). As each tooth is sharpened, rotate the blade down a bit to bring the next tooth into position.
The teeth on the blades are set in a particular way, depending on the type of blade and its intended usage. Some teeth are straight inline with the body of the blade; others curve right, or left. As you sharpen each tooth, rotate the flat face of the abrasive disk so it matches the direction and curvature of the next tooth.
Touch the flat part of the wheel lightly to the top of each tooth, and gently arc the wheel down along the top of each tooth, making sure the contact sharpens all the way to the end of the tooth. Repeat the process for each tooth, making sure that the wheel contacts and follows the top of the tooth correctly (this is very important). You want the sharpened surface to feather into the original shape of the tooth.
It sounds more complicated than it is in practice, but if you follow this rule, the blade will stay sharp longer and give more clean and accurate cuts, close to the original factory sharpening. I should mention that I use this sharpening protocol primarily with 3-TPI blades.
Finer blades can be sharpened, but are more time consuming and require progressively smaller abrasive wheels to accommodate the smaller clearances required to sharpen each tooth. As I rarely use anything other than the 3 TPI bands, I limit my sharpening efforts to these bands.
Since the sharpening process creates a brightly polished surface on the top on each tooth, it is easy to tell where you started and thus, where you need to stop when you have completed sharpening the entire blade. My 18" ACM bandsaw blades require a 150" long blade and it takes me approximately three to five minutes or so to complete the sharpening process on a 3 TPI blade.
Obviously, my sharpened blades are not as good as new, or even professionally sharpened blades. However, they are sharp afterwards and allow me to continue cutting with a minimum of downtime and expense. I can usually get about 8-10 sharpenings per blade, although on occasion, I have gotten as little as six.
Note: Check the abrasive disk after it has been used to sharpen 10 times and replace as necessary. If you are using small diamond disks to sharpen the blade, the life of the diamond disk will be significantly longer than the abrasive disks.
Abrasive or Diamond Disks?
Although my original sharpening protocol uses abrasive cut-off disks in the Dremel tool, you can also use small diamond disks to sharpen the blades. Diamond disks actually produce a higher quality sharpened surface because you have more choice over the abrasive grit range with diamonds.
If you prefer to use the diamond disks, choose fine or very fine grit wheels for the best quality sharpened surface. With either the abrasive or diamond disk wheels, use a very light touch when sharpening the teeth. It's quite easy to remove too much metal, reducing the overall life and cut quality of each blade.
Sharpening the Top of each Tooth vs. the Entire Tooth
For a more thorough sharpening, you can elect to sharpen the entire tooth, instead of just the top portion only. Since most of my bandsaw work is gross resaw work, sharpening only the top portion of each tooth is faster than sharpening the entire tooth, which requires two separate operations.
To sharpen the entire tooth, a supplemental sharpening protocol and abrasive attachment is required. Round abrasive or diamond stones can be used to sharpen the underside of each tooth. Long thin stones that are very close to the gullet size of the underside of each tooth work best.
The underside of each tooth is sharpened much the same way as the top portion, using a very light touch. Gently raise the stone under each tooth to sharpen the underside area of each tooth. If you have the capability to reduce your rotary tool to 5,000 rpm's, a slower speed will make the tool and the stone easier to control, especially when sharpening the underside portion of the tooth.
When sharpening the underside portion of the tooth, take care to keep good control of the tool. The rotation of the stone coupled with the curvature of the underside of the tooth can make to stone 'race' along the curvature of the tooth. Use a firm grip to control the movement of the stone under the tooth. This is easier than it sounds, but does require a bit of extra care.
Closing Thoughts
It does take a bit of practice to get good at using this sharpening protocol, but when you do, it can save you a lot of time and money. Some may argue that it's easier to just buy a new blade, but if your blade goes dull on a holiday weekend and you've got a few bowl blanks to process, you'll appreciate being able to complete your projects with a minimum of fuss and downtime. Give it a try and see for yourself!
Better Woodturning and Finishing Through Chemistry...
Steven D. Russell
Eurowood Werks Woodturning Studio
The Woodlands, Texas
============================================
A couple of other posts from my notes:
-----------------
This subject comes up on the turning forum all the time, for just the same reason - nails/metal buried in the wood.
To get a serviceable resharpening yourself, put a metal cutting disk on your Dremel Tool, and lightly touch the "Bottom" edge of the tip of the tooth with the flat of the cutting disk. This is the edge that is facing you when the blade is mounted. Just a light touch is all that is needed. You will only see a couple of sparks, but this is enough. You certainly would not want to do this on a 10-14 TPI blade, but from your discription of what you were doing, I assume that this is a 3-4 TPI blade. I do this on most all my blades and get very good - nearly new - results, and can do it 5-6 times per blade. Only takes a few minutes, less time than it take to walk from the shop and call Timberwolf or Highland Hardware.
Mark-
-----------------
i resharpen the same way that mark does.can sharpen a 3 tooth 105 inch blad as quickly as changing one ...bob davis
-----------------
BONUS: Steven Russell's web site is full of great stuff. Here is his page on woodturning tips:
http://www.woodturningvideosplus.com/woodturning-tips.html
JKJ
Steven Russell is an expert in many things including woodturning.
I found this in my notes from 2006 after experimenting with sharpening bandsaw blades myself.
Steven wrote this in 2002, posted in 2003 on another forum; it helped me "hone" my sharpening method.
============================================
How To Easily Resharpen Dull Bandsaw Blades
Steven D. Russell -- Friday, 27 June 2003, at 8:26 a.m.
Resharpening Bandsaw Blades
I save significant amounts of money every year in my production woodturning studio by sharpening dull bandsaw blades quickly and efficiently using my "On the Bandsaw" sharpening protocol. This protocol works equally well with standard steel bandsaw blades as well as the higher quality silicon steel blades. It can be adapted for use on carbide tipped bands quite easily.
For the bulk of my studio's bandsaw work, I prefer to use high quality silicon steel blades. These blades last longer initially (as well as after being sharpened) than many of the less expensive steel blades I have used in the past. Even using high quality bandsaw blades, I can dull a new blade in two hours or less. My record for dulling a brand new band is 30 seconds, resawing Australian Dead Finish.
Typically, I will get a couple of days out of a new blade before it needs to be resharpened. With careful sharpening, I can usually sharpen each band approximately 8-10 times using abrasive cut-off wheels and 15-20 times with fine diamond wheels, before they're pitched into the rubbish bin.
The best cutting performance is achieved with the second through fifth sharpenings (abrasive wheel) and second through tenth with the diamond wheel; the sixth and later sharpenings are very dependent on the accuracy of the earlier sharpenings.
The cutting performance will degrade slightly with each sharpening, but the sharpened blade will still cut and track easily through the wood, wet or dry, if the sharpening was done with care. I should mention that this protocol will not duplicate a new factory sharpened edge quality. Nor can you duplicate a professional sharpening by using this protocol.
However, the sharpened blade will work very well for rough cuts and non-critical cutting such as gross resaw work, making turning squares, corner removal on bowl blanks, dimensional cutting, etc. I would not try to make paper-thin veneer with one of my resharpened blades, but for most of the work a woodturner demands of their bandsaw, it would be appropriate.
Why Sharpen Blades?
If you are an occasional or hobby turner cutting clean dry wood, you will no doubt get a few months or more out of your blade before it becomes dull. However, if you are using your bandsaw daily in a production environment - resawing, making bowl blanks, turning squares, pen blanks and cutting through lots of bark and buried 'goodies' typically found in yard wood (like bullets, rocks, wire fencing, horseshoes, dirt pockets, concrete etc) - you will no doubt see shorter life in your blades.
In addition, if you are resawing exotic timbers with high silica contents or very dense and hard timbers like Lignum Vitae, Desert Ironwood, or Australian Dead Finish, your blades life expectancy will be quite short, measured in a scant few minutes, or perhaps a few hours.
My sharpening protocol is quite simple and does not require a lot of time or effort. Most turners just replace the blades when they become dull. However, in a production environment, the frequent replacement of dull blades can be quite expensive.
Without sharpening my dull blades, I would use approximately 125 blades per year. At an average cost of $25.00 per blade for my 150" bands, that amounts to $3,125.00 per year - just for bandsaw blades. By sharpening the blades when they become dull instead of replacing them, I can get 15-20 additional sharpenings out of each blade. This represents a significant savings versus using a new blade every time one becomes dull.
Searching for the Answer
When I first started turning full time, I soon learned that I could dull a new bandsaw blade very quickly. Cutting wet timber and species with a high silica content (especially with the bark still attached) dulls the blade in very short order. In addition, the wet extractives from some timbers can be very destructive on a sharpened steel surface. I looked at having the blades sharpened professionally, but the cost was nearly the same as a replacement blade and required driving 45 miles one way to the sharpening shop. Not a desirable solution by any measure.
Therefore, I began to investigate ways to sharpen the blades myself. Every way I discovered required too much time, equipment, effort, or money. I wanted to find something that was fast and easy, requiring no significant monetary investment. Most of the professional sharpening shops just laughed when I said I wanted to sharpen the blade...on the saw! I think one chap is still laughing and rolling around on the floor.
Problem Solved
There is not too much room to work under the bandsaw guides and I wanted something that was quick, small, lightweight and reasonably accurate. After crashing and burning with the professional sharpening shops, I had just about given up. A few days later, I lucked into several truckloads of White Ash, Pecan and Winged Elm.
However, I only had one blade left that was still sharp and I knew it would not last long with Texas Pecan, which I affectionately refer to as -Pecan-Crete- because it seems as hard as concrete when it is dry. However, I had six blades left that were too dull to use. Yes, I could have just bought some new blades, but being born in the Chinese 'Year of the Rat' made me want to stretch a little more life out of the dull ones.
I began to scan every tool I had in the studio, looking for ideas to sharpen the blade. Then it hit me... the Dremel Moto-Tool! Its small size and lightweight, high RPM motor was just what I needed.
At first I tried to use the flat abrasive stones, which worked well, but did not last very long. Then, I tried the thin abrasive cut-off wheels and my problems were solved. They are quite durable and maintain their flat face well after repeated sharpenings.
Sharpening the Blades on the Bandsaw
First, unplug the saw and put on a full-face safety shield or safety glasses. In addition, wear an appropriate respirator or dust mask to handle any of the abrasive/metal dust that is generated. Then, set up a good strong light (100 watt) that illuminates the bandsaw blade clearly. (I use an adjustable height stool to sit on that allows me to have my eyes inline with the cutting 'zone.')
Next, whilst wearing gloves, fully rotate the blade and check for stress cracks, or other damage to the blade. If anything shows up, throw the blade out. I only sharpen blades that are free of defects for safety reasons. Some chaps weld broken blades, but I do not.
Next, mount a thin abrasive cut-off disk onto the appropriate mandrel and chuck it into the Moto-tool collet. Sharpen the blade on the bandsaw; with the tension set just enough to keep the blade straight, whilst you rotate it with your gloved free hand.
With your left hand, advance the blade down by hand as each tooth is sharpened (or vice versa if you are left handed). Use your right hand to hold and control the Moto-tool, which is set to the lowest speed (10,000 rpm). As each tooth is sharpened, rotate the blade down a bit to bring the next tooth into position.
The teeth on the blades are set in a particular way, depending on the type of blade and its intended usage. Some teeth are straight inline with the body of the blade; others curve right, or left. As you sharpen each tooth, rotate the flat face of the abrasive disk so it matches the direction and curvature of the next tooth.
Touch the flat part of the wheel lightly to the top of each tooth, and gently arc the wheel down along the top of each tooth, making sure the contact sharpens all the way to the end of the tooth. Repeat the process for each tooth, making sure that the wheel contacts and follows the top of the tooth correctly (this is very important). You want the sharpened surface to feather into the original shape of the tooth.
It sounds more complicated than it is in practice, but if you follow this rule, the blade will stay sharp longer and give more clean and accurate cuts, close to the original factory sharpening. I should mention that I use this sharpening protocol primarily with 3-TPI blades.
Finer blades can be sharpened, but are more time consuming and require progressively smaller abrasive wheels to accommodate the smaller clearances required to sharpen each tooth. As I rarely use anything other than the 3 TPI bands, I limit my sharpening efforts to these bands.
Since the sharpening process creates a brightly polished surface on the top on each tooth, it is easy to tell where you started and thus, where you need to stop when you have completed sharpening the entire blade. My 18" ACM bandsaw blades require a 150" long blade and it takes me approximately three to five minutes or so to complete the sharpening process on a 3 TPI blade.
Obviously, my sharpened blades are not as good as new, or even professionally sharpened blades. However, they are sharp afterwards and allow me to continue cutting with a minimum of downtime and expense. I can usually get about 8-10 sharpenings per blade, although on occasion, I have gotten as little as six.
Note: Check the abrasive disk after it has been used to sharpen 10 times and replace as necessary. If you are using small diamond disks to sharpen the blade, the life of the diamond disk will be significantly longer than the abrasive disks.
Abrasive or Diamond Disks?
Although my original sharpening protocol uses abrasive cut-off disks in the Dremel tool, you can also use small diamond disks to sharpen the blades. Diamond disks actually produce a higher quality sharpened surface because you have more choice over the abrasive grit range with diamonds.
If you prefer to use the diamond disks, choose fine or very fine grit wheels for the best quality sharpened surface. With either the abrasive or diamond disk wheels, use a very light touch when sharpening the teeth. It's quite easy to remove too much metal, reducing the overall life and cut quality of each blade.
Sharpening the Top of each Tooth vs. the Entire Tooth
For a more thorough sharpening, you can elect to sharpen the entire tooth, instead of just the top portion only. Since most of my bandsaw work is gross resaw work, sharpening only the top portion of each tooth is faster than sharpening the entire tooth, which requires two separate operations.
To sharpen the entire tooth, a supplemental sharpening protocol and abrasive attachment is required. Round abrasive or diamond stones can be used to sharpen the underside of each tooth. Long thin stones that are very close to the gullet size of the underside of each tooth work best.
The underside of each tooth is sharpened much the same way as the top portion, using a very light touch. Gently raise the stone under each tooth to sharpen the underside area of each tooth. If you have the capability to reduce your rotary tool to 5,000 rpm's, a slower speed will make the tool and the stone easier to control, especially when sharpening the underside portion of the tooth.
When sharpening the underside portion of the tooth, take care to keep good control of the tool. The rotation of the stone coupled with the curvature of the underside of the tooth can make to stone 'race' along the curvature of the tooth. Use a firm grip to control the movement of the stone under the tooth. This is easier than it sounds, but does require a bit of extra care.
Closing Thoughts
It does take a bit of practice to get good at using this sharpening protocol, but when you do, it can save you a lot of time and money. Some may argue that it's easier to just buy a new blade, but if your blade goes dull on a holiday weekend and you've got a few bowl blanks to process, you'll appreciate being able to complete your projects with a minimum of fuss and downtime. Give it a try and see for yourself!
Better Woodturning and Finishing Through Chemistry...
Steven D. Russell
Eurowood Werks Woodturning Studio
The Woodlands, Texas
============================================
A couple of other posts from my notes:
-----------------
This subject comes up on the turning forum all the time, for just the same reason - nails/metal buried in the wood.
To get a serviceable resharpening yourself, put a metal cutting disk on your Dremel Tool, and lightly touch the "Bottom" edge of the tip of the tooth with the flat of the cutting disk. This is the edge that is facing you when the blade is mounted. Just a light touch is all that is needed. You will only see a couple of sparks, but this is enough. You certainly would not want to do this on a 10-14 TPI blade, but from your discription of what you were doing, I assume that this is a 3-4 TPI blade. I do this on most all my blades and get very good - nearly new - results, and can do it 5-6 times per blade. Only takes a few minutes, less time than it take to walk from the shop and call Timberwolf or Highland Hardware.
Mark-
-----------------
i resharpen the same way that mark does.can sharpen a 3 tooth 105 inch blad as quickly as changing one ...bob davis
-----------------
BONUS: Steven Russell's web site is full of great stuff. Here is his page on woodturning tips:
http://www.woodturningvideosplus.com/woodturning-tips.html
JKJ