I finally managed to wear out a grindstone, from the original diameter of 250 mm to 190 mm. I learned a couple things installing the replacement.
First, the old grindstone barely submerges its edge in the water, but of course a new one submerges a lot further. I realized that I don't need to put as much water in the trough with the new grindstone, which reduces the chances of spilling.
Second, I'll keep the old grindstone for sharpening wide blades like cleavers and mower blades. This is an alternative to a custom made universal support with longer legs.
Interesting post, Herman. I think of a worn Tormek like a bank balance after completing some form of education; the wallet is lean, but the mind is enriched. A worn Tormek grinding wheel is a mark of honor, a "red badge of courage".
You have also discovered the real reason a Tormek grinding wheel might be considered "worn out". The diameter has become too small to reach the water level, when the water trough is mounted in the normal manner. The water trough in the T8 corrects this by being able to be raised or lowered. I think the same thing could be done by placing shims under the water trough. At 170mm, the wheel still cuts. the hollow grind amound is still less than the garden variety 150mm (6") dry grinding wheel.
When the idea of replacing a worn out SG-250 with a new SB-250 comes up, my thought is to stop using the SG-250 when it is an SG-200 and has more life left.
I like your idea of using your SG-170 for cleavers. Lowering the grinding wheel would have the same effect as raising the support bar.
Keep up the good work!
Ken
Quote from: Ken S on June 12, 2017, 09:11:39 PM
I like your idea of using your SG-170 for cleavers. Lowering the grinding wheel would have the same effect as raising the support bar.
Thanks. I don't recall this notion having been brought up before, and I wanted to document it.
Quote from: Ken S on June 12, 2017, 09:11:39 PMYou have also discovered the real reason a Tormek grinding wheel might be considered "worn out". The diameter has become too small to reach the water level, when the water trough is mounted in the normal manner. The water trough in the T8 corrects this by being able to be raised or lowered. I think the same thing could be done by placing shims under the water trough. At 170mm, the wheel still cuts. the hollow grind amound is still less than the garden variety 150mm (6") dry grinding wheel.
When using a grindstone that small, other problems arise. The honing wheel becomes an obstruction and must be removed. Other parts of the machine also become an obstruction. I think it's better to replace with a new one when the diameter gets that small and save the old one for cleavers and mower blades and the like. It's always nice to have a back up in case it's needed.
Excellent thought, Herman. We need to get past the notion of using up the last bit of grit on the wheel and order the replacement while there is plenty of life left in the grinding wheel for rough work.
This topic reminds me of something from my student days. I saw a photo of a Mussolini's Mother's Medal. The basic medal was round with hanging bars beneath, one for each baby. This particular woman had nine bars! It would be tacky, however, we could have a similar medal for Tormek grinding wheels. :-\
Ken
One other issue is keeping the stone wet. Pumps have been discussed on here before, but how do you keep the sediment out of them, so they don't get ruined?
I could see, placing a sponge, or some other removable object in the water tray, that would give some support, for say another water tray. (fill, place on top of sponge, push down to put wheel on, then start so it gets wet)
Long stuff, would make me want an old Tormek, pre drive wheel (drill turned a different way allows longer objects). But I doubt cleavers would be that much of an issue.
To quote the Car Talk guys, "The stingy man pays the most". After a certain point, I think the logical long run choice is to just bite the bullet and order an extended support from Robin and a new grinding wheel. You will only cry once, however your cleavers and long knives will be very sharp for a very long time. :)
Ken
Quote from: Ken S on June 15, 2017, 08:09:33 PM
To quote the Car Talk guys, "The stingy man pays the most". After a certain point, I think the logical long run choice is to just bite the bullet and order an extended support from Robin and a new grinding wheel. You will only cry once, however your cleavers and long knives will be very sharp for a very long time. :)
Ken
My view, is I prefer the extended support, but I come from a use up what you have, and try to prove it works for you and your payback rate, and then buy when the money isn't an issue, kind of guy.
SADW,
I understand your thinking. The expression has a different meaning up north, however, I think "Yankee thrift" applies. (My mother's family were all New Englanders, and thrifty.)
Please note that my recommendation is to purchase the new grinding wheel while there is still useful life in the worn stone. A worn stone with enough remaining diameter can be a very useful tool for a long time. I do not advocate discarding a stone with useful life remaining.
Ken
Quote from: Ken S on June 16, 2017, 05:05:47 AM
Please note that my recommendation is to purchase the new grinding wheel while there is still useful life in the worn stone. A worn stone with enough remaining diameter can be a very useful tool for a long time. I do not advocate discarding a stone with useful life remaining.
Even when the old grindstone is officially worn out (190 mm diameter, I think) and is a pain to use for most purposes, it can still be used for things like cleavers and lawn mower blades that are so wide the Universal Support rods are not long enough. You do have to remove the honing wheel. Which is something you sometimes have to do anyway and so it's designed for easy removal.
With the EzyLock it's no problem to switch between grindstones.
I'm not a professional sharpener and I'm not a professional wood worker, so it's hard for me to justify purchases like the extended universal support. I use my Tormek to keep my knives and tools sharp, and at some point extra purchases just can't be justified. What I have now can be used to keep them all sharp.
Herman,
I completely understand. Honestly, the main reason I ordered the extended support was to support another forum member's efforts. That stated, I have found it useful in several ways.
As far as thrift, while I am more relaxed with Tormek expenses, I am the guy who as a student spent a day walking around in the rain (with no umbrella) looking for the best price on an umbrella. :)
Ken
Quote from: Ken S on June 18, 2017, 12:04:07 AM
As far as thrift, while I am more relaxed with Tormek expenses, I am the guy who as a student spent a day walking around in the rain (with no umbrella) looking for the best price on an umbrella. :)
Ken
I understand. I have a couple of favorite sayings or maybe there are more than a couple. One was taught to me years ago and has only lately born fruit. "First loss is least loss", it was told to me by a Jewish lady so I will attribute it to Judaism. It means, if you have to sell at a loss, the first markdown is the least mark down. In other words, think about it and assess your first offer and see if you can live with it and then TRY to live with it. It may be the least markdown. What does this sage advice have to do with this conversation? Hmmm, I do not know. Oh yeah, use the old grindstone for a paperweight.
Ken, there is a contributor on YouTube that I like and he brought to market a measuring tape and I bought two just to support him. I needed them like a hole in the head but I bought them anyway. They are actually useful but I had enough measuring tapes already. I am getting soft in my old age.
Jeff,
Perhaps we are going soft in our old age. :)
Sooner or later, those of us who use our Tormeks will need to purchase new grindstones. The question is not whether or not to purchase a new grindstone; the question is when. Since we can use worn grindstones for some necessary functions, "amount of use" is not a factor. A worn grindstone will give the same hours or miles of use whether it is the only grindstone or as a relief pitcher for rough work.
What will be a factor is the amount of hollow grind from a new grinding wheel versus a worn grinding wheel.
In my case, I sharpen one Chinese cleaver. I am both sharpener and customer. The two logical choices (costwise) are using waterstones or freehand on the Tormek.
Someone regularly sharpening professionally should have enough volume not to be concerned about the cost of an extended support or a new grinding wheel if needed. It is just part of the cost of doing business. If your business can not absorb these costs, either you are not sharpening enough cleavers to make it worth your while or you are not charging enough.
I plan to remove my grinding wheels from active service once they wear to 200mm. At that point, they still have plenty of life remaining, which I fully intend to use, They just won't be my everyday wheels.
I remember the water pump suggestion. I would just put my money toward a new grinding wheel and march on.
Steve uses eight worn grinding wheels (4 pairs) as weights to keep his farmers market table stable on windy days. I'm impressed!
Ken
Even when the old grindstone is officially worn out (190 mm diameter, I think) and is a pain to use for most purposes, it can still be used for things like cleavers and lawn mower blades that are so wide the Universal Support rods are not long enough.
This brings up the ad nauseum subject of the T4. The stone starts at 200 mm and you would junk it 10 mm later.
I believe that I saw Ken S say the same thing here:
When the idea of replacing a worn out SG-250 with a new SB-250 comes up, my thought is to stop using the SG-250 when it is an SG-200 and has more life left.
I could be wrong but as he is so much a proponent of the T4, I do not think so. Fine, the T4 is infinitely lighter and more manageable than the T7/T8 but if you are going to obsolete T4 stones after 10mm, where is the cost effectiveness? Ken, what do you say?
Jeff,
The answer came up in dinner conversation with my friend from Sweden. He would just say, "You're wrong".
You deserve a more complete answer. I understand your thinking in this matter. It is based on a very correct statement by a real deal Tormek guru, Jeff Farris, who also founded and moderated this forum. At the time of the question, "the Tormek" in the US meant only the larger, 250mm SuperGrind or T7. The issue was that after a certain point of wear, the wheel became too small in diameter to reach the water in the trough. Trying to use it further would involve some fancy and not very productive footwork reconfiguring the water trough or introducing another water source. It could be done, however, it just is not practical. The logical, easy solution is just to replace the grinding wheel.
While the water is the main issue, there are other concerns. As the grinding wheel wears, clearance starts to become more difficult. Tricks like removing the leather honing wheel for more clearance with long tools help, but the work no longer flows as easily.
As the wheel wears, the hollow grind effect increases. In itself, this is not a problem. It does look different, and may not be the desired edge. That is a debate fir other days.
The lift on the new T8 raises the water level, thus extending the useful life of the grinding wheel. The lift feature also has the benefit of easily lowering the water to keep the wheel out of the water during work breaks. NOTE:It is still good practice to dump and clean the water trough after sharpening sessions.
The T4 and earlier models this size are designed around a 200mm diameter grinding wheel ( the SG 200 instead of the SG 250). The water trough is smaller and rides closer to the wheel axis. The amount of wear possible is similar, but not equal to the T7. However, a replacement SG 200 costs $104 US versus $184 for the SG 250. At a practical level, there is no cost advantage with the larger grinding wheel.
It would be possible for Tormek to design a 150mm or even smaller series. Like the highly collectable diminutive Stanley Number 1 bench plane, a miniature Tormek would be cute, and might have some uses. The 200 mm size offers a good balance. It is noticeably lighter to carry than its larger brother, yet still large enough to be a work horse. Most home shop grinders use six inch (150mm) dry grinding wheels, which eventually weaar to become five inch wheels. They are also about half the width of the SG 200.
I have never advocated for the T4 based on lower cost than the T7 or T8. When comparing "apples for apples", in this case including the TT-50 truing tool and the SE-76 square edge jig with the T4, IMHO, the cost difference is negligible. I feel the cost difference, which is the real issue, between the wear and replacement cost if the SG200 and SG 250 is also negligible. For me, the real difference is portability. If the Tormek is stationary, either is fine. In a more mobile situation, especially for older users, the T4, at half the weight, is my hands down favorite.
T4, T7, T8, or a vintage SuperGrind? There is no bad choice, just some of the options may be better suited to one's needs.
Ken
Quote from: jeffs55 on June 28, 2017, 05:37:56 AM
Even when the old grindstone is officially worn out (190 mm diameter, I think) and is a pain to use for most purposes, it can still be used for things like cleavers and lawn mower blades that are so wide the Universal Support rods are not long enough.
This brings up the ad nauseum subject of the T4. The stone starts at 200 mm and you would junk it 10 mm later.
No. My comment about the 190 mm diameter applies to the T7/T8, not the T3/T4.
As Ken points out, the T4 has a smaller frame and water trough, as it's designed to work with grindstones that have a diameter of 200 mm or less, down to something far less than 190 mm.
And by the way, when you replace that 190 mm grindstone you might do the math and think that because 190/250 equals 76% you're discarding 76% of what you paid for. But since the area of the circular grindstone is proportional to its diameter, you're actually only discarding (0.76)² or about 58%. Still a bothersome amount, which is why we're so tempted to find uses for those old grindstones.
Good thoughts, Herman. It's handy having a resident physicist!
Ken
A while ago, I asked about using worn T7/T8 wheels on the T4. What I found is that the 250mm wheel is wider than the 200mm (T4) wheel. Bummer.
Rich,
If you buy a T8, the lifting water trough will allow you to get more life out of your grinding wheel. :)
Ken
Quote from: Herman Trivilino on June 28, 2017, 07:32:19 PM
Quote from: jeffs55 on June 28, 2017, 05:37:56 AM
Even when the old grindstone is officially worn out (190 mm diameter, I think) and is a pain to use for most purposes, it can still be used for things like cleavers and lawn mower blades that are so wide the Universal Support rods are not long enough.
This brings up the ad nauseum subject of the T4. The stone starts at 200 mm and you would junk it 10 mm later.
No. My comment about the 190 mm diameter applies to the T7/T8, not the T3/T4.
As Ken points out, the T4 has a smaller frame and water trough, as it's designed to work with grindstones that have a diameter of 200 mm or less, down to something far less than 190 mm.
And by the way, when you replace that 190 mm grindstone you might do the math and think that because 190/250 equals 76% you're discarding 76% of what you paid for. But since the area of the circular grindstone is proportional to its diameter, you're actually only discarding (0.76)² or about 58%. Still a bothersome amount, which is why we're so tempted to find uses for those old grindstones.
Great reply, Herman.
I contacted support asking about the wear limit of the SG-200, the T4 grinding wheel. The answer is practical rather than numeric.
"As long as it runs in water you can use it".
Comparing a grinding wheel with another round object which wears slowly and is discarded before being fully cunsumed, is anyone driving on bald tires?
The first experiment I did using the Norton 3X wheels on my Tormek was with the not quite six inch (150mm) wheel I removed from my dry grinder. I had purchased the 46 grit wheel to grind away extensive mushrooming on two wood spliting wedges for a friend. The Tormek could handle very regular of just starting mushrooming; this mushrooming was the result of looking the other way for a very long time. A mushroomed head on a struck tool like a cold chisel is a safety issue due to the possibility of breaking off and causing injury.
I had thought of using 3X wheels on the Tormek ever since reading a one time post by a member who put his dry grinding wheel on his Tormek. He stated that it removed a lot of metal, and then he dropped out of sight. He used "a cheap Delta wheel". I thought, why not try a good 3X wheel?
The six inch wheel was just too small for the T7. The situation changed when I added a T4. I added some paper shim to reduce the half inch bore to twelve millimeter. I tried grinding a quarter inch bolt and was impressed with the amount of metal quickly removed. The six inch wheel is usable in the T8, but not ideal. I purchased eight inch 3X wheels in both 46 and 80 grits. Both work very well wet with the Tormek. Converting the bore diameter required drilling out a piece of plastic pipe. The 3X wheel removes metal much more quickly than the blackstone. When the 3X wheels finally become too small to "run in water"with the T4, I will return them to dry grinder duty with my dix inch grinder, thus lowering the wasted percentage. (Either the 46 or 80 grit is sufficient; there is no need for both. At either $40 or $50 US, a 3X wheel brings a lot of grinding fire power to the Tormek for a small investment. This is a very workable low cost solution for the woodturner who occasionally reshapes a turning tool.
In my case, I would start looking for nearby woodworking shows when my grinding wheel was appriaching 210mm. When the Tormek is being demonstrated at shows, one can often purchase jigs and accessories at an unadvertised 20% discount. The discount would sweeten the lost percentage. At 200mm, I would start using the new wheel, reserving the worn wheel for rougher projects. At 200mm, it has much useful life remaining, and would extend the useful life of the new wheel.
Ken
"As long as it runs in water you can use it".
That is actually the best answer that could be given. Brilliantly simple and totally accurate. If you could rig a raised water trough you could keep on using it until the curvature of the stone was so acute that it makes the edge of your tool too weak to be practical. Good job Ken.
Thanks, Jeff.
I agree about the simplicity and accuracy of the comment. The thanks go to Stig and his support team.
Ken
Quote from: jeffs55 on June 29, 2017, 02:44:07 PM
"As long as it runs in water you can use it".
That is actually the best answer that could be given. Brilliantly simple and totally accurate. If you could rig a raised water trough you could keep on using it until the curvature of the stone was so acute that it makes the edge of your tool too weak to be practical. Good job Ken.
I've already got an easy (for me) way around that, when I get to that point. My house still has one of the old metal laundry/soaking tubs, used back in the days with a washboard. (drain hose hangs up top)
Presoak the wheel, then turn on the faucet over the wheel on a dribble and then drain into a pickle bucket for taking outside.
The machine will sit above the tub, so no electricity/water meeting. I also plan that I will only use this for rough chip removal, to make the replacement stone last longer.
I have a LONG time to go to get to that point, and buy that time, I may no longer watch for and refurbish old tools, if I already have them.
I just would still prefer that, to a higher speed grinder and the heat involved.
Quote from: Ken S on June 29, 2017, 11:07:22 AM
I contacted support asking about the wear limit of the SG-200, the T4 grinding wheel. The answer is practical rather than numeric.
"As long as it runs in water you can use it".
Interesting. My SuperGrind 2000 (predecessor to the T7) has a sticker on the side with a scale that allows me to easily read the grindstone diameter. The largest number on the scale is 250 mm and the smallest is 190 mm. Is there no such scale on the T4?
Good question, Herman. Yes, the T 4 has such a scale with a range from 200mm to 165mm. The T7 has the same range as your SuperGrind. No surprise. The scale on the T8 has a range from 250mm to 180 mm. The lower limit is no doubt due to the adjustable water trough.
Let's approach this from a different view point. Herman, may we use you as our reference person? Looking back at your history with your grinding wheel and making your best guess for the future, how many more grinding wheels to you estimate you will wear out?
Do you anticipate doing much of the grinding which caused the most wear on your grinding wheel?
I have a similar question with my car, a 2011 Equinox with just under 100,000 miles. My mechanic tells me the brakes still have some life left in them. (I'm getting nervous, however, I am not a mechanic.) In the past, I have kept vehicles too long, and ended up paying too much in repair costs. I plan to keep the car for another two to three years before we downsize to one vehicle. I anticipate replacing the brakes one time. my question is do I replace them very soon and enjoy the benefit of new brakes or drive those miles with well worn brakes?
With a Tormek wheel, whether or not one squeezes the last micron out of the the grinding wheel, it will eventually need to be replaced. Do we want to use a new wheel, with the benefit of a larger diameter or a gallant attempt to capture a few more percent?
My gut feeling is that many of our individual answers lie somewhere in the middle. I welcome other thoughts.
Ken
Well, Ken, I suspect my new grindstone will last about 7 or 8 years. I hope to last at least that long, myself. Hopefully much longer. So, maybe 2 or 3 more if I'm lucky.
Reminds me of my uncle. He wanted to replace a blown out light bulb in his vehicle. At the parts store they sold them in packs of two. He told the youngster behind the counter that he needed only one and didn't want to pay for two. He was told that's the only way they sell them, and that he could just hang on to the extra because he was bound to need it sometime soon. My uncle told him that he didn't suspect he'd be around long enough to be able to use the extra!
Another good post, Herman. The story about your uncle gave me a good chuckle. My kind of guy. :)
Ken
I liked that story, I worked with a guy who lost the lower portion of his leg to a land
mine in Vietnam. When the plant implemented safety shoes, he insisted he only should have to buy 1 since it didn't matter what happened to the foot he already lost, he could just put a new one on. The plant safety guy finally convinced him to buy a pair of steel toe cowboy type boots. On the second day of wearing the new boots he came in and requested medical leave to get his leg repaired down in St. Louis. Apparently he tried to take his boots off when he got home and ripped the foot off of his artificial leg not thinking that you have to be able to bend your ankle to put cowboy boots on or off. And he obviously has no control over what the joint in his artificial leg does.
The plant safety guy got harassed about that until the day he retired.
Does a SG250 for a T8 that is worn below 200
work like a new stone on a T4
The stone for the T8 is wider, so if you are thinking about using your worn out T8 stones on a T4, it will not fit.
The T4 shaft is slightly shorter than the T7-8 shaft and is made differently as well . This subject has been covered in a previous thread(s). One is:
https://forum.tormek.com/index.php?topic=2834.0
Quote from: bisonbladesharpening on July 04, 2017, 03:51:53 AM
Does a SG250 for a T8 that is worn below 200
work like a new stone on a T4
It has the same diameter but it's wider, by 50 mm, I believe. The frame on the T4 is smaller, so it's probably more tolerant.
When my T4 first arrived, I was not able to have enough time to actually sharpen with it for a while. What I was able to do was set it side by side with my T7 and do some in depth build comparison. I was initially surprised with how many parts were shared. The bolts, nuts and washers which hold the things together are essentially the same parts. The shafts have the same diameter, only the length is slightly different. The T7 uses a 250 mm diameter grinding wheel, hence the SG 250 designation. The T4 uses a 200mm diameter grinding wheel, the SG 200. The T7 wheel is 50mm thick;the T4 wheel is 40mm thick. They share a common 12 mm bore size. Incidentally, a 250mm wheel is not quite the same as a ten inch wheel, which is why some of competitors' wheels barely fit.
My first CBN wheel is eight inch by one and a half inch or 38mm. This is only slightly thinner than the SG 200. I bought it for the T4. It has a one inch bore diameter and uses a 12mm reducing bushing to fit on the Tormek. It fits nicely with no modification. To my surprise, it also fits on the T7 size Tormek just as well, again with no modification.
It is presently very early in the morning. I would wake the rest of my household if I went down to my shop to verify whether or not the T4 shaft is long enough to hold an SG 250. Even if it did, the water trough is too narrow.
I have used eight inch Norton 3X wheels and my 180 grit eight inch .CBN wheel on the T7 and T8, however, I did this only to see if it was possible. It is posdible, however, this size works more efficiently with the T4. The T4 was dedigned for this size.
The T4 could easily be modified to work with worn SG 250 wheels by a machinist. The modification would not be difficult; it would be expensive and require a custom water trough and probably a custom shaft. Such a customized T4 would cost more than a new T7 or T8, both if which include s new SG 250.
As much as the old Yankee "fix it up, make it do, make it last" is ingrained in me, I can not make sense costwise of trying to use a Tormek grinding wheel beyond its useful life. By all means, as it becomes near that point, reserve it for some work. Use it, like Steve Bottorff does with eight worn out wheels, as a weight to hold down his folding sharpening table in the wind. Use it as a counterweight with line and pulleys or as a door stop.
One of the design pluses with the Tormek is the large grinding wheel. Don't nullify this by using tiny wheels.
Ken
T4 verses T7 water trough.
So they don't have the same mounting points? You couldn't just use your T7 water trough, with a custom shaft?
Ken, on the brake subject.....
Things to consider. How is your hearing? It is one thing if you are deaf, or have hearing difficulties and can't hear your brakes squeak, it is another, if your always blasting the radio, and ignore the sounds your car makes. Not any different then listening to the grinding when using a Tormek. Change of pitch, you changed the angle.
What kind of terrain and driving. Off road, 4x4, can cause more punishment and more use of the brakes, then a hyper-miler.
SADW,
Thanks for your thoughts. I think my hearing is OK for my age. I am senditive to car noises. ( I was a troubleshooter for thirty five years with Ma Bell.) When I listen to the radio in the car (about half the time), I listen to NPR news and classical mudic. I am not a blarer.
I drive like an old guy, conservatively and mostly on secondary roads.
The T4 and T7 troughs have different mounting points. The T4 trough is smaller. I think the T4's heritage is more for a European market, with more knife work. The T7 US market is primatilt with turners.
Ken