A couple of years ago, I purchased a used T-7 system for a good price. After having a great deal of difficulty
getting the original SG-250 stone to sharpen with pressure applied, I put the machine aside. Last month, I
posted a thread here asking for advice about how to properly tighten the "cutting" stone on a T-7. After reading
the advice posted to said thread, I've decided to upgrade the T-7 system by purchasing & installing an EzyLock
MSK-250 shaft.
Along with the shaft upgrade, I'd like to order anything else necessary to bring the T-7 back to service. The T-7
will be used primarily as a sharpening system for various sized chisels. When I purchased the system, it came
with the following items: a tool rest (with micro adjust dial), a leather honing wheel, an SG-250 grinding stone
(with 210mm of diameter remaining), an SE-76 Square Edge Jig, a WM-200 AngleMaster and [what I believe
is] an SVM-140 Long Knife Jig (no number on the jig).
As I mentioned, the SG-250 was worn down to 210mm, so it was suggested (early on) to replace the original
grindstone with an SB-250 Blackstone Silicon version, which is still sitting in its Tormek box.
When I researched what comes standard with the T-7, I realized that the following items are missing from our
used system: (1) TT-50 Truing and Dressing Tool, (1) SP-650 Stone Grader and (1) PA-70 Honing Compound.
I realize that the TT-50 Truing Tool and the PA-70 Honing Compound are necessary for general operation of the
T-7 system, but one thing I'm unsure of is whether or not the SP-650 Stone Grader is used with the Blackstone
Silicon grindstone. In other words, is the SB-250 a direct replacement for the original SG-250 grindstone and,
more to the point, is it used in exactly the same way (rough for material removal and smooth for sharpening)?
Along with the items I've identified as being missing, any thoughts on what we might add to our system to improve
the chisel sharpening operation would be much appreciated.
Any thoughts on adding the SJ-250 Japanese Waterstone for chisel sharpening would also be well received.
Thanks very much for your time ...
Use the stone grader on the blackstone in exactly the same way as you would the regular grey stone.
I've not used the Jap stone myself so cant comment on it save to say my chisels get plenty sharp enough on the combo of regular wheel and leather honing to preclude me from ever bothering to invest in such an esoteric difference in sharpness. Perhaps if you need to hand carve some tricky grained hardwoods it might make a difference???
The honing compound and truing tool are, you're quite right, must haves.
My only other question would be why do you want the silicon blackstone wheel for chisels, are they turning chisels and therefore High speed steel? If not and they're regular carbon steel bench chisels then the blackstone (designed for HSS) is superfluous to your need.
There is a lot of talk about the Japanese stone. I own one and can say that it is not necessary to sharpen anything. It is a polishing tool and no more. The honing wheel with the honing compound is all you need to make anything more than shaving sharp.
Roy,
I am glad you are still with us. I didn't mean to come down hard on you. I can certainly understand busy schedules.
As you state, the TT-50 truing tool, honing compound, and stone grader are essential components of the Tormek. They are "must haves". Not quite in the must have category, but not far behind is the EZYlock shaft, especially if you plan to use more than one grinding wheel or travel with your Tormek. Depending on the age of your T7, it may already have a stainless steel shaft. My first T7, 2009 vintage, came with the regular stainless steel shaft. It was not as convenient as the EZYlock, but eliminated the rust problem. I would give a lower priority to replacing a regular stainless shaft.
I would not replace your SG-250 grinding wheel at this point. It still has some useful life, and you will need a training period. Give your SG-250 a good truing and dressing with the TT-50. Remember, it is better to use several very light passes. Make sure you have the jig tightened.
As I have (too) frequently posted, I believe chisels are the best tool for learning to use the Tormek. I would start with the 3/4" and become very fluent with sharpening it. Then move to the other sizes, reserving the very narrow chisels until last. They have less bearing surface, so, in my opinion, are the most difficult to sharpen. I would stick with the standard SG-250 grinding wheel and basic Tormek technique. Once you have become very proficient and experienced with this, you may want to try introducing the SB-250 for special purposes. Use the SG-250 first. I have all three wheels and rarely use anything except the SG-250.
Before considering the SJ-250 Japanese wheel, make sure you have perfected your technique. When you reach that level you may or may not be interested in the Japanese stone.
Ken
Thanks for the informative replies, folks!
I'm gleaning from the replies that I may have made an [expensive] mistake in purchasing the SB-250
grindstone. This is more than a little bit troubling because the fellow I purchased the T-7 system from was a
guy who demonstrates the system. You see, after I received the system, I immediately noticed that the original
SG-250 "grey stone" was worn down, so I immediately queried the seller about getting a new stone. After explaining
that we were in the timber framing business -- and that we employ Barr chisels (for the most part) -- he recommended
the SB-250 "black stone."
Is it the board's consensus that we won't be able to sharpen our framing chisels as well with the black stone?
https://www.youtube.com/watch?v=OZTke08xWvc
The stone was more about how it verses the other stone, works on different metals (current ones verses the tool steels of yesteryear). What materials are the chisels made from?
"Is it the board's consensus that we won't be able to sharpen our framing chisels as well with the black stone?"
I don't know. Most chisels sharpen very well with the standard SG-250 grinding wheel. Tools like chisels are what the wheel is designed to cut.
My initial thought, assuming you own the blackstone and cannot return it would be to set it aside for several months until you really know the regular stone. At that point, you could try it and make your decision based on experience.
If possible, I would return the stone.
Ken
You might want to check sharptoolsusa.com. Look under Jeff's blog and read his blog on Which Tormek Grinding Wheel is for me? By the way, the other blog entries are all interesting.
Ken
the simple answer is:
The blackstone can sharpen anything the grey SG-250 can but not vice versa. The blackstone is a "harder" ceramic and as such is designed to enable the removal of steel from more modern "exotic" alloys of steel, in particular high speed steel which is the steel of choice in tools which will get hot in their application (wood turning chisels and drill bits etc)
The chisels you use for framing are what I would categorise as "bench chisels" and are generally manufactured from carbon steel which is softer. Its also cheaper to manufacture and doesn't withstand heat as well as HSS. But bench chisels aren't typically subjected to high temperatures in their working life so it doesn't matter.
The SG-250 is sufficiently hard to cut (and therefore sharpen) carbon steel but is ineffective cutting HSS. On the other hand, the SB-250 is harder and designed to cut (and therefore sharpen) HSS. So the blackstone can sharpen everything but the grey SB stone can only sharpen the softer/older steels.
Just to confuse, the blackstone cant really handle carbide either which is even harder than HSS, for that you really need diamond.
Rob, we never had problems with alloy steps when we were British colonies. In her infinite wisdom, the motherland only allowed inferior steel to be exported to the colonies. :)
Ken
Quote from: Timberwright on May 05, 2015, 07:00:33 PM
After explaining that we were in the timber framing business -- and that we employ Barr chisels (for the most part) -- he recommended
the SB-250 "black stone."
Is it the board's consensus that we won't be able to sharpen our framing chisels as well with the black stone?
Oh, you'll definitely be able to sharpen your chisels with the SB grindstone. I've never used one but my understanding is that it will work faster than the SG grindstone. So it could very well be that you were given sound advice from someone who has experience with both grindstones.
As I understand it, the limitation of the SB is that it cannot be changed from coarse to fine with the stone grader as quickly and as easily as the SG. I would think that for framing chisels you wouldn't need the grindstone prepared fine. Or if you do, it would not be as critical as it would be for a finish carpenter. So it could be that the SB is best for your application.
You will quickly become proficient sharpening your chisels. The biggest hurdle will be getting the ends square, but you will be impressed with how well the chisels will perform and how quickly and easily you'll be able to sharpen them and keep them sharp. You have enough left on your SG that you'll be able to use it and make your own comparisons with the SB. I'm interested in hearing about your experiences.
Checkout the chisel sharpening you tube at barrtools.com. This is not framing as seen on allotment homes thrown together with dull chisels being pounded with framing hammers. These chisels are for post and beam work with large mortise and tenons skifully cut with razor sharp tools. I once watched an episode of The New Yankee Workshop where Norm went along on one of these projects far from any electric power, including generators. Everything was done by hand! Every framing chisel and auger bit was razor sharp. After showing Norm their sharpening technique and watching him sharpen, one of the framers offered Norm a job.....as an apprentice!
I would say the difference in these guys' chisels and those of a true master finish carperter would be that the framing chisels would have a steeper bevel angle. I would not expect to see any less edge polish. If the Tormek works on these chisels, and the toolmaker does refer to normally using a grinder at his shop (hollow grinding) I would have no doubts using a Tormek for these, the toughest edges.
The website is interesting as is the sharpening video.
Incidentally, I presume these chisels are made out of carefully hand forged carbon steel. Because of its finer grain structure, carbon steel will always take a keener edge than high speed steel. The strength in HSS is not in keenness, it is in durability. Carbide carries this even further. It will hold a somewhat dull edge (the best it can do) for an amazing length of time!
I would expect to see no cutting advantage with the SB-250. The SG-250 is designed for carbon steel.
It is nice to see such high quality tools still being made.
Ken
Agreed. You'll have no problem using either the grey or the black wheel. In one respect, the blackstone wheel does allow you the flexibility to sharpen high speed steel as well as carbon steel if/when you may have the need to.
Who knows....you might find a decent quality drill bit (HSS) has blunted right when you need to counterbore a huge bolt hole.....then the blackstone would prove mighty useful because you could give that bit a new edge just by hand in a matter of seconds whereas you couldn't with the original grey stone.
So the blackstone gives you an element of future proofing if you expand the Tormek's use into tools made of HSS.
Quote from: Ken S on May 07, 2015, 05:23:09 AM
Checkout the chisel sharpening you tube at barrtools.com. This is not framing as seen on allotment homes thrown together with dull chisels being pounded with framing hammers. These chisels are for post and beam work with large mortise and tenons skifully cut with razor sharp tools.
I understood that to be the case. The framing of tract, or even custom, homes using milled lumber requires very little chisel use. Timber framing is entirely different and it does require razor sharp chisels. When it comes to the use and sharpening of chisels I defer to you because you have far more experience than me. I would think, though, that the SB grindstone would be better suited to sharpening large numbers of these huge timber framing chisels than the little ones you'd use to make dovetails for your china cabinet drawers.
QuoteI once watched an episode of The New Yankee Workshop where Norm went along on one of these projects far from any electric power, including generators. Everything was done by hand! Every framing chisel and auger bit was razor sharp. After showing Norm their sharpening technique and watching him sharpen, one of the framers offered Norm a job.....as an apprentice!
I recall an episode of This Old House where something very similar to that occurred. I believe it was the first project house without the original host Bob Villa. The job was to be a barn conversion but it turned into the construction of a new barn to be used as a residence. Timber framing was featured and Norm was there to help.
I hate to be the contrarian view, however, I have mixed feelings about the SB-250. I have not used mine much, and I certainly do not consider my tests comprehensive. I admit there may be some operator error factoring in.
That said, I have found the SG-250 works as well for high speed drill bits as the SB-250. The SB might have an advantage when many bits are involved. However, for the occasional bits, the SG works fine.
In the test I did grinding high speed lathe bits, both the SG-250 and SG-200 (T4 wheel) noticeably outperformed the SB stone.
When I dressed (trued) the SB stone, the mud created made quite a mess. I did not have this problem with the SG wheel. This may just be part of the stone composition. That alone would not prevent me from using the SB stone, however, with the combination of things I have experienced, I would not put the SB stone on the Tormek unless I felt it would do the job substantially better than the SG.
Read Jeff's blog on sharptoolsusa. The SG is designed for carbon steel. I would not use the SB for carbon steel tools.
Ken
Okay, Ken, so I read Jeff's blog on the Tormek website. It would seem that the preferred stone for the chisels
we use for traditional joinery is the grey stone (SG-250). Once again, this really has me thinking ...
Will the reduced diameter of our original grey stone (210mm) have any impact on our ability to bring our
Barr chisels back to where they should be?
By the way, the posters who assumed that timber framing chisels have to be extremely sharp are correct.
I initially learned traditional joinery from masters living in the south and, much later, picked up a few new
tricks from craftsman in the northeast -- and all of them continuously seek to keep the error in their joinery
to less than the width of a business card. When one considers the fact that the faces of some heavy construction
timbers can be as wide as 14-inches, less than a business card's width requires a lot of delicate finishing work.
In closing, there are many occasions when a sharp framing chisel is integral to the job -- especially when
fitting joinery together in preparation for a frame raising. As I have never mastered a sharpening technique,
we're [presently] forced to have our chisels sharpened by an outside source. The T-7 is my hope to eventually
learn a sound sharpening method. The best framing chisel in a joiner's box is always the sharpest one in a
joiner's box.
Thanks for your time ...
I think you should purchase a new, full diameter SG-250 grinding wheel. You need full confidence in your sharpening equipment, and the reduced diameter of your present wheel leaves you with doubts. Keep your present wheel as a spare. As your confidence in your equipment gradually grows to include confidence in your own sharpening skills, you will know the answer to your diameter question, based on your own experience.
Do keep us posted on your framing odyssey.
Best luck,
Ken
I disagree with Ken! It is too easy for us to just throw other peoples money at this issue, rather then what it really needs, their time.
http://forum.tormek.com/index.php?topic=178.msg519#msg519
If you find someone or someplace that will swap you the unused SB for an SG, then I would say go for it. That said, Jeff Farris the former main moderator, still member (but doesn't post as much), said the stones minimum usable diameter is 7" (aprox 178mm) so you have a way to go on it.
If you have the angle setting tool you should be able to get the correct angle on your chisels, so IMHO, you would just be throwing money at a new stone and that would make you feel like your just wasting more money, then learning how to use the system. In my view, you would be better off with either a garage sale chisel, or buying another chisel instead, to LEARN and spend machine time with, rather then the ones you rely on day in and out for work. Learn first before you learn on something your being paid to do.
This isn't something you just are automatically able to do, any more then you were able to cut with less then a business card's error, without practice.
Quote from: Ken S on May 08, 2015, 12:01:51 PM
I think you should purchase a new, full diameter SG-250 grinding wheel. You need full confidence in your sharpening equipment, and the reduced diameter of your present wheel leaves you with doubts.
Ken, here you suggest that the man buy a new stone because his is worn down to 210mm. Yet previously you have advocated for the T4 whose wheel is only 200mm. Are you suggesting now that the 200mm stone is somehow lacking?
Thanks very much for the replies, folks. Very, very informative -- and I'm looking forward
to the day that we bring the T-7 back to productive operation.
By the way, swapping the black stone for grey seems like a very good idea, at this point.
Timberwright, I also think that you shouldn't invest in a new grindstone. Your 210 mm SG or your SB will get your chisels sharp. I still believe that the SB will get them sharp enough and will do the job faster. If I were you I'd do some practicing before investing in another grindstone.
As I said before, your biggest challenge will be getting a square end. Getting them sharp will not be difficult with the Tormek. Anyone with the craftsmanship required to be a timber framer will have no problems quickly mastering the Tormek to sharpen chisels. Just make sure the grindstone is true, mount the chisel properly in the jig, and keep watching the end to make sure it's square. Apply more pressure to one side as needed to keep the end square. I doubt you'll have any problems.
Jeff,
If the topic were a general post, I would agree with you about the diameter of his present SG wheel being more than adequate. As you have correctly noted, I have often advocated using the T4 with a 200mm stone.
However, I was not answering a general question. Timberwright posted about a very unusual situation. He is a very new Tormek user who wants to do very demanding sharpening with his Tormek. He has stated doubts about his reduced diameter grinding wheel being adequate for his tasks. He does not have confidence in his equipment.
I do not detect that money is an issue with him. As such, I do not think it unwise to recommend purchasing a new SG-250. A new, full diameter SG-250, specifically designed for grinding carbon steel tools such as his framing chisels is only $184 USD and would give him the confidence he needs in his equipment. He still has the learning curve ahead of him, regardless of what wheel he uses. This choice would give him a wheel he trusts. He needs that psychological edge.
I am certainly not stating that a wheel worn to 210 has no useful life. It has plenty of useful life left, and he may well use it after he gains experience with his Tormek. If he does not have that initial confidence, he will discard the Tormek and move onto something else. Ignorance would have triumphed over skill once again.
In general, I feel the T4 is up to any sharpening. In this case, due to the larger size of the framing chisels and the steeper bevels, I would favor the T7. I would not back away with a T4; I just think the T7's larger diameter wheel would be better suited for the task.
I find no "bargain" in using a wheel not designed for his tools which might someday possibly sharpen high speed steel, if he should ever happen to want high speed tools. Tormek has to the best of my knowledge never claimed that the SB wheel will even equal the SG with carbon steel, let alone do things faster. Based on his posts and blog, I get the impression that Jeff Farris was generally quite happy with the SG stone. I never recall him writing about actually using the SB stone.
Incidentally, to set the record straight, Jeff Farris stopped posting to the forum in July of 2014 under his own name, and shortly after that as moderator. He no longer has any affiliation with Tormek or this forum. No one regrets that more than me. Although I have never met his personally, I have come to like him and have very high regard for his Tormek experience. I consider us very lucky to be able to access his posts, blog, and videos and wish him only the best with his new direction.
I would add one thing to my recommendation for Timberwright: Barrtools has a very good chisel sharpening you tube on its website. i would study it several times. Make special note of his bevel angles and that he usually begins with a grinder in his shop. He builds on the hollow grind. If you are obsessed to restoring your barrtools, send one in for factory resharpening. Use it as a model. Contact the company with specific questions. Barrtools seems like a customer friendly small company. You might learn a lot from them. They are accustomed to working with framers.
And, I will stay with my recommendation of purchasing a new SG-250. Don't let others' well meant suggestions of saving you money interfere with your progress. Tool up for your job at hand. Don't worry about future "what ifs".
That's just my opinion.
Ken
This is where Ken and I disagree, and I believe it to be because we are both playing mind reader. (all we have is what you have posted, and it can be read both ways)
He views you as not having confidence in your equipment, I view your lack of confidence as a lack of use/experience with the equipment. (want to make sure before using)
Please consider basing your decision on whichever is more accurate!
Did Jeff sell his company, or just retire? (his company still sells Tormek, if he didn't sell it)
I know he stopped posting as him and when Stickan took over normal duties, Jeff (pretty sure) just has posted since as Admin. (Feb of this year)
So he is no longer a demonstrator, but still I believe has some ties. I thought I remembered something about retirement, which I hope he is enjoying.
SADW, if we did not disagree from time to time, this would be a very dull forum. :)
I remember reading on the forum several years ago that Jeff had sold sharptoolsusa, lock stock and barrel to Advanced Machinery. The new owners (wisely) have continued to use his videos and have left his blog on the site. His videos and blog remain one of the best sources of Tormek information, as have his forum posts (on this and other forums).
I believe Jeff's role as forum administrator ended last fall. The Admin posts since then were probably Stig or someone else from from Tormek.
Jeff is still working, happily, I believe, for another company. He started out many years ago selling Tormek and turning tools. His present position allows him to combine sharpening with a lot of turning tools.
I don't know of anyone, at least in the United States, who has Jeff's depth of Tormek knowledge. Unless one has access to one of the Tormek classes in Sweden, in my opinion, the best course of Tormek study is a diligent study of Jeff's posts and trying to locate a good class. Robin Bailey's school in Bath, England seems a good candidate. Steve Bottorff's fine class should be available on DVD shortly (please update us, Steve).
Ken
I'm going to jump in and make one tiny correction here Ken.
Jeff (Farris that is) did talk about the SB stone as likely to cut carbon steel chisels slightly faster than the grey stone. I've not gone to the trouble of looking up the thread but it related to my decision to buy it when I was struggling to sharpen my planar blades. Jeff's logic went something like this:
The SG stone is designed to cut carbon steel (soft metal relative to this discussion)
The SB stone is designed to cut HSS (hard steel relative to this discussion)
If the SB stone can cut HSS which is harder than carbon steel then it follows it will cut carbon steel more easily.
So back to your logic Ken......your recommendation is for this particular chap to buy a new 10" stone. I have no comment to make on whether or not he should remain on the worn stone or buy a new one. I do think if he buys a new one he is missing a trick by failing to buy the SB capability.
Put it this way, by buying the SG stone it will do one job...carbon steel
by buying the SB it will do all the same jobs as the SG (but faster) AND other jobs if needed. So it provides a future capability that may well prove useful whilst having no negative impact on the current need for carbon chisels. In fact, its better (faster) at sharpening carbon chisels.
So I'm struggling to follow the logic of why the SG is a better choice?? The only caveat would be cost, I haven't looked at an A to B comparison of the 2 stones but if the SG were much cheaper then I would probably buy that one given there isn't a role for the harder qualities of the SB today. If the price difference is small, again, logic would suggest the SB is a more versatile solution.
Rob,
You have both the SG-250 and the SB-250. Have you tried the blackstone with carbon chisels?
Ken
I do have both stones and I never take the SB off. It's been installed ever since I bought it (for exactly the reason I describe above). I use it to sharpen everything including of course HSS.
Rob, I believe the OP has already purchased the SB grindstone. That's the only reason I was discussing its use for his chisels.
Once again, very, very informative posts.
Yes, I (the O.P.) received our used T-7 with a few missing bits and a grey stone that was worn down to 210 mm. Noticing the diminished diameter
of the SG-250 right away, I contacted the seller and informed him that we needed the machine for sharpening framing chisels (primarily). In response,
the seller offered to sell me an SB-250, at a discounted price, and assured me that it would be suitable for our needs ... and that is how we came into
possession of the black stone.
At this point in time, I'm waiting for a check or two to come in. Once we have the funding for it, I will place my order for the missing Tormek accessories,
which includes the upgraded EzyLock Main Shaft, and install and/or use them. After that, I will install the original SG-250 stone and practice with it on
some old chisels that were taken out of service due to severe chipping. Assuming that we eventually get positive results, I'll give the SB-250 a try.
That sounds like a good plan. Best of luck and do keep us posted.
Ken
just as a tip....when you come to grinding those chipped bevels...make sure the stone is as rough as possible because they will take a long time to remove. Keep MASSIVE downward pressure with your fingers, far more than you think is reasonable, it wont hurt the machine. Keep regrading the stone with the rough side of the grader, and I mean every minute or so because it will glaze quickly and stop cutting with that huge surface area of bevel to remove. Ensure you mount the chisel on the top support bar so you're sharpening with the wheel coming towards you rather than the lower position. The upper position is a more aggressive cut which you'll want for dinged bevels.
Once you get them sharp, a tickle to bring the edge back wont be such a drama but removing dings means removing a lot of steel and that takes a long time on the Tormek if its not cutting optimally.
Bottom line....keep the stone cutting by keeping it graded rough, frequently.
Thanks for the great post, Rob.
As I understand it, the black stone (SB-250) is harder than the grey stone (SG-250). Bearing in mind that I've never used either type
of cutter, please excuse the "new guy's" question: Do you think that the black stone would give better service as a "repair" stone?
In other words, do you think that the black stone would be more effective in reviving the chipped chisels I previously described?
Here's to learning something new every day.
Cheers
don't give posting "new guy" questions a second thought.....we all started the day we bought a Tormek didn't we :-)
Your question about the blackstone is a good one and I'm not 100% certain this is the right answer but here goes the theory, I'll then add my own personal experience given I have both stones.
The theory is that because the blackstone is a harder ceramic and capable of cutting High speed steel (harder then your carbon steel framing chisels) then it "should" cut your carbon steel more aggressively than the grey one might. Thus we can deduce it would be a better choice for dinged tools because it will remove steel faster.
My practical, real life experience isn't quite as clear cut as that. Here's my take:
I had the regular grey stone for about 5 years and did all my bench tools with it plus knives and indeed anything else that needed sharpening (lawn mowers, secateurs etc). About 3 years ago I got back into wood turning and bought the Tormek turners jig kit to help handle the complex profiles of the likes of bowl gouges and skew chisels etc...all of which are tricky to sharpen to say the least.
Add to that the fact that turning tools get hot due to the friction with the fast spinning wood.....so the solution to that difficult environment is make them out of high speed steel because it holds an edge longer and can withstand higher temperatures without its temper being drawn.
I bought the blackstone as a dutiful customer does.....because its designed for HSS right?
Now in practice, I found that the grey stone is not good at sharpening HSS because its just too soft, although it can do it, slowly. The blackstone can certainly do it. But when I use it on my standard plane irons and bench chisels I cant honestly say I notice much difference from the grey stone??
So, I'm a bit confused about that. The blackstone should in theory work faster "downstream" and the grey stone shouldn't work at all going "upstream". In reality I find very little if any noticeable difference downstream with the SB but the SG does struggle with HSS.
To add to the conundrum, I also bought the planar jig and found that rather slow. Bottom line is that hard metals with big surface areas like wide chisels and planar knives don't give up their steel to the Tormek easily. Bench plane irons are a doddle because the surface area (less steel) of the bevel is small. Your narrow chisels will be a doddle for the same reason but once you get to an inch and above and especially if they're dinged (you need to remove a lot of steel) its harder work. The problem is the ceramic stone glazes over quickly and needs the surface regrading (roughing up) to keep it cutting.
I'd be interested to hear any other perspectives on the real life experience performance of the SB.
Bear one thing in mind...you're unlikely to do any harm whichever stone you try out because they do last a long time so just "have at it" and post away as you bump into problems and we'll abuse you whenever we get chance :-)
Quote from: Timberwright on May 13, 2015, 10:01:11 AM
Once we have the funding for it, I will place my order for the missing Tormek accessories, which includes the upgraded EzyLock Main Shaft, and install and/or use them. After that, I will install the original SG-250 stone and practice with it on some old chisels that were taken out of service due to severe chipping. Assuming that we eventually get positive results, I'll give the SB-250 a try.
You have the SE-76 Square Edge jig and a new SB-250 grindstone. I recommend you go ahead and get some practice on those old chisels while you wait to order the truing tool, stone grader, and honing compound. The Tormek is not a fussy piece of equipment, it's a work horse designed to grind steel in a precise way. Just remove the parts of those old chisels that make them dull and they'll be sharp. You're timber framing, not carving piano legs. If you don't get them as sharp as needed, go ahead and finish the job with your usual sharpening methods. The Tormek will have removed the lion's share of steel needed to reshape the tool and get the nicks out.
You may find that you don't need the new main shaft.
I would tentatively agree with Herman that practice is of course a good thing but beware setting out grinding wide bevels with no ability to get the stone cutting again once it glazes! Without the grader and/or the diamond truing tool you'll get frustrated very quickly at the stones inability to cut and that will put you off using the tool. You'll wind up unfairly judging it based on its performance when glazed. As I've already said, my experience of its performance when glazed is not good. You really do need to keep roughing it with the stone grader or better yet, true with the diamond jig as that give the roughest (most cutting) surface possible.
I ran a test with the SG and SB wheels. I placed identical 3/8" (10mm) square metal lathe cutting bits in the SE-76 and ground for a timed five minutes. These bits are at least HSS. To my surprise, the SG removed noticeably more steel. I trued the SB wheel and ran the test again with the same disappointing results.
I used a lot of pressure for these tests. The handbook states that the SB will cut even with very light pressure. I may have been using too much pressure for the stone to cut well. It may also have glazed and needed to be graded during the five minute period. I do not consider my initial test results conclusive.
Incidentally, the SG wheel with the T4 removed the same amount of metal during the test as the T7 SG.
Ken
Well that just doesn't make any sense??? Metal lathe cutting bits would be tungsten carbide I would imagine which makes even less sense in that they're even harder than HSS.
I just don't understand that at all?
Ken, try a light pass with the truing tool over the SB grindstone. I suspect it's clogged.
Rob,
Inserts for cutting tools are usually tungsten carbide. Bits which don't use inserts are usually HSS or related alloys. (Just like carbon steel can be sharpened more keenly than HSS, HSS can be sharpened more keenly than carbide. The edge just doesn't last as long (by a wide margin).
I agree that my results are puzzling. I would have expected the SB tool to remove more HSS. That's why I am keeping the jury out until I investigate "operator error" on my part.
Ken