Reviving a T-7

[Timberwright]

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 ...
   

[Rob]

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.

[jeffs55]

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.

[Ken S]

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

[Timberwright]

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?

[SharpenADullWitt]

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?

[Ken S]

"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

[Ken S]

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

[Rob]

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.

[Ken S]

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

[Herman Trivilino]

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.

[Ken S]

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

[Rob]

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.

[Herman Trivilino]

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.

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 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.

[Ken S]

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