Tormek Community Forum

Hello,
I am a newcomer in the Tormek community and I am French, so forgive my broken English in advance.
Could you give some advice on my case and help me to make a decision.
I am looking for a Tormek station to sharpen my knifes collection. (Mostly Global Knife) and few scissors.
On internet, I found a second hand Tormek Supergrind 2000 (sea attached photo)
https://drive.google.com/file/d/0B17r4s9bvmkgZkljNUlWbDlBYXhkQlhZZnBSaUU0cDJxMXlF/edit?usp=drive_web (https://drive.google.com/file/d/0B17r4s9bvmkgZkljNUlWbDlBYXhkQlhZZnBSaUU0cDJxMXlF/edit?usp=drive_web)
It is 10 year plus age and the selling price is 300 Euro.
Is it wise to buy this machine knowing that I'll have to upgrade it with :
MSK-250 Kit
LA-220 part because the leather honing wheel seems damaged on the picture
and ideally the grinding stone need to be replaced by SJ-250 Japanese water-stone to suit my usage.
Plus few jigs as TT-50, SP-50, SVX-150,SVM-00 etc.
I can't find the price for MSK-250 Kit , but the global budget with all part could be another 400  to 500 Euro.
And a brand new T7 standard station is sold at 539 Euro and I have to add HT-706 Hand tools kit and a SJ-250 stone.
What are your advice on this case ? what should be my best offer to buy this used machine ?
Is the Motor will handle 10 more year ?
Thanks in advance for your answers.
Regards

Welcome to the forum, Tournevis.

Looking at the photo, it seems like the grinding wheel has worn down to somewhere between 200 and 220 millimeters diameter. it still has some useful life, however, most of it is already been used. With your cost calculations, I would factor in the cost of a replacement SG-250 grinding wheel.

I would suggest you look into a new Tormek T4. I have used both the T4 and T7. For your collection of knives, the T4 is more than adequate. You would be getting a new machine with seven year warranty. I believe you wold be getting much more tormek for your Euros with a new T4.

Keep us posted.

Ken

   Welcome to the forum, Sheang.

   I agree with Ken, consider very carefully before buying a used Tormek. There have been other posts written previously in regard to this. I personally have suffered the rusted drive shaft and cracked grinding wheel issue due to the rusting of the shaft. The new cost of a unit can quickly become attractive in comparison to some of the required repairs on an older unit.

I suggest the T7. There has been a long history of debate over which to buy, the T7 or T4. Remember my motto," you can use less of more but you cannot make more of less". That means that you can eat half a loaf of bread but you cannot make a whole loaf from a half.

To follow through on Jeff's motto, why would one pay for a whole loaf of bread just to make one sandwich?

If cost does not matter, a new T7 would certainly serve your needs. If cost is an important consideration, I believe a new T4 would be more cost effective than either a new or older T7 or Supergrind. I base this belief on having worked with both a T4 and a T7. In my opinion, I find little difference between the capabilities of the T4 and T7. Certainly knives and scissors are well within the capability of the T4.

Ken

Ken, what if you get hungry later?

Jeff,

I was able to grind off about the same amount of a metal lathe tool bit with the T 4 and T7 in the same time. So, with the price difference between these, the T 4 owner has grocery money left over.

Ken

Thanks to all for your input and comments  :)
I'll will seriously consider the T4 .
Let's estimate the cost of T4 + SJ-200 + HT-706
In the same time, I'll make a honest offer to the 2000 owner and see what's his position, meaning 100 Euro vs 300 Euro for the value of jigs.
Do someone has detailed technical data sheet and reference of the Supergrind 2000 electrical motor ?
I wonder if some functionalities are embedded or can be added : (on oldies and T4/T7 stations)
1) Variable speed
2) Clockwise and anticlockwise spinning
3) Automatic torque adjustment

Waiting to read your valuable and appreciated answers.
:D

Quote from: Tournevis on July 14, 2015, 11:03:05 AM

I wonder if some functionalities are embedded or can be added : (on oldies and T4/T7 stations)
1) Variable speed
2) Clockwise and anticlockwise spinning
3) Automatic torque adjustment

Waiting to read your valuable and appreciated answers.
:D

Sheang,

None of the three options you are mentioning is implemented on current T7 and T4 models, which means that it cannot be added to Tormek Supergrind 2000 as a Tormek supported upgrade.

Jan

Tournevis,
As mentioned previously this the topic of which to buy has been talked to death on this forum. Ken S is a major fan of the T4 and I am not. I am going to say one more thing to you and then you have to make your own decision. On 8-1-2010 "Joe" asked this question,
"How far down do you let your stone wear before you order a new one? At what size can you no longer use the stone? I sharpen 100-150 knives per week.  Thanks."
He got this answer from Jeff Farris who was the importer of Tormek into the United States and the administrator of this forum for years.
It's not very easy to use once it is below 7 inches.
You are starting out with a stone that is 8 inches in size. Which do you think will last longer, the 8 inch stone or the 10 inch stone under the same usage? EVEN if you can use the stone when it is smaller than 7 inches, which one will last longer? The decision yours.

Jeff,
My choice is not made yet. I am just on the way to get an estimated cost for T4 station.
I'll decide really when I'll have the answer from the actual owner of the Supergrind 2000. If he accept my proposal of 100 Euro, why not fully refurbish the 2000.
Wait and see.  :(
In the mean time, I am looking for maximum technical data about the motor which is key for me. Is there any spare part list for the engine ? (If needed ?) Where to buy ?

Jeff,

You are taking Jeff Farris' statement out of context. The statement applies only to the 250mm wheel size of the T7. In 2010 I do not believe the T4 size machine with 200mm wheel diameter was even available in the US. The handbook which came with my first T7 (purchased in 2009) states that the 1200 model (predecessor of the T4) was "not available" with 115 volt 60Hz electrical power in the US. Therefore, I do not believe Jeff Farris ever sold or demonstrated the 1200. By the time the T3 and T4 models were introduced, Jeff was no longer affiliated directly with Tormek.

I have found several conflicting statements about the wear limits of the 250mm grinding wheels. For convenience, I will accept the seven inch limit. it is also listed on p.155 of the present edition of the handbook. That same page lists 150mm (six inches) as a practical wear limit for the T4 200mm grinding wheel.

One must also factor in the cost of a replacement wheel in the equation. The replacement cost of an SG-250 is presently $185 US. The replacement cost of an SG-200 is $105 US.

I do not see wheel wear and replacement costs as a decisive factor favoring either the T4 or T7.

Ken

Jan,

Good luck with your offer. Dropping from 300 Euros to 100 would be a rare find. I hope you would be so fortunate, however, I would be surprised.

Regarding the motor, having to replace a Tormek motor seems a very rare occurance. Replacement motors are available, however, the cost would not be practical. Before replacing a tormek motor, I would first check with a local motor repair shop. Motors are motors.

If the motor on this unit seems iffy, I would walk away.

If you are still thinking in the cost range of a used Tormek, I still believe you would be better served with a new T4. I would not worry about the motor of a new T4 failing.

Ken

Ken,
You are so right, the old Tormek station was sold  >:(
So,next step waiting for New T4 Quote.
A New T7 will cost 539 Euro in promotion.

Quote from: Tournevis on July 14, 2015, 04:06:36 PM

In the mean time, I am looking for maximum technical data about the motor which is key for me.

Sheang,

Data sheets for T7 motors are not publically available  :( . What we know from Tormek www pages is following:
Motor: Industrial single phase, 200 W (input)
230 V, 50 Hz or 115 V, 60 Hz. Continuous duty, Maintenance free.
Silent running, 52 dB. 25,000 hour life.

If you are interested in further details, it is a single-phase AC induction motor, with run-type capacitor, which is permanently in series with the auxiliary winding. So called Permanent-Split Capacitor motor.

In the thread "T-7 overheated" http://forum.tormek.com/index.php?topic=2360.15 you can find photo of the name plate from my T7 motor (reply#22) and lot of other details.

Based on my measurements, during grinding and honing the motor load is only some 5% of full load. Do not worry about the motor, there is no known reason for it.

Jan

"I wonder if some functionalities are embedded or can be added : (on oldies and T4/T7 stations)
1) Variable speed
2) Clockwise and anticlockwise spinning
3) Automatic torque adjustment"

Tournevis, I believe you would be better served by just using the Tormek for its designed purpose. I am not opposed to innovation, however, I think there was good planning involved in the Tormek.

1) Variable speed. The speed limitation is the point where water would leave the trough. I do not see where slight variation is motor speed would bring any real benefit.

2) Clockwise and anti clockwise spinning. This might be useful, however, I am sure the reason it is not designed into the Tormek is the possibility of accidentally using the leather honing wheel revolving into the edge. This would be unsafe.

3) Automatic torque adjustment. Why? You could take your tormek to a local custom machine shop and have it modified to have all these things. However, you would probably end up with a Tormek costing at least twice what a new unit would cost, and not having any more practical functionality.

I certainly do not mean to discourage creativity, however, I would suggest you begin by spending some real quality sharpening time with a three quarter inch (19mm) bench chisel. Learn how the Tormek works with the most basic tool to sharpen. Learn the differences in sound and feel with sharpening. A solid knowledge of the basics will stand by you very well.

Ken

Ken,
My thoughts about Tormek station are quite positive.  :)
"Designed for sharpening, taking in account key parameters in purpose"
Angle setting, Jigs to ensure repeatability, grinding, honing, water-cooled etc..etc..
I think that Tormek is part of high end solution.
To make an analogy with car market, I would say top 5 of deluxe worldwide car makers.
Before spending a significant budget on the solution, I am trying to evaluate "how far" Tormek is differentiated from other makers.
That's why I Raised 3 questions. But perhaps they are too theorytical at your eyes.
1) Variable speed. For me, in fine sharpening, one of the main parameter is the "cutting speed". The equation is simple to understand, 250 mm diameter X constant rpm will not equal to 175 mm diameter X constant rpm. So the cutting speed will have big variation day after day usage. And depending on the hardness of the steel we deal with, It may have a significant quality impact.
2) Clockwise and anti clockwise spinning. At this stage, the solution is to turn the station by 180° to swap grinding to honing operation, for that you need the rotation base accessory, otherwise, operator need to turn around the station. From my point of view, a reverse switch will solve the dilemma and reduce the footprint for workspace and facilitate workspace lighting for "safety" reason.
3) Automatic torque adjustment. As I understand today, but I might be wrong, the sharpening operation is still very "operator dependent" meaning the result will depend on the force you will apply on the assembly of knife and jig and mostly how consistently you will apply it, specially when you will have to rotate the blade when it curves. That's why my question.

You are absolutely right, once more, I should Learn how the Tormek works with the most basic tool to sharpen and acquire much more knowledge of basics on sharpening. I will certainly invest on a new T4 station as you suggested.
My dream is to cover all kind of sharpening needs of my home.
Cooking : Blender blade, meat slicing disk, Mandoline blades, all sort of knifes, scissors
Workshop : chisels, cutters, electrician knife, scissors, etc.

And later on, perhaps, we can open a topic to share some "design" continuous improvements or jig wish-list.  :D
Cheers
Sheang

Quote from: Tournevis on July 15, 2015, 06:38:41 PM
1) Variable speed. For me, in fine sharpening, one of the main parameter is the "cutting speed". The equation is simple to understand, 250 mm diameter X constant rpm will not equal to 175 mm diameter X constant rpm. So the cutting speed will have big variation day after day usage. And depending on the hardness of the steel we deal with, It may have a significant quality impact.

In my experience this is a small difference that doesn't have a significant effect on the grinding operation.

Quote2) Clockwise and anti clockwise spinning. At this stage, the solution is to turn the station by 180° to swap grinding to honing operation, for that you need the rotation base accessory, otherwise, operator need to turn around the station. From my point of view, a reverse switch will solve the dilemma and reduce the footprint for workspace and facilitate workspace lighting for "safety" reason.

A simple reverse switch would reverse the direction of rotation of the motor but that wouldn't work because the drive wheel would then slip.

Quote3) Automatic torque adjustment. As I understand today, but I might be wrong, the sharpening operation is still very "operator dependent" meaning the result will depend on the force you will apply on the assembly of knife and jig and mostly how consistently you will apply it, specially when you will have to rotate the blade when it curves. That's why my question.

I don't understand how an automatic torque adjustment would compensate for the amount of force applied by the operator. The amount of steel removed at any one location depends not only on how much force is applied by the operator but also on how much time the operator spends grinding at that location.

Tournevis,

i would like to make one more comment regarding purchasing an older, used Tormek. We have a number of members of this forum who happily use older Tormeks. Some have had their machines for a long time, and some purchased them already used. As with an older automobile, an experienced mechanic can use anything mechanical which is older more easily than a beginner. You may eventually become an experienced Tormek user, and I hope you do. However, for the present, as a beginner, I believe you would be better suited with a new machine.

I believe you will be able to sharpen many of the items on your wish list with the Tormek. Some will require more experience than others. I would suggest you take a careful look at the marketing side of the Tormek website. Anything not listed there is probably not easily sharpened with a Tormek. I am sure the marketing department wants to put its best foot forward.

I believe the Tormek is well designed for its intended purpose. in skilled hands it can be surprisingly versatile. That does not imply that it is equal to much more expensive specialty equipment. I think you are imposing illogical constraints with your requirements. To me, the deciding factor should be can the Tormek produce sharp edges?

I have used the Tormek with and without the rotating base. Even now that I have one, I sometimes do not bother with it. Picking up the Tormek to turn it around is not a big deal, especially with the T4. Mine is set up where it is often just as easy to move to the other side of the bench. I consider the rotating base a nice to have accessory. You will probably want it at some point. I would not feel pressured to purchase one right away. Mine happened to come as part of an extra package deal with my second T7. I do not consider it a priority. (My first T7 was stolen during a home burglary.)

By the time your grinding wheel has worn to 175mm, hopefully you will have the experience to use your Tormek more efficiently. Your expertise should more than compensate for any diminishment in surface feet per minute.

One of the design features I especially like about the Tormek is that it works well in a wide range of torque. You can really lean on it. Or, if one is older and more prone to pain in the hands, the Tormek can be used with very light pressure. It takes a little longer with lighter pressure, but hopefully experience will also help compensate for that.

The Tormek is not a Rolls Royce; nor is it priced that way.It is a well designed and built tool with a long life and capable of much fine service. I hope you will enjoy it as such. Some of my tools, hand and power, originally belonged to my grandfathers. I hope my grandchildren will enjoy using my Tormek.

Do keep us posted.

Ken

Ken,
Thanks for your comments.
I just received 2 Quote for new machines and will have a couple of questions before final decision.
First quote is T4 + SJ-200 + HTK-706 + RB-180 + TT-50 = 776 Euro
Second quote is T7+SJ-250 + HTK-706 + RB-180 = 987 Euro
The delta is 211 Euro.
Now what do I have for 211 Euro ?

motor life time :T4 = 10K hours, T7 = 25K
Working time : T4 = 30 minutes per hour, T7 = continuous running
Warranty : T4 = 7 years, T7 = 7+3 = 10 years

My thought is that T4 suitable to my needs and learning phase. T7 is really for professional which is not my case.
But I scare a little bit about the fact that I can run only 30Mn/hour. Does that mean that it will overheat quickly ? Is there a thermal automatic breaker inside ?

All advices will be appreciated
Sheang

I wish Tormek would get past this thirty minute nonsense. I can not imagine burning out a motor with the T4. If that was indeed a real issue, Tormek would not include the seven year warranty. As I have stated earlier, if a user should have a motor problem within seven years, Tormek will correct the problem at no charge. The zinc casting machined housing top design change from the T3 to the T4 acts as a heat dissipater. I have personally seen a T4 running almost continually all day. There was no problem with it. toward the end of the day, I even touched the top with my hand. It felt only mildly warm. Based on my experience, I ignore the thirty minute idea.

Regarding the motor life time: If you are young and starting a business where you will be continually be running your (only) Tormek eight hours a day or more every day, After a couple decades you might wish you had purchased the T7. For the home user, you won't live long enough to get past the theoretical motor life. Unless you are in a heavy industrial situation, I would not be concerned.

I would focus on your needs and the work environment. The T4 will certainly more than satisfy your needs requirements. If you have a large work area with a dedicated sharpening station, the T7 might be the preferred choice. If you have a smaller work area and need to move your Tormek around from time to time, or if you have any mobile thoughts, I would opt for the lighter, smaller T4. "Mobile" might include bringing your Tormek when invited to a friend's home for dinner. Sharpening your friend's knives would make a very considerate thank you for a good meal.

I have mixed emotions on the kits. I bought my jigs individually. I do not have an ax jig. Neither do I have an ax. If you plan to sharpen all the tools included in the jig kit, the kit is probably a good idea. If money is tight, I would initially forego the SJ wheel and rotating base unless you get them at a discount while purchasing your main unit. You can always add them later should you decide you need them.

I think of the T4 as a lifetime investment, suitable for far more than your "learning phase".

Keep thinking and keep posting.

Ken

Quote from: Ken S on July 16, 2015, 05:22:33 PM
I ignore the thirty minute idea.

Ok then, I 'll forget this but why Tormek is writing this on their documentation ?

Quote from: Ken S on July 16, 2015, 05:22:33 PM
Regarding the motor life time: If you are young and starting a business where you will be continually be running your (only) Tormek eight hours a day or more every day, After a couple decades you might wish you had purchased the T7. For the home user, you won't live long enough to get past the theoretical motor life. Unless you are in a heavy industrial situation, I would not be concerned.

Yes I am young, I am only 62 but it's not my intention to start a business  :o

Quote from: Ken S on July 16, 2015, 05:22:33 PM
I would focus on your needs and the work environment. The T4 will certainly more than satisfy your needs requirements. If you have a large work area with a dedicated sharpening station, the T7 might be the preferred choice. If you have a smaller work area and need to move your Tormek around from time to time, or if you have any mobile thoughts, I would opt for the lighter, smaller T4. "Mobile" might include bringing your Tormek when invited to a friend's home for dinner. Sharpening your friend's knives would make a very considerate thank you for a good meal.

I have limited work space and need to tidy everything after each task. I like the idea to bring the Mobile T4 to a dinner instead of bringing flowers or/and wine !  ;D (Any idea on how to tell this to my darling ?)

Quote from: Ken S on July 16, 2015, 05:22:33 PM
I have mixed emotions on the kits. I bought my jigs individually. I do not have an ax jig. Neither do I have an ax. If you plan to sharpen all the tools included in the jig kit, the kit is probably a good idea. If money is tight, I would initially forego the SJ wheel and rotating base unless you get them at a discount while purchasing your main unit. You can always add them later should you decide you need them.

Globally, I got a 22% discount on retailed public price on everything. Example T4 418,80 discounted to 354, T7 703,20 discounted to 539, HTK-706 183,3 discounted to 143.
That's why I prefer to order SJ and Rotating base now. These conditions are available until the end of July only. You know, always the same commercial argument.

So it's decided, I will place the order of T4 configuration tomorrow unless some expert come up with valid argument.
Thanks to all and special thanks to Ken to guide me in the first steps of a long journey.  ;)
Sheang

That kind of a discount is hard to pass up! My one suggestion would be to consider the diamond truing tool and the SE-76 square edge jig. You will need the truing tool to keep the grinding wheel true. The truing tool is part of the T7 package, so most of us forget about needing to purchase it with the T4. (I forgot this time.) It is essential. I sharpen mostly chisels, so, for me, the SE-76 is my main jig. If you do not sharpen chisels, you may not need one. It is easily added later, if need be. My priority suggestion would be to place the truing tool before the SJ wheel or the rotating base.   

Bon chance! (Please excuse my very limited French.)

Keep us posted.

Ken

Quote from: Tournevis on July 16, 2015, 03:36:34 PM

First quote is T4 + SJ-200 + HTK-706 + RB-180 + TT-50 = 776 Euro

Ken,
The truing tool is TT-50 reference ?
If yes, it is included in my T4 Quote above.
If not, tell me what's the Tormek part number, I'll order it.
Merci beaucoup
Sheang

Yes, that is the correct part number.

Ken

Tournevis,

You ask some very good questions; I am glad you do. This forum is designed for sharing information. None of us begins with the answers. None of us has all the answers. We an all expand our knowledge through dialogue.

Keep exploring and asking questions!

Ken

Ken,
I really appreciated your help.
Today, I was about to place the order to the supplier from whom I got the quote we are talking about.
Checking my email, I got another proposal at 720 Euro instead of 776 best price.
I was confused and start to investigate what's going on. My first idea was to check who is authorised dealer in France, therefore I go clicked on "Where to buy" on Tormek AB site. And when I click on the link it show up a page which have nothing to do with Tormek.
So I am lost and I am afraid to have to postpone my decision to buy until I'll get clear view of Tormek distribution in France and associated service providing. It's useless to have 7 years warranty if nobody can provide the service.
Then, I though about Amazon in France where I have an account. They do display Tormek but a close check reveal that vendors are based in Germany and their price are out of market.
In conclusion, could you help me to find out "what's going on in France ?"
Is Tormek AB is aware of this situation ?
And finally, the most important for me "who is authorised dealer for Tormek in France" ?
With this list, I can check to whom I can order my T4 station.
Sheang

Hi,

RBE Innovation Systems
Z.I. rue Gustave Eiffel
02200 Villeneuve-Saint-Germain
Tel. 03-23 73 85 17
Fax. 03-23 73 17 78
rbe@groupe-bvd.com
www.rbemachines.com

Please call them and thay will help you to get your Tormek. Then the machine will come with the right manuals in French too.
If you buy a machine outside France you will get the Handbook and manuals of that country.

Best, Stig

Thanks stig,
Did you ckecked their  website link ?
As you advise, I'll call them to obtain the French vendor list.
Regards, Sheang

Hello All,
D day for me today.
I just received all package of my T4
(http://img11.hostingpics.net/pics/438263IMG0799.jpg)
Now time for UN-boxing and discovery
Hurray
Thanks for your help.

Enjoy!

I had the pleasure of unboxing and discovering a new T4. Savor the experience. Enjoy learning the feel and sounds of your Tormek, and do keep us posted.

Ken

ps I have thought of a situation where the dreaded thirty minute supposed limitation would present a problem. As long as the operator is human, you should have no problem. If you plan to use an android operator, the thirty minute nonsense might prove problematic.

Bonjour Sheang,

I am also trying to convince myself to buy a Tormek and one issue that I couldn't see being considered is the wheel size.

The T-7 wheel is 2" wide with a diameter at start of life of 10" and at end if life is 7".
The T-4 wheel is 1 5/8" wide, starting at 8" diameter and ending at 6".

Using the formula for the volume of a cylinder as 'volume = length * pi * dia * dia / 4' we get

    T-7 starts with 157 cu" and ends at 77 cu" - so volume consumed = 157 - 77 = 80 cu".
    T-4 starts with   82 cu" and ends at 46 cu" - so volume consumed =  82 - 46 = 36 cu".

From this I conclude that there is more than twice as much useable life in the T-7 wheel compared to the T-4.

Ken might like to comment on this observation.

Martin

Welcome to the forum, Martin!  :)

Your calculations concerning the useable volume of the T7 and T4 grindstones are correct.  :)

From this point of view the T7 grindstone offers a more economical solution.

To be fair with the T4, when truing the T4 stone you remove slightly less material than when truing T7 stone. This is because the volume of the removed material is proportional to current wheel circumference.

The other thing you should consider is the total price of the unit and its weight.
If these two things are not a problem for you, then buy the T7, otherwise buy the T4.

Jan

Jan,

FYI here is the Aussie pricing from Carbatec in A$:

    T-7 (incl TT-50 & SE76) $989.00
    T-4 (plus tt-50 & SE76) $630 + $124 + $91 = $845
    Premium for T-7 = $144 (+17% compared to the T-4) for:
        Increased grinding capacity (+~100%)
        Larger motor (+66%) with 100% duty cycle (+100%)
        Increased weight (+77%)
        All steel construction + other features.

Martin

Reading between the lines of your reply Martin, I think you've already decided.  :)

TORMEK is an investment for at least 20 years, and from this point of view, the price difference is negligible.

Owning TORMEK is a pleasure and it's an advantage on your side.

Jan

Quote from: tkmartinc on August 18, 2015, 09:17:59 AM
Bonjour Sheang,

I am also trying to convince myself to buy a Tormek and one issue that I couldn't see being considered is the wheel size.

The T-7 wheel is 2" wide with a diameter at start of life of 10" and at end if life is 7".
The T-4 wheel is 1 5/8" wide, starting at 8" diameter and ending at 6".

Using the formula for the volume of a cylinder as 'volume = length * pi * dia * dia / 4' we get

    T-7 starts with 157 cu" and ends at 77 cu" - so volume consumed = 157 - 77 = 80 cu".
    T-4 starts with   82 cu" and ends at 46 cu" - so volume consumed =  82 - 46 = 36 cu".

From this I conclude that there is more than twice as much useable life in the T-7 wheel compared to the T-4.

Ken might like to comment on this observation.

Martin

I yelled this from the mountain tops to no avail. Please read all my comments on this from the beginning of the topic. Here is one quote of mine, "You are starting out with a stone that is 8 inches in size. Which do you think will last longer, the 8 inch stone or the 10 inch stone under the same usage? EVEN if you can use the stone when it is smaller than 7 inches, which one will last longer? The decision yours."

I believe we have not been looking at the whole picture.

I do not dispute the math showing that the larger 250mm grinding wheel has more useful grinding surface before being replaced. However, those who actually wear out a grinding wheel will discover that the replacement SG-250 costs almost twice as much as a replacement SG-200. (presently $105 USD versus $184, higher on eBay) To be accurate, one should factor in the replacement cost per unit of abraded grinding material. Personally, I do not feel this is a meaningful difference.

If one calculates the surface feet per minute, the T$ and T7 are almost identical due to the slightly higher T4 motor RPM.

One measurement remains relatively constant; the T7 weighs almost twice what the T4 weighs and is physically larger. If you subscribe to the notion that bigger is always better, and are still driving an oversized gas hog car, you will prefer the T7. The T7 may also fit your needs more closely if you are in an industrial work environment. If, like Steve and Doug, your "industrial environment" includes moving your Tormek extensively, you should weigh the difference in grinding wheel life with carrying twice the weight every time you set up.

Bigger is not always better. Lie-Nielsen manufactures updated copies of the old Stanley Chisel plane. These planes have nothing in front of the blade, which allows them to reach into tight places. The original Stanley was a large plane, about ten inches long. Lie-Nielsen makes both a same size model and a new smaller model. The smaller model outsells the larger. In my opinion, it is a more useful tool because of its nimbleness. I believe most of us would be well served with the smaller Tormek unit. Be honest, how many of us really sharpen large planer blades regularly?

My forty year old dry grinder, like most of the dry grinders on this forum, started with a six inch diameter grinding wheel, now reduced somewhat. I think calculating wheel wear is overblown. I also think obsessing over the cost difference between the T4 and the T7 is overdone. Both are capable tools. I would concentrate on the work environment. For use in a factory or fixed location busy sharpening business, the T7 makes sense. I also think that for a more mobile or smaller shop environment, the T4 is the logical choice. I used the T7 for several years before using the T4. I like both. There are no bad choices here, just individual preferences.

Ken

Ken, you're right, the price of the grindstone is only a stone in the mosaic of complex decision-making.  :)
Yet it seems to me good to clarify which of the stones (T7/T4) is more economical.

Based on the verified results of Martin's calculations, T7 grindstone offers 80 in³ of usable material, while T4 offers 36 in³.

Based on prices reported by Ken, 184 USD for T7 grindstone and 105 USD for T4 grinstone, we will get the following unit volume prices:

T7 184/80 = 2.3 USD/in³
T4 105/36 = 2.9 USD/in³.

Conclusion: The usage of T7 grindstone is more economical.

Jan

P.S.: To be fair with the T4, when truing the T4 stone you remove slightly less material than when truing T7 stone. This is because the volume of the removed material is proportional to current wheel circumference. On the other hand, T4 grindstone will produce larger hollow grinding and therefore wear faster than T7 grindstone.  Maybe these two effects compensate each other. So, the conclusion remains valid.

I am once again, vindicated. Based on your math,
T7 184/80 = 2.3 USD/in3
T4 105/36 = 2.9 USD/in3.
            2.9 USD = $2.90
          - 2.3 USD = $2.30
difference is               .60 cents x 44 cu inches = $26.40 saved using the T7 assuming each stone is used to uselessness. I do not see the average hobbyist using either stone to destruction but if that time comes, the end is further away with the T7. The only saving grace of the T4 then becomes the weight factor. If that is paramount to you, then you have only one choice and that is the T4. Good luck. 

Jeff,

I concede. Based on the math you and Jan have provided, it would appear that for each grinding wheel consumed, the T7 has a $26.40 cost advantage. After seven grinding wheels are consumed, the person who paid the $180 more for the T7 would start to be ahead. Add to this, one would have to calculate the difference in electricity cost between 120 and 200 watt motor usage.

I realize there are people who have consumed more than seven wheels. Steve and Doug are certainly in that category. I also concede that anyone who consumed that many wheels might be better served by the heavier duty machine.

In my opinion, the main factor in which Tormek to choose has always been usage, not cost. As a hobbyist retiree, I appreciate the lighter weight and smaller bulk of the T4. I am not anti T7. In fact, I tend to use both models interchangeably. I am presently revisiting the SB-250. I want to resolve the nagging feeling that my disappointment with it may be because of my own lack of knowledge. Based on Steve's comments, I believe the SB may be useful for more than heavy duty work. I want to find out. As Tormek does not yet manufacture the SB in the smaller size, that would be a plus for the T7. I remain open minded on this.

Whenever I have to move the Tormek, I always prefer to use the T4. It has plenty of power for my work, at half the carrying weight.
The choice is yours; as stated, I do not believe there is a bad choice.

Ken,
   You know you might gain that $26.40 several times because of having to make less trips to your Chiropractor due T7 backache syndrome! ;)

Point well taken, Elden.

Ken

In my opinion it is not a matter of weight so much as it is a matter of awkwardness. The T7 is awkward to carry due to design fault. There is just no good hand hold. I know it has a handle, both of mine do. Still, it is not the easiest thing in the world to move. Forget it if you have water in the trough. EMPTY the trough.

Ken, you are correct, we have to calculate the difference in electricity cost between 120 and 200 watt motor.  :)

It is not easy to estimate the electricity price for completely consumed grindstone. However, let's try.

Assuming that T7 grindstone can sharpen 2000 knifes before it is completely consumed and assuming we need on average 5 minutes per knife, we get:

2000 knifes x  5 minutes = 10 000 minutes = 167 motor hours.

Assuming further, that auxiliary preparatory work will take up the same time as grinding, we get, that the T7 grindstone may be fully consumed after 2 x 167 hours = 334 motor hours.

Now we can calculate the price of electricity for the consumed T7 stone:

334 motor hours x 0.13 USD per kWh x 0.2 kW = 8.7 USD

where
0.13 USD per kWh is current residential price of electricity in the USA,
0.2 kW is motor input power for T7.

What concerns the T4, with 0.12 kW input power motor, I hope we can assume that the price of electricity will be 60% (0.12 kW/0.20 kW = 0.60) of the amount for T7:

0.6 x 8.7 USD = 5.2 USD

It's really just a rough estimate based on numerous assumptions and simplifications. You can easily modify the figures, based on your experience, and get new results.
Nevertheless, the conclusion that T4 is slightly more economical than T7, what concerns electricity consumption, will remain valid.

Jan

Quote from: jeffs55 on August 18, 2015, 06:40:52 PM
I am once again, vindicated. Based on your math,
T7 184/80 = 2.3 USD/in3
T4 105/36 = 2.9 USD/in3.
            2.9 USD = $2.90
          - 2.3 USD = $2.30
difference is               .60 cents x 44 cu inches = $26.40 saved using the T7 assuming each stone is used to uselessness.

Jeff, I rethought your calculation, and I have to tell you, that the savings using the T7 stone may perhaps be even higher.  :) We may multiply the unit volume price difference 0.60 $/in³ with the whole usable volume of the T7 stone. So we get:

80 in³ x 0.60 $/in³ = $48.

Explanation: Imagine, that the whole usable volume of the T7 stone is composed of the more expensive T4 stone material. Then the cost of the T7 stone would be 80 in³ x 2.9 $/in³ = $232, which is by $48 more than the real price $184 reported by Ken.

Jan

Jeff,

You make a very good point about the real carrying issue being awkwardness. I don't think the problem is really a design fault. I just think the Tormek, like so many machines, was designed to be primarily stationary. It would be interesting to examine one of the original Tormeks, the model powered by an electric drill. At some point, the Tormek engineers must have decided that there were two markets for the Tormek. The European model was smaller, lighter, and more generally used for sharpening knives and scissors. The North American model was larger, heavier, and more marketed toward woodworkers. These two models cross functioned, but with different design parameters. In my opinion, the T4 is the first model to combine the best features of both.

At half the weight of the T7, the t4 is definitely easier to carry. However, like the T7, it is awkward to carry. The awkwardness is due to the weight of the grinding wheel. With the wheel removed, the T4 is a joy to carry. Without the wheel, it weighs almost nothing. More importantly, it has much better balance.

My solution for this would be a carrying case shaped like a bowling bag. The grinding wheel would be stored in a separate compartment directly below the Tormek. The Tormek and wheel would be securly stowed and the case would be balanced.

I would keep the case small. it could also hold the water trough, USB, a few essential jigs/accessiries and extention cord/LED light. My preference would be to carry these in a separate case. Carrying one case in each hand would balance the load. An arrangement with wheels and a handle might be nice.

My basic point is that leaving the grinding wheel mounted is what makes the Tormek awkward to carry. The new EZYlock shaft is a big help in carrying the Tormek.

Jan, your math skills are formidable. I have never used an electrical invertor, and have no idea of their wattage limits. For a really mobile operation, if the 120 watt T4 would work with an invertor, that could be a game changer. I enjoy your mathematical musings; they make me think.

Ken

Thank you Ken, for your kind words.  :)
You know, when you're able to describe something with mathematical formula, though very simple (+, -, x, /), you become master of the situation; you can discover something about the world around us.

I enjoy many of your aptly expressions; they expand my vocabulary.
For example mathematical "musings". I have found following explanation:

(http://img19.rajce.idnes.cz/d1902/11/11771/11771137_37021e568ec44478b9ce7dc74d286378/images/musing_definition.jpg?ver=0)

Jan

Ken,
The term design fault is incorrect as you maintain. It just was not designed to be moved around much like an anvil is not a mobile fixture.
Jan,
Thank you Jan for your input but I had a thought. You have determined that the T4 is more economical to run. In your thoughts did you take into consideration that the T4 will always have to run longer to do the same job as the T7? Based on C=πD the T7 wheel is 31.4 inches in D and the T4 is 26.69 inches in D. Based on the T7 being 10 inches and the T4 being 8.5 inches. The difference is 4.71 inches. The T4 wheel then is about 15% smaller in circumference than the T7.
You would therefore have to run the T4 15% longer to do the same job and so use 15% more electricity and take 15% more of your time. You are the math wizard so see if I am right. thanx

Yes Jeff, you are thinking logically correct!  :)

You have made only minor numerical mistake, assuming the diameter of T4 stone is 8.5". In fact it is only 8" and therefore the T4 wheel is even 20% smaller in circumference than the T7.

So, your numerically corrected conclusion may read "You would therefore have to run the T4 20% longer to do the same job and so use 20% more electricity and take 20% more of your time."

This would be true provided that the circumferential speeds of both stones are identical. But in fact T7 has 90 RPM while T4 has 120 RPM. For this reason the circumferential speed of a new T4 stone is by some 7% higher than the speed of a new T7 stone. [(120 RPM x ¶ x 8") / (90 RPM x ¶ x 10")]

For simplicity, I have ignored both issues mentioned above, in my previous calculations.

So, the corrected price of electricity consumed by T4 could be (60 + 20 - 7)% of the price for T7:

(0.60 + 0.20 - 0.07) x $8.7 = $6.35

My previous conclusion, that T4 is slightly more economical than T7, what concerns electricity consumption, remains valid.

Jan

Mr Euclid of Alexandria might point out that the grinding wheel of the T7 revolves at 90 RPM and the grinding wheel of the T4 revolves at 120 RPM....... ;D

Ken

I do not want to confuse any of the readers. Jeff, like many on this forum, is quite experienced with his two vintage Tormeks. i happen to be more of a late comer to the Tormek, and have a more recent T7 and a T4. I am no stranger to older tools. I am happy as a clam with my grandfather's well tuned 1891 vintage Stanley jack plane. I would probably snap up a vintage Tormek at a very low price (in a heart beat) rationalizing that I would use it with the SJ or SB grinding wheel.

I happen to think a new Tormek user who is also inexperienced in sharpening is best served with a new machine. The learning curve is hard enough without having to contend with possible problems from an older machine. I believe the only bad choice in purchasing a Tormek is paying a lot for an older machine in need of a lot or repair. The newer shafts are stainless steel, even before the EZYlock shafts. The older, non stainless shafts were prone to rusting and freezing with the grinding wheels. Repairs are easily done by the user, however, a new grinding wheel and EZYlock shaft will cost around $250 USD. I have found most used Tormeks are overpriced when the cost of repair is added, compared to getting a new machine.

I happen to like the T4 because of its size and weight. I also have no criticisms of my T7, especially if I do not have to move it much. Personally, I would forget cost and go with whichever Tormek suits your work environment. Do not agonize over which one is the right choice. There is no wrong choice; either will work fine.

This forum would not be as enjoyable if everyone was thinking in lockstep.

Ken

Quote from: Ken S on August 20, 2015, 05:00:50 AM
I happen to think a new Tormek user who is also inexperienced in sharpening is best served with a new machine. The learning curve is hard enough without having to contend with possible problems from an older machine.

Agree.

Would like to add that the newer kits also come with darn near everything that one would 'need' for regular and accurate stone maintenance and angle setting.

The Taiwanese versions do NOT include these sort of items last time I checked.