Tormek T7 problems

[Ken S]

I agree, we have not reached the full potential of the Tormek. Even in the few years (since 2009) that I have used a Tormek, the developments have been amazing. The EZYlock stainleaa steel shaft; the SB and SJ grinding wheels; the DBS-22 drill bit jig; T4; T8; several redesigned jigs. Development is ongoing.

Some of the advances in knife sharpening that you might envision in the future are already here. Google Steve Bottorff and Robin Bailey. Both are forum members as well as very experienced knife sharpeners and teachers. Robin has designed and manufactured a well designed oversized universal support. Steve has written a book on sharpening and has produced an excellent DVD package. He has generously posted some parts of his DVD on the forum and on you tube.

I think you will be pleasantly surprised to read about some of the knife jigs and techniques post be forum members. Ideas get bounced around and improved by various members.

Please feel free to learn from our ideas and add your own thoughts.

Ken

[Herman Trivilino]

I don't divide the angle setting.

That's the source of your problem.

[Herman Trivilino]

I did the horizontal sharpening today and so far the result was okay. I was able to sharpen the knife at a 30 degree angle and the result was okay. ...

If you set the Angle Master at 30° and sharpened both sides, you have an edge angle of 60°. That's appropriate for a cleaver or machete.

Is there any disadvantages when sharpening on the horizontal position?

It doesn't remove steel as fast, but many prefer it because you have more control. I prefer to use a homemade platform jig and sharpen towards the edge.

[Ken S]

Herman's small knife tool started out as a better way to handle small knives than the Tormek platform jig. In fairness to the Tormek platform, it was never designed for small blades. The constraint is the width of the jig. It is wide enough that one side of the knife can not be ground full length. Herman's jig is the width of the grinding wheel, so it works well with both sides.

Herman based his design on the platform with the scissors jig, which sits lower than the platform jig. The jig is still usable with scissors. Herman has sharpened a machete with his jig. Its use extends far beyond small knives.

I think one of the small knife jigs should be part of a well equipped sharpener's kit. (For the record, I feel the same way about Tormek's small blade tool, which works differently.)

Ken

[Jan]

Angpanday, I think you are in a difficult situation because:
1)   the knife blade is too thick for the knife jig and
2)   the knife blade tappers towards the edge.

The hardware solution of the issue ad1) was described by Wootz. This issue has to be resolved because such a thick knife is not correctly centred in the knife jig.

The solution of the issue ad2) is in your hands without any hardware changes. When setting the desired edge angle using the AngleMaster whose setter is touching the primary bevel, you have to correct for the tapering angle of the blade.

Because your knife is thick the angle of your blade (primary bevel edge angle) may be some 20° or more. If your desired edge angle is 30° you need to set 30° - 20° = 10° on the AngleMaster. 

In my understanding until now you were ignoring the blade tapper and so unintentionally sharpening an edge angle 30° + 20° = 50° which could resulted in throwing the knife back at the operator when sharpening towards the edge.

Jan

P.S.: I have assumed you set the edge angle as shown in the handbook picture.

[angpanday]

Jan, yes I measure the angle from how it is shown on the book. From my observation using the angle master. If I set the angle at 25 the knife will not throw back at me, but once I go above 30, it has that tendency to happen.  The 30 degree angle will show a nice looking cutting edge ( around 1 to 1.5 mm ). Below 30 will show a much wider cutting edge ( 2-3mm ) which is not appealing when you plan to sell the knife :-(

[Jan]

The reason why the cutting edge is wide for angles below 30° is too small angular difference between primary and secondary edge angle. 

Imagine that your primary edge angle is some 24° and you set the secondary bevel angle for 26°. Than you will get wide cutting edge. When you enlarge the secondary bevel angle to 28° you will get significantly narrower cutting edge. 

Good luck! Please keep us posted. 

Jan

[angpanday]

Because your knife is thick the angle of your blade (primary bevel edge angle) may be some 20° or more. If your desired edge angle is 30° you need to set 30° - 20° = 10° on the AngleMaster. 

In my understanding until now you were ignoring the blade tapper and so unintentionally sharpening an edge angle 30° + 20° = 50° which could resulted in throwing the knife back at the operator when sharpening towards the edge.

Jan

Your formula is very confusing?


I also use the Tormek T7 to sharpen thin kitchen knives ( 2-2.5 mm ). The angle I use 25 degrees.  With that angle from the Angle master it will create a nice cutting edge.  Around 2mm wide on both side.

Now with the thick 3/16 blade. At 30 degrees it will create a  2mm wide cutting edge.  However, it will have an unbalance cutting edge. One side will be  2mm the other will be around 2.5mm .  Now if I do the mods on the jig I think it will fix that problem.


If I will follow your formula and set it to 30-20 = 10 degrees on the Angle master. How big will the cutting edge be 5mm? or even more...

[Jan]

Yes, the formula is confusing at first glance. The formula is valid when the AngleMaster setter is touching the wide primary bevel, shown blue in the sketch below. It was my attempt to explain your issue.   

If the AngleMaster setter is touching the secondary bevel, shown red, than no correction is necessary. It is a standard situation described in the handbook. 

Jan

[WolfY]

Except for agreeing with all above I would add my experience.

D2 and alike hard metals have to be handled with very light pressure and slow move. Otherwise the metal will cut into the stone when used against the wheel. I prefer this method as u can see the water getting up on the blade and know that you are parallel to the stone. Also the sharpening position works better for me and it's easy to leave the knife with the jig when measuring the angle with the WM-200 that I use frequently.

Don't forget to deduct the first bevel angle when you measure with the WM-200 as it is optimized for straight primary bevel.

[Ken S]

I have never worked with D2 steel. I have found that I have more efficient grinding with HSS by using a lighter touch. (I usually grind away from the tool, too.)

Some experimenting may pay good dividends.

Ken

[angpanday]

Yes, the formula is confusing at first glance. The formula is valid when the AngleMaster setter is touching the wide primary bevel, shown blue in the sketch below. It was my attempt to explain your issue.   

If the AngleMaster setter is touching the secondary bevel, shown red, than no correction is necessary. It is a standard situation described in the handbook. 

Jan

Jan, if there is already an existing cutting edge on the knife. I think the best thing to do is just regrind the existing bevel.  Now from the existing cutting edge I will be able to know what angle it already have.... then from there I will just chase it to the desired angle.

[Jan]

I agree with you, Angpanday! 

I personally use for setting the cutting edge angle the kenjig concept, which is based on geometrical relations, and which is immune to blade tapering problems. It works also fine when the secondary bevel is very narrow. 

Jan

[Ken S]

Thanks, Jan. It means a lot to me that you, with your formidable math background, recognize my practical little tool.

Ken

[Herman Trivilino]

Jan, yes I measure the angle from how it is shown on the book. From my observation using the angle master. If I set the angle at 25 the knife will not throw back at me, but once I go above 30, it has that tendency to happen.

If you set the Angle Master at 30° and sharpen both sides, you have an edge angle of 60°.

In Reply #22 you posted a chart showing edge angles. The largest is 40°, which is appropriate for a butcher knife.

Why are you sharpening your knife at 60°? That's an appropriate edge angle for an ax, machete, or cleaver.