Square Grinds with SE-76

[Steve Brown]

I just sharpened a 3/4" chisel in the SE-76, made sure it was perfectly square in the jig, ground it on the 220 and it came out skewed. What did I do wrong? Too much pressure on one side, the jig is out, what? It's a new stone, never been dressed.
Steve

[Jeff Farris]

Steve,

First, bring the bar down to just barely above the grindstone and examine the gap between the grindstone and the bar. It should be precisely parallel.

Next, confirm that the tool sides are precisely parallel with each other, and that the tool is of a uniform thickness.

I have found a distinct pattern of the tool walking away from the reference edge when tightening the clamping bar. It seems very difficult to control, but if you check it carefully a couple times before you start grinding, I think you might find that the tool has squirmed slightly away from the reference. take just a tiny bit of pressure off the clamping bar and push it against the reference again and retighten the clamp.

Let me know how it goes.

[ionut]

Hi Steve,

I agree with Jeff before doing any sharpening with a new stone you have to verify if the grinding surface is parallel with the universal support.
I always true a stone out of the box, the stone may be out of round or the grinding surface not parallel with the universal support.

I have occasionally seen the same behaviour Jeff is telling about. In addition to his suggestion you may try the following: before clamping the tool make sure it is rested tightly against the reference, hold the clamp flat on the tool and give to the knob on the far side a quarter to a half a turn (don't tight this one) and after that tight the close knob; or clamp the tool in the middle between the knobs, that way it is easy to apply the same pressure on the tool sides so the tool will not het skewed during the process or during tightening.

The flatness of the back may also affect the squareness of the edge, if the surface where the tool is clamped is not in the same plane with the surface at the cutting edge you will not get a square edge,  what you can do there if is not too bad is to lower the tool in the jig as much as needed to have the clamping surface in the same plane with the surface at the edge.

Thanks,
Ionut

[ionut]

... also if I remember correctly there was a similar thread not long ago and you may want to look into information you find there too.

Ionut

[Steve Brown]

So, after reading  and re-reading all the posts from Jeff and Ionut, I think the light finally came on. The SE-76 has two outside stationary bars. The inside bar, the clamping bar, once the tool is positioned against the reference edge on the right (with the handle facing the operaor), the clamping bar should be parallel to the two outside stationary bars. If the clamping bar is not parallel, the sharpening will skew to the side (or away from the side) that is applying the greater pressure. If, by the same token, if the sharpening is coming out skewed, even if the clamping bar appears to be parallel, the operator may be applying uneven pressure on the tool against the grinding wheel, or the tool may be out of square because of the way the back is flattened or some other unusual condition. If this is the case, the operator can tighten or loosen the adjustment knobs by a quarter  ;Dor eighth turn on the clamping bar to compensate. It is apparently important to check the squareness periodocally while sharpening. Does any of this make sense? 
Steve

[ionut]

Hi Steve,

I am not sure if I get you correctly. The top part of the SE-76 is a reference surface on which the flat back of the tool will rest. Another reference part is the right solder on which the side of the tool rests and aids for squareness. The differential torque applied on the knobs may slight move the tool, that is why most of the times I clamp the tools ion the middle of the jig so I have maximum control on those knobs also after they get tight the tool will not move as I apply pressure while grinding. The grinding pressure applied differently on the too may influence the square edge but more than that will be caused by how much you move the tool outside of the stone. For tools with a smaller width than the stone I never move the tool outside of the stone more than a mm at the most two, for tools that are wider like plane irons I always keep around 10mm (3/8") on the stone and I compensate for over-grinding the center to not end with a concave edge. This means I grind the corners a bit more than the center. Don't overlook the back flatness, if the area where the tool is clamped is not in the same plane with the cutting edge you will never end with a square edge. The parallelism of the clamp itself has nothing to do with the squareness or the edge, the clamp is meant to adjust on the face of the tool that is not used as a reference surface as it does not influence the cutting edge in any way. If you follow the steps below you should end with a square edge:
- if you know the tool is flattened properly skip this step, if you don't know find out, if it is not it should be flattened properly. If you would do sharpening entirely by hand you only have to flatten the area close to the cutting edge. If you plan to use any honing jigs or the tormek you have to make sure that if not all the area from the place where the toll gets clamped in the jig is in the same plane with the cutting edge, this will get corrected before starting to sharpen and troubleshooting anything else.
- make sure if the stone is true to the universal support, if it is not true the stone and do it in small steps.
- when you lock the universal support for any operation ALWAYS apply pressure consistently in the same place - over the left side leg (the one with the adjusting wheel).
- clamp the tool, if you rest the tool side on the shoulder hold it against it while you tighten the knobs. If you suspect the knobs moving the tool while tightening hold the clamp over the face of the tool and move the far know until it contacts the clamp, give it another 1/4 to 1/2 turns only. Tighten the close knob. If the tool has parallel sides you can use a square to verify the squareness in comparison with the reference part of the jig (not the clamp). Or you can follow Jeff suggestion for this part.
   - if this is still not leading to a square edge, clamp the tool in the middle of the jig and tighten the knobs alternatively in multiple passes until you achieve similar pressure on both knobs.
- adjust for the bevel angle and when established take to jig off the universal support.
- press over the left post and tighten the left knob and then the  right one.
- put the jig back and start grinding - for cutting edges smaller than the grinding stone with don't more the tool outside of the stone more than 2mm, for wider ones always have 10mm on the stone. I you suspect differential pressure applied by you is a problem remove your fingers from the close area to the edge and apply pressure by pushing with one hand from underneath the tool up behind the jig, using the other hand to move jig left and right.
- you can stop any time during the grinding and check the edge. DO NOT UNCLAMP the tool, if you have to do that for any reason you have to start again from setting the bevel angle.
- from this point you know.

Ionut

[Steve Brown]

Hi Ionut,
The Tormek really is an excellent tool, but you do have to learn how to use it properly. I do understand all that you are saying. I just didn't realize how important it is to check your work while sharpening is in progress and I didn't realize that you can't move the tool in the jig after you start sharpening. Also, for me I believe that using bench stones for flattening the back is better because for one thing you don't have a moving target and for another thing, you can go to the higher grits which I believe is essential. So now, I'm going to be making a hard maple butcher block countertop. Do you have experience using the planer blade jig and do you have the silicone blackstone? Thanks for your help,
Steve     

[ionut]

Hi Steve,

Yes I use the planner blade jig and it is working great, setting it up is a bit trickier than the square jig but as soon as you catch it's functionality it is easy,  the manual is a perfect resource for using it. I have posted an alternative way to set it up which seems to be easier for me and you can find that post somewhere under the Planner Blade Sharpening folder, I would suggest you to apply the method described in the manual fiorst. I also recently got the black stone which in my opinion is the way to go for HSS blades I also posted about it in the General folder, the stone does a much faster job compared with the original stone. Being a harder stone is prone to get glazed easier but you have the stone grader that can be used to restore the cutting action.
I agree, Tormek is an excellent machine but as with other tools to be successfully you have to pay attention to what you are doing, it is just a matter of learning which are the strong points of this system, the principle of working and after that applying these things while sharpening will get you where you want to be.

Ionut