1/4" Bevel Edge Chisels

[kennyk]

Great post, Mike.  I had just sat down at my computer with me SE-76 in hand.  The front surface was a bit rough.  A couple minutes with a six inch second cut mill file and the roughness was gone.  Another five minutes removed a ridge in the inside rear surface.  My method seems adequate; Mike's is superior.

Kenny, you seem quite stressed.  Have you tried slowly sharpening  a 3/4" chisel?  I hate to sound like a broken record, but all you write about are out of square quarter inch chisels. If you take the time to work through the bug with an easier wider chisel, with practice you will soon be up to speed.  Once you get the hang of it, I don't think you will have any trouble meeting your deadline.  Change your mindset to doing the easiest tool first, one at a time.  Think just one tool. With practice you should be able to sharpen most chisels in ten to fifteen minutes. Do the easiest ones first.

Ken

Yes,  I've just tried a 3/4" chisel.  First I trued the stone.  I applied force to the micro adjust leg before I tightened the screws, and made several passes.  Then I put my 2" square on the surface.  The 6 thou gap at the outer edge to about 3/4" in from the edge was not acceptable. so I reset the support by putting pressure on the non micro-adjust leg.  This cured the mjajority of the gap but I still have a very gap at the edge.

Next I tried Mike's lapping of the SE76 face with a brand new block of granite, and papers up to 1200 grit. 
Once I was happy with that I squared the 3/4" chisel in the jig using my 2" square to the front face, and put it on the T-7.

I put hardly any pressure at all, and made a few passes. and you know what.  I'm still getting a considerable  skew to the right ( handle towards me, looking down on the chisel from above).   and I'm utterly fed up.  I simply cannot waste any more time on something that clearly does not perform as the marketing hype claims.  The fact that there are so many things to check and things that could interfere with the operation that the instructional information does not cover causes me huge concern.

[RobinW]

I would like to address some of the points made by kennyk in post #33.

"My point about the Universal support is that it is possible to align or misalign (at this stage I still don't know which) it by putting pressure on the leg without the micro adjust before tightening both screws.  Yet nobody has taken me up on this and I'm feeling that it's being glossed over.   it's not when the height is adjusted. it's when locking it in position."

I find it difficult to understand why you would pull up or push down on the end of the usb. Of course due to the necessary difference between the inside diameter of the holding sleeves and the outer diameter of the usb legs there must be a small difference and any external pressure will cause the usb to cant by a small amount. Why would you do the above?

If the usb and the wheel surface are not bang on parallel then you will have great difficulty in getting anything square, so why induce and error by applying pressure to the usb?

Jeff the Moderator has already advised, and so did I as per yesterday's procedure, that when setting the height, apply downward pressure (it is only finger pressure) directly above the threaded leg and this causes the usb to sit on the micro-adjuster. Clamp that leg, then the other.

When both usb legs have been clamped, pulling up and down on the usb horizontal arm will induce a small deflection, which I suspect is more from the body of the machine than my strength in bending a 10mm steel bar

I have just done the following test. With both legs clamped and the top of the usb bar 36mm above the wheel, I could pull up and press down and cause the bar to be 0.5mm up and down. That takes a fair force which I would not do in normal use.

Despite my views, above, I have also just undertaken your request:-

"To over exaggerate the phenomenon, I'd like somebody to loosen the locking screws, torque the support bar either by putting pressure on the leg without the micro adjust ( the left one if the power switch is to the rear of the machine) or by pulling the outer edge of the support bar up and locking the non-adjust leg first.   Once it's in that position, I'd like someone to grind a bevel and report back whether it is square.   Then I'd like them to loosen the support locking screws again, put downward pressure on the outer edge of the bar and re-lock as before and run the same grinding test."

I used a depth gauge from the top of the usb to the wheel - it was easier than trying to get the vernier beneath the usb.

When I locked the smooth leg, pulled up on the end of the usb (machine beginning to lift off bench), and then locked the threaded leg I got 0.5mm difference between inside and outer side.

If I locked the smooth leg, pressed down on the usb and then locked the threaded leg I could induce a difference of 1.5mm. I should point out that the forces I applied would not be applied in normal life!

I then dropped the usb down on to the wheel,and confirmed that the usb was consistent with the wheel as per yesterday's post.

With the usb resting on the wheel, if I then locked the smooth leg only, and lifted up the end of the usb so the machine was just being lifted, I could measure a gap of 0.75mm at the outside and 0.25mm at the inside.

If I then locked both legs and re-lifted by the end of the usb, I could measure 0.1mm at the outside and zero at the inside.

Conclusion - When the usb is locked it takes quite a load on the usb to cause a deflection.

I didn't bother trying to do any grinding because if I induced a 1.5mm offset in the usb I would expect to get skewed results.

Regarding your post #45, if I was getting a skewed grind, I would not apply pressure to, or re-adjust one leg, of the usb.

I would apply more finger pressure to the side of the chisel needed to square it up.

If that didn't work, I would ease and retighten the clamps of the SE-76 as these can induce twist.

If that didn't work I would re-align the chisel in the SE-76 as it could be the 'bicycle wheel' effect as posted previously.

Some time ago I posted about having some 3d modelling done with very small angular changes (typically 0.5 ~ 2.0 degrees) applied to a chisel in two planes, against another curved surface (wheel). This showed that very small angular differences at the SE-76 can induce apparently large effects at the end of the chisel.

[Rob]

Kenny.  To isolate the problem I've suggested (in another thread) that one of the forum members hooks up a Skype or face time call with you to coach you through the process.  It might be that there is a flaw somewhere with your particular machine and this may throw light on that.

I believe Stig would normally take this approach but regrettably the Scandinavian Holiday pattern has come at just the wrong time.

I would suggest one of the US based chaps help you out due to the time zone and cultural alignment.

[kennyk]

I find it difficult to understand why you would pull up or push down on the end of the usb. Of course due to the necessary difference between the inside diameter of the holding sleeves and the outer diameter of the usb legs there must be a small difference and any external pressure will cause the usb to cant by a small amount. Why would you do the above?

If the usb and the wheel surface are not bang on parallel then you will have great difficulty in getting anything square, so why induce and error by applying pressure to the usb?

Jeff the Moderator has already advised, and so did I as per yesterday's procedure, that when setting the height, apply downward pressure (it is only finger pressure) directly above the threaded leg and this causes the usb to sit on the micro-adjuster. Clamp that leg, then the other.

As I pointed out in my previous post, when I did as Jeff advised and ran the truing tool across the surface I got a gap at the outer edge of the stone when I put my 2" square against it. By gap I mean over 6 thou at the outer edge, which tapers to nothing 3/4" in from the edge.  By putting pressure on the other leg before clamping and running the truing tool I do not get the same result.

Every single chisel yields this result.

I'd welcome some thoughts.

[Herman Trivilino]

Also, I'm currently of no mind to put the grading stone anywhere near the wheel, as there is no way to guarantee that I'm not going to take it out of true at this stage, and undo the work of the truing tool and I KNOW that it has curved the grinding edge of the wheel badly before, to the point that it needed 8 passes with the truing tool.

You have to use the stone grader to dress the surface of the grindstone.  If it's putting the grindstone out of true then you have a defective grindstone.

[kennyk]

Kenny, where are you located?  I wonder if there's anyone nearby who could help.

I'm near Glasgow.  The school itself is in East Renfrewshire but  I live in North Lanarkshire.

[kennyk]

Also, I'm currently of no mind to put the grading stone anywhere near the wheel, as there is no way to guarantee that I'm not going to take it out of true at this stage, and undo the work of the truing tool and I KNOW that it has curved the grinding edge of the wheel badly before, to the point that it needed 8 passes with the truing tool.

You have to use the stone grader to dress the surface of the grindstone.  If it's putting the grindstone out of true then you have a defective grindstone.

Perhaps I'm looking at this from the wrong angle.    I'm used to flattening Waterstones to tolerances where if there is any light whatsoever showing between the surface and a square, then it's not flat enough.

The last time I  tried putting force on the stone grader I succeeded in curving the surface of the grindstone,  I can only presume because it rocked slightly or I put too much pressure on one side at a time?   Am I using too much force?

To me the phrase "Apply Light Pressure" in the instructions is somewhat meaningless.  There is no point of reference. Is it enough pressure to say, leave a thumbprint in a blob of blutac? or do I want to make a dent or full thumb impression?

[Rob]

Didn't realise you were in Scotland.  One thing that occurs to me.  Why do you need the whole bevel ground?  If your students are just paring mostly then could you not get away with a (say) 1 mm microbevel at a higher grind than the existing bevel (say 30 degrees)?

Then you would have significantly less grinding to do (I'm not a fan of grinding entire bevels with the Tormek), the edge would still be sharp and more hand controllable to keep straight.

But coming back to the original issue, are you saying you're unable to get the usb to be parallel to the wheel even after you've trued it with the diamond dresser, even by applying judicious pressure on the usb legs at tightening time?

Because if you cant do that then there must surely be something wrong with the usb threads or the inserts into which they're threaded?

[Rob]

Also, I'm currently of no mind to put the grading stone anywhere near the wheel, as there is no way to guarantee that I'm not going to take it out of true at this stage, and undo the work of the truing tool and I KNOW that it has curved the grinding edge of the wheel badly before, to the point that it needed 8 passes with the truing tool.

You have to use the stone grader to dress the surface of the grindstone.  If it's putting the grindstone out of true then you have a defective grindstone.

Perhaps I'm looking at this from the wrong angle.    I'm used to flattening Waterstones to tolerances where if there is any light whatsoever showing between the surface and a square, then it's not flat enough.

The last time I  tried putting force on the stone grader I succeeded in curving the surface of the grindstone,  I can only presume because it rocked slightly or I put too much pressure on one side at a time?   Am I using too much force?

To me the phrase "Apply Light Pressure" in the instructions is somewhat meaningless.  There is no point of reference. Is it enough pressure to say, leave a thumbprint in a blob of blutac? or do I want to make a dent or full thumb impression?

I must say, if I'm regrinding an entire bevel (that's usually a fair bit of steel) I WANT the stone to be as abrasive as poss.  The stone is at its optimal cutting quality directly after truing.  So why grade with the SP650?  Grade with that SP650 AFTER the stone has lost its cutting action not before.  By grading a diamond trued stone even with the rough side is actually lessening the cutting action as well as putting the trueness at risk with a hand operation.

Here's another tip that works really well for me.  Buy a cheap diamond T type dresser (about £8).  Run the usb up to about 1mm away from the wheel and rest the dresser on the usb and square on to the wheel then gently apply pressure.  That thing will shift a lot of ceramic off the wheel and it will necessarily be parallel to the usb.  You can see it all by eye as you do.  It achieves two things:
1/ you rejuvenate the cutting quality of the wheel very fast
2/ its all visible as its within view because the usb is so close to the wheel that by eye you can check the parallelism as you go whereas with the diamond truing tool, its more slick sure, but the usb is way above the stone and the truing tool is hanging off it upside down and you cant judge by eye how its progessing in terms of parallelism.

[Rob]

by the way pm me your batphone number if you want to talk this through.  I'm going to Jersey tomorrow so wont be able to help after tonight. 

[kennyk]

Didn't realise you were in Scotland.  One thing that occurs to me.  Why do you need the whole bevel ground?  If your students are just paring mostly then could you not get away with a (say) 1 mm microbevel at a higher grind than the existing bevel (say 30 degrees)?

Then you would have significantly less grinding to do (I'm not a fan of grinding entire bevels with the Tormek), the edge would still be sharp and more hand controllable to keep straight.

But coming back to the original issue, are you saying you're unable to get the usb to be parallel to the wheel even after you've trued it with the diamond dresser, even by applying judicious pressure on the usb legs at tightening time?

Because if you cant do that then there must surely be something wrong with the usb threads or the inserts into which they're threaded?

All of the chisels I've been working on have been ground at random angles, and all have badly convex edges.  The previous tech used a worn oilstone as well which didn't help either.   I'm trying to get them all uniform, as I feel it's fairest on all the kids that have to use them that they get consistent chisels.

After truing, I measured the wheel edge using the side as the reference for my square.  I'd need to re-do it and check with the usb again to be 100% I'm not giving misinformation.

the threaded leg is at 90% to the bar, and the bar itself seems straight too.

Is it possible that the truing tool itself is out of alignment?

Just to clarify, I wasn't using the stone grader  directly after truing.  it was when I checked the stone with a square later on (after a few gradings) that I discovered the convex surface.

[Tormek moderator]

In the photos, you're assuming the old bevels are perfect, and it appears to me they are not.

If you try to correct a .006 deviation by torquing the Universal Support, you will undoubtedly waste time and effort and cause yourself a great deal of frustration. That amount of deviation can be corrected by moving your thumb from the middle to the long point edge.

You are going to have to give up on the idea that every component is in perfect alignment and the tool comes out perfectly. You are dealing with an abrasive. The cutting action will change as the stone is used. It is not, nor will ever be, completely uniform in cut across the surface or through it's depth.

Quit worrying about getting the stone out of true with the stone grader. The stone grader is an absolutely essential piece of the puzzle. I promise you, if you rely on finger pressure and leaving the short point off the stone, checking the results while working, you can create a perfectly square edge on a grindstone that is badly out of alignment with the Universal Support. I have done it thousands and thousands of times. I'm not condoning leaving your stone in such a condition, just pointing out that perfect alignment does not guarantee success, but misalignment doesn't preclude it.

[Rob]

Kenny.  I've texted you my contact details.  By all means call me if you like.  Cheers.  R

[RobinW]

"As I pointed out in my previous post, when I did as Jeff advised and ran the truing tool across the surface I got a gap at the outer edge of the stone when I put my 2" square against it."

I would suggest this is the first issue to be resolved. After using the truing tool, the surface of the wheel should be parallel to the usb. Ignore the side of the wheel and using a square against a side which you cannot guarantee, and plays no part in the sharpening process.

Do not apply any offset pressure to the usb when setting the height for the truing tool.

I feel that you are moving from one issue to another and certainly gets me confused.

Resolve the above fundamental requirement. Until that is resolved you'll be chasing your tail with no fixed reference.

[Rob]

I've just chatted to Kenny on the phone en route from school to home. Hopefully we'll have a dialogue later and see if we can punch through some of the variables.