Square Edge Issues with SE-76

[RobinW]

I have just spent the weekend with my new T7 and a bunch of chisels for sharpening and also as practice prior to trying my plane blades. I have also a spent a lot of time looking at a lot of previous entries on the Forum relating to achieving a square edge. Although I have not achieved the ease of sharpening as demonstrated by Jeff Farris, and still some way to go, I thought I would pass on some of my experiences so far!

When I observed that I was not getting a square grind, I checked out how the universal support and wheel aligned; re-trued up the wheel (even though it looked OK against the support and I would not expect to do this on a brand new item); tried to check how the chisel(s) were square or not in the jig; tried to assess if the face of the jig was square to the registering face against which the chisel abuts; couldn't come up with a simple method of checking whether the holes in the jig were at 90 degrees to the reference face in the jig or parallel to the front face of the jig; and anything else which I could check that might affect the outcome. I could write a dissertation on this lot alone!

Conclusions and queries:-

a) Having used the side of the wheel to flatten the back of the chisels (and I experienced the same issues as reported by others in the Forum) it occurred to me this practice can introduce an area of error. As per the Tormek book, flattening 25  - 30mm (1 - 1.25") from the edge of the chisel, this does not mean that the back face at the edge end of the chisel is still in the same plane as the area  nearer the handle where it is clamped in the jig. So this can introduce a 'twist' in plane of the back of the chisel between the edge and the clamp area. The amount of metal removed in flattening should be small and insignificant, but it is an area of error introduction. The only way this can be eliminated is to flatten the back of the whole chisel, and that is not possible using the side of the  wheel, and not something any of us would like to spend our lives doing by hand.

b) Trying to prove whether the front face of the chisel is parallel to the back of the chisel is another issue, especially when using firmer chisels which are tapered. We are now getting into the realms of precision measurement which would require some measuring kit and not what I want to spend my time on.

c) As most of my chisels are, like me, getting on a bit, I also checked the sides for straightness, and found these, also like me, are not ramrod straight. This is another source of misalignment when placed against the reference face in the SE-76.

d) When a chisel is in the jig against the reference face and clamped using the nearest locking knob, looking end on to the chisel in the jig it could be seen that the back of some chisels were not sitting completely flat against the jig. Small amounts of light be seen between the items. This is due to the pressure from the clamp and discrepancies in the back of the chisel causing the chisel to cockle in the jig. This becomes more of an issue depending on the length of the chisel blade available. With the minimum of 50mm chisel blade protrusion from the jig as per the manual, the clamp was now having to cope with the chisel area near the neck or handle and this is where the shape changes from flat to round. This was overcome by changing the pressure from the nearest clamp and tightening up the far away clamp, or fiddling between the two. Not exactly slip in and clamp as per demo videos.

e) The nearest I have achieved for achieving a square edge is to place the chisel in the middle of the jig and as per instructions for Japanese blades which are generally short, and fiddle around until the grind starts to look square. This now becomes an eyeball job rather than the purpose of a square jig and takes some time. I found it difficult to determine what is the reference point or face on the jig. The front face of my jig is not machined whereas the back face is. So where to use an engineer's square and check chisel alignment is unknown. Impossible to put inside the jig when occupied by a chisel. The next issue with this is how to check for squareness. As the blade protrudes from the jig by 50 - 60mm it requires a very small engineer's square with a handle section less than 50mm long - which I do not have at present - to do this task. More time has been spent trying to find a source, and in a previous Forum entry someone advised that Starrett make one. Their website shows one as 75mm (3") but this I believe refers to the blade. However I have just had a call back from Starrett that the inside length of the handle section is 37mm so this will do the trick.

So where does this leave me?
I think I will go back and check and reflatten the back of the chisels which may look out of true from the Tormek wheel and re-do them on a Waterstone for as big an area as my hands will allow. Plane blades have been previously done this way and will stay that way!

For any firmer chisels with tapered blades, or any which are not dead straight along their side, then I expect I will mount them in the centre of the jig and use a small square to check for alignment. The SE-76 jig will aid grinding as a guide but not fulfilling its intended use.

For bevel edge chisels with straight sides I will have another attempt and hopefully I can get the jig to work as the designers intended.

As for plane blades, this may be another story in the future!

Maybe Tormek could re-consider their jig design for the next generation, where the jig is extended towards the wheel and the chisel clamped close to the edge. This would allow clamping to be done in the flattened back area, and square alignment would also be achieved near the edge which would also make it more accurate by eliminating any chisel side discrepancies. Sketch thoughts can be made available!

For some years I have not been able to justify to myself the cost of a Tormek machine, but having taken the plunge I have to get it to work effectively and efficiently. It certainly can produce sharp edges as witnessed by my trial wood cuts and the sticking plasters on my fingers!

So any comments on the above experiences and how to get  up the learning curve would be appreciated.

[Ken S]

Robin,  welcome to the forum.  Kudos for a very thoughtful, articulate post.

I am curious.  Are the chisels you are sharpening off square consistently or randomly?  My gut feeling is that if the angles are consistent, the Tormek or Tormek user may be the culprit.  if the angles are random, I would look at the chisels.

I have mixed feelings about flattening the backs on the side of the Tormek wheel. I am more comfortable doing most of the flattening and polishing on water stones.  (In truth, after doing much of this my hands are not comfortable....a product of aging, I guess.)  I like to flatten the entire back of the chisel unless it happens to be concave. (the opposite of having a "belly")

I would suggest starting with just one chisel of a middle width.  Three quarter inch seems to be a forum favorite.  Spend some time with this chisel making sure the back is very flat and the sides are parallel and straight. Use your flattened stones or sandpaper on glass for this. Make this your "perfect chisel".

Carefully place this perfect chisel in the SE-76 and grind a bit.  Check the new edge for squareness.  Make sure your square is indeed worthy of its name.

If your grind is still not square, but is consistent, sharpen all of your skew chisels.......

Seriously, this is an interesting and common situation.  Keep on posting.

My grandchildren are calling.

Good luck and lots of patience and thought.

Ken

[RobinW]

Thanks for your interest.

Just had a quick check on some of the chisels. When placing a straight edge across the back of the blade in the area where they would be clamped, they are slightly bowed or convex. Thus when in the jig, the clamp would tend to pull the right hand side of the chisel upwards (when looked down from above). This would, all other things being equal, make the top right hand corner of the chisel to be lengthened and the left hand side (still using the same vew) to grind away. This has generally been the case as confirmed by turning the chisel over and seeing the slope on the bevel. More experimentation required.

I am away until next week when I'll start again.

[RobinW]

After several (!) attempts I managed to get my all my chisels, bar one, sharpened and square but I could not say I have developed a specific procedure that could be followed for fast and effective repeat operations. The one remaining chisel has a distorted back (see comments later) and is adequately sharpened for general chopping.

I investigated small squares - that's a separate subject in itself - especially where others had left reviews about various makes and stated they were 'not square'. It is strange that manufacturers specify their squares with a linear error over length and not as 90 degrees plus or minus a few arc minutes or seconds. The price I was quoted for a small square by one well known manufacturer was about one third of the cost of the T7!

I bought two small squares namely:-

a) Woodpecker Minisquare (made in USA) which has internal dimension of 28.5mm x 51mm ( 1 1/8" x 2" for the imperialists who may read this),

and

b) Richard Kell Plate Square (made in UK) measures 63.5 x 47.6 mm (2 1/2" x 1 7/8") along its two longest edges and is accurate to within 0.0005", that is 0.01mm, along any reference face.

Quite different in style, material and thickness, but both very accurate and check out spot on against each other, and show up my other squares. They proved a godsend in being able to check the squareness of a chisel or plane blade without having to remove it from the SE-76 jig.

I then took the plunge and tried my No 6 plane blade (2 3/8" wide) and this sharpened and squared without any difficulty. (Probably beginner's luck.)

Then the No 4 plane blade (2" wide) didn't want to play. The angle of the grind was inconsistent and I could change this with applying and releasing pressure from the holding screws in the jig.

The No 3 plane blade (1 3/4" wide) had similar issues.

Throughout sharpening all these blades I kept applying felt tip marker to the ground edge and checking the results after a few strokes across the wheel. Not quite the fix and use scenario I had expected, but it was they only way I could make progress

Having developed OCD with regard to the use of this sharpening jig, I managed to understand what is really happening and how the slightest error can be magnified.

It is not known to what accuracy the SE-76 jig is manufactured with regard to the 90 degrees between the axis of the mounting holes and the shoulder against which the chisel is held. Nor do I have the means to check this. Also the front face of the jig is not fully machined and has some small raised parts, so this face cannot be used as a measuring reference.

However I did use the blade of a large square fitted into the jig (like a chisel would be) and scribed a line across the wheel. This showed the line to be no more than 1 degree off, and is the same result when the universal support is lowered against the wheel. But this is the total error between the jig, mounting bracket and the other manufacturing tolerances of the wheel, drive shaft, motor and chassis of the Tormek.

Having thought about it (a lot) I have the following understanding of errors and how introduced.

When a blade is mounted in the jig it meets the wheel and grinds the face at the set angle of say 30 degrees. As the blade is secured in the jig about 75 mm (3 inch) away from the wheel, any small horizontal angular misalignment at the fixing point in the jig is magnified at the edge of the blade.

For example if the side of the blade is slightly curved and causes a misalignment in the horizontal plane of say 1 degree, then this causes a larger arc length at the edge of the blade.

(This is the same as a bicycle wheel. An angular movement of 1 degree at the hub results in a small arc length at the hub, and whilst the wheel rim moves through the same angle of 1 degree there is a significant increase in the angular arc length.)

This angular misalignment (for want of a better term) has the effect of causing the ground area of the blade to be distorted and look trapezoidal due to a compound mitre angle effect with the original 30 degree set angle. This horizontal misalignment is the biggest factor in not achieving a square end.

Likewise if the blade can be rotated or twisted in the jig in the vertical plane due to an inability to sit completely flat in the jig (either due to jig machining; distortion in the blade; pressure effects from the holding screws and clamp; ) then this will cause another compound mitre effect at the area being ground in a different plane to that described above. I don't know if there is a proper technical definition for a compound-compound mitre.

So installation of the blade in the jig against the shoulder may require some very minor tweaking to reduce the angular misalignment.

Another way I corrected some of the grinding errors on two of my plane blades was to ease off the appropriate holding screw on the SE-76 and insert a feeler gauge behind the plane blade, so applying a  'twist' to the blade and bringing it back to achieve an even grind. I was using feelers in the range 0.1 to 0.4mm (0.0039 to 0.015") and it was significant how these changed the ground area.

So in summary, I can only advise that 'square edge' jig will be that if all other things are perfect.

In practice I can only advise that one should sight the blade end on against the light and check for any light between the back of the blade and the jig to check whether the blade is properly seated.

Continually use a felt tip marker in conjunction with a small engineer's square to check progress. If the grind area is trapezoidal it is either due to horizontal angular alignment issues or twist of the blade relative to the wheel. If applying finger pressure does not rectify the grind, re-align the horizontal angle of the blade or try inserting a small feeler gauge between the back of the blade and the jig depending whether it is perceived  as a twist or angle alignment problem.

I would suggest, if Tormek read this, that the next generation of jig include a horizontal angular adjustment facility (circular plate with micro adjusting screw) and maybe a vertical twist adjustment screw also.

I trust this helps others as I've been up a steep learning curve and this is the first thing I have tried with the T7! It's a good thing the motor is continuously rated! Despite the trials and tribulations, my blades are now very sharp and square and my sharpening results are now getting better than I had previous managed. A couple of more plane blades and then I can get back to thinking about doing some work with them!

[Ken S]

Robin,

What a fascinating and thorough post.  i'm at a disadvantage now because my Tormek is 150 miles away.  (I'm on the process of moving.)

A couple questions come to mind:

First, how much pressure are you putting on the blades you are grinding? 

Second, mention using a blade projection distance of three inches (75mm for you non-imperialists).  Have you tried a shorter projection distance? ....perhaps with a lighter touch?

You sound like you are making very good progress.  Working through this initial frustration will benefit your technique in the long run.

I would be curious to learn the official Tormek manufacturing specs for the degree of acceptable error from 90 degrees with the SE-76.  This is not a criticism of the Tormek company or its products.  The machinist world works on tolerances. Nothing is "exactly", although some tolerances are truly amazing. The tolerance is determined by the needs of the parts.  Things are either "in tolerance" or not.  Your squares are inspected that way, also.  Use and store them very carefully.  Richard Kell seems like a very innovative toolmaker.

I noticed the machining on my EZY Lock shaft and the DBS-22 looked very polished.  The knife jig looked more crudely cast and machined.  It is probably more than adequately finished; it just didn't wow me.  You may want to  do a little careful tuning of your SE-76.  A front surface with some bumps wouldn't directly effect the blade grinding.  However, it would cause your square not to register properly for inspection.  I would flatten it with some abrasive paper on glass or granite or a flattened stone.  If your 90 degree fence seems not quite as square as you like, some gentle filing might carry the day.  Be sure to use a file with a safe edge (no teeth on one face to prevent filing into the wrong area).

Don't get discouraged, and do keep posting.

Ken

[RobinW]

Courtesy of my friends at A. Mylne & Co (Yacht & Commercial Vessel Design since 1896, part of Ace Marine Ltd, Ivy Cottage, Church Lane, Limekilns, Fife, KY11 3HP, UK; www.mylne.com) and their 3D modelling package, I have managed to confirm my suspicions concerning the effects of small angular misalignment and applied twist to a blade fitted in the SE-76 jig.

Attached are two jpeg images of the same situation created in the 3D modelling package. These show a 25mm (1") wide 5mm thick chisel being ground at 30 degrees. Also applied is a 2 degree horizontal misalignment (applied with an 80mm centre of rotation from the blade cutting edge - explained below) and simultaneously a 2 degree twist in the vertical plane. These nominal 2 degree error sizes have been used to illustrate the combined effect.

The 80mm was an arbitrary size as the Tormek book says the blade should protrude from the jig by 50 to 75 mm (2 - 3"), and allowing a bit more to get to the axis of the universal jig gives near enough 80mm.

These images very closely illustrate a result I recently experienced where there is a change in the ground edge and two angled faces like an inverted 'v'.

Another result from this particular issue is that one side of the chisel is 2mm shorter than the other, and one corner is 1mm low.

By playing with different small errors and whether they are additive or subtractive (direction of rotation), then various long corners and trapezoidal ground faces can be created, confirming my previously posted views of compound-compound angle effects. I have seen most of the effects in my recent experiences of sharpening!

It is satisfying to prove my suspicions are correct, and it takes only small errors, even 1 degree, to have some noticeable effects.

So all I can advise, is to keep monitoring the grind using felt tip marking, adjusting the blade in the jig and pressure changes etc to counteract any undesirable grinding.

Many thanks to David Gray and Albert Montserrat at Mylne & Co for their assistance.

**I thought 'Attachments and other options' below would allow me to attach the jpegs, but apparently not. Is it possible to submit a picture?

[Ken S]

Robin,

You lost me.  (As I stated in my previous reply, my Tormek and now my machinist tools are temporarily 150 miles away due to a move.)

A one inch width 5mm thick chisel shouldn't have a lot of flex.  Is the error you describe due to the chisel not being flat and straight; the chisel not being mounted straight in the jig or the jig/machine being out of alignment?  A difference of 2 mm in one inch (25.4mm) should be easily visible.  That's quite an error.  If that was typical of the Tormek, reviews and sales would plummet.

When you apply pressure on the blade being ground, are you applying that pressure in the middle of the blade?  And, how much pressure are you applying?

I hope other forum members will join in.

Ken

[RobinW]

KenS - Sorry if I have confused you. What I was trying to illustrate is that very small angular horizontal misalignments, with or without very small amounts of twist of the blade in the jig, can cause noticeable effects at the edge and bevel.

When I was sharpening and producing squint edges, I was getting a long side on the chisel which was typically 0.5 - 1mm longer than the other side. My suspicion that very small angular effects could cause this effect is why I tried the modelling software.

With a result of 2mm this is hopefully the very worst case scenario as anyone would have stopped and reconsidered what is happening before getting that far off track. I was just trying to illustrate a combination of effects which could give this result.

Regarding pressure I apply to the blade, I use less than when I sharpen by hand on a waterstone, as I am trying to go slowly in the light of the problems I have experienced. I generally apply pressure in the middle of the blade hopefully to eliminate errors created by me (I can make plenty!).

I also re-true the stone at 90 seconds and regrade the stone to the finer value, all so that the rate of metal removal is slower, hopefully more under control, and gives me more time to think.

Yesterday, after re-truing the stone, I then tried sharpening a chisel. The grind was again not square with more coming off from the outside half of the stone (ie the side away from the motor housing). Throughout all my efforts with this machine, I realised that this is the general result I get. I also realised that the noise level was different as I went across the stone towards the outside of the stone indicating it was working harder towards the outside. More investigation required!!!!!

[RobinW]

The paranoia is setting in!

After my last post, I ran the machine, and thought that the wheel was not running true with a small sideways movement, so took it apart to see what is happening. There is radial play in the bush at the wheel end and this measures as 0.1mm which is within spec.. There is no play at the honing end bush. I checked how much sideways movement the stone has and this is inside spec..

However the stone seemed to be eccentric radially as checked against the universal mounting support and there was also a difference between the outside and inside diameters so re-trued the wheel again. The noise made during re-truing (done very very slowly) confirmed the eccentricity and the difference in the diameters.

Two chisels were then re-sharpened and this went well. I realised that I use either a single finger in the middle of the blade, or a finger on each side, and the pressure is very light. (Considerably less than I apply when I massaging my temples as I try to solve my problems!) Pressure is so light that it would be described as 'tickling' the chisels on the wheel.

Again using felt tip marker applied to the area being sharpened, (reapplying it frequently), quickly indicates what is happening. I also found that releasing or applying more pressure to either of the clamp screws of the SE-76 jig seemed to have as big an effect as applying more or less pressure from my finger.

Whatever the variables are and their causes not being fully understood, I am now getting confident that I can overcome them (by hook or by crook!) and the end results are now very acceptable.


 

[Ken S]

Robin, "you have certainly fought the good fight".

Your experience reminds me of when I started to cut mats for my photographs about fifteen years ago.  I decided to do this because the local framing stores did such a poor job.  I bought a C&H mat cutter, which cost then what a Tormek does now.  For a couple months my results were frustrating.

At the same time, I had a hobby interest in machine shop layout (and tools).  I started applying some of the layout procedures to mat cutting, and finally reached a level where I could quickly and repeatable cut very precise mats with very little actual measuring by rule.  The satisfaction came as a result of much frustration, study and work.

I hope your are now starting to feel that same well earned satisfaction.

As an aside, it would be interesting to examine the sharpened tool edges of someone like Duncan Fyfe.  I would be curious to know how square the edges were of a renowned cabinetmaker.  After all, sharpening has been traditionally done by hand with stones.

Overkill fussiness about squareness?  I don't think so.  While most chisels and planes are not really critical for squareness, it surely makes life simpler to be able to reliably sharpen a shoulder rabbet plane blade square.  I know the people of Tormek in Sweden follow this forum.  (I received a couple emails from them regarding one of my posts.  Good job, Sweden for following up on your customers' frustrations.)  I hope they have been reading your posts, Robin.  They make a very good product and I hope will continue to keep refining it.

Good posts, Robin.  Keep posting.

Ken

[RobinW]

I'll finish off this particular topic with a slight diversion.

After taking early retirement after a career in marine and offshore engineering (which is probably why I'm obsessive about getting things straight and square), I took myself off to college for two years full time, then two years part time, for Furniture Restoration which had three distinct subjects of cabinet making; upholstery and finishing.

My first class in the cabinet making class, where we had to make some basic joints, reminded me why I gave up woodworking at school! However I managed to change that for the better!

My appreciation of the skill levels attained by the makers pre-modern machinery era is unbounded. I have always appreciated good furniture and it is only when you have a go that you understand the ability of the 18 - 20th century makers. There are many good makers these days, and their skill levels are undoubted. They say a bad workman blames his tools and I've seen plenty of that, but I also believe that you can't make a really good job with bad tools, but can make a bad job with good tools. Sharpness in woodworking is king, and squareness and straightness give you the confidence in the tools that you automatically concentrate on the job in hand not whether the tool is good enough.

I practised and practised sharpening my chisels and plane blades on waterstones, hundreds of hours, and managed to get to a pretty good standard. Whilst I was aware of the Tormek and had seen it demonstrated at woodworking shows, I could not justify the outlay. (Still can't really!) However as my finger joints did not fancy a long session bringing a bunch of tools back up to scratch I took the plunge. It has been a strange learning curve, but now feel I have got up the hump especially as I understand the various factors which can affect the squareness of the grind.

A couple of years ago in a Furniture and Cabinet Making magazine there was an article about the  Edward Barnsley furniture works in the south of England, and I noticed that they used a Tormek. A few weeks ago I was down that way and went for a look at their furniture (see www.barnsley-furniture.co.uk). The quality is staggering. It is good to see that they continue in the tradition of taking on a select few as apprentices.

My next sharpening issue is my hand saws - maybe Tormek can come up with a jig for that!

With that back to the grind!!