Author Topic: Skew chisel grinding.....was a grind!  (Read 22563 times)

Offline Rob

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Re: Skew chisel grinding.....was a grind!
« Reply #15 on: June 12, 2013, 12:15:22 am »
Gouges are OK Ken...its skews and planar blades that are just out of its league.  Basically its the combination of HSS coupled with a large surface area.  It simply takes too long. This is not a user error...because the stone cuts again after truing.  It just glazes too fast....the material is too hard for the grade of stone.  I love the jigs and I love the tormek for sharpening...cant live without it.  But for shaping....I'm done and I'm going to get either a belt or dry grinder with a really low grit wheel.  I like your 46 grit idea. Those Norton wheels get great reviews and I also like the idea of the bgm 100 to re deploy my investment in jigs
Best.    Rob.

Offline Ken S

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Re: Skew chisel grinding.....was a grind!
« Reply #16 on: June 12, 2013, 03:07:06 am »
Interesting point, Rob.  I assume the planer blades may require grinding away some nicks, rather than being what Ian Kirby might call merely "blunt".  That would involve removing a lot more metal.

Reshaping a skew chisel would also involve removing a LOT of metal.  It would be nice of you could use a friend's or Axminster's belt grinder with a coarse belt to see how well it worked.

My experience with the Norton 46 grit wheel has only been with carbon steel.  I could try it with one of the odd metal lathe bits I have.

When I set up my photographic darkroom, I made the decision that I wanted to be able to do most things in house.  I specialized in black and white work.  I had occasion to need 16x20 color prints a few times.  It seemed more cost efficient to send them out rather than add the equipment to do them in house.  Reshaping a high speed skew or removing planer blade nicks may be cases where it is more cost effective to send the work out.  That doesn't mean that touch up sharpening couldn't remain in house.

I have noticed that Lie-Nielsen now offers their wood chisels in O1 carbon steel as well as A2.  The A2 can hold an edge longer (at certain bevel angles).  The O1 is easier to sharpen with regular sharpening equipment. L-N must have felt many customers preferred ease of sharpening to edge longevity. Maybe our steel has gotten beyond the range of our sharpening tools.

Do keep us posted on this.

Ken 

Offline Herman Trivilino

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Re: Skew chisel grinding.....was a grind!
« Reply #17 on: June 12, 2013, 03:28:42 am »
I think that's the way to go.  If Tormek are paying Alan Holtham to demo the bgm-100 then the "games up" with respect to shaping...they're basically admitting its not fit for purpose.

I think Tormek is paying for that promotion of the BGM-100!

It's an admission of the limitations of its wet grinder, but it's also a promotion of it!!

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Offline Herman Trivilino

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Re: Skew chisel grinding.....was a grind!
« Reply #18 on: June 12, 2013, 03:38:04 am »
Rob, my dry grinder is a forty year old Sears with six inch wheels.  It has served me well enough.  I have a Norton 3X 46 grit wheel on one side.  The other side, which has not been used since I purchased a Tormek, has a Norton80 grit white wheel.  I have thought about swapping it out for a rust removing plastic wheel.

Do you prefer that to the wire brush wheel?

Quote
If I was buying a dry grinder today, I would probably buy an eight inch slow speed Baldor.  I would swap out one of the wheels with the Norton 3X 46 grit wheel.  Probably a finer, maybe 80 grit for the second side, although not a priority.

That would be a nice set up.  Near the end of the video Alan mentions a set up using two BGM-100's, one on each side of the grinder.

Throw in a couple T7's, with one of each of the three Tormek grindstones, and you'd have first-rate sharpening center.   :o

Quote
I have not tried reshaping with my Tormek.  I have watched Jeff reshape a gouge on the turning DVD.  While not super quick, it did not seem that arduous a task.  Is the problem the tool or the technique?

Or is it the steel?
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Offline Herman Trivilino

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Re: Skew chisel grinding.....was a grind!
« Reply #19 on: June 12, 2013, 03:47:34 am »
Maybe our steel has gotten beyond the range of our sharpening tools.

I think it has, Ken.  As you know tungsten carbide steel is so hard it requires diamonds to sharpen it.

Steels keep getting harder, requiring more expensive and varied types of abrasives.
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Offline Rob

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Re: Skew chisel grinding.....was a grind!
« Reply #20 on: June 12, 2013, 08:56:03 am »
Thanks for those responses chaps...very interesting debate this.  I too (Ken) have thought it might be just easier to outsource the really tricky tools to avoid the capital investment cost in equipment and in terms of planar blades, I think that's my conclusion.

With skew and other tricky wood turning high speed steel I really couldn't forgive myself for failing to handle those in house. Not rational I know but it seems somehow wrong to send out a poxy skew chisel :-)

But I think Herman's hit the nail on the head with the hardness of modern day steel.  We seem to have reached a tipping point where we value edge retention over anything else.  It almost seems to be going in the direction of disposable because once you get to carbide, you're done without industrial strength equipment.  That LN idea of a choice of softer steel appears to be a reaction to this to an extent.

One solution could simply be that I get all my skews that I want to reshape (five belonged to my Father) and have a service do the grunt work.  Then I keep them honed thereafter on the Tormek.

I'd be interested to see if your Norton 46 grit can make a dent in that High speed steel Ken.  If you fancy conducting that experiment it would really help corroborate the dry grinder approach.

And, Herman...I love the idea of a bank of grinders....sort of sharpening HQ :-)  I'm sure Tormek's marketing folks would love that!
Best.    Rob.

Offline Ken S

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Re: Skew chisel grinding.....was a grind!
« Reply #21 on: June 12, 2013, 12:06:19 pm »
Herman,

When I bought the Norton 80 grit white wheel, it was a big improvement over the hard gray wheels which came with the grinder. It definitely runs cooler than the harder gray wheels.  (The binder is the difference.  In the white wheels the binder is softer and breaks down more quickly.  This exposed fresh sharp grits.  It also wears the wheel more quickly.)

In fairness to it, it would be a better tool in hands more experienced than mine were then. 

Sorry, my grandson is awake.  I have to close now.

Ken

Offline Jeff Farris

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Re: Skew chisel grinding.....was a grind!
« Reply #22 on: June 12, 2013, 02:11:27 pm »
Hey guys,

While I will admit that shaping a skew is my least favorite job on a Tormek, it isn't impossible. This discussion has hit most of the most important methods, but I want to reinforce those and add a couple that have been missed.

1) Work in the vertical orientation.
2) Regrade the wheel with the coarse side frequently and aggressively.
3) If your wheel is stalling, clean the drive wheel with a bit of 80 grit sandpaper.

Not previously mentioned

4) Work at the edges of the stone, with half the width of the skew off the stone. Effectively doing half the job at a time. The reduced contact area speeds material removal.

5) Sharpen your skew with a radius. This profile, preferred by Richard Raffan and Alan Lacer, comes together much faster, because, like a gouge, the contact area at any one point in time is very small.
Jeff Farris

Offline Rob

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Re: Skew chisel grinding.....was a grind!
« Reply #23 on: June 12, 2013, 02:17:55 pm »
that's interesting Jeff.  Good tips there.  You know I did complete the reshaping of the skew...so it's not that it cant be done...just took too long...sore fingers etc.

Those techniques are very cunning...keep as little steel on the stone as possible to reduce surface area...why didn't I think of that!!

I think I will radius one of my skews actually, but I still need at least 2 straight ones for creating quick bevel type cuts in spindle work (I make magic wands for the local school fair).

I have been cheating while I sort this out by simply offering the old skews by eye....getting close and leaning on the USB...then just grinding a micro bevel free hand right at the tip.  Not pretty or a uniform bevel but at least the very edge is razor sharp.  Since that's all that's cutting....it seems to work fine without all the sweat.  That's just freehanding so a hell of a lot quicker than any other method too :-)
Best.    Rob.

Offline Ken S

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Re: Skew chisel grinding.....was a grind!
« Reply #24 on: June 12, 2013, 04:04:01 pm »
Good thoughts, Jeff.  I remember Ernie Conover kept a narrow wheel on his ten inch Baldor grinder.  Another thought, I believe going back to one of the Iles, is dressing a crown on your wheel to nessen the contact area.  That might work better with narrower dry grinder wheels.  I like Jeff's idea of working on half at a time.

Maybe I am fortunate that my grandfather left me two skews of the garden variety Sears kind with carbon steel.

Rob, what are the starting and ending points of your skew makeovers?

With the planer blades, I assume we are talking about enough grinding to remove nicks rather than just restoring a slightly dull edge.  Many of us may already have a belt sander/disk sander in the shop.  (mine is presently not operational yet.)  Tom Lie-Nielsen writes about having sharpened many plane blades on his belt sander.  It might be possible to do some preliminary grinding this way.  Grind the nicked bevel at a right angle first.  Maybe start a rough bevel with the belt sander.  Then switch to the tormek for the final grinding.  Just an idea.

I will try a lathe bit on my 46 grit wheel and belt grinder.

One thing I wish we had on this forum was input from the engineering department in Sweden.  Several years we had a post by a guy who tried using his dry grinding wheel on the Tormek.  He claimed some success, but has not posted since.  That idea has always fascinated me.  What I would like to read is whether or not Tormek has considered a much coarser wheel.  If they have, has it not been produced for technical or economic reasons?

Ken

Offline Jeff Farris

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Re: Skew chisel grinding.....was a grind!
« Reply #25 on: June 12, 2013, 05:52:14 pm »

One thing I wish we had on this forum was input from the engineering department in Sweden.  Several years we had a post by a guy who tried using his dry grinding wheel on the Tormek.  He claimed some success, but has not posted since.  That idea has always fascinated me.  What I would like to read is whether or not Tormek has considered a much coarser wheel.  If they have, has it not been produced for technical or economic reasons?

Ken

It has been tested pretty much non-stop for the 20 or so years I've been associated with the company. A very coarse wheel presents a couple problems. First and foremost, it's a "one-trick pony". Anything that can cut very fast has no other function. Tormek has built its reputation on the flexibility of the SG stone and prefers that approach. The next most significant problem is stone wear. Given the bonding methods necessary for the water bath, a very coarse stone wears very, very quickly.

Rob,

Given what you've written in your last response, take a look at a negative rake scraper. That's essentially how you're using your skew. A negative rake scraper (which you can create from any scraper) will give you that simple, straight and relatively clean cut you're getting from the skew and hold up better to the use.
Jeff Farris

Offline Rob

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Re: Skew chisel grinding.....was a grind!
« Reply #26 on: June 12, 2013, 08:06:00 pm »
Thanks Jeff, I'll take a look at the scrapers you suggest.  To embellish a bit more on these wands I make...they're riddled with fine detail which is essentially around coves and beads and every possible permutation thereof.  Because the stock is very thin and typically about 17" long...they start to really vibrate once I'm in the middle (between centres of course).

The skews are incredibly useful for cutting these fine details and need to be really sharp or I risk snapping them.  The kids school fair is 2 weeks away so I'm in full production mode right now and hope to produce around 50 of varied design. I can do about three an hour if I really focus, two is more normal.  The Tormek is right by my side.

I've even got a recipe for my freehanding of (one of) the skews after today...I set the usb to 43mm (for my 3/4" roughing gouge) using a spacer block a la Jeff's instructions....then using that protrusion I know if I lean the ferrule of the chisel on the usb and eyeball the 90 degree offer against the wheel I'll get a real fast grind of the tip.  This micro bevel is exactly like a bench plane iron and works a treat.  I hone it on the strop to get the burr off because when that oak wand is spinning...any rough edge just exaggerates the wobble and vibration.  I'll find some pics and wack them up later.

Thanks for the advice anyway Jeff and Ken. 
Best.    Rob.

Offline Ken S

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Re: Skew chisel grinding.....was a grind!
« Reply #27 on: June 12, 2013, 09:37:28 pm »
Jeff.  Excellent answer.
Thanks,
Ken


Offline Rob

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Re: Skew chisel grinding.....was a grind!
« Reply #28 on: June 13, 2013, 01:20:15 am »
some of the wands I'm skewing

« Last Edit: June 13, 2013, 01:25:38 am by Rob »
Best.    Rob.

Offline Herman Trivilino

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Re: Skew chisel grinding.....was a grind!
« Reply #29 on: June 13, 2013, 02:04:16 am »
We seem to have reached a tipping point where we value edge retention over anything else.  It almost seems to be going in the direction of disposable because once you get to carbide, you're done without industrial strength equipment.

The vast majority of casual users of edge tools and cutlery rarely, if ever, bother with sharpening.

Our local sharpening service no longer does hand saws.  My guess is that the newer saws can't really be sharpened.  The tips of the cutting teeth are hardened to the point that they're brittle.  They don't break off because only the very tips of the teeth are hardened.

We're starting to see the long-promised developments of surface physics.

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