Author Topic: Unconsistent results using T8  (Read 428 times)

Offline Tomikay

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Unconsistent results using T8
« on: November 21, 2021, 05:25:35 pm »
Hi, Forum,

I still have problems to get consistent results using my T8.

Initial situation:

1) The stone is freshly prepared with the TT50. The surface is exactly perpendicular to the outer edge of the stone.
2) I fix the universal support carefully as described in Tormeks videos: soft touch above micro adjust screw, fixing this side first, later the other.
3) I also clamp the chisel into the jig as shown in the videos: aligned with the stop, the mirror side (hope, translation ist correct??) fits perfectly with the jigs surface. The device is set correctly, the screws on the left are tightened firmly, the "control strokes" on both parts of the device merge into each other.

Problem:

1) The stone is not worn out evenly.  There a stripe of about 6 or 7 milimeters on left side remains brighter. You can also see this when I move the clamped chisel on the stone from left to right side: the strip left by the EdgeMarker is getting stronger and stronger towards the right side of the stone.
2) The cutting edge of the chisel is therefore clearly crooked.
3) Yesterday, after long time and plenty of trials, T8 worked satisfying, 2 chisels became okay. Today: Nothing worked, several attempts, lot of time, result was a mess. Non- traceability of results drives me really crazy.

I have tried out a lot now:

1) I fix universal support again and again, trying slightly different pressure at slightly varying finger position.
2) loosened the stone and moved a quarter turn on the shaft.
3) I work carefully when grinding without pressure on the universal support so as not to get it out of parallel.

And now I can't explain to myself what's going on anymore.
The system CANNOT be so error-prone that such different results are given.

Could the machine have a blow away? It was delivered in damaged packaging, in addition, the protection of the shaft was slightly pressed in and the attached SJ 250 was damaged a little.

Or do you think there still is an error operating my T8?

Thank you for reading this long text, hope to get some Input here!

Greetings from Dusseldorf
Thomas

Offline Tomikay

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Unconsistent results using T8: photos
« Reply #1 on: November 21, 2021, 05:53:00 pm »
Hey folks,

here some photos to my post above.

Offline cbwx34

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Re: Unconsistent results using T8
« Reply #2 on: November 21, 2021, 07:33:30 pm »
I'm sure others will have input on the sharpening part, (I'm not a chisel sharpener), but my comment is on truing the wheel.

The goal is not to make "The surface is exactly perpendicular to the outer edge of the stone", but it's to make the surface parallel to the Universal Support.  So how you set the support bar to true the wheel, you need to duplicate this when you set up to sharpen the chisel.

Not sure if it'll change the results you're getting, but something to look at.
Knife Sharpening Angle Calculators:
Calcapp Calculator-works on any platform
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Offline RobinW

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Re: Unconsistent results using T8
« Reply #3 on: November 22, 2021, 01:22:53 pm »
As advised above, the angle between the stone grinding surface and the side of the stone is irrelevant.

Before you do any more truing up of the stone surface, with the machine stopped, lower the universal support bar until it is almost touching the surface of the stone. Do not apply pressure to the bar when lowering it, just use the threaded adjuster for the last part for fine control.

Then get down and looking against the light, check if the surface of the stone is parallel to the underside edge of the support bar. (At the moment ignore the few millimetres from the edge of the stone where you say there is a different colour.) Slowly rotate the stone and check that the stone surface is still parallel to the bar.

If the stone surface is bang on parallel to the mounting bar, then you have the beginner's problem of mastering the grinding of a chisel.

If the stone surface is not parallel to the bar, then you will have to re-true the surface using the TT50. Do this very lightly otherwise you may be taking off more surface than you need, and it ends up in the bottom of the water trough.

If the majority of the stone surface is parallel to the bar apart from a few millimetres near the edge, do not worry about that at the moment, you have plenty of surface to use for chisel sharpening. The idea is to get your chisel grinding technique improved first.

Once you have most of the stone surface parallel to the mounting bar, I would advise you look up the information on this Forum under "Hand Tool Woodworking" and the entry "Newbie needs tips on keeping things square." There is advice there plus other references to entries on how to get chisels and plane blades square.

Through all this re-truing and chisel grinding, a light touch should be used. There is no need to apply pressure to try and compensate for things which are not properly understood.

Offline Ken S

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Re: Unconsistent results using T8
« Reply #4 on: November 22, 2021, 06:22:12 pm »
Good points.

Those of us old enough to remember learning to drive standard transmission "stick shift" vehicles may remember stalling out a few times. Soon this became second nature.

Be patient. With persistence, your chisel problems will soon fade away.

Ken

Offline tgbto

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Re: Unconsistent results using T8
« Reply #5 on: November 23, 2021, 04:22:29 pm »
I would also add that I always find it helpful to keep in mind the physics of what you're trying to do : are you putting stress in the system that will make it work outside of its tolerances, are you applying forces in the intended directions, are you applying a torque somewhere it shouldn't, do you have a symmetrical input to the system when you want a symmetrical result, ... ?

Putting significant pressure on the stone where the edge is being ground is OK (not with diamond stones though), but you have to do make sure it does not come from trying to bend the universal support. When sharpening a chisel (or knives) on a flat whetstone, you press the edge down on it with your fingers located close to the edge, not from the handle. The pictures seem to point more to a systemic issue with how you clamp the chisel, or how you exert pressure on it. It reminds me of an issue i was having sharpening the first bits with the DBS: by applying pressure to the sides of the jig rather than evenly, i was bending the jig/USB ever so slightly so i was grind more on the external side of the stone, I could hear it even more than feel it.


Enjoy the learning curve ;)

Offline simonh

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Re: Unconsistent results using T8
« Reply #6 on: November 24, 2021, 08:00:25 am »
I presume you are using the Tormek SE-77 jig for chisel sharpening.  If so you can use the two screws on the top of the jig to change the angle of the chisel to the stone and get a square edge.  Slacken one screw 1/4 turn and tighten the opposing screw, grind 1 or 2 passes and check if you are square, if not adjust again (if you made the problem worse you need to slacken the oposing screw).  Have a go and you will soon understand how the screws work.

Offline micha

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Re: Unconsistent results using T8
« Reply #7 on: November 24, 2021, 01:47:08 pm »
Another thought regarding the fact that some chisels went well and others didn't:
If chisels are warped or twisted, effects may be similar to what you were experiencing. Can you check the chisels are 100% straight?

I've definitely seen some that weren't straight at all, and these weren't necessarily the ones that seemed to have taken the most abuse.

Offline Ken S

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Re: Unconsistent results using T8
« Reply #8 on: November 24, 2021, 03:53:04 pm »
To keep this in perspective, squareness problems did not begin with the SE-77 and T8. Jeff Farris addressed this issue in a blog about the SVH-60, the jig which preceded the SE-76 in the days of the SuperGrind.

I will share part of my personal learning curve. I am not a naturally talented sharpener. For several years, I did not use my TT-50 truing tool. I lacked the confidence to try it. What finally changed that was the extreme frustration caused by a grinding wheel quickly and continually glazing. I got to the point where I put my truing tool in a separate support bar and truing the glazed grinding wheel around every thirty seconds. I did it enough that I learned a lot about the truing tool and became fluent with it. I earned that skill.

You can do the same thing with chisels. Start with practice chisels, 3/4” Irwin Blue Chip chisels are a good choice. Don't handicap yourself with bent or misshapen chisels. Don't start with narrow chisels; they are actually more difficult to sharpen. The standard sage advice about using a marker and a square will stand by you. Check early.
Practice.

It will become easier.

Keep us posted.

Ken

Offline Herman Trivilino

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Re: Unconsistent results using T8
« Reply #9 on: November 29, 2021, 06:54:48 pm »
If, after repeated attempts, you cannot get good results I would contact Tormek support.

There was someone, a few years ago, had the same problem with a T8, if I recall correctly. There was no definitive understanding of the cause of the problem, but I suspected that the support bar was not parallel with axis of rotation of the grindstone. If this is your problem you will forever have problems squaring chisel ends.

On the other hand, it is much more likely that nothing is wrong with your machine and you are just not using the right techniques, as this is perhaps the most common beginner problem.

Keep practicing. Try to find old beat up chisels that you can practice on. Lots of people have them in toolboxes and rarely use them because they are not sharp.
Origin: Big Bang

Offline Ken S

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Re: Unconsistent results using T8
« Reply #10 on: November 30, 2021, 11:42:29 am »
Thomas,

I agree with Herman about the importance of emailing Tormek support. There is no cost, and the support personnel are very experienced Tormek employees.

I have a suggestion for testing that your support bar and grinding wheel are parallel. Attached is the link to the Tormek TTS-100. This is the tool I use to set up my chisels and plane blades. In my opinion, it is a more advanced tool than the Anglemaster. I consider the TTS-100 and SVD-186R to be Tormek's most advanced set up and jig combination. The two small revolving metal wheels make the TTS-100 compensate automatically for wheel wear. You can even switch back and forth between the T8 and the T4 with no adjustments. I don't know why Tormek never incorporated this innovation  to chisels and plane blades. The metal wheels work better if you draw a spoke on each with a fine tipped marker.

https://www.tormek.com/usa/en/accessories/other-accessories/tts-100-turning-tool-setter/


The two holes, A and B, provide two consistent, repeatable Distances between the support bar and the grinding wheel. I use the closer hole B for chisels. I placed a piece of blank white labelmaker tape in one of the three Projection slots. With the support bar set to hole B, using the Anglemaster, I adjusted a chisel to a 25° bevel Projection and marked the length with the same fine tipped marker and noted the degrees. I did this in 2010 and have not needed to use the Anglemaster since then to get consistent chisel and plane blade bevels. (I made several other angle marks at the time, but have not used them. The original piece of tape is still in service.)

You can use the TTS-100 to check parallelness. Set it on one edge of the grinding wheel to where the two wheels just start to turn. Then slide it over to the other edge and repeat the test. If the wheels turn at the same Distance, the grinding wheel and support bar are parallel.

The TTS-100 can also be used to mark a square line on the grinding wheel.

Do not become discouraged.

Ken