Slow Grinding - Stone loading up

[Shaun]

Hello All,
I have been using my T7 for a couple of years now and really enjoy it. But with harder steels I find that the stone loads up after a while. So I dress the wheel with the coarse stone. I also bought the SB250 wheel to help with those harder steels.
What I am finding that the dressing stone wears out very quickly and the wheel is still not grinding very quickly.
Not sure I am explaining my situation very well but with harder steels whether planer blades or drill bits the going is slow to the point that I am honing rather than sharpening. If I true the wheel it is good for a while. Am I pushing to hard?
Thoughts anyone?
Shaun

[grepper]

If you aren't already, try using the edges of the dressing stone.  The edges can be much more effective than the flat sides.  If your dressing stone is really used up, get a new one.  They are considered disposable.

True the grinding wheel with the TT-50 truing tool.  That should do it.

I have not tried it, but you might also try a regular dressing stone for bench grinders.  Maybe someone else here has and will chime in on that idea.

[Rob]

I'm afraid you may be in for a bit of an expectation readjustment Shaun.  I recommend you grab a coffee and sit in front of the planar blade sharpening forum for a good hour.  Read as many of the threads as you can.  There are some encouraging one's by a very competent individual names Ionut who found various tricks to help with keeping the stone cutting on planar blades.  I myself (who bought the jig) had less success.  There is little doubt that some brands of planar blades are manufactured from very very hard alloys indeed and they are troublesome to sharpen.

But trawling through that forum will give you some insights as to whats possible as it may be you can get them reasonably sharp, particularly if they have no deep nicks you're trying to grind away.

[Ken S]

The SB-250 responds better with less grinding pressure.

Also, if you do not have a TT-50 truing tool, you really need one. (Everyone needs one. It is essential for both the T7 AND T4.) Use is often and lightly.

I agree with Grepper that the stone grader, like tires on a car, is a consumable item. The next time you visit a Tormek dealer, bring your stone grader with you and compare it with a new one (in a box). You may be surprised, as I was.

I also agree with Rob that forum results with the SB-250 have not been generally positive. At this point, I am not convinced of whether the issue of the grinding wheel or the operator technique. I am convinced that we need more extensive training material on the SB.

Just a possibly related thought: Harder steels respond better with finer hand file grades. With soft steel, you can hog away with a "bastard" file (the correct acceptable term). Harder steels do better with second cut or smooth files and probably lighter pressure. Try using less pressure. It may be that grinding harder steel just takes more time. (I do not offer this as a total explanation.)

Keep posting.

Ken

[Rob]

Ken's mention of the diamond trying tool is worthy of emphasis as regularly truing the wheel was the only way I could persuade the SB to cut my planar blades (12" Startrite SD300 model)

[Shaun]

Thanks Guys for all your inputs. Will check the forum and videos for further insight.

Today was doing some 6" jointer baldes and going was slow. So after reading through some of the forum contributions, I did use the edge and flats of the grading stone with a lot more pressure and a quicker side to side motion. My thought process was that this would create some cross texture on the stone making the surface more aggressive. Definitely sped up the sharpening process. Baldes had nicks that had to be ground out. Then graded the stone to 1000 for the final sharpening.

Think I was too gental with both the grading stone and the grinding stone.
I will continue to read through this forum. Thanks to all for your input. This forum is a great support.
Shaun

[grepper]

Yes.  Don't be afraid to really bear down on the dressing stone.  You won't hurt the T7.  Especially with harder steel, if you are trying to maintain a rough wheel, you may spend as much time dressing the wheel as grinding.  The rough surface can become smooth very quickly.   It may be annoying, but it's just part of the process.

I believe Rob has the most experience with planer blades.  He has posted often regarding sharpening them. 

[Rob]

There are two critical factors in sharpening any steel that is either very hard or has a large surface area ( like a skew chisel) or both (like planar blades)

First is to keep the stone cutting ie aggressive, second is to apply as much pressure to the grind as you physically can muster. You won't hurt the Tormek by literally leaning your weight on it during grinding. The big challenge with planar blades is the wheel glazes so fast you are forever dressing it back to aggressive. I've found the most aggressive you can get it is with the diamond truing tool. It cuts well after that but it still glazes very quickly with hard planar blades. Ionut recommended grinding without water in the trough for an even more aggressive cut but that procedure was frowned on by a previous moderator with a fair bit of experience

I found the stone grader not capable of getting the stone anywhere near as aggressive as the diamond tool and that was what was needed to keep metal coming off my SD300 knives. In the end, I started using a cheap diamond T dresser hand held against the wheel just to rough it back up because it got so labour intensive having to keep stopping to diamond dress it with the truing tool. That kind of worked but it sure eats your wheel diameter quickly. There's no easy solution I suspect

[Ken S]

I have not sharpened planer blades.I have reshaped a gouge, the other stressful sharpening operation. I had very good success reshaping the gouge by using a Norton 3X grinding wheel mounted on my Tormek.

With planer blades, I would differentiate between those with nicks to be ground out and those which are merely dull (not quite sharp). The not quite sharp blades can probably be sharpened with the Tormek grinding wheels.

For more major grinding, the 3X wheels, with either 46 or 80 grit work much faster. Either will work. The 80 grit is only slightly slower, but is more easily controlled. Use the harder grade. I use them wet in the Tormek. They are very usable, but not an ideal match with the Tormek. They have a one inch (50mm) width. the diameter is eight inches (200mm). Finish by grinding with the Tormek wheel. Ihave previously posted how to modify the bore diameter to fit the Tormek. If you cannot locate my description with the forum search, let me know.

I do not have enough experience with the SB-250 to speak with authority. However, Stig has informed me that,unlike the SG, the SB works more efficiently with a lighter grinding pressure.

Ken

[Rhino]

Dear Ken,

I thought of using other wheels on the Tormek.  I don't have a lot of shop experience so could you help me out. 

I understand standard grinding wheels have 5/8 inch holes.  How well do they fit on the 12 mm Tormek shaft?  Do I have to buy an adaptor?

Thanks and Kind Regards,

Rhino

[Ken S]

Rhino,

I sent you a PM. Please check your messages.

There is a document on the forum about these wheels. I drew it up and someone posted it for me. It should come up in a search. I will look for it.

My grandchildren have arisen. I will post more later.

Ken

[Elden]

http://forum.tormek.com/index.php?topic=2674.msg14338#msg14338

http://forum.tormek.com/index.php?topic=2527.msg13047#msg13047

I haven't located Ken's article yet. I think I remember it.

[Ken S]

Thanks, Elden, for posting these links. I do believe that the 3X wheels offer a very workable low cost option for reshaping with the Tormek. If cost was not a consideration, I would use an 80 grit CBN wheel.

I have recently found very inexpensive ($3 to $5 US) sets of plastic insert grinding wheel reduction bushings. For anyone without access to a drill press this would be the practical choice. Ebay has many listings for these bushings. The smallest inside diameter is 1/2". It will be necessary to add a paper or plastic shim.

Ken

[SharpenADullWitt]

I know some brands of wheels, come with bushings.  I doubt I will try this on the Tormek (have enough high speed grinders, to put them on), I have wondered how well the wheels work, since I thought most were speed rated (isn't there a minimum effective speed as well?).

[Ken S]

You are under no obligation to try this.

All I can say is that it works very well on my Tormek, and at a fraction of the cost of a CBN wheel. Worst case scenario, if you already have an eight inch dry grinder, the 3X wheels also work very well dry.

Ken