Honing woes

[Danielsyzygy]

I have had my T-8 for about a month now and I'm really struggling with the honing wheel. It takes a very long time to polish my carving gouges edges.
I am using the DF-250 diamond wheel and after sharpening I often have to go to my 1200 grit diamond bench stone just to reduce the cut marks from the wheel before honing. This is not ideal since I'm not as precise with holding the angle as the machine with jigs. It even takes a long time to remove the 1200 grit scuffs.
The DF-250 is 600 grit and the PA-70 honing compound is 8,000 grit, isn't this a really big jump?
Perhaps I am doing something wrong, has anyone else encountered this scenario?
Thanks in advance for any advice.

[jeffs55]

Are you using enough honing compound? When was the last time you applied any? It breaks down and going from the grits you describe sounds like quite a stretch. You may have to go to another intermediate grade wheel. I don't have any diamond wheels so anything I say is just my thoughts.

[Ken S]

Welcome to the forum, Daniel.

A couple of suggestions:

When you are grinding, make the last few passes with very light pressure. I normally use the SG. The lighter final cut makes a smaller scratch pattern. I would think diamond wheels would react the same way.

The jump from 600 grit to 8000 grit seems large. I have heard a range of grit numbers for PA-70 from 3000 to 6000. With your post, the heard range now is 3000 to 8000. Frankly, I don't believe anyone really knows. PA-70 is a good product. In fact, I think grit numbers are only one factor.

Do you have an SG-250? If so, it can be your middle stone. Use the stone grader for a longer time to maximize the smoothing effect. I tried using it for over a minute and was surprised to learn that what I thought was ""1000 grit" was actually coarser. In fact, as most carving tools are carbon steel, you might try using just the SG.

Keep us posted.

Ken

[micha]

Hi Daniel,
and welcome to the forum.

The following thread may be also interesting for you: https://forum.tormek.com/index.php?topic=4382.msg31167#msg31167

I'd endorse Ken's suggestion of using the SG wheel, if you have one. I feel it leaves a surface that is easier to polish than the DF Stone.
(I even feel the same compared to the DE stone, but might be wrong).

In the long term, if you need mirror finish bevels very often, a SJ wheel might be the (more effortless) way to go.

Mike

[Danielsyzygy]

Thanks guys! Yes I have the SG but I have chosen the diamond wheel in order to use the flat side and prevent a hollow ground edge, not possible on the SG I have read. Many of my deeply curved and larger gouges would not do well with the hollow ground edge I fear.
I feel like I use enough compound, it certainly creates a considerable mess as it peels off under the blade. I will try the lighter touch on the diamond wheel.
I think I read there is a hard felt wheel that fits the T-8, that intrigues me, does anyone know about that?

[micha]

Some of us use felt wheels, and so do I. Just felt with some 1 micron diamond compound.

It's definitely great for deburring. Of course it polishes bevels too, but with the even finer grit it will also take longer to smoothen the traces of the coarser wheels. Yet I don't know how the side of a felt wheel would perform on a flat grind.

Another thought: You mentioned larger gouges- if you have very wide bevels,you got a lot of area to polish, which will obviously take longer than just polishing a quite narrow edge.
And the leather wheel will polish a quite narrow portion of a flat ground bevel at a time, too.

Now I'm not an experienced carver, but for my turning tools I just ignore the hollow grind. The felt wheel is also 250mm, so it matches that of the grinding wheel which makes honing/polishing quite consistent.

Have you already seen the information here?
https://forum.tormek.com/index.php?topic=3840.msg25740#msg25740

[Ken S]

Micha, thank you for posting the very informative link.

I don't recall having an issue with Tormek hollow grinding before the marketing department gave us diamond wheels. We just made our tools very sharp and used them. We all knew that theoretically the 250mm diameter grinding wheel of the Tormek created a very slight hollow grind. As I have stated previously, I can easily detect the hollow grind with a 150mm grinder. When using the Tormek T7/8 or T4, even after careful examination, I have to guess. With identical chisels, determining which chisel was ground with which model is definitely a guess.

Although marketing tells us how important flat grinding is supposed to be, that urgency has not filtered into the thorough kind of explanation the handbook has provided with edge grinding. Watch the excellent Tormek online classes. While flat grinding has started to be mentioned, the workaday knife sharpening demonstrated is still edge sharpening done primarily with the venerable SG by experienced hands.

Ken

[micha]

I also think it's not a problem (or even might mean some advantage) in most applications. For carving gouges, it's up to the carver to decide. Some of these look really weird to me. (The gouges, not the carvers)  

It sure gets more noticeable with wider bevels. Out of curiosity, I replicated the illustration from the manual with a more extreme bevel, 15mm wide, where the concavity reaches 0.2mm. Even that would probably not be a problem with most tools, but I can imagine it could make a difference when e.g. hollowing out with a gouge that has the bevel on the 'wrong' side.


Mike

[Danielsyzygy]

Thanks all, I will try the SG next.

[tgbto]

I was wondering, as there seems to be an agreement that the area close to the edge will always somehow be convex (due to the play in the jigs, the misalignments, the out-of-squareness and out-of-roundness of the wheels,  the imperfections in handling, the softness of the honing wheel, etc.), if anyone had ever been able to actually observe or measure said convexity ?

It would probably show on one of wootz's awesome SEM scans, but maybe a "simpler" interferometer would allow to quantify the convexity (or concavity for larger bevels) that we *actually* get from using a wheel as opposed to the one we would get if the surface of the bevel was geometrically identical to that of a wheel model. It would also be fun to be compare an edge sharpened by a tormek guru who would obviously be much more consistent than a newbie such as I, not only in terms of sharpness, but also in terms of overall geometry.