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Internal bevels on curved gouges; important?

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  • Internal bevels on curved gouges; important?

    Me again. Hopefully you're not getting bored of me yet!

    I've been reading a lot about sharpening and I've seen a few high-profile carvers commissioning their curved gouges with small internal bevels (we're talking 6mm-25mm tools here with curvature from #3 to #9). I can definitely see how this helps carve but how important is it?

    If it is as helpful as it looks, what tool I need to do this? The videos online show people using oil stones but I'd much rather use diamond for various reasons. So the question for me is; what's the diamond equivalent of a shaped oil stone for internal bevels? What grades are needed?

    I think my options are

    - DMT file for serrated knives (only available in fine)
    - DMT honing cones (also fine only)
    - DMT wave (which honestly I'm not convinced by as I bet the sides get in the way, but just leaving it here as I can get both pretty cheap)

    The file is cheap but I'm worried that by virtue of the small radii I may accidentally dig it into the tool and spoil the edge... So by that token maybe the cones or Wave - with their very large range of radii - make sense.

    I'd very much appreciated your thoughts!

  • #2
    I like an interbeve, especially carving in harder wood. It gives me a little more control .And cuts better . I would think the fine DMT would work. at least tell you became more comfortable with the sharpening process.


    • #3
      Hi again Jof,

      The advantages of the internal bevels are supposed to be that you can lower the angle that the tool needs to be held to engage the wood during a cut without having to narrow the included angle of the edge to the point that it makes it weak, the internal bevel forces the removed chip back upon itself (to a small degree) up/away from the tool, and it makes it easier for some tools to be used "upside down" so that you can get double profiles from a single tool. That last one only applies to straight, alongee, and fishtail gouges (not chisels, v tools, spoon gouges, or back bent tools) and the others also apply to long bend gouges. The biggest advantage I see is that it guarantees elimination of internal factory grind marks. I have also used it to some degree to eliminate rust pits at the edge when restoring older tools. On the few tools where I have purposefully introduced internal bevels, I have experienced no real advantage or disadvantage in use.

      Some professional (and for that matter amateur) carvers advocate it while many don't bother with it at all. I don't purposefully introduce inside bevels for most supposed reasons but I am sure there are some small ones on my gouges simply from stoning and honing the inside surface near the edge, eliminating factory grind marks and/or removing burrs from sharpening. I use oil slip stones and/or "machinist files"(stones actually) and have for many years with satisfactory results. I have them and use them. They work well so why do something different? The ones I own are "rough" and "fine" and I really just use the ones I have out of habit and because of very good past results. They tend to be widely available, do their work quickly, and will last a lifetime in normal use. If I were to guess I would say that my "fine" slip stones are in the 1000 grit range and that gets me close enough to bring the final edge to the desired polish/sharpness through honing. I see no advantage to using a diamond stones for this application. The one exception to the slip stones is that I use fine (1200 grit) wet and dry abrasive paper folded enough to approximate the internal radius on small (1 and 2mm ) gouges, Since the establishment of an internal bevel is something that you should do on an initial-use or rare occasion, I see no reason as to why you couldn't do it with abrasive paper on an appropriate convex surface, dowel or similar set up if you want, without buying a specialized file or stone. The problem I see with a "wave" is the fact that the radius will be close to what you need in a very limited area of the stone. If necessary, I would try the paper method first to make sure it was something I really wanted to do to my tools before investing in a stone.

      Any initial shaping performed on my tools is done (carefully) at a standard bench grinder and or on stones by hand. Sharpening is performed on stones, diamond or oil depending on circumstances, and then the tools are polished, sometimes on strops or power honed. I normally just power hone on an inexpensive soft cotton wheel with honing compound mounted in my drill press which reaches the internal surface at the edge, so I would anticipate some extremely slight rounding in the process. I have tried different high-end honing systems and tried tools sharpened with a variety of systems. So far I haven't found any that was quicker, have given me a better edge or was any cheaper. Tool maintenance is normally power honing/stropping or in extreme circumstances, simple stoning with fine stones followed by power honing or stropping. That seems to be sufficient for my needs whether I use the gouges bevel-up or down. The ultimate test is in the cut and the finished surface and if it works, then good. If you feel the need to lower the tool-to-wood cutting angle to an extreme or if you have issues with any of the other functions of the tool that internal bevels are supposed to help with, then try it on one, just slightly at first, to see if that helps you. If it doesn't then you have your answer and it is better to find out with one tool as opposed to several, and on one that you can correct easily with no permanent damage, such as on a straight gouge. The main thing is to eliminate any internal grind marks and to get the surface at the edge polished up nicely. It takes both surfaces of the edge (bevel and "non-bevel") for the edge to be truly sharp and fit for work. It's fine to listen to other carvers for guidance but much better to find what works best for you in your unique circumstances and resources. Have fun.


      • #4
        I put a little internal bevel on all my palm tool gouges. I use 1000 to 1500 wet-dry sandpaper. Most of the time wraped around wooden dowels of different diameters. My mallet tools I just strop on the inside to clean and smooth the inside. I have put micro chipped a cutting edge more than once in hard woods do to a cutting edge thinned to much.
        Last edited by Claude; 03-28-2019, 05:36 PM.


        • #5
          Jof: what kinds of woods do you propose to carve? I can't see the value (for the effort) with soft woods like basswood and jelutong.
          Would you plan to do a lot of mallet work? Those gouge edges can use extra support from the strike forces.

          I was taught to use different shapes of leather to hone the inside curves of gouge sweeps. "Three passes only. No more is needed."
          Even a tennis ball makes a good strop for big edges.

          Brian T


          • #6
            Hi jof, yes an internal bevel is something you need for keeping your tools in tune, . I'm not gonna write you a book on the subject . But if could reference back to WCI issue # 37 and read Chris pyes article you'll fine some great info on your question.


            • #7
              As you can see, you get varying opinions on whether you need it or not! I have been carving about ten years and haven't ever tried it on my gouges. I primarily carve basswood , but sometimes harder woods, both palm tools and mallet tools for realistic and caricature carvings. It may be of more use in architectural carvings, but I would just see how my tools cut without it. You can always do it later if you feel the need. I sharpen most of my tools by power with a Burke sharpener and the only thing I do to the inside of the gouges is to buff them to remove any wire edge.
              'If it wasn't for caffeine, I wouldn't have any personality at all!"



              • #8
                Thanks everyone. You are an awesome bunch. Continue to be very glad I found this forum. Some individual replies:

                Originally posted by YME View Post
                The advantages of the internal bevels ....
                Wow, what an amazing response! That makes a lot of sense and things are much clearer to me now. Thank you very much for taking the time to write all that.

                Originally posted by Robson Valley View Post
                Jof: what kinds of woods do you propose to carve? I can't see the value (for the effort) with soft woods like basswood and jelutong. Would you plan to do a lot of mallet work? ...
                Currently basswood but I definitely imagine myself working with harder woods. Regarding mallets I can't say for sure where I'll be going, but right now things are more of a cautious tap than a full on whack

                Originally posted by hobo View Post
                ...But if could reference back to WCI issue # 37 and read Chris pyes article you'll fine some great info on your question.
                Thanks for the tip - that article is excellent. I managed to find it on the site


                • #9
                  None of the major tool manufacturers recommend that modification. They are all silent.
                  I have yet to read any established bladesmith endorse a composite bevel edge.

                  However, if you took this to its extreme = all inside bevel and no outside bevel, you have the crooked knives of farriers.
                  You have all the crooked knives and adzes of the Pacific Northwest carving tool designs.
                  Brian T


                  • #10
                    I use mainly palm gouges, carving mostly basswood and some cypress, a little white oak. I do not use an inside bevel, but make a couple of passes inside after honing to clear off the burr.Works fine for me, but using full size gouges and mallet with hardwoods is a whole different ballgame.

                    Someone mentioned Chris Pye's practice, but I've only seen him use full size gouges, often with mallet. You can't go wrong following his advice, but bear in mind the tools he recommends doing it on.