Grooving

[RobinW]

I don't do much wood turning, but whenever I sharpen up some gouges I make a hash of my SG250 wheel, the latest effort is shown below. I try not to apply much load to the tools, but still end up with an undesirable surface, and subsequent loss of material by the time I have used the diamond truing tool. Most sharpening is straight tools - plane blades and chisels - and I haven't grooved the surface when doing those, even with narrow chisels. Suggestions welcome.

[jeffs55]

Seems to me like you are holding the gouge in one place to long. I have never sharpened or owned a gouge but what else could it be?

[Ken S]

Robin,

I think we have a truing problem. I vaguely recall Jeff Farris posting that he would routinely take a light cut with the TT-50 Truing Tool before sharpening a gouge. (This should be verified.)

Being out of true sneaks up on you....

A freshly trued grinding wheel has the side benefit of being the most coarse for a short period.

Kehep us posted. I suspect this may be a common problem.

Ken

[RobinW]

Hi Jeff and Ken,

Thanks for responding. A couple of points why I am a bit baffled with my mess.

Watching the video by Jeff Farris, I note that he is generally keeping the ground face of the tool pretty much in the same area of the stone. I deliberately sweep or stroke the gouge across the face of the stone, trying to keep it on the move all the time, in an effort to prevent grooving the stone. Failed big style! I haven't been out to check, but I note that Jeff had the tool set to position 4, whereas I am sure I am at position 2. I don't see why that should cause my problem.

The stone had been re-trued as I did a touch up on a plane blade before doing the gouges, so I started off with a good surface.

It is not the first time I have grooved the stone - so definitely in need of corrective training.

[RichColvin]

Robin,

I get that too when I'm shaping a gouge, particularly a bowl gouge, and especially with HSS.  (I use the SB stone.)

Once the shape of the tool is right, I only have to lightly regrind to resharpen.  It is much less of an issue then, though after 20-30 touch-ups, I do have to re-true the stone.

The real key is light touches on the resharpening.   Plus, that takes away less steel & your tool will last longer.

By the way, the angle setting should have no effect either way on this.

Kind regards,
Rich

[Rob]

Hi Robin

I'm afraid the bad news is there's no way to completely eradicate the grooving when sharpening gouges, especially deep fluted bowl gouges as has been stated already.  The reason is straightforward enough, they're High speed steel which is of course much harder then your typical carbon steel plane/chisel blade and also the grinding friction is concentrated in a very small surface area with a huge amount of leverage when you consider the position of the handle.

The good news is you can minimise it and nearly all the methods have already been mentioned save for one which is easily the best.  Firstly, go make sure the stone is as rough as you can get it.  max roughness is achieved as Ken said by truing.  Second max roughness with the stone grader on 220 grit.  But there's another way I've discovered which is as rough as the truing tool but a million times faster which is to use a diamond T dresser with the USB literally 1mm from the stone.  This acts as a means of holding the dresser dead flat against the wheel to keep it true.  Works a treat, ultra fast.  Change the water once done.

Second, do avoid one spot if you can, allow the gouge to dance around the whole width of the stone and take light passes.  Takes longer but digs less and slows the grooving.

Best of all though, using the adjustable collar on the SVD 185/6 elliptical grinding jig, slip the tool to the end of the travel and grind off the heel of the bevel until you've done about half the bevel.  Then adjust it back to the desired angle but just sliding the collar to the other end of the stop and tighten the black plastic knob.  Now when you grind the (primary) bevel it only has to remove half the metal and it goes MUCH faster.

It's the same concept as a micro or secondary bevel on a chisel and it has no effect at all on the cutting performance of the gouge when turning since all the action is happening at the very edge.

What I've found over the years is that when you're shaping a gouge for the first time and you're removing a lot of metal, you're going to groove the wheel...so just live with it and keep retruing using a diamond dresser, little and often to keep the wheel sharp.  When sharpening ie once your desired shape is there, grind the secondary bevel and then from that point forward, just keep the shorter primary bevel sharp.  I promise you that you'll be amazed at how fast you can sharpen that bevel from then on....literally a single pass will do it.  No exaggeration, one pass will put a new edge on.  In fact, if I'm not too far over the rest, I frequently don't even remove the jig from the gouge.  I'll sharpen, leave the jig on, turn and then return to the Tormek for a single pass touch up as often as the job needs.  I tend to do this with very hard, unforgiving woods, especially if they have gritty bark on them.  Once you need to go well over the rest, you cant use this technique as the jig snags on the rest, preventing the edge from reaching it's goal.  I do this with both spindle and bowl gouges.

I also have an SB wheel, specifically because my primary use is HSS turning tools and honestly, I see no difference between that and the old grey wheel. 

Final point, Grinding HSS with fine point tools will wear away your wheel faster than bench tools made of carbon steel, it's just a fact of physics but using the methods above will minimise the wear and keep you turning with razor sharp edges.

Hope that helps.

[RichColvin]

Robin,

Rob is right on about the rounding off of the grind.   I have seen this too.

I typically aim for a 50% cutting edge / 50% secondary bevel.   That is different from plane or chisel blades which might have only 1mm of cutting edge.

The SVD-186 manual discusses how to do this, as shown here :




Rob's idea of leaving the jig on the gouge is an interesting one.  Will have to explore it more. 

His point about not wasting time is something I want to explore using an idea I saw on an AAW blog.  I would adapt it to mimic the TTS-100 with 55, 65, & 75 mm holes for the protrusion setting.  I like the jig below on the left, and will make a single block that has all three depths.  I will secure that block to the bench so I can quickly set the jig on the gouge, sharpen it, and get back to turning.  Will save me having to swap the TTS-100 as both a protrusion setting jig, and a universal bar setting jig. 



Kind regards,
Rich

[Rob]

I rather like those dome shaped, turned protrusion setters Rich....very twee :-)

I've done similar to achieve the same result by just screwing ply stop blocks directly onto my sharpening station top.  They're placed exactly the correct distance from the edge to correspond with the protrusion setting I'm after.  I place the SVD 186 over the gouge and then pop it down flat on the table until the tip hits my stop, then, to avoid the gouge rotating away from top dead centre (ie with the flute facing straight up) I pinch it with my left hand against the jig whilst simultaneously tightening the knob to lock the tool in the jig.

[Hatchcanyon]

Yes it is true gouges may be the most demanding tools on the stone. For shaping/sharpening gouges I always use the SB stone. The SG seems to be the wrong one for HSS.

Until now I have shaped and sharpended several gouges alwas trying to sweep over as much stone surface as possible. Shaping sometimes leads to a quite shallow depresion in the stone. Never got such a terrible stone distortion as shown in the picture above. Resharpening a worn gouge is quite quick and does not "eat" much stone.

Rolf

[Ken S]

This is a fascinating and usefel topic.

I'm the guy with very good woodturning training, but very little lathe time. As such, my sharpening time with woodturning tools has been oriented toward forum projects and preparing for demonstrating the Tormek.

I reshaped a half inch (12mm) spindle gouge using a 46grit Norton 3x grinding wheel (wet) on my Tormek. The procedure went quickly and worked well. However, my wheel developed a groove about 2mm deep. This grooving was accentuated by the width of the wheel, one inch (25mm). I was and still am reluctant to use the TT-50 Truing Tool on such a coarse grinding wheel. The test was just before I figured out a good truing alternative.

I keep both 46 and 80 grit 3X wheels (the harder grade) in my arsenal of wheels for the Tormek. (I purchased both grits for testing; either one is sufficient.) They let me have the fast grinding of adapting Tormek jigs to a dry grinder without all the dry grinding limitations of overheating, dust and sparks. This method is also cost effective, as a 3X wheel costs $50 US, less than the BGM-100 and no extra grinder and wheels are required. I will state that the 3X wheels are specialty tools and not replacements for the Tormek SG and SB wheels.

I also tried reshaping a one inch (25mm) skew chisel using the SB and SG wheels. I made a big mistake in this. I assumed the skew profile matched the TTS-100 profile. It did not, which resulted in a LOT of unanticipated grinding time. A wiser sharpener would have measured first and altered the profile gradually over several sharpenings. Eventually the skew profile would match the profile, with much less wear and tear on the sharpener.

What I eventually discovered during this process was that using the SB in the horizontal position with a lighter touch worked best. Also, I dressed/trued the grinding wheel very frequently. The Freshly dressed wheel cut really well for a short period, and then needed dressing. As described in the handbook, I used a thirty second traverse time with the truing tool to create a rougher surface than my usual ninety second time.

I reached the point where I just wanted to be done. Rich mentions efficiency. I found that using a second universal support for the TT-50 noticeably improved efficiency. I would leave the first universal support set for the distance of the jig. The second support has the TT-50 left in place and left set for almost no clearance. The support switch is faster than resetting one support.

During this, I became more comfortable with taking deeper truing cuts. I still prefer lighter cuts, and wholeheartedly recommend light cuts for beginners. With experience, it is nice to have a little more cutting muscle in reserve.

I also tried using a diamond tee dresser. It worked very well. Regardless of the chosen method of stone redressing, I would suggest using the TT-50 for the final sharpening.

I do not believe we have reached the full potential of the Tormek in this operation.

Rich's homemade wooden protrusion blocks are a good example of the "Popular Mechanics Home Workshop" thinking. This is a noble tradition of craftspersons making their own tools. The TTS-100 is the offspring of wooden gage blocks.

Called away. Time to post. I will return.

Ken

[Rob]

I must say Ken, I really like the innovation of using those Norton wheels on the Tormek to overcome the shaping problems well documented in previous posts here.  If I hadn't already invested in alternative kit (incl the BGM 100 and a regular bench grinder amongst others) I would have gone that route myself coupled with the easy lock quick release mechanism.  Out of curiosity, is the hub of the Norton wheels the correct diameter for the Tormek spindle or did you need to pack it in any way?

[Ken S]

Good question, Rob.

The Norton 3X wheels use a series of bushings to sixe down to 5/8" (somewhere around 14 or 15mm) The Tormek shaft is 12mm. I used a short length of 5/8" outside diameter schedule 80 plastic water pipe. The inside diameter is 7/16", which can be drilled out to 31/64" or probably 12mm. Cut the drilled piece to length and fit it into the grinding wheel with the other bushings. As these are coarse wheels, this arrangement should be more than accurate enough. I have posted more details about this in the past.

Ken

[RobinW]

Thanks to all for the responses. I can't do any updates at present as other things have priority.

It's interesting that others have had similar experiences as myself, and whilst undesirable, it's nice to know that I'm not alone and the feedback (as ever on this Forum) is very knowledgeable. I do like the idea of two bevels on the gouges.

To paraphrase Captain Oates "I am just going outside and may be some time", and like General MacArthur "........ I shall return". (might be a while!)

[Ken S]

Robin,

You mentioned this topic in a drill bit topic.  I will answer here to avoid hijacking the other topic. In my testing with CBN wheels, they seem a logical choice for harder steel which can wear grooves in the standard grinding wheel. As with any grinding wheel, I try to use the whole surface, however, it seems less important with CBN backed by steel.

Ken