Observation on the P&N Bowl Gouges

Re: Observation on the P&N Bowl Gouges

JamieDonaldson

>Mark- if you look closely and next to a Sorby of the same size you will notice the flute on the Sorby is U shaped and the P&N is more of a V. I noticed the P&N does clog up much more easily with shavings, especially if they are wet.I much prefer the Sorby, and let my students grind away the P&N.

Re: Observation on the P&N Bowl Gouges

Phil Joines Krum, Texas

>Because of the V shape of the flute an Ellsworth type grind has a small dip just at the start of the side grind. It doesn't seen to make much differance on mine.

Re: Observation on the P&N Bowl Gouges

Lyn J. Mangiameli

>I always find this interesting, as there are enough reports from those who have complaints about chip clearance with parabolic (which is what the P&N appears to my eyes to be) and V shaped flutes, and those who don't, to suggest some credibilty must lie in each camp.

I simply don't experience this problem with either the P&N or the Glaser. Indeed, Jerry was kind enough to provide me with identical gouges except for flute shape (U vs V) that I could experiment with. In my hands, there were no problems with the V shape and the U shape offered no improvement.

Yet clearly respected tuners (Joe Fleming is one who immediately comes to mind) have reported they prefer gouges like the Sorbys that have U shaped open flutes. In contrast, I have a couple of Sorby's and they never see any action at all, as I so much prefer the Glasers.

So perhaps it is differences in technique, or perhaps it is that I just step up in gouge size if chip clearance is not occuring at the rate I'd like. I'm not sure, but can say that I have never personally percieved the narrower flute shape as ever detracting from chip clearance.

Lynn...

TDaniel

>I agree Lynn....it has to be in technique. I keep my handle VERY low and cut with the side of the tool...not the tip. A "V" grind just does not work for me on green wood. With a Sorby gouge the chips just roll out of the flute in a long continuous ribbon and hit the wall or floor about 20 ft away...no clogging.

TD

Lynn dip in tip

Darryl Hansen

>Lynn in the previous post there was mention of a small dip in the tip of Glasser gouge when grinding the "Ellsworth" type grind. I find the same thing when sharpening on the Tormek using the same settings as with a Crown or Taylor gouge. Both the later have "U" shapes. What's the fix??

Darryl, I'm not Lynn but...

TDaniel

>I have an answer to your problem. Profile jigs DO NOT give you the desired profile; they assist you in getting that profile. All the jigs give you a precise and repeatable nose angle and a precise and repeatable side angle...everything else is "by eye". If you are getting the "parrot beak" on the end of the gouge try grinding it away by removing metal before or behind it as necessary. Don't depend on the jig to do it all.

TD

Re: Darryl, I'm not Lynn but...

Darryl Hansen

>Thanks TD You'll do just fine. I thought there was an easy answer. I have been going to the bench grinder to round the tip a bit more than the jig allows.. but wasn't certain that was the right thing to do...Darryl

Re: Yes....

Lyn J. Mangiameli

>the jig controls the angles, but doesn't control the amount ground. The "dips" almost always occur because grinding on the narrow tip (with it smaller contact area) results in more rapid removal of steel than occurs when the larger area of the sides is all in contact with the wheel (this is just the difference it takes between sharpening a thin bevel on a plane or chisel blade compared to how long it takes to try to flatten and refine the entire back). Thus you will generally need to spend more time working the sides than at and near the tip. A good way to help with all of this is to mark the entire edge to be ground with a black magic marker, then you can see where you are removing steel and approximately how much. In the end, as Terry says, you need to sharpen to what your eye tells you is right. The trick is to now how to troubleshoot the errors you eye detects. In this case, you need to spend less time on the tip and more time on the sides.

Re: Yes....

Joel Hunnicutt

>I had the same Problem when sharpening with a tormek and Jeff Farris (Shpartools USA) told me that I was spending too much time on the wings. Once the grind is established. One or two continous sweeping passes are all that are required to refresh the edge. I followed his advise and after several sharpenins, the tool shape came back.

Re: Observation on the P&N Bowl Gouges

Joe Fleming

>Phil,

You shouldn't have a dip in the cutting edge near the tip. You are probably grinding that spot a little too much compared to the tip or the side.

Joe Fleming - San Diego

Re: Observation on the P&N Bowl Gouges

Joe Fleming

>I can't comment on the "respected" part, but I can comment on the gouges. I use four bowl gouges regularly: My Sorby 1/2 and 5/8" (bar side) and my Glaser 1/2" and 5/8". I grind the Sorby gouses differently than the Glaser gouges.

Glaser gets the more "Ellsworth-like" grind. I would call it a Jordan grind. The nose angle is about 55 to 60 degrees and the wings are ground such that the cutting edge is STRAIGHT. You can do this with a "V" shaped gouge because the sides of the flute are straight. The wings are 1" long or longer.

I use these tools for four purposes: 1 - Rough stock removal. With their weighted handles, they bounce around a lot less. 2 - Shear cutting/scraping on the outside of vessels. This means the handle is way down and the cutting edge is presented at around a 45 degree angle to the wood. The bevel is NOT rubbing, hence the scrape description. This cuts a fine shaving with the burr on the tool. 3 - For taking very fine finishing cuts on the inside of the bowl. If you grind off the heal of the bevel, the Glaser gouges have very little metal in the tip of the tool. The cutting edge is very short because of the "V" shape, so the shaving is very small. The handle weight keeps any chatter reduced to a minimum which is important in the final cuts. Makes a nice finish cut. 4 - Because the nose angle is different than my Sorby gouges, the handle angle is different. I sometimes use the Glasers just because the handle is in a more comfortable or controllable position.

The Sorby gouges have about a 40 degree nose angle and the wings are not ground back so far - maybe 1/2". They are slightly convex.

I use the Glasers for most outside and inside cutting on bowls and vessels. I grind the heal of the bevel off so that the effective node bevel is only about 1/8" or less. I find that the 40 degree nose angle gives better tool control for push cuts because most of the force of the handle (back) hand pushes the tool in the direction of the cut. With the steeper angles like my Glasers, the force vector is more directed into the wood instead of the direction of the cut.

I still haven't mentioned flute shape too much. My Glasers do clog more when doing "Sorby" cuts as described above. The effective cutting edge in these cuts is right at the tip and just behind. With a "V" flute, the size of chip you can take for a given cutting depth is less because the radius of the effective cutting edge is smaller. Trying to take a deeper cut means a wider chip is forced into the narrow flute - hence the clog. Also, when taking a scraping pull cut with a Glaser, the long wing takes a very wide chip and, therefore, is more prone to clogging. I suspect, however, that if I ground the Glasers more like the Sorby with a convex wing, the clogging would be a lot less.

Joe Fleming - San Diego