Vari-Grind Problems

Re: Vari-Grind Problems

Richard Allen

>The distance the "V" arm is extended is primarly responsible for the nose angle.

The angle of the arm on the jig is primarly responsible for the side angles.

The jig assist you in grinding the tool. You can of course grind more in differnt places to provide a different grind without adjusting the jig.

The best way to setup the jig is to have a tool which has a grind that you like. Using the "V" arm distance to set for the nose and the angle of the arm for the side angles. Just keep adjusting till you match the profile.

Good luck

Re: Vari-Grind Problems

Bill Grumbine, Kutztown PA

>Hi George

If I had to guess, I would say that you are getting the majority of your catches on the top of the grind near the spot where the edge ends and the top of the flute begins. Grind it a little bit more keeping everything adjusted to the same angle. Stay away from grinding the nose though, concentrating on the sides. You will eventually flatten out the "hump" at the back side of the edge, and I think you will find the tool less grabby.

Bill

Re: Vari-Grind Problems

George Van

>Thanks for the tips.

I will go give them a try. The only other bowl gouge I have is a new Crown PM 1/4" bowl gouge. That came with the nose flute 90 degrees, no back sweep at all. I was going to grind that next but now I will wait.I'm sure a model gouge would be best.

I will check back and tell how it goes.

Thanks, George

Re: Vari-Grind Problems

TDaniel

>George, I have both the Sorby and the Wolverine with the vari-grind. The Sorby is much easier to use but the setting is the same. It looks like you may need to move the bar to the right a notch or so. You want the side wing less steep. If the flute were pointing straight up the wing should follow a line to 4 o'clock if that makes sense. Look at the tool grinds library and you'll see several examples of good grinds. Also, it is best to start shaping the tool with it upside down. After you get the shape you want then grind to the inside edge to (to the flute). Phil Wall showed me this and it works well. An easy to use shape is a well rounded end; avoid a point unless you have several gouges and want a point on one of them.

TD

Re: Vari-Grind Problems

George Van

>Thanks Terry, do you mean to lower the leg on the Vari-grind a notch or two, or back the V bar out away from the grinder a little?

I finished the grind before I saw your post and used it to start hollowing a 7" cherry bowl which in short order caught and ripped the bowl off the tenon and across the floor. A piece of the curl was still caught on the edge 3/4 of the way to the top.

George

You are right, the side feels too straight, feels like i'm using a skew.

gouge presentation

Larry Hancock; Ardmore, OK

>George,

In your last message you mentioned that it was on the inside of the bowl where you had the big catches. I would think that it is not the grind on the gouge but the way the gouge is presented to the wood that is causing the catch. The tool rarely causes a catch, we as turners put the tool in a position that will cause a catch. If you face the gouge flute away from the wall being cut, with the handle slightly down and the gouge rotated back to the left just enough to allow a cut to begin it is nearly impossible to catch. The cut is coming off the lower edge of the nose where the cutting edge is closest to the area of the gouge supported by the tool rest. Roll the handle to the right just a little and the bevel will be rubbing with the cutting edge rolled down and the cut will stop. The picture below shows how it will look in cutting position.

Larry

Re: gouge presentation, image 2

Larry Hancock; Ardmore, OK

>This image shows that the bevel of the gouge is aligned with the direction the cut is going. The top of the flute is just rolled back enough to clear the nose of the gouge for cutting action to occur on the lower side of the gouge.

Larry

Re: gouge presentation, image 3

Larry Hancock; Ardmore, OK

>If you present the gouge to the bowl wall in this manner you will have lots of bad catches if you don't know how to use this cut. Terry D. uses this cut a lot and I use it at times because it presents a nearly vertical edge to the wood and will give a good cut but it will also produce bowl shattering catches if the flute near the wall has a chance to get into the wood. You are cutting with an edge that is out away from the contact area of the gouge on the tool rest. When a catch occurs it will roll the gouge to the left into the bowl wall and since the flute is facing up it will try to impel the bowl on the big side ground cutting surface, on my gouge that would be about 1 1/4" of cutting edge on the side. That is a pretty hard for a bowl to handle and it will usually tear it apart or break the bowl foot where attached to the lathe.

Larry

Re: gouge presentation, image 4

Larry Hancock; Ardmore, OK

>This picture shows the amount of cutting edge that can catch in the side of the bowl if you present a gouge to the wood this way. There is more than one way to hollow a bowl. Pick one that get the job done for you and then try variations as you learn more. You can see from the pictures how I grind my gouge. It is 65 degrees at the nose and sharpened with a wolverine jig. I have had lots of catches over the years and it wasn't because of the grind, it was the way I presented the tool to the wood.

Hope this helps some.

Larry

Re: gouge presentation, image 4

Everette Harmon

>Excellent pictures and advice.

Everette

Re: gouge presentation

Mike Rubes

>Hi Larry,

Those are great "demo" pics and advice. Thanks for posting the pics, it is always so much more helpful to see a pic of what someone is talking about.

Thanks,

Mike

Hoping for lathe time today in Apex, NC

Re: Vari-Grind Problems

TDaniel

>George, with the lever facing up and the wingnut on bottom you would move the lever to the right. To change the nose grind angle you would move the gouge toward or away from the wheel. These jigs only give you the nose angle and the side angle; everything else is by "eye". You have to know what you want the tool to look like before starting to grind. None of these jigs will automatically give you a useable profile but they make it easy to accomplish one if you know what you want going in.

TD

I will vouch for Larry's method

TDaniel

>Larry and I use our gouges quite differently but I have seen him use his as he is describing here and I can vouch that it works. With fingernail gouges a lot depends on toolrest height, handle position, grind angles, end shape, etc. and all these have to be worked together. It is possible to have one grind that will do it all (though some disagree with this). If you have several gouges you can customize the grinds for particular uses. If you can get with someone who uses the fingernail grind bowl gouge and try their grind until you find one that you like then copy that grind you will find that easier but be aware that all grinds do not work well with all lathes. A larger swing will allow a steeper nose grind and a toolrest that will go lower will likewise allow a steeper nose angle. When Larry was here I noticed that he cuts near the tip of his gouge and he got a very good cut; I cut with the side of my gouge and get a very good cut. As the saying goes, "there is more than One-Way (excuse the word) to skin a cat."

Thanks for the help!

George Van

>Thanks Larry, if OneWay used your great photo explanation it would have saved me a lot of time. You showed (image 3) and explained exactly how I got the catch! I tried this grind hoping to have a better shearing approach on the side of bowls to reduce ridges. I was able to use the side approach with the old grind angle as it was a less aggressive fingernail grind angle as shipped from Sorby. Being less experienced, maybe I should go back to it but I think I will try to learn this angle for now, after all the woodshed is � full. Thanks for taking the time to take the photos and post. These should be in the library under DO�s & DON�Ts ! I will save this page for reference.

Richard, I will take my gouge and be looking for an example tonight at my first AAW local (130 miles) meeting in Superior, WI.

Terry, I will use your adjusting info when I have a form to follow. Your tool rest reference is a good one, the rest on my PM45 only allows me to lower to the bottom line of the gouge, not level with the edge, this forces me to be out and downward a lot of the time. I got some steel from Enco and will be making a more friendly tool rest shortly. A different lathe would be nice but I think I had better learn the basics to better choose the best choice for me.

Thanks again, George

Re: gouge presentation, image 4

Wally Dickerman at Green Valley, Az.

>Nice to see you posting here Larry. As usual you've made a very good presentation. I use the gouge much the way you've shown it in your photos. I agree that catches occur because of the way the gouge is used, not because of the grind. When the bowl gouge first came to this country in the very early 80's they were all ground straight across, like a roughing gouge. Everybody used them that way, and they could give you problems when working inside a bowl.

Wally

Re: Thanks for the help!

Don Orr

>I have to agree with George. It is incredibly helpful to see what NOT to do in addition to what is correct in a very specific, graphic way.

Thanks very much to all! Another great learning experience on Woodcentral.

Re: gouge presentation, image 3

Bill Grumbine, Kutztown PA

>Hi Larry

Very nice presentation! This is one scary cut though, and I rarely use it. I don't even bother teaching it. Most students are content with the thrill of shear scraping the inside of a bowl. ;-)

You might want to consider posting this as a separate thread for the benefit of those here who might not be following this one.

Bill

Re: gouge presentation, image 3

Mike Schwing from Maryland

>I use cuts 3 and 4, (pics 3 and 4) a LOT. I do mean a lot. As Ellsworth describes number 4, its a "shearing cut". I don't know enough to comment on that but I find number 4 to be wonderful for a finishing cut. I start by touching the bevel on the work, but no edge, and then carefully rotating the flutes upward until I see or hear cutting action taking place. Then careful movement forward, never rotating any more upwards on the flutes, will follow the profile and give a remarkable finish. As I approach the bottom of the bowl with cut 4 I have to sometimes rotate inward on the flutes a bit. Incidentally, if the tip of the grind becomes too rounded as opposed to having a small point, it will catch badly with ease on bowl interior bottoms. One must take care to clear shavings in advance of cut 4 used as a finishing cut.

Cut 3 can be done with confidence reliably. I have to use it when working on something deep that won't allow the side grind to do the cutting. One can definitely overdo cut 3, and it will actually cut on both sides of the grind, tip and all - something to avoid. When I see this happening I have been taking too big a bite, back up, and take only half again as much.

Thanks for the pics!

Re: gouge presentation, image 3

Russ Fairfield

>This cut is easier to make if the bevel is ground to a convex curve, rather than the concave profile that is made by the grinding wheel. I have a photo of this bevel profile in the "Grinds Library"

With the conventional concave bevel the tool is riding on the cutting edge and the heel of the bevel. There is nothing there to prevent the cutting edge from digging into the wood.

With a convex bevel, the cutting edge is supported by the bevel below it. This supporting bevel will be quite wide, and the tool will be easier to control, when the curve of the bevel is close to that of the inside of the bowl.

Re: gouge presentation, image 3

Bill Grumbine, Kutztown PA

>That explains a lot Russ. I have a concave grind, since I come straight off the wheel using a Wolverine jig. It is rare though, that I have tearout that cannot be fixed with either a nice sharp scraper or a shear scrape with the bowl gouge. I use the cut described in pictures #1 and #2, followed up by either the shear scrape or a scraper.

Bill

Re: Thanks for the help!

Larry Hancock; Ardmore, OK

>George,

I just hope you enjoy your turning. As you have the opportunity to be around more turners and get more experience you will learn all types of grinds and tools to use for different situations. You have a good source for information here but hands on experience with another turner will speed up the learning process.

Larry