Yet Another Grinding Question

[Jon Finch]

Hi all, my first post!

I had a pretty lengthy post typed out that got sucked into the ether and I don't think I'll retype it so I'll try for a readers digest revision...

What effect does the leg angle on the vari-grind jig have on the tool being ground?

What effect, if any, does the distance the tool is projected from the front of the jig have on the tool being ground?

Looking around I see all sorts of suggestions on where to adjust this jig. I'd really like to ensure that my understanding of this is correct. Perhaps it all really just doesn't matter...

Here's a picture of my attempt at grinding a fingernail profile to a traditional ground bowl gouge. I either have not ground the sides enough or I have got an issue with where I've set my vari-grind jig (2" tool projection and 23 degrees between the handle side of the tool and the jig leg). Also, it looks to me like I've messed up the bevel angle on the tool making it too sharp. It looks to have about a 40 degree angle while a bowl gouge should be closer to 60???

Please critique my grind.

BTW, I had much better success using this tool ground like this then how it came with the traditional grind (although the extra practice on all those failed attempts might also explain why I was finally successful finishing a bowl).

Is it customary to post a picture of your first bowl?

[David E Keller]

Yes to the photos on the first bowl.

I don't think it matters what the exact angle of your grind is. More acute angles are harder to use for deep cuts because it's harder to rub the bevel. The tip looks a little pointy but that may be the photo. If you find a grind that works for you, stay with it. I think the jig is helpful for being able to replicate the grind that works for you.

[Steve Schlumpf]

Jon - Welcome to the Creek!

To answer your question:

What effect does the leg angle on the vari-grind jig have on the tool being ground?

Leg angle will determine the angle of the nose. Course, that also depends on how close you have the control arm to the grinding wheel.

What effect, if any, does the distance the tool is projected from the front of the jig have on the tool being ground?

The length extended will determine how long your swept back wings will be.

Also, it looks to me like I've messed up the bevel angle on the tool making it too sharp. It looks to have about a 40 degree angle while a bowl gouge should be closer to 60???

Just me but the nose angle on my gouge is set at 42*. It works for me but is harder to control when doing the inside bottom of a bowl. Just something to consider - the steeper the angle - the more aggressive it will be.

Is it customary to post a picture of your first bowl?

I would say we love photos of all your turnings - but especially those items that are firsts!

And, as this forum is composed of many members of differing skills and experiences - you will get many views of what works best. Pick and choose from everything - but find out what works best for you!

Welcome! Looking forward to seeing some of your work!

Here is a video that Oneway offers that may help answer some of your questions: http://www.oneway.ca/multi-media/wolverine_videos.htm

[Jon Finch]

What effect does the leg angle on the vari-grind jig have on the tool being ground?


Leg angle will determine the angle of the nose. Course, that also depends on how close you have the control arm to the grinding wheel.


What effect, if any, does the distance the tool is projected from the front of the jig have on the tool being ground?

The length extended will determine how long your swept back wings will be.

Hmmm, I need to think about your answer... I was thinking the leg angle adjusts how "smiley" the grind is (when viewed from the side). i.e. if the angle is zero then you essentially have the tool in the wolverine without the vari-grind and you'll end up with a traditional grind with vertical sides when viewed from the side. As the jig leg angle is increased the grind moves down the side of the tool making it more and more "smiley" as the angle increases.

And I was thinking the amount the tool projects from the jig is mostly inconsequential to how the grind ends up. You just need it to extend enough to clear the wheel as you grind the tool.

All this assuming you use the wolverine arm to get the correct bevel angle.

The video from Oneway and the info at Thompson Tools and the info at Craft Supplies (Talon set-up jig PDF) all use different angles and tool projections which is what lead to my curiosity.

I'll take a picture of the "first" when I get home tonight.

[Steve Schlumpf]

Jon - it is hard to put into words - but I tried to explain the basics as I have come to understand them. Everything does work together and when you vary one portion - you vary the outcome.

The basic leg angle (to me) is used to set the nose angle but this has to be combined with how far you have the rest placed from the grinding wheel.

The length the gouge is extended from the holder does impact how long your wings will be. I have a block set up so I can take any of my 3 gouge and set the depth before sharpening. One gouge is 1 3/4", one is 2" and one is 2 1/8". The amount of wing - at least on my gouges - goes up with amount extended past the holder.

Again - everything works in combination and how smoothly you keep the tool moving while sharpening.

[Jon Finch]

Ahh, I just rewatched that video on the Oneway site. At the end it shows how to set the jig up to duplicate an existing gind. He uses the wolverine arm extension to adjust the bevel at the front of the tool and the leg angle on the vari-grind to adjust the bevel on the side of the tool. Adjusting each independent of each other and then readjusting again... rinse and repeat until both bevels lay on the grinding wheel.

So the leg angle must be changing the relationship between the bevel angle at the front of the tool and angle on the sides.

I don't know why I can't seem to wrap my head around this...

[Jon Finch]

Pics of the first successful bowl (no finish, just sanded and I need to use a scraper or learn to cut smoother on the inside).

Also roughed out a bowl from a piece of cocobolo I had laying around. It needs to dry out a bit before final turning.

And a couple of my failures. Cracked foot and turned too thin...


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Back to my grinding issues. I think I'll try regrinding it using the instructions from the Thompson Tools site. And maybe increase the bevel angle.

[John Keeton]

Hi all, my first post!

I had a pretty lengthy post typed out that got sucked into the ether and I don't think I'll retype it so I'll try for a readers digest revision...Welcome to the creek, Jon! I am a real newbie on the lathe, so I am no help on your actual question.

But, I can tell you that I lost MANY posts to the ether until I finally, and now habitually, block my post, right click, and copy it to my clipboard before I click submit.

I lost count of the dozens of times (probably way more than that) this has saved me. For some reason, I have real trouble keeping a good connection with the SMC server. I don't have that problem with any other site, and until your post, I thought it was just me.

[Bernie Weishapl]

Welcome to Creek Jon. You got some good info but wanted to say nice first bowls.

[Ryan Baker]

Ahh, I just rewatched that video on the Oneway site. At the end it shows how to set the jig up to duplicate an existing gind. He uses the wolverine arm extension to adjust the bevel at the front of the tool and the leg angle on the vari-grind to adjust the bevel on the side of the tool. Adjusting each independent of each other and then readjusting again... rinse and repeat until both bevels lay on the grinding wheel.

So the leg angle must be changing the relationship between the bevel angle at the front of the tool and angle on the sides.

I don't know why I can't seem to wrap my head around this...

That's it!

The angle of the leg determines how the grind angle changes as you move from the tip to the sides. The projection of the tool from the jig does not matter at all (except that using a fixed amount is easier for some people to reproduce, depending on technique). The angle of the nose is set by the extension of the V arm. The amount of the "fingernail" and the shape of the grind are determined by the amount of grinding you do in each of those locations, not by any setting of the jig.

Here is the way I do it. I stick the gouge in the jig 'about the right amount'. (I don't measure. I change grinds between tools so often that I don't find any fixed setups to be useful to me.) Put the jig into the V arm and adjust the V arm extension until the nose bevel matches up to the wheel. Rotate the tool (with the grinder still off) to check whether the grind angle still matches on the sides. If it does not match, you need to change the leg angle and go back to adjusting the nose angle again. (The leg angle takes the most time to get right, so it helps to not have to change that too often.) Turn on the grinder and sharpen away.

The nose angle can be anywhere from about 40 degrees to 70 degrees or more. They are useful in different circumstances, and everyone develops their own preference. Same is true for the shape of the grind and the amount the wings are swept back, etc.