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Chance Raser
09-11-2016, 4:23 AM
So I have a grinder now, cbn should be here Thursday or Friday so I started making the wolverine jig. I got the plans from here:
http://www.eberhardt.bz/shop_notes/turning/sharpening/jigs/sharpening_jig.pdf

I am making some changes based on what I think will be easier /better for my style of fabrication. For all I know the changes could be a mistake, I'll soon find out.

The plans and some of the materials, I had all the steel lying around.
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Got some of it cut out and prepped.
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It's kinda funny, I printed out (to scale) the two styles and drew my redesign on the back of one. Wouldn't you know it, I ended up cutting up the one with my drawing on the back!

Lots of test fitting, drilling, hand filing and finally welded the bolts on.
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The nylon washers were not intended, but I had over drilled one of the holes so I had to make mid plan adjustments. I think they will work out perfectly tho.
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Now I have to finish the top half, clean everything up and paint.
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I hope to finish tomorrow, we'll see if I get garage time.

Brice Rogers
09-12-2016, 5:29 PM
Nice looking wolverine jig.
I made a Captain Eddie Castiline $2 jig and am happy with it. I think that both can reproduce the David Ellsworth grind nicely.
I sharpen using the Captain Eddie jig and then between sharpenings I touch up with a diamond file. Because the bowl gouge leaves a concave surface, it is quick to touch up with the diamond file because it is only removing material on the two edges.

Chance Raser
09-14-2016, 1:57 AM
I got the top together. Now a little grinding and painting to come.

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Rich Riddle
09-14-2016, 11:44 PM
Keep us updated on your progress.

Chance Raser
09-15-2016, 2:31 AM
I painted it lady night, just got it assembled.


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I am pretty happy with the way it turned out. I'll take a few more pics tomorrow.

The nylon washers turned out to be a really good thing that happened by accident.

Next on the list: the other half of the wolverine which mounts under the grinder and slides in and out. Does anyone have a measurement from center of wheel to center of slide out? It's going to have 8" wheels on it.

After the slide out I plan on building my take on a roborest!

Brice Rogers
09-16-2016, 7:26 PM
Google "Ellsworth grinding jig dimensions" and click on images. You'll see a lot. You can also Google wolverine jig manual and get some different dimension.

I think that for the Ellsworth grind on a bowl gouge, generally most folks probably go out 7" (or 7-3/16") from the surface of the wheel (measured horizontally and not diagonally) and four inches down from the center. Many or most people have a 2" stick-out from the holder, but some use 2-1/4" inches

Much of it depends on the exact grind you're trying to get. I did an experiment of different stick out distances of 1" to about 3" and found that by increasing or decreasing the distance from the wheel surface to the pivot point would end up with essentially the same front angle.

I think that one of the primary purposes of the grinding jig is to ensure consistency from one sharpening to another in order to minimize how much metal you're grinding off and to minimize sharpening time. So, with your jig and with the positioning of the base pivot point, you have four inter-related adjustments that you can make.

Chance Raser
09-21-2016, 2:11 AM
Well I got started on the adjustable tool rest, aka roborest. I made some changes, largely based on materials I had in my garage and my desire to use an indexing plunger to keep the rest where I set it. This is essentially what I wanted and ordered:

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So in order to only use one index plunger all the adjustment holes had to be in a single arc. So this is what I came up with

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The full design

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And where I am currently at


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Chance Raser
10-07-2016, 1:17 AM
Finding very little garage time lately. But here is my progress.

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John Nesmith
10-27-2016, 7:10 AM
Can you explain the indexing plunger? I can't figure out what it adds over the standard roborest pin.

Thanks.

John K Jordan
10-27-2016, 11:35 AM
Can you explain the indexing plunger? I can't figure out what it adds over the standard roborest pin.

I haven't seen a Roborest but from the pictures it looks like a long pin goes all the way through two indexing vanes, well below the grinding wheel. The indexing plunger Chase shows could be placed where a long pin would not clear the wheel. I can't tell from the pictures whether a through pin would clear the wheel on the current design.

A single indexing pin on one side only should work ok but care would have to be taken to insure rigidity of the frame and index pin support as well as precision in both bushings. Any flexing or slop could result in an inconsistent grinding angle depending on the forces on the rest. If it did turn out to be not sturdy enough a redesign of the indexing vane angles and adding a second one on the other side could change that, or use two indexing plungers.

I'm interested in hearing how this works out. I love to see people designing and building tools and jigs. I sketched out a similar sharpening rest once but never took it further. I added a micro-adjustment for when I wanted to match an existing grind that was not an angle provided by the indexing.

JKJ

Chance Raser
10-28-2016, 1:20 PM
Can you explain the indexing plunger? I can't figure out what it adds over the standard roborest pin.

Thanks.

A few reasons went into selecting an indexing plunger.

The primary reason as john pointed out the plunger is only required on one side. This was important for me building my own adjustable rest because it would be far easier to get a pin (or plunger in my case) to only have to line up with one side vs. having to line with two sides. Not that it would have been impossible, but the roborest is made from one piece of steel mechanically bent and then both sides are probably drilled from the same orientation. regardless of how it was done, surely it was manufactured with more sophisticated equipment than what was at my disposal. so, main reason, easier to only have to align one side.

second reason was i liked that the plunger is spring loaded. you pull on the knob, rotate the table, release the knob and it finds the hole.

Things that went into that plunger selection:
my goal was to only need one plunger, and since the plunger would be static it meant the alignment holes had to be in a single arc unlike the roborest. After lots of design and trying to get a larger plunger to fit (in sketchup)i came across that particular plunger at a great price.

I ended up selecting that particular plunger because it had a 4mm pin. I just happen to have some electrical drill bits, i beileve it is the #21 which has a diameter of 4.04mm which was just large enough to provide some clearance and small enough to have very little slop.

the 4mm pin also kept the single arc small enough to not get into (BARELY) the nut holding the CBN wheel on the grinder. Its really close. ill post a pic. To get the arc radius i had to account for the hole size necessary plus the minimum distance i wanted (read: amount of material) between the holes.

for the record, the roborest is probably a better tool, and most definitely worth the price. Its just that i like building shit, and thought this would be fun.

In the end, i am extremely happy with the outcome. there are definitely things i would change if i ever am ever inclined, but right now it works great.


I haven't seen a Roborest but from the pictures it looks like a long pin goes all the way through two indexing vanes, well below the grinding wheel. The indexing plunger Chase shows could be placed where a long pin would not clear the wheel. I can't tell from the pictures whether a through pin would clear the wheel on the current design.

A single indexing pin on one side only should work ok but care would have to be taken to insure rigidity of the frame and index pin support as well as precision in both bushings. Any flexing or slop could result in an inconsistent grinding angle depending on the forces on the rest. If it did turn out to be not sturdy enough a redesign of the indexing vane angles and adding a second one on the other side could change that, or use two indexing plungers.

I'm interested in hearing how this works out. I love to see people designing and building tools and jigs. I sketched out a similar sharpening rest once but never took it further. I added a micro-adjustment for when I wanted to match an existing grind that was not an angle provided by the indexing.

JKJ

you are correct John, the pin goes through both sides. The rigidity is well within acceptable (at least at my current skill level). I would say the movement fits within the definition of negligible, i dont get an flexing or slop, but i also don't push on the platform with any notable force, really its put the scaper up there, hold with one finger and rotate against CBN wheel.

I will say tho, if you have thought about micro-adjustment then this probably wouldnt suite you.

Ill get a few more pics posted tonight, pics with it on the grinder.

John K Jordan
10-28-2016, 4:03 PM
Where did you buy your indexing plunger? I want one for an indexing plate for the lathe.

JKJ

Chance Raser
10-30-2016, 3:46 AM
Where did you buy your indexing plunger? I want one for an indexing plate for the lathe.

JKJ

http://www.jwwinco.com

The pics I meant to post:

Like I said, really close. This is obviously adjustable by sliding the the whole thing away from the grinder. When set right, there is about 1/16th between grinder wheel and platform and the platform can swing through the full motion.

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