India stone grinding jig

[TorontoBuilder]

I dont have plans or a the time to mill nice comb shaped thin bent profiles to hold abrasive stones to the surface grinder for diamond grinding, so I whipped up a design I'm confident should work well enough.

This jig is specifically to hold Norton Crystolon/India combination bench stones but will work for any 2" x 6" stone.

1/2" x 2" x 6" cold rolled steel, milled flat and parallel, bored and threaded 10-24 at 2" o.c. from the center to allow side plates to be mounted. Then both sides will be given the slightest kiss in the surface grinder to true to the surface grinder using aluminum oxide wheel.

1/4" x 3/4" x 6.5" cold rolled steel, milled flat and parallel, bored, countersunk and threaded for 10-24 at 2" o.c. from the center to allow side plates to be mounted to main body. the the sides will be bored for seven holes located 2.75" o.c. from the centerline and threaded 4-40 for nylon tipped grub screws that will be used to hold the grinding stones securely to the jig while grinding.

I figure this is accurate and secure enough to provide the stones a level surface to a high level of precision.

Of course I'll mount the jig to the magnetic chuck

 

[jorogi]

Looks like a computer generated image so perhaps you're just at the design stage. I was looking at the same issue, still in the design (a rather grandiose term) stage too, but I do have a tool for the same basic task and it works well.

Basically my plan I to cut two 3/4" bars an inch or so longer than the stone and drill 2 holes in each such that the stone can nest inside the holes.
Two pieces of all-thread, nuts and washers fitted through the holes and long enough to straddle the stone and you have a basic vise.
Place the stone on the mag chuck or relatively flat surface, clamp the vise to it and turn on the magnet. Badda bing, badda boom you have a secure stone ready for grinding and in less time than it took me to type this up (I recognize that comparison sets the bar very low).

Design options;
grind, mill or somehow finish the bars,
make multiple holes for different length stones,
likewise the screws,
thin rubber "soft jaws",
make the "jaws" long enough to butt up against the side fence whilst centering the work piece on the mag chuck.

I am very proud of this design as it is quick, simple, effective, versatile and uses up some of the hundreds of feet of 3/4" square bar I have. I would normally design an overly complicated, hydraulicly actuated, numerically controlled, invertable device that takes years too long to make and never really works the way it was envisioned to. Just think how much worse I could do if I could get a computer to help me.

 

[TorontoBuilder]

Looks like a computer generated image so perhaps you're just at the design stage. I was looking at the same issue, still in the design (a rather grandiose term) stage too, but I do have a tool for the same basic task and it works well.

Basically my plan I to cut two 3/4" bars an inch or so longer than the stone and drill 2 holes in each such that the stone can nest inside the holes.
Two pieces of all-thread, nuts and washers fitted through the holes and long enough to straddle the stone and you have a basic vise.
Place the stone on the mag chuck or relatively flat surface, clamp the vise to it and turn on the magnet. Badda bing, badda boom you have a secure stone ready for grinding and in less time than it took me to type this up (I recognize that comparison sets the bar very low).

Design options;
grind, mill or somehow finish the bars,
make multiple holes for different length stones,
likewise the screws,
thin rubber "soft jaws",
make the "jaws" long enough to butt up against the side fence whilst centering the work piece on the mag chuck.

I am very proud of this design as it is quick, simple, effective, versatile and uses up some of the hundreds of feet of 3/4" square bar I have. I would normally design an overly complicated, hydraulicly actuated, numerically controlled, invertable device that takes years too long to make and never really works the way it was envisioned to. Just think how much worse I could do if I could get a computer to help me.

Yes mine was fusion render

I'm only at the conceptual stage, and I like the idea of two more robust side clamping bars with variable width spreader bars better. With some modifications like a vee notch in the midline of the bars to be able to grind round stones too.

12.75" long side bars, to do the 11 1/2' norton stones too...

Thanks for sharing your ideas for the same type tool.

 

[RobinHood]

Both of the above are excellent ideas and are what I would consider the “Rolls Royce” version of a hold down system for grinding stones. Great projects too!

Here is what I use:

A) three small pieces of paper to support the stone in three spots off the mag chuck (first side only, because it is not yet flat). Check to see if it rocks; if it does, add more paper packing until it no longer rocks
B) 3/4”x1”, wider than the stone, mild steel block in front & behind (relative to the direction you are grinding)
C) two strips of old band saw/hack saw blade, shorter than the stone, on either side maged down at an angle - as a “comb”
D) start grinding

If you have trouble setting the comb, use a thin strip of foam under the teeth side to set it at a slight incline, then mag it down. The magnetic force will compress the foam only until the teeth engage in the side of the stone, securely pulling it down onto the chuck.

For round stones, use your steel blocks such that they form a V in front of and behind (relative to the direction you are grinding). You can use a shorter piece of old saw blade on either side as a comb.

 

[jorogi]

Looks like a computer generated image so perhaps you're just at the design stage. I was looking at the same issue, still in the design (a rather grandiose term) stage too, but I do have a tool for the same basic task and it works well.

Basically my plan I to cut two 3/4" bars an inch or so longer than the stone and drill 2 holes in each such that the stone can nest inside the holes.
Two pieces of all-thread, nuts and washers fitted through the holes and long enough to straddle the stone and you have a basic vise.
Place the stone on the mag chuck or relatively flat surface, clamp the vise to it and turn on the magnet. Badda bing, badda boom you have a secure stone ready for grinding and in less time than it took me to type this up (I recognize that comparison sets the bar very low).

Design options;
grind, mill or somehow finish the bars,
make multiple holes for different length stones,
likewise the screws,
thin rubber "soft jaws",
make the "jaws" long enough to butt up against the side fence whilst centering the work piece on the mag chuck.

I am very proud of this design as it is quick, simple, effective, versatile and uses up some of the hundreds of feet of 3/4" square bar I have. I would normally design an overly complicated, hydraulicly actuated, numerically controlled, invertable device that takes years too long to make and never really works the way it was envisioned to. Just think how much worse I could do if I could get a computer to help me.

Sorta like this. Couple of hours, no finishing just made sure the surfaces were smooth. Need to turn some smaller OD washers. No holes in the middle, couldn't see the point. Magged down I couldn't budge the stone. Just material lying around. The bar stock I got a couple of years back, it used to be the security fence around the Sears garden center at Hillside Mall, the contractor didn't want to waste the time and wages etc. taking it in for recycling and when I assured him I would use it and not cash it in he said "back up your truck ". Probably 20 panels ?

 

[TorontoBuilder]

Sorta like this. Couple of hours, no finishing just made sure the surfaces were smooth. Need to turn some smaller OD washers. No holes in the middle, couldn't see the point. Magged down I couldn't budge the stone. Just material lying around. The bar stock I got a couple of years back, it used to be the security fence around the Sears garden center at Hillside Mall, the contractor didn't want to waste the time and wages etc. taking it in for recycling and when I assured him I would use it and not cash it in he said "back up your truck ". Probably 20 panels ?

that's a sweet deal.

The jig looks perfect, no need for any sort of base.

 

[jorogi]

Thank you Sir and thank you for the kick in the butt to get on with it.

 

[Tom O]

Sears goes back a number of years we use to play in that field.

 

[jorogi]

I don't think I ever saw the place before Hillside, Sears has been gone for a while now. My wife remembers when the mall opened and her first job was at Zellers there, long since gone too.

 

[jcdammeyer]

I don't think I ever saw the place before Hillside, Sears has been gone for a while now. My wife remembers when the mall opened and her first job was at Zellers there, long since gone too.

I remember the Sears gas station at Hillside.
Anyway. This thread is very interesting.

Please explain to someone who hasn't got a clue how you will flatten the stone once it's held in place.

And once the stone is flat where is it useful other than say sharpening a hand planer blade.

 

[jorogi]

Precision ground stone are typically ground flat on a surface grinder. As you buy them they are not flat. A PGF stone is used to remove burrs etc. from precision surfaces such as bedways, milling tables, mag chucks etc. They cannot sharpen things.
CàLem video. Very good as always.

 

[TorontoBuilder]

I remember the Sears gas station at Hillside.
Anyway. This thread is very interesting.

Please explain to someone who hasn't got a clue how you will flatten the stone once it's held in place.

And once the stone is flat where is it useful other than say sharpening a hand planer blade.

Diamond wheel grinds off the sharp edges of the abrasive, so you can stone machine surfaces to knock down dings and such without wearing the surface.