CBN wheel question

[tom martin]

I recently purchased a CBN wheel and am about to mount a holder for my Tormek jigs. I had done this with my AO wheels and really liked it to grind new profiles prior to sharpening. I mounted the wheel on the right side of the grinder and my Tormek jig holder was on the left so its time to build a new one (the current one slides into the wolverine tube to lock down and is offset to the left to accommodate the tormek holder.)
I started thinking about it and thought "Why not mount it on the back side of the grinder?" The wheel would be going away from the tool as it does on the Tormek instead of into the tool on the front side.
My question are:
1. Is anybody doing this already?
2. Does anyone think this is a bad idea or unsafe?
3. Would this be advantageous in putting a bur on scrapers?
Thanks,
Tom

[alex grams]

1. I don't do this (no need to)

2. I don't think it is that unsafe. My only concern is metal shavings being throw up, instead of down, so be sure to have eye protection.

3. Maybe on a scraper, yes, but I get the feeling it is going to be a rough burr.

I think the other thing to consider is that the tool is going to be pulled away from the wheel, so you may have to be more cognizant of keeping firm contact against the wheel, and avoiding any 'chatter' from the tool not resting evently. The traditional down movement pulls the tool into the wheel, and also has gravity helping do the same.

[Jeff Gilfor]

Good question. Has come up various times in other forums as well.

All bench grinders are designed to rotate the wheels down. The reasons are two-fold:

Safety-wise, it is better for the sparks and debris to fly away from the user; if there is a tool catch, the tool will be thrown down into the support (rest), and not up into you.

AND

Most sharpening is done with a support of some sort. Either a platform or jig that is designed to be supported from below. If the wheel turned the other way, support would need to be above the sharpening edge, thereby obscuring view of the process.

That said, there's no scientific reason not to have things the other way around, as long as you properly design a sharpening rig to accomodate this and a good view; AND you take precautions as far as sparks and tool flying are concerned.

A burr raised on a scraper with an upwards rotating wheel would probably be bigger. Bottom line is that the burrs raised by grinders are sketchy. They are rough, and don't last more than a few seconds when turning. Using a diamond card, stone, or burnishing tool will do a much better job at raising a usable and longer lasting scraper burr.

[tom martin]

Thanks for the replies guys,I have to agree with both of you, When I looked at the grinder again last night I realized my homemade tormek bar holder worked fine on the back side of the grinder. So I sharpened my bowl gouges with the wheel spinning away from the tool. It does send sparks up and away, but with the CBN wheel it was minimal. The bad news was it appeared to blue the edge on the gouge (may have been pushing a little) easier than in the other orientation. The platform from the wolverine work fine on the back side so I sharped my heavy scraper but I wasn't too impressed with the bur. It was longer than when it was sharpened on the front side and was probably more fragile. There was no noticeable improvement in the scraping and it seemed to dull quicker.
I am going to stick with grinding on the front side.
Thanks,
Tom

[Thom Sturgill]

If tghe Trormek is like my Grizzly, it turns very slow and in the opposite direction. Both are issues when mounting the rig on a standard grinder.

[Eric Gourieux]

Here is my set up. I'm not sure about reversing the setup, as you suggested. All I know is that my Tormek sits there collecting dust as I use my CBN's for EVERYTHING. I now have fellow turners asking me to sharpen their tools.




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