Advice on Grinders

Hi David, for my money, the best types of grinders for sharpening (knives, blades, drill bits etc etc) are slow slow slow and with a water bath is even better. You want a fine grit stone, not one of those nasty 100 mile an hour things with the real rough stones on them. This means that you probably need a reduction gearbox on the side of it since there arent many grinders that turn that slow just off the motor.

Good luck! Shaun (in mount isa)

Grinders are a dime per dozen, shop-wise. Except Baldors. :)

An 8" would be fine, on a pedestal, which you can make yerself pretty easily out of angle iron, etc. Or buy. Might also look at Harbor Freight, depending on what yer local guys are asking.

But what the other poster said is quite true: I would rough it out on an 8" grinder, and finish it on one of them slow-rpm water jobbies. Sears sells one for $33, which I bought. If you want the exact model number, ask here or email me if I miss the post.

Altho, a fine wheel on yer 8" grinder could do it as well, since you're not really looking for a cutting edge. Just have to be more careful. This would def'ly be faster, too.

Many people have 8" grinders, and 6". A 6" wouldn't be bad for finishing either.

So, in summary, an 8" plus the water jobby would be the "right" way to do it. An 8" with 8" coarse and fine wheels would be the *fast* way to do it. And an 8" coarse with 6" fine (either a sep 6" grinder or just another 6" fine wheel--or smaller, for that matter), would be fast and almost-right. :) Also depending on how accurate you want that edge to be.

A belt sander would be more versatile. It can cut and shape ferrous, non-ferrous, wood and plastics. You can make a surface flat with it and clean up a round. I use a 120 grit silicon-carbide belt for metals and an aluminum-oxide belt for wood. I much prefer a 6 inch model and think they are better built than the smaller versions.

If the OP decides to buy a grinder, I would like to share my experience that there is a world of difference between cheap grinders and good grinders like Baldor. Get a Baldor if you can, even if it means buying used.

Belt sanders are great (I have about 4), but probably not for small stuff like 3/8 rod. With a good fixture, tho, a belt sander would do a great finishing job, f'sure.

Ig's endorsement of Baldor is valid (even older Rockwell et al), but from a practical pov Sears/china grinders are more than adequate for most jobs. My sears (6", 8") are fine after 10 years. btw, virtually all Sears power stuff IS chinese. Some of it really shitty.

The most important thing, imo, is a balanced wheel. The best grinder in the world is near-useless w/ a shitty off-balanced wheel. The worst grinder with a balanced wheel will do the job.

Indeed. Ive probably 4 good grinders around the shop, most being Baldors (one Souix), yet I only for the most part use the one with the fine wire wheel on one side, and the deburring wheel (3M) on the other..and the one I use to sharpen TIG electrodes.

Viturally everything else goes on the (2) 1x48 belt sanders, or the 2x72 belt sander or the 6x 48..which gets the bulk of the metal removing work.

Including and particularly knife making

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

A, uh, keen idea, indeed! :)

Neater, quicker, better product--win-win-win! Just gotta slot the end of the rod. Also, have quite a choice of blades: Xacto, etc.

Now for the Dremel Qs. :)

Did the OP say threaded rod? How offensive.... Brass rod, dude, brass rod--thread what you need w/ a die.

The Group generally offers free advice, but there is a charge for Design Improvements.

Pay, or God will punish you.

Here we have 2 types of bench grinder mostly, 3600 rpm and 1800 rpm, where you are the numbers might be a little different because we are on 60Hz mains in the US. For making metal go away you want the 3600 rpm For more control without burning -tool grinding and sharpening 1800rpm A good quality grinding wheel can cost as much as a cheap mass market grinder, don't be surprised. The ones which come with the grinder make good paper weights.

Yep the speed quoted here seems to be a standard of 2650rpm, can't find any locally with multiple speeds. Is the wheel supplied likely to be useable enough to complete my current stated project? Thanks,

David

Yep am aware of that one, that's where I got some modifications for the original Scientific Amercian article. I've thought about mounting something like a razor blade on it, but not really certain how do to best do that, and I'd like it look professionally built, just as a matter of pride :-).

Thanks,

David

Australia must be have 50 Hz power then. That would be a loaded speed, free speed probably probably about 2875 rpm. On 60 Hz that would run 3450.

There are lots of rules of thumb about grinding wheels. The harder the material, the softer the wheel and vise versa. Google this group for Harold Vordos's posts on the subject, he's a pro grinder.

GWE

The wheel supplied will be very hard and prone to making a good deal of heat, take light passes if that is a consideration and get a cheap dressing brick ( very coarse block of hard silicon carbide) to open the wheel up and expose sharp abrasive grains.