@Baldpate:
Just a few words of caution if I may – I do NOT want to turn this into an ‘elf n safety” diatribe but as you say you know nothing about such machines here are a few simple words of caution for your own safety:
A) In industry nobody is allowed to mount a wheel on a grinder of any size or type unless he/she has been on a course. The reason is obvious (which makes a change for the “e n s elfs” these days) a grinding wheel is different to, say, a circular saw blade because it consists primarily of bits of grit of one sort or another glued together to form a disc (or cylinder). Normally speaking, unless it’s a cut-off disc (which is not for use in a bench grinder) there is no reinforcement – just grit and glue putting it very simply;
B) The basic reason for all this caution is that an exploding wheel is a truly frightening and potentially VERY dangerous thing. At the very least severe damage will be caused to any building or tools, benches, etc, that get in the way of fragments, and what it could do to the human (or animal) body just doesn’t bear thinking about;
C) Although I’ve never been on a “proper” industry course I was lucky enough to have a good bit of training in this area during my RAF apprenticeship. This included a film (no DVDs in those days!) showing a grinding wheel not much bigger than yours letting go. As said, horrendous in a big way;
D) OK, enough of the scare mongering, what’s to be careful of really?
First, do NOT exert too much pressure of the work piece/the tool being sharpened by pushing hard against the wheel. And this machine is NOT a substitute for a sanding disc or a belt or a file – at the very best, trying to remove lots of metal quickly with a bench grinder will result only in a wheel which is “glazed” and therefore useless until it’s been re-dressed;
Second, NEVER run the machine without the guards in place and ALWAYS use safety glasses;
Third, if as been suggested already, you decide to change at least one of the wheels for a better one (particularly the roughest grade wheel on most cheap bench grinders are pretty useless and will anyway wear out pretty quickly), DO - PLEASE – take a length of string to the shop with you! What? STRING? Yes, when choosing a wheel of any type it’s most important to check that it isn’t cracked. You just tie the string into a loop through the centre mounting hole then suspend the wheel in mid air. Tap it (gently) with a screwdriver or something and you’ll hear a sort of ring tone (a bit like a small bell). If you hear a dull “clunk” the wheel is cracked and you’re NOT taking it home with you, OK?
Fourth, when mounting the new wheel make sure that the printed paper discs on each side of the wheel stay there when you mount the wheel – as well as stating the manufacturer’s name, grit type and the max allowed rotation speed (which should NEVER be exceeded) these discs are there as safety compression washers. Note you do NOT need to over-tighten the wheel retaining nut/s (the grinder’s shaft rotates in a direction to automatically tighten the retaining nut/s). And you MUST use whatever distance pieces or collars which came with the new wheel to make sure that the new wheel sits snugly (but is neither sloppy nor a force fit) onto the shaft. It’s obvious that if you’ve had to remove the wheel safety guard to get the old wheel off/new wheel on, then the safety guard MUST go back on before you switch on again. PLEASE!
That’s about it really. Quite simple stuff when you know and not at all time-consuming.
A couple of words on usage if you like:
E) Keep an open tin of water by the grinder and use it REGULARLY when sharpening cutting tools – if the tip of the tool goes blue or even a bit yellow (never mind red) then you’ve lost that part of the tool (the overheating has softened the edge) so you’ll have to – GENTLY – grind all the discoloured metal away and start again. On small chisels, screwdrivers, etc, this will happen VERY quickly so it’s “a few seconds against the wheel then into the water then back to the wheel again" as a constant process – one of the reasons why getting the tool angles correct is a bit of a learning curve;
F) It may be a good idea to find a really old tool or piece of genuine scrap and practice a bit first;
G) Someone has already suggested a pink grit wheel for tool grinding. I’m certainly NOT an expert on grinding chisels, etc, but personally I’d prefer a brown grit (light-ish sandy colour) for that job;
H) Someone else has I think mentioned a green grit wheel but personally I only use that for sharpening brazed carbide (metal) lathe tools, and touching up (only) masonry drill bits, etc;
I) The little adjustable rest in front of the wheel that came with the machine will be of some help in getting the angles you want but you’ll likely find you’d like something a bit better after a few tries. You’ll find plenty of ideas on the internet (or send me a PM) but to start with do use the rest provided but as far as you’re able, using a protractor or something to set up the 30 degrees (or whatever angle you need) before starting to grind;
J) THEORETICALLY one is not supposed to use the flat side of the wheel for grinding. In practice we all do it (especially with some jobs it’s impossible not to) so just remember that the wheel was not constructed for this use (it’s stronger on the front edge facing you) so use even less tool pressure against the side of the wheel than you would on the front;
J) It is possible to re-dress a badly glazed or scored wheel. There are 2 possibilities, either a “star wheel” dressing tool (NOT expensive) or a big “block” of “black stoney stuff” which is even cheaper than the star wheel tool. Personally I prefer the star wheel. Both are easy to use – just GENTLY (that word again!) bring the dressing tool into contact with the edge of the wheel and keep it there until any irregularities, grooves, etc, are worn away. DO NOT – EVER - use these tools against the side face of the wheel.
Hope all this helps and is not overkill. It’s not designed to frighten you off either.
The machine you’ve got is perfectly OK if used with a little knowledge and a bit of respect. Like machine saws for example, once you’ve got beyond the basic stage of having a shaft which turns regularly, concentrically, and smoothly, it’s much more to do with the blade you fit (in this case the wheel) and how you use the tool that will determine your success.
And yes, induction motors which take a few seconds to wind up to speed (and back down again) are perfectly normal.
That little machine will last you a lifetime – as someone else said, I really CANNOT get my head around how “they” do it for the price.
Best of luck and enjoy mate.
AES
