What speed bench grinder?

[David Wadstrup]

Hello,

I'm relatively new to woodworking, and up until now, have done all of my grinding and honing on Japanese Sigma Power ceramic stones(I am a hand tool guy whose "wood shop" is in his apartment's living room.) They work fast and I really, really like them. Honing is fun and easy. Grinding, however, is another story. I have a few of the coarser stones for re-grinding -- a 120, 240, and 400 grit -- that do cut fast(ish) and are pretty resistant to dishing. I've been able to fully regrind chisels and smaller plane blades without too much trouble. I can't say that I enjoy the experience, but given that I do all of this in my living space, I've been reluctant to introduce a powered form of grinding. Today, however, I needed to regrind the primary bevel on one of my 2.25" A2 bevel up plane blades. After about an hour's worth of work(no exaggeration!), I gave up. It was just too much metal to remove by hand, requiring multiple, labor intensive, messy re-flattenings of the stone throughout the process. NOT FUN.

So, I've decided I need to invest in a bench top grinder. I've done quite a bit of research on the differences between dry and wet grinders and bench top sanders, and the dry seems to be the one that would suit me best -- I'll likely continue to regrind chisels and smaller cutting tools by hand, and use the grinder only for the heavier plane blades and severely chipped edge tools. Specifically, the custom tuned Baldor offered by Tools For Working Wood. I have 2 questions regarding this purchase:

1. Should I buy the slow or fast speed?

I've read that quenching a tool is best avoided -- it can leave invisible(but damaging and edge weakening) fractures in the tool's edge. Not letting the tool get hot enough to require quenching, or to overheat it, seems to me the best approach(or using a metal heat sink(magnets?).) Obviously, the faster grinder runs hotter. But, it grinds more quickly. What is the relationship between heat and metal removed? The slow grinder will, used long enough, overheat the tool if not ground with caution. And since it will take longer to grind because of its slower speed, might heat up the the steel at a similar ratio(to metal removed) to the faster cutting fast grinder. Does this make sense? What would you buy?

2. Is using a tool like this in a living room, albeit very occasionally, just plain stupid? Fumes and sparks and safety-wise?

I'd really appreciate any advice anyone has to offer. Thanks for your help.

David

PS If you want to talk me into a wet grinder or bench top sander I'm all ears.

[Tony Rodoracio]

David,

I have the slow speed grinder with the Baldor motor that you are talking about. It is awesome! The motor is smooth and quiet and the wheels spin freely with no wobble. I would reccommend it over the high speed. It is very forgiving in that it will not overheat the metal if you use a light touch. I don't need to use water with this grinder , it is that cool.
As far as using it indoors.....No Way. The friable wheels run cool but they shed abrasive and make what I would describe as a sandy mess. If you use a light touch there are very few sparks. Good luck

[Bill Geibe]

We had a Baldor grinder in the school shop I taught in. It wasn't as high-end as the models you are looking at but the kids ran the heck out of it from when it was new until I switched schools 20 years later. The thing never even needed a bearing replacement. The ones that you are looking at are impressive, premium machines.

Some things you may have already thought about: The larger diameter the grinding wheel the higher the surface speed and the greater the heat build-up. So the 6" grinder will cut cooler for any given RPM. However, the 8" wheel will leave a less concave surface on your chisels, etc.

I run an inexpensive 3600 RPM, 6" grinder in my small basement shop and have no problems with dust or fumes from blade sharpening. Just make sure the machine is on a suitable surface that will be resistant to sparks and can be cleaned easily of any grinding residue.

Bill

[Joe Cowan]

At the cost of the slow speed grinder (8"), I think I would just buy a Tormek and have the advantage of all their jigs that are available.