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+-- Thread: Which Bench Grinder? (/showthread.php?tid=7349313)
RE: Which Bench Grinder? - Bibliophile 13 - 07-24-2019
As a rule, get the coarsest grit you can. You’re doing your honing on bench stones, so there’s no advantage to a finer grit on a grinding stone. A coarser grit will work faster, which is the whole point of the grinder in the first place.
RE: Which Bench Grinder? - wmesquite - 07-31-2019
The linked Tradesman grinder looks nice if you want to use Tormek jigs, and it does come with 2 CBN wheels. But I have no clue why they run it down to 400 RPM for grinding. And for its price I picked up 10 grinders, including 6 pedestals. Yes, I had Tool Acquisition Disorder. The first was an Taiwanese 6" Delta, runs smooth, terrible tool rests that can mostly be fixed, but stamped steel wheel guards that are not heavy enough to give a really solid rest. Others are all industrial rated, 7"-10", mostly Baldors and Deltas.
The folks on OWWM who sold and repaired this level of grinder thought Baldor was the lower cost survivor which made decent grinders. They thought the Deltas were a bit better, with the true industrial tools like Cincinnatti, US Electical, Queen City or Hammond a distinct step up in quality and smoothness, if perhaps less practical for home shops- my Queen City weighs 400 lbs with pedestal.
Baldor grinders don't have precision bearings, except possibly their carbide grinder. Decent quality but plain old 6203's on the 6", ISTR up to 6206's on the 10". They do have end bells of adequate strength to hold decent sized bearings in reasonably accurately bored bearing housings. And they are balanced pretty well; the end result is generally a smooth running grinder. Though I have a 6" Baldor that has too much vibration; at least I only bought it for the pedestal. If you get the ones with cast iron wheel guards, then you get decent tool rests that are solid.
My grinding style is perhaps similar to the TFWW technique. I never let the wheel or its scratches touch the face of the tool. When time to grind, I swipe the blade across a fine diamond stone in the desired profile (eg straight with chisels)a couple times, making a flat on the tip a bit less than 1/100"- removes any wear bevel and aids grinding. If I need to change the profile or steepen the bevel angle, then I grind at 90 to the wheel without changing the tool rest angle, then use the fine diamond stone. I grind until there is only a tiny bit of shiny left on the tip. I grind fast until I am starting to thin the edge, then I lighten up, and very light as the edge is almost gone. I look at the tip frequently as I finish up, it tells me where to grind. When I am done and I start honing, the remaining tip is always cleaned up/honed away before the bevel side of the tool is honed across the whole edge.
I use a coarse 46 grit wheel at 3600 RPM on a 7" grinder- a 46 grit grinds faster and much cooler. End result is similar to an 80 grit at 1800 RPM- as the speed drops, the coarseness of grind goes up. So speed can be useful in addition to getting faster results. I also found a cool grinding 54 grit wheel for my 10" Baldor which works great. It spins at 1800 RPM, but the larger wheel increases SFPM. Having a larger wheel lets it stay cooler. My edges don't burn unless I let the wheel go too long between dressings- I use the flat Diamond dressing tool sold by Woodcraft etc, and make the wheel flat, slightly kill the corners of the wheel.
If you go straight from the grinder to usage as in turning, a higher grit is useful. I hone turning tools on something similar to a Worksharp so don't really need higher grits much. But for other edge tools that get honed- Use a coarse wheel! Yes, get a cool grinding wheel, such as a Norton 38A J6 46. Learn the codes, don't get harder than J, open structure/porosity at least 6. At 46 grit you can get this slightly harder wheel, lasts much longer, needs less frequent dressing, and tosses less grit. I don't understand a need to go below 1800 RPM even for turning tools. Get a 3 phase grinder and a cheap VFD if you want variable speed.
I recommend having 2 grinders- one space set up with a 46 grit wheel set for 25 degree bevels, one set for about 30 degrees. Ultimate in repeatability until you have really used up the wheel noticably. Another space set up with a cutoff wheel a'la Bob Vaughan. That leaves one space left for a finer CBN wheel if you like for turning tools. And swapped for a cheap coarse wheel for mild steel.
IMHO vintage grinders are the way to go, though 15 years ago I did score a brand new Baldor 7307 off ebay for $125. Older Craftsman are decent enough and cheap and plentiful; you do need to replace the rests. If you don't like flying grit, get one with exhaust guards, and put canvas or something over them. On Baldors, go for ones with exhaust guards and cast iron tool rests, then they come with the bigger machined wheel flanges. I still like the 7" grinders better, I recommend them or bigger. Nice toolroom 7x1" wheels at McMaster, else wide 7" wheels are hard to find. For every 2 dozen 6" models I saw 10 7" models, 3 10" models, and 1 8" model- at least among 10 year old or more used grinders . Older cast iron pedestal bases are cool, but the Baldor shelving style base is really good- weight it down with heavy tools, you get a 150-200 lb base. Or make your own base with a lower and middle shelf and do the same weighting down. Mass reduces vibration.
Hand grinders can work pretty darn well, but the wheel does have to be aligned at first, which is tedious. Get one with a cast iron tool rest that isn't worn inside- helical gears are the best. Use the same cool grinding wheels, almost as fast as a powered grinder. Good for 3/8" to 2" blades with a bit of practice. A bit thinner or wider works but is more challenging; 1/8" or 2 5/8" near impossible without adding a treadle to the grinder- or an apprentice. Maybe I'll post about them someday, they don't get much love.
I must say Derek's article on adding CBN wheels and the Tormek rests to modern grinders is very good. The CBN wheels being better balanced, never need dressing- and easily swappable sound great. You want to avoid changing a regular grinding wheel as much as possible. But I have a different perspective on using coarse grits, especially when tools are honed after. For which I must thank SMT on Badger Pond 15+ years ago.
So ends my treatise on which grinder.
Regards, Wade
RE: Which Bench Grinder? - Hank Knight - 07-31-2019
(07-31-2019, 02:43 AM)wmesquite Wrote: [color=#000000][size=small][font=Calibri]. I also found a cool grinding 54 grit wheel for my 10" Baldor which works great. It spins at 1800 RPM, but the larger wheel increases SFPM. Having a larger wheel lets it stay cooler.
Wade, Where did you find a cool grinding 54 grit 10" wheel? I have an older Sioux 10" grinder that runs very smoothly and has good too rests. I have had difficulty finding anything but the standard gray wheels for it. What arbor is your wheel sized for? Does it require bushings to fit your grinder?
TIA.
Hank
RE: Which Bench Grinder? - Bill Lyman - 07-31-2019
[quote pid='7769476' dateline='1564559019']
So ends my treatise on which grinder.
Regards, Wade
[/quote]
Thank you.
Bill
RE: Which Bench Grinder? - Timberwolf - 07-31-2019
(07-31-2019, 07:34 AM)Hank Knight Wrote: Wade, Where did you find a cool grinding 54 grit 10" wheel? I have an older Sioux 10" grinder that runs very smoothly and has good too rests. I have had difficulty finding anything but the standard gray wheels for it. What arbor is your wheel sized for? Does it require bushings to fit your grinder?
TIA.
Hank
.......................
Hank, check Ebay....I didn't see any 54grit but did see several 60 grit wheels for sale.
RE: Which Bench Grinder? - Hank Knight - 07-31-2019
Thanks, Jack. I'll check it out.
RE: Which Bench Grinder? - wmesquite - 07-31-2019
(07-31-2019, 07:34 AM)Hank Knight Wrote: Wade, Where did you find a cool grinding 54 grit 10" wheel? I have an older Sioux 10" grinder that runs very smoothly and has good too rests. I have had difficulty finding anything but the standard gray wheels for it. What arbor is your wheel sized for? Does it require bushings to fit your grinder?
TIA.
Hank
Hi Hank,
You ask good questions. Standard shafts on 10" grinders are 7/8". Industry lingo for cool grinding wheels is toolroom wheels. Pretty much every 10" wheel 1" wide has a 3" arbor hole and is unsuable on a bench grinder; the flanges are not big enough. After looking for at least 6 months on ebay, I found some with a 1 1/4" arbor. You can buy an adaptor for this size to 7/8" from McMaster.
A quick glance at ebay showed a few 10" toolroom wheels with a 2" arbor. These are adaptable. They make wire wheel adapters that are sized right, but they are less than optimal. You can make a good one yourself- glue some pieces of MDF to make it thicker, turn it to 2" diameter, drill 3/4" center hole, turn inside to the 7/8". Or save a step and buy a 6" long piece of 2" diameter softish plastic rod, cut the length smaller, then drill, turn. If you can drill accurately enough, then that saves a step too.
Or there is the gold standard of getting a 1 1/4" arbor wheel. I saw one that was described as grinding wheel 46 grit 10" Norton 32A 10x3/4x11/4. This would work fine, if not be optimal width.
I have a spare or 2 but they are buried. I'm trying to add a pic of mine, looks like I need to upload to the web, will do later.
RE: Which Bench Grinder? - Hank Knight - 07-31-2019
Thanks for the info, Wade. I was shooting from the hip when I posted my question. The arbor on my 10" Sioux grinder is 7/8", not 3/4 as I posted. The adapter/bushing issue has been a bother for me. I can find toolroom wheels for my grinder, but I've been hoping to find one of the friable ones (white or pink). It appears they are not made in a 10" version. I get along fine with my gray toolroom wheels which are in good shape. The grinder is a 1750 RPM model and, even with the increased FPM linear speed, it does well for basic grinding tasks, and I don't burn my edge tools with it. I like it because I adapted it to use my Tormek jigs long ago and the 10" wheel size is a perfect match for the Tormek. One of these days I may try making my own adapter; but, unless I find a perfect replacement wheel, I'm relatively satisfied at the moment.
Thanks for your help and your explanations.
Hank