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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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What bench grinder for tool bit sharpening?
Several discussions here pointed out to me the importance of proper bit
sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? TIA Uwe |
#2
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Two things are important.
First, the grinder must have a good "fine" wheel. The one which typically comes on the grinder will probably be of poor quality. But a good one is not very expensive... And you need a wheel dresser to keep it clean and flat. The coarse wheel is a lot less fussy... Second, you must have a good, solid, flat "table" on which you rest the work. The table must be adjustable so you can set it at the proper angle to the centerline of the wheel (generally 7 degrees). I have a cheapie grinder I've had for years. The one which came on the grinder was a piece of pressed steel, sloppy, unadjustable and not very flat. So, I made a proper table for it and it works great. Another thing you need is a pot of water to cool the work. I picked up a grinder stand down at HF that has a built in water pot... Jerry "Jaggy Taggy" wrote in message ... Several discussions here pointed out to me the importance of proper bit sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? TIA Uwe |
#3
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"Jerry Foster" wrote in message . com... snip------ Second, you must have a good, solid, flat "table" on which you rest the work. The table must be adjustable so you can set it at the proper angle to the centerline of the wheel (generally 7 degrees). I have a cheapie grinder I've had for years. The one which came on the grinder was a piece of pressed steel, sloppy, unadjustable and not very flat. So, I made a proper table for it and it works great. Given the opportunity, I'd do everything in my power to get you to think differently about the table. When you're sharpening brazed carbide with a diamond wheel, where angles tend to be critical, and the operation does *not* lend itself to offhand grinding, I fully agree, but for sharpening HSS, where you are inclined to get involved with chip breakers and strange configurations almost every time you grind a toolbit, a table generally is nothing more than a nuisance that will hinder your learning to hand grind. I grind tool bits without so much as a tool rest, preferring to have the open face of the wheel at my disposal without anything interfering with its free use. Once you get on to grinding in that fashion, it's almost impossible to go back to using a tool rest. I highly recommend a pedestal grinder that is mounted at chest height, which can be as simple as a single wheel, aluminum oxide, 60 grit, J or K hardness, vitrified bond. No tool rest. Use a dressing stick to keep the wheel in trim. It's very important to be comfortable when you're sharpening toolbits, especially if you're blanking one out. Standing erect without leaning over as you grind should be your objective. If you have the luxury of two wheels, a coarse (46 grit J hardness) is nice, but you can get along without it if you're limited to a single ended spindle. I use 1/2" x 7" x 1-1/4" wheels that are customarily used on cutter grinders and small surface grinders for tool sharpening. They are generally formulated precisely for grinding HSS (typically 38A abrasive) and are readily available. You may have to make the adapter to fit your grinding motor to run them, but it's not much of a project if you choose to do so. I'll gladly provide some tips in that regard if you're interested. Harold |
#4
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I use
1/2" x 7" x 1-1/4" wheels that are customarily used on cutter grinders and small surface grinders for tool sharpening. After spending 100 dollars on 2 norton 10 inch grinding wheel that are not so great, I wish I had bought surface grinding wheels. Probably a bit more money and a little work to make the hubs, but I'm sure they will work better. chuck |
#6
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I wish Id known you needed 10" wheels. I have a few new ones..... I could be pursuaded to replace the new Norton bench grinder wheels with better quality ones if the price is right. |
#7
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"Jerry Foster" wrote in message . com... Two things are important. First, the grinder must have a good "fine" wheel. The one which typically comes on the grinder will probably be of poor quality. But a good one is not very expensive... Local place has 6" silicon carbide wheels on sale for about $17, 80 grit. Whaddy think of that price and grit? |
#8
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"jtaylor" wrote in message ... "Jerry Foster" wrote in message . com... Two things are important. First, the grinder must have a good "fine" wheel. The one which typically comes on the grinder will probably be of poor quality. But a good one is not very expensive... Local place has 6" silicon carbide wheels on sale for about $17, 80 grit. Whaddy think of that price and grit? What's more important is what do you intend to grind with the wheels? Silicon carbide (green or black wheels) is not to be used for HSS under any circumstance. Only aluminum oxide should be chosen for grinding on steels of all kinds. If you're grinding brazed carbide tools, the 80 grit green wheels work, but I rarely ever use one. Silicon carbide is really bad on your health, and just about as hard on carbide. The hardness of carbide as opposed to silicon carbide is not great enough for decent cutting. Diamond is the abrasive of choice for sharpening carbide-----and the difference between diamond and silicon carbide is huge. If you're talking about sharpening carbide, I strongly suggest you investigate a diamond wheel and forget about the silicon carbide idea. It's a decision you'll never regret, unlike using green wheels. Harold |
#9
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First why use the grinder solely for sharpening lathe bits. The wheels
are easily changed. A wire brush is very handy. For HSS you want aluminum oxide wheels, but a silicon carbide wheel is good for carbide. Not as good as diamond, but good enough. It may not be recommended, but I have mounted a cut off disk in a bench grinder too. You can also couple a flexible shaft to a grinder. Oh yes and buffing wheels. Then there are the rubber wheels that get abrasive bands on them. With a little work you could drive a belt sander with a grinder. As far as recommendations.........One that does not bog down when you lean into it. Robert Bastow disliked 8 inch grinders that run at 3450 rpm. Too high a surface speed. I like my 8 inch grinder, but it is belt driven and does not turn at 3450 rpm. The people that have neat tables that tilt love them. I usually just grind tool bits freehand. A lot faster after you get use to it. Ditto for sharpening drill bits. I did make kind of a table that I could use to grind accurate angles. But I have forgotten why I did that. Dan Jaggy Taggy wrote: Several discussions here pointed out to me the importance of proper bit sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? TIA Uwe |
#10
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but a silicon carbide wheel is good for carbide.
Not as good as diamond, but good enough. I tried some norton silicon carbide wheels on my baldor carbide grinder. They will cut, but I ended up with lots of tiny chips in the edge. I got a cheap diamond wheel from enco and it is like night and day difference! The glendo with a 1200 grit diamond wheel is awesome. I usually only use the 600 wheel for carbide though. |
#11
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Charles A. Sherwood wrote:
but a silicon carbide wheel is good for carbide. Not as good as diamond, but good enough. I tried some norton silicon carbide wheels on my baldor carbide grinder. They will cut, but I ended up with lots of tiny chips in the edge. I got a cheap diamond wheel from enco and it is like night and day difference! The glendo with a 1200 grit diamond wheel is awesome. I usually only use the 600 wheel for carbide though. What's a Glendo? What 600 grit wheel do you use? -- - - Rex Burkheimer WM Automotive Fort Worth TX |
#12
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What's a Glendo?
What 600 grit wheel do you use? The glendo is a small "power hone" that uses 5 or 6 inch diamond wheels for sharpening. It turns very slow, perhaps 200-300 RPM. The wheels appear unique and are probably custom. It will put a mirror finish on any toolbit (carbide or HSS). It runs slow enough that using diamond on HSS doesn't seem to be a problem. They use to be sold by J&L and I bought one with one of their famous 25% off sales, but it appears they sell direct now. do a web search for glendo or accufinish. They are fairly pricely. chuck |
#13
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Glendo is a *company*, not a product. http://www.glendo.com/
He may be referring to an Accu-Finish, can never tell with some people. Glendo makes a really nice little sharpening table called the Grind-R-Table. Anyone who has subscribed to one of the Village Press mags in the last 25 years has seen them, they're very often advertised. I bought one years ago along with a Darex M3 and diamond sharpener setup (all from Glendo) using their quickmount system. I put it all on a steel table on a Baldor pedestal mounted in front of a Baldor 7306D grinder. I used this setup for a long time and sharpened many a lathe bit and many a drill bit with it. I put nearly $800 into that setup, but now I'm done with it. Anyone interested? I can post pix and details if so. Grant Erwin Kirkland, Washington What's a Glendo? |
#14
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Rex,
Check www.accu-finish.com for Glendo sharpening system. I've had one for years set up on a basic 6" Sears grinder. Bob Swinney "Rex B" wrote in message ... Charles A. Sherwood wrote: but a silicon carbide wheel is good for carbide. Not as good as diamond, but good enough. I tried some norton silicon carbide wheels on my baldor carbide grinder. They will cut, but I ended up with lots of tiny chips in the edge. I got a cheap diamond wheel from enco and it is like night and day difference! The glendo with a 1200 grit diamond wheel is awesome. I usually only use the 600 wheel for carbide though. What's a Glendo? What 600 grit wheel do you use? -- - - Rex Burkheimer WM Automotive Fort Worth TX |
#15
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Jaggy Taggy wrote:
Several discussions here pointed out to me the importance of proper bit sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? TIA Uwe I've had pretty good luck with the Harbor Freight "Tool & Cutter Grinder" (which ISN'T really THAT machine, but is really a "Carbide Grinder"). It's like a bench grinder, but has two **FAR** better adjustable tables instead of tool rests, and uses FACE grinding steel-backed wheels. They usually come with two Si-Carb "green" wheels, but white Al-Ox. wheels are available for sharpening HSS. These grinders cost about $140, but are often on sale for $120, and are a good value at either price. Enco, KBC, etc. also sell similar imports for about 50% more than HF ... I can't see that they are any better. A Baldor costs several times as much. Alternatively, you can get a Glendo "Grind-R-Table" for an existing bench grinder, for about the same price as the whole HF unit. I have one of these too, and it's nice, but you can't beat the HF unit for the price. Dan Mitchell ============ |
#16
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Dan,
I looked at one of those at the local H.F. store and it has been in the back of my mind for the last few weeks. What bothered me about them was that I thought the rpm might be too high for resinbond diamond wheels, do you have an opinion / experience on that? Kent Frazier "Daniel A. Mitchell" wrote in message ... I've had pretty good luck with the Harbor Freight "Tool & Cutter Grinder" (which ISN'T really THAT machine, but is really a "Carbide Grinder"). It's like a bench grinder, but has two **FAR** better adjustable tables instead of tool rests, and uses FACE grinding steel-backed wheels. They usually come with two Si-Carb "green" wheels, but white Al-Ox. wheels are available for sharpening HSS. These grinders cost about $140, but are often on sale for $120, and are a good value at either price. Dan Mitchell ============ |
#17
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"Jaggy Taggy" wrote in message ... Several discussions here pointed out to me the importance of proper bit sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? There are half-speed grinders that run at, IIRC, 1800 RPM instead of 3600-ish. They take a bit more time but lessen the chance of heat damage. Woodturners use 'em. Brian, in Cedar |
#18
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On Thu, 17 Mar 2005 01:44:40 GMT, Jaggy Taggy
wrote: Several discussions here pointed out to me the importance of proper bit sharpening for lathe work. I should start getting a proper bench grinder, but what would people here recommend as a grinder which would solely be used to sharpen bits?? TIA Uwe ============================================== Suggest that you take a long hard look at disk/belt sander. Typically one with a 4 X 36 inch belt and 6-inch diameter disk. You can get zirconium oxide [blue norbide type ] belts from Enco in a number of grits, and can pick up adhesive back silicon carbide disks in finer grits at most auto parts stores. Zirconium oxide belts seem to grind very rapidly and much cooler than the aluminum oxide belts. Use the belt for roughing and the disk for finishing. You can get a mirror finish if you wish. The angles that you can set with a "miter" gage that comes with the typical belt sander (or grinder) are not accurate so I suggest fabricating a block on which you can clamp the tool and set with a machinist's protractor. Fabricate an angle-setting block that you can use to accurately set the table angles and use to set the "miter" gage perpendicular to the disk/belt. You can also use this to set the table [slot] parallel to the face of the wheel, disk or belt. By using the angle-setting gage for the table and setting the tool angles with a machinist's protractor, you can get repeatable results. Otherwise, you will grind a tool, it won't cut right, you will grind some more, etc. and will never be sure what works and why. If you go with a grinder, buy a diamond dresser, and fabricate a holder so you can "drag" the diamond across the wheel at the correct angles using the "miter" gage while maintaining it parallel to the guide slot. A sharp wheel makes all the difference in the world. A useful hint is to use an abrasive bristle brush to remove the burrs from your newly ground bits and give the hand-honed effect in a few seconds. I bought the one I use at ACE hardware. It is about 5 inches in diameter, has a 1/4-inch shaft, with medium grit nylon bristles. Another tip is to keep a spray bottle [old Windex type bottles work fine] filled with water and lightly spray the grinding wheel while grinding. This keeps the tool much cooler as the water evaporates and avoids thermal shock when you dip the tool. This can be very hard on carbide. You can add a small amount of water-soluble oil [water pump lube @ 99cents a can] to avoid rusting. Avoid oil on the table/slot as this will attract and hold grit. I like Teflon spray. It is dry and very slick. It also seems to protect against rust. It would be helpful I can post pictures of the tool holder block and replacement miter gage to the dropbox. |
#19
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Yes, please do.
TMT |
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