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    Default Tool grinder options

    I bought a Central Machinery tool grinder to sharpen carbide scraper and also carbide / hss lathe tooling. The wheels that come with the grinder are SUPER aggressive and far beyond what I would want to use for 90% of my work. I have 2 additional standard style grinders for that type of quick grind work. I was hoping to capitalize on the existing tables. Nor do I want to buy a 800 dollar lap to "properly" grind the scraper. I was hoping to find a source for 800, 1200 and possibly 3000 grit wheels that bolt on. It's that or I spend a bunch of time that I don't have building a tilting table and such for the bench grinder / chinese made disc and laps. It's a 4 bolt pattern that is about 60mm vertically and 80mm diagonally. I have a lathe cross slide to scrape in so I can actually make use of it lol. Help would be great
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    If you go to Ebay, you can find a lot of folks selling these: 6"x 1/2" Diamond Electroplated Flat Lap, Lapidary polishing disc Grinding, glass | eBay

    I think the 1/2" refers to the central hole diameter, but you may want to clarify with whatever vendor you chose. I'm sure it's not width, as I bought some of these and the steel backer in ~750u or so.

    Do a search for diamond lapping disc. Look for what meets your needs, buy a range, then make a magnetic chuck that bolts on in replacement of one of your wheels.

    Be aware that these are not long-life, and a careless "dig" when contacting scraper to wheel could cut through the thin diamond coating (easier with the finer grits). They're also used at lower speeds and ideally with water to cool and lubricate, so you might need to use a VFD or other speed control for optimal life. This is especially true if using HSS on the disc, the diamonds must be kept cool to avoid thermal damage.

    Nice thing is with a mag chuck, replacing discs is trivial and pretty accurate as long as you made a good, flat chuck. Make sure to remove the disc before running the grinder at full speed again, otherwise wear a suit of armor.

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    Two things about electroplated (lapidary) disks.
    First, they're designed for lower speed and don't perform so well around 3500 rpm.
    Second, if you make a magnetic chuck to hold them, make sure that you add a boss that fits tightly in the center hole. Otherwise you will have balance problems and a lot of excitement (of the wrong type) when the disks will chase you bouncing between the walls and machines in your shop.

    You can find (at higher price diamond cup wheels that are a direct plug-in or easily adaptable. I suggest to get one of smaller diameter, which will be cheaper and would have slower surface speed.

    Here is an example from Shars on eBay

    Paolo



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    Quote Originally Posted by Paolo_MD View Post

    You can find (at higher price diamond cup wheels that are a direct plug-in or easily adaptable. I suggest to get one of smaller diameter, which will be cheaper and would have slower surface speed.

    Here is an example from Shars on eBay

    Paolo


    The shars is exactly what I was looking for, ie bolt on solution to get me going. Is the 150 grit diamond on the same scale as the others? The one I have now (wrong bolt pattern) is 3000 and was the grit suggested by the guy that teaches scraping classes. Thanks!

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    Default Do your own homework

    Quote Originally Posted by speedfreak24.7 View Post
    The shars is exactly what I was looking for, ie bolt on solution to get me going. Is the 150 grit diamond on the same scale as the others? The one I have now (wrong bolt pattern) is 3000 and was the grit suggested by the guy that teaches scraping classes. Thanks!
    My apologies in advance for being blunt, but I think you need to do your homework and research. Plenty of threads here, tons of videos on YouTube, good info on the Web.

    I guess that with "the guy that teaches scraping classes" you refer to Richard King. He strongly advocates using a slow speed grinder/lapper, like a Glendo (or KK Calamar, or one of its clones). It is not too difficult to build your own starting from a wet stone grinder, geared motor/motor + reduction gearbox, etc. Again, many ideas and suggestions on the web.

    Paolo

    PS The grit suggested for sharpening carbide scraping blades are 100-150 to rough-in the curvature; 6-800 for rough-sharpening and ~1200 for finish-sharpening.

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    Quote Originally Posted by Paolo_MD View Post
    My apologies in advance for being blunt,
    My apologies for telling you to do your own research and not taking your shit. I was simply fing asking if the scale of said diamond grit was the same scale... I have obviously done my research to get this far. I simply have a machine that I was looking for a non 900+ dollar solution that I will use 2 times a year. I also checked ebay for 300 rpm motors... there was a 400 dollar example and examples that were obviously sub 1/4 hp motors, as a 300 rpm motor would be a good starting place IF I was to fabricate my own. The current bolt on abrasives for my "diamond tool grinder", maxes out at 150 grit from the suppliers I have found. I run a non machining business AND I am finishing my engineering degree, which means I don't have a ton of free time to design and build my own version of the glendo. So pardon the f out of me if I ask if the grit of the finest stone I can get for my particular machine is the same grit scale as the 3000 grit lapping disc I already own ( but doesn't share the same bolt pattern). It's not for a multi million dollar project. It's to sharpen the anderson scraper that I bought that doesn't come bloody sharpened. The guy that Mr King in fact directed me to visit and consult with in my area, fucking died. And Mr King and every contact I have, doesn't know of anyone that does carbide scraper sharpening as a service. So this is the next step. If I can get the result I want with a shars disc that you were nice enough to reference. Then I will do that, if not I will move to the next step of making a 5:1 belt drive conversion for one of my 1750 rpm bench grinders. That isn't my best option, because the building that my lathe and mill are in, got demolished after the foundation was compromised from flooding. Said machines are sitting in an adjacent building that don't have 220v power in. SOOO, with my compromised fabrication capacity... I asked a relatively simple question. Sidebar, not everyone has the room or funds to spend several hundred dollars to sharpen a piece of steel that gets used once every 5 years. It's simple economics: Economy of space, money and time.


    If YOU did your research... You would have read what the f I wrote... "...I was hoping to find a source for 800, 1200 and possibly 3000 grit wheels that bolt on." So from that one sentence you could in fact infer that I knew what I was looking for and that was wondering if someone knew of a source that made bolt on 800, 1200 and 3000 grit wheels that bolted the fuck on. however the A non asshole reply, would have simply been, no, they are not made, or yes they are made by norton or whoever. The aforementioned machines the majority of people are using aren't the same bolt pattern, which is why the question came up to begin with. To that end, neither Grizzly or Central Machinery sell replacement parts for this machine. If I could find a bolt on solution, it might be as easy as getting a sub 1hp VFD and dialing down the speed to 300-360 rpm, and finishing out the whole project in less than an hour. My tool grinder also comes with a water cooling tray and cutting fluid that feeds right to the cutting surface, and could possibly work well enough for my purposes. IF you had done YOUR research, you would also know that there are 3 scales for abrasives: Mohs, vicker and knoop scales... as such the materials that cover 800-3000 grit could range from alumina, silicon carbide, boron carbide, quartz, flint, garnet, emery and corundum. Because as I know diamonds are usually in the 8000-10,000 range on the scale I am familiar with, hence the question to clarify if they are even measured on the same scale given the disparity in expected grit numerical range and available "diamond" grits . SO if you knew that, you might realize that asking if they are rated on the same scale,and if there is a bolt on solution for my application. As such, the questions actually fall into reasonable quandaries. FYI Richard said 3000 " works sweet" which is why it's at the high end of my scale... Again, you might want to do updated research yourself. LOL, next I will ask how you dress a diamond wheel and you will probably have a heart attack about that too. (given I usually dress wheels with diamond tools... since you typically dress or machine with materials harder than the part being machined or dressed... LOL.)

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    QT: [chinese made disc and laps. ] Best to find a plate mounted grinding wheel with 1/16 - 1/8 diamond that fits your machine. 120 to 320 grind well, 500 to 3000 are very fine and grind a better finish at a slower rate so good to rough with a green wheel when using finer wheels. You should not grind any steel with a diamond wheel and should diamond grind wet only.
    Concentration is important for wheel life,, A 50% wheel is 50% filler and bond.( I don't know if anyone make 50 % wheels )

    Best to line-up mark wheel to mount hub, tighten screws and rotate under an indicator to mark high and lows.
    Then place shims behind wheel to make it run .002 or better/less face run out. This because when you expire one small spot of the wheel the wheel is mostly shot.. so you don't want to waste .010 or what ever of the wheel at the end of life. At grinding you want to always watch for the high place and do grinding there on the high place so to keep the wheel as flat as possible.

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    Quote Originally Posted by michiganbuck View Post
    QT: [chinese made disc and laps. ] Best to find a plate mounted grinding wheel with 1/16 - 1/8 diamond that fits your machine. 120 to 320 grind well, 500 to 3000 are very fine and grind a better finish at a slower rate so good to rough with a green wheel when using a finer wheels. You should not grind any steel with a diamond wheel and should diamond grind wet only.

    Best to line-up mark wheel to mount hub, tighten screws and rotate under an indicator to mark high and lows.
    Then place shims behind wheel to make it run .002 or better/less face run out. This because when you expire one small spot of the wheel the wheel is mostly shot.. so you don't want to waste .010 or what ever of the wheel at the end of life. At grinding you want to always watch for the high place and do grinding there on the high place so to keep the wheel as flat as possible.
    Yup I have the water cooling all ready dialed. https://images-na.ssl-images-amazon....L._SL1000_.jpg is more or less my setup. Sounds like I might have to settle for a roughing setup for now with the shars 150 wheel. Any suggestions for gear driveboxes for std bench grinders? Ones I have found ar NEMA32 small motors.

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    speedfreak24.7
    I don't want this thread to degenerate and you to make a fool of yourself more than necessary.

    Generally, for lapping and grinding at low speed with fine abrasives electroplated on a lapidary disk you don't need much power and 1/4 hp is already way too much, especially if you're using gear or belt reduction.

    For gear motors, gearboxes, etc. Surplus Centers are your best friends, after Google, of course. Perhaps, look for DC motors as well,

    And, speaking about Google, probably, five minutes spent searching the web would have solved your big confusion you have with grit (= measure of the diameter of the abrasive particle) vs. hardness. Here, perhaps, a link that will help understanding grit (first result with google, by the way). Here is another table going much finer with the grit/mesh.

    Is your tool grinder three phase? The Central Machinery one that I have and all the others I have seen are single phase. If it is single phase, it would be extremely hard, if not impossible to control it with a VFD, since the start winding has to get disconnected by the centrifugal switch after a certain speed (otherwise it will burn) and you would also need to find a way to exclude the capacitor (if it has one) from the equation. Bottom line, if it isn't three phase already, it would be a lot of effort/money to control it with a VFD.

    I use my Central Machinery grinder to sharpen HSS lathe tooling. at least in mine, the trunnions of the two tables are a royal pain. For shaping a scraping blade, you can use the 150 grit wheel with the table set at 90° (i.e. blade on the same plane as or parallel plane to the axis of the wheel). You can grind the negative rake while finishing at low speed on fine grit.

    I understand that you don't have much time and you can spend only once the little money you have. For $200 or less you can find a slow moving wet grinder (look into woodworking tool sharpening) and, given that you don't need much adjustability for the tool rest (for most jobs you can sharpen with a -5° rake angle, if the cast iron is very soft, you can go to -8°, if it is too hard, you can reduce to -3°), you can cut wood blocks at different angles and, if you really want, cover the wood with some sheet metal.

    My apologies, but I'm a semi-old fart, grown up before Internet, when it was much more difficult to gather information and I really get upset when I encounter anybody who doesn't do enough homework to document him- or herself at least on the basics, before asking questions. I find also unacceptable and disrespectful when you write "the guy that teaches scraping classes" instead of calling him by name, especially considering that you have corresponded with him (by the way, again, Google would have helped you also in this: if you search "scraping class", almost all the results on the first page point directly to Richard King).

    I stand for what I wrote in my earlier post and, as each of my posts in this thread, I try to be as helpful as I can and I talk about only things I know.

    Regards,

    Paolo

    PS To dress diamond wheels (the ones with diamond in a matrix, not the electroplated ones, of course) you use iron, since at high-enough temperature, it eats up carbon from the diamond.
    Last edited by Paolo_MD; 06-27-2019 at 10:45 PM. Reason: correcting a couple of typos (I need new reading glasses).

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    For scraper only sharpening you do/may want the finer wheel. The 500 will be the start of super finishing grit size and will give a mirror finish pretty quick. No need for roughing unless you chip the scraper edge.

    For slow RPM if needed you can groove the OD of the wheel on the back side and then run a belt to another motor mounted on your bench with it having a small pulley. Just use pi R square to know the Circumference of your grinding wheel and that of the drive pulley, and compare the numbers

    Plenty of small water pumps so you can make a 5 gallon bucket coolant system so no worry about hazz-waste.

    https://www.amazon.com/s?k=aquarium+...b_sb_ss_i_1_13

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    Quote Originally Posted by Paolo_MD View Post
    speedfreak24.7
    I don't want this thread to degenerate and you to make a fool of yourself more than necessary.

    Generally, for lapping and grinding at low speed with fine abrasives electroplated on a lapidary disk you don't need much power and 1/4 hp is already way too much, especially if you're using gear or belt reduction.

    For gear motors, gearboxes, etc. Surplus Centers are your best friends, after Google, of course. Perhaps, look for DC motors as well,

    And, speaking about Google, probably, five minutes spent searching the web would have solved your big confusion you have with grit (= measure of the diameter of the abrasive particle) vs. hardness. Here, perhaps, a link that will help understanding grit (first result with google, by the way). Here is another table going much finer with the grit/mesh.

    Is your tool grinder three phase? The Central Machinery one that I have and all the others I have seen are single phase. If it is single phase, it would be extremely hard, if not impossible to control it with a VFD, since the start winding has to get disconnected by the centrifugal switch after a certain speed (otherwise it will burn) and you would also need to find a way to exclude the capacitor (if it has one) from the equation. Bottom line, if it isn't three phase already, it would be a lot of effort/money to control it with a VFD.

    I use my Central Machinery grinder to sharpen HSS lathe tooling. at least in mine, the trunnions of the two tables are a royal pain. For shaping a scraping blade, you can use the 150 grit wheel with the table set at 90° (i.e. blade on the same plane as or parallel plane to the axis of the wheel). You can grind the negative rake while finishing at low speed on fine grit.

    I understand that you don't have much time and you can spend only once the little money you have. For $200 or less you can find a slow moving wet grinder (look into woodworking tool sharpening) and, given that you don't need much adjustability for the tool rest (for most jobs you can sharpen with a -5° rake angle, if the cast iron is very soft, you can go to -8°, if it is too hard, you can reduce to -3°), you can cut wood blocks at different angles and, if you really want, cover the wood with some sheet metal.

    My apologies, but I'm a semi-old fart, grown up before Internet, when it was much more difficult to gather information and I really get upset when I encounter anybody who doesn't do enough homework to document him- or herself at least on the basics, before asking questions. I find also unacceptable and disrespectful when you write "the guy that teaches scraping classes" instead of calling him by name, especially considering that you have corresponded with him (by the way, again, Google would have helped you also in this: if you search "scraping class", almost all the results on the first page point directly to Richard King).

    I stand for what I wrote in my earlier post and, as each of my posts in this thread, I try to be as helpful as I can and I talk about only things I know.

    Regards,

    Paolo

    PS To dress diamond wheels (the ones with diamond in a matrix, not the electroplated ones, of course) you use iron, since at high-enough temperature, it eats up carbon from the diamond.
    At the time I wrote it, I was going to write what his name was. But I couldn't log into my email due to giving someone else access and the shitstorm that followed. Only after could I search for his name. Given the breadth of people I speak to in a week, I don't remember anyone's name. If you took a psych class you would understand why. I am also a 40 year old Marine Corps vet, with a TBI and other crap. So my memory isn't as functional as it once was. As such, sometimes names just don't come to me unless I have had personal face to face time, even then I often just remember their faces. Disrespectful to me is calling someone hey dude, or guy. I obviously hold him in high enough regard if I mention him and it conveyed the required point without excess words or time.

    Again, a search result is only as good as the input. I am sure you have more word choices to enter than I do given you obviously know more about it in general.

    MY tool grinder is likely the same central machinery version you have, or similar enough. They tend to change the part number but not change features. It's single phase. I have controlled single phase motors with vfd, however there remained the question of if I could go that low.

    I try to do my own research, however when the "pros" at the companies that make the products you are trying to buy are usually just schooled up regular people.. They tend to say no we don't have that, and not have further information.

    See THAT is what was an excellent idea. I can totally swing 200 dollar machine if I can find one. In regard to " Surplus Centers" what exactly do you mean?

    Simple response about the grit situation, "oh, you might be mixing up grit and hardness scales." For someone that claims to hate answering questions that can be found elsewhere... you sure do it alot.

    Keep in mind google only answers the questions you ask. If I search for "carbide scraper sharpening", "carbide scraper sharpening service", it's all about what you enter and there is an almost infinite amount of searches and results. Most results show or detail HOW to sharpen, which I already know. Since in the end that is all I really want to find is someone that will sharpen the damn thing for xx dollars so I can finish my stupid cross slide, and I try variants of that and get carbide sharpeners that only do endmills or saws... I find that out after calling around. It was your bad for assuming how much research I had done to get here. It would have taken the same amount of time to just answer the question than go the condescending route. Don't make the mistake thinking that I am "making a fool" of myself by being assertive rather than being a little girl and bowing down to some dude on the internet. Especially while I assert that your claims about lack of research etc are categorically incorrect and pretty much prickish. I reserve the right to be a take no shit from anyone Marine Veteran, as you are self proclaimed semi old fart. But don't think "I really get upset" actually makes me give a shit about your feelings. It's a free country, you can get upset. But don't be surprised when no one is there to hand you a tissue because you jump to conclusions about things like how much research I have done before I ask a question in a medium that is solely configured for said actions.

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    @ Paolo_MD
    Have a question to run by you. Wondering what your thoughts are regarding the grinder seen in the link below,
    Rikon - 8in Slow Speed Grinder

    Wheels are 8in 60 & 120 grit white alum oxide, slow speed 1700 rpm 1/2hp.

    Grinding Cleveland t15 HSS 1/2x1/2 tool blanks, the grinder up to it?


    What say you?
    Pep

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    Quote Originally Posted by speedfreak24.7 View Post
    In regard to " Surplus Centers" what exactly do you mean?
    Pretty sure he means Burden's Surplus Center aka Surplus Center of Nebraska.

    Don't make the mistake thinking that I am "making a fool" of myself by being assertive rather than being a little girl and bowing down to some dude on the internet.
    But that's exactly what you are doing: making a damned fool out of yourself. Stop being such a prickly asshole. You are NOT earning respect for your attitude. And nobody asked you to bow down to anybody. Okay?

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    Quote Originally Posted by pepi View Post
    @ Paolo_MD
    Have a question to run by you. Wondering what your thoughts are regarding the grinder seen in the link below,
    Rikon - 8in Slow Speed Grinder

    Wheels are 8in 60 & 120 grit white alum oxide, slow speed 1700 rpm 1/2hp.

    Grinding Cleveland t15 HSS 1/2x1/2 tool blanks, the grinder up to it?


    What say you?
    Pep
    1/2 Hp is not much Hp for an 8" wheel

    https://www.amazon.com/DEWALT-DW758-...gateway&sr=8-4

    But (Precision-machined aluminum tool rests allow the user to accurately position work]
    not so good / look flimsy /

    Slow speed if good for 8" wheel but 3/4 or 1 hp would not likely stall grinding HSS tool bits.
    Snagging mild steel is easier than HSS..
    Last edited by michiganbuck; 07-29-2019 at 04:37 PM.


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