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Carbide grinding implements???

Discussion in 'A BEGINNER'S FORUM (Learn How To Machine Here!)' started by Glenn Brooks, Feb 16, 2017 at 2:24 PM.

  1. Glenn Brooks

    Glenn Brooks H-M Supporter - Premium Content H-M Supporter-Premium

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    Hello all,

    so every one says,"you gotta grind carbide tooling", but I havent seen advice regarding what size of grinder to use, proper wheel grinding speeds, or actual composition/grit of grinding wheels etc. Do you need two different grits? If so, what is best??

    I'd like to put together a carbide grinder. Looking for what constitutes a proper set up.

    thanks,
    Glenn
     
    Last edited: Feb 16, 2017 at 2:41 PM
  2. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    I only do a bit of carbide grinding so I just switched a 6'' AO wheel for a SiCa wheel in 100 grit. It works fine for sharpening brazed carbide tools.
    Not the most sophisticated set up but it got me grinding carbide with a minimum of fuss.
     
  3. mikey

    mikey Active User H-M Supporter-Premium

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    Whatever happened to Christian Poulsen? He'd be the perfect guy to take this question.
     
  4. Doubleeboy

    Doubleeboy Active User Active Member

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    Picked up a Harbor Freight cheapie diamond grit grinding wheel, probably for saw blades and made a backing plate /arbor arrangement and use it mounted in old HF mini lathe I picked up cheap well used. Makes for a nice tool for doing brazed carbide. When doing brazed carbide if I need to grind much on the steel shank under the carbide I use AO carefully then touch up the carbide part. I use USA made brazed carbide tooling when doing interrupted cuts and touch em up with the above rig.
     
  5. Eremius

    Eremius United States Active Member Active Member

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    Silicon carbide (green) or diamond wheels are needed for grinding carbide.
     
  6. jocat54

    jocat54 Active User H-M Supporter-Premium

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    I use a really hacked method. I use and old washing machine motor running at it's lowest speed (1125rpm I think) and made an arbor to fit the cheap Chinese cup diamond wheels (120 grit) about $10.
    The motor is probably to fast but sometimes you just use what you have and it sharpens the cheap brazed carbide pretty well. Made a rest for it and use it pretty often.
     
    JR49 likes this.
  7. JimDawson

    JimDawson Global Moderator Staff Member Director

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    I'm going to respectfully disagree with that statement. Green wheels or diamond is desired, but not ''needed''. I grind almost all of my carbide on a standard gray aluminum oxide wheel on my bench grinder. You just have to push a bit harder. Carbide grinds pretty fast once it gets red hot.:rolleyes: I should note that I normally use only the finest Harbor Freight AR8 bits. I do also have both green and diamond grinders, but I rarely use them.
     
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  8. JR49

    JR49 United States Active User H-M Supporter-Premium

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    I'm with Jim, All the brazed carbide tools that I use are from HF. Sure, you can spend hundreds on a nice diamond, or silicone carbide grinding set up. Or you could do as I did over 2 years ago. I spent under 10 bucks on some little diamond discs with 1/8 " shanks (like what fits in a Dremel collet). I put the shank of the tool bit in a vise, and sharpen-shape- form, pretty much anything I want to the carbide, If I start getting close to the steel shank under the carbide, I simply switch to an aluminum oxide stone and clear out the steel. In 2 years, I've only used 1 or 2 of the 5 discs that came in a pack with the 1/8" arbor. Now I'm not figuring in the cost of my dremel, I've had it for probably 35 years. If you don't have one, you should have one. Happy Machining, JR49
     
  9. Glenn Brooks

    Glenn Brooks H-M Supporter - Premium Content H-M Supporter-Premium

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    So, at what speeds are diamond and silicon carbide wheels supposed to spun? I've heard everything from 250 RPM up to 1750....

    Thanks,
    glenn
     
  10. Chipper5783

    Chipper5783 Active User H-M Supporter-Premium

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    I used a silicon carbide wheel on a 6" bench grinder for years. It is set up with the regular tiny little tool rests. It worked okay, but not great. Carbide is hard and I found it ground slow and would heat up. I always meant to make up a good rest - just never quite got around to it.

    Because another solution came along: http://www.hobby-machinist.com/threads/carboloy-excello-tool-grinder.37715/

    I got a 10" diamond wheel (it is a belt drive machine, runs at about 2000 rpm), designed for grinding on the side, with quite a wide face (I thought I got the grinder at the good price, the wheel cost a crazy amount of $$). It is fantastic, you can grind fast, the tool stays much cooler and it leaves a nice finish on the tool edge.

    I'm not saying you should try to look for or duplicate a purpose build industrial carbide pedestal grinder. All I am saying is that a good grinder set up is very nice and I find that a diamond wheel is much better than the SilCar.

    Let us know how you make out. Regards, David
     
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  11. Glenn Brooks

    Glenn Brooks H-M Supporter - Premium Content H-M Supporter-Premium

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    Chipper, sweet looking machine you have there. Did you ever find out a manufacturing date? It looks like pre WW II, or high end early 1950's, judging by the nice cast bronze builders plates in the photos. master Motor company is still around and might be able to tell what era the motor came from. I called them a few months ago out of the blue and their sales guy did a terrific job researching my old motor on my Burke #4 horizontal mill.

    Thanks for you input on carbide grinders. I want a legitimate carbide wheel - tired of the general purpose silica wheels over heating, nearly melting, the tooling I touch up every few days.

    Glenn
     
  12. Eremius

    Eremius United States Active Member Active Member

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    I can drive my lawn mower back and forth from work but that doesn't mean it's the right tool for the job. :D

    It is good to know as an option for when you are in a pinch though.

    Yes, a tool grinder is the ideal option and it looks like you have a really nice one!
     
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  13. Chipper5783

    Chipper5783 Active User H-M Supporter-Premium

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    I'll share the rest of the story. I had long been wanting to get a better way of grinding small tools. I have 4 regular bench grinders (they just seem to keep multiplying - 2 were my dad's, 2 came as projects) - so I intended to make up a nice rest for one of them. Then this opportunity came up at an auction (don't we all shop there?). The grinder was still in use, sounded fine running (3 phase of course - another plug to folks to get 3 phase power sorted out, it really opens up some great machine options). Anyway, I ended up paying $400 for it (kind'a got carried away). The next item to sell was a Cincinnati T&C grinder - also still connected and running. It also went for $400 (way more machine, but not for me) - I have since picked up a Cinci#2, but that is another story. http://www.hobby-machinist.com/threads/cincy-2-tool-and-cutter-grinder.46750/

    The insulation was crumbling off the wiring to the motor (and it was operating on 440V). I got it fixed up and used for a bit, however the wheels were in poor condition. So I did some research for the "ideal" wheel, based on my application. What the heck, throw caution out the window - I paid 2x the cost of the grinder for just the one wheel. Now I have $1200 into the machine. I spent a bunch of time making a pretty little table miter guide (per normal auction procedure, small components are separated/ gone from the machine). Sure it is great for touching up or major grinding of brazed carbide - but for that kind of $$ I could buy a lot of tooling options. Pretty sure I'll never get my investment back, but it works sooo nice (which for me makes it worth it).

    There is a lot of talk on this web site about wanting to get a good machine for very cheap. What can I say, I try to get equipment as cheap as I can. One is forever hearing about the guy that got a fantastic old machine, lots of tooling for practically nothing. That's great when it works out and I'm glad to hear folks stories of when it does. I have picked up some equipment/tools at what I think were pretty smoking deals myself - but I encourage folks not to focus on the price. When you find a good piece of kit, don't be afraid to pay for it (eventually that purchase price, and the associated pain will fade).
     

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