What's new
What's new

Newbie - grinding carbide on surface grinder?

richard newman

Titanium
Joined
Jul 28, 2006
Location
rochester, ny
I'm going to make some carbide blade guides for a band re-saw. Intending to braze carbide blanks to steel, then true up on the surface grinder, hopefully just a dusting. Have Boyar Schultz 612, no coolant.

What type of diamond wheel should I use?

Can I use it dry or do i need a mister?

Suggested depth of cut, cross feed, speed of traverse?
 
Richard,

I would use a 100 grit wheel, run the table slow, cross feed not a big deal for light dusting. Probably don't need a mister for light dusting but I would recommend a vacuum of some sort to catch the dust as it is pretty hazardous to your health. A hepa vac or vent the vac outside so you don't have to breathe the dust. Good luck.

Big B
 
I don't know what your guides look like but there are a couple of possible problems. If you're brazing carbide to steel you should look into TriMet. You can read about it here.

Brazing Carbide | Lucas-Milhuapt

If you're grinding steel/carbide with a diamond wheel you should first undercut the steel so that a minimum of steel is ground with the diamond wheel.

Gene
 
As to brazing carbide to steel, we did a lot of it and always used silver solder. I'm not sure of the concentration of silver but we never had a problem using it. You do need to grind the black scale off from it to make the silver solder bond. I used a silicon carbide wheel (green wheel) for that.

Big B
 
carbide grinding suggestions

Since it sounds like you are doing only a few pieces, a 1/4" wide wheel should be sufficient. Resin bond and 75% concentration for cooler grinding and gentler on the carbide. 100 grit will get you below 32 microinch, 220 grit below 16 microinch. Avoid grinding the steel if at all possible--the diamond dissolves in the steel thus dulling very quickly. Heat is your enemy therefore light passes and fast traverse. Without coolant, try .0002 to .0004 inch per pass at 3 to 6 inch per second. Infeed on the upstroke, sparkout on the return stroke.

True the wheel with a brake dresser. If you don't have one, indicate the wheel so it runs within .001". Get an aluminum oxide dressing stick, 60 or 80 grit for a 100 grit wheel , 120 grit for a 220 grit wheel. When the wheel gets dull (the carbide gets hot) force the dressing stick into the face of the wheel. Don't be bashful, the idea is to remove bond and expose fresh diamond.

The tangential grinding forces will be high. Make sure your workpieces are adequately blocked in!
 
<>If you don't have one, indicate the wheel so it runs within .001". <>


Good advice I think. But, to me it feels like chalk chattering on the chalkboard for me to use my Interapid DTI to indicate in my diamond wheel. So, to avoid making flats on the carbide ball-tip of the DTI, I used a bit of Delrin and made a plastic tip protector about .125" diameter that snaps into place by vitrtue of having a slightly undersized hole relative to the DTI probe tip. Once I had made that accessory I did not hesitate to use my DTI on the diamond wheel. Took all of five minutes. A sacrificial protector could be made of steel or aluminum too, but the plastic has enough give to allow a good firm snap-on arrangement.

Denis
 
I do this kind of stuff sometimes. Maybe I can be useful here for once.

While common to me diamond wheels are not cheap for a one off.
So, I'm going to go with a e-poop wheel.
Given a deserted island and one shot I'd go 220-240 grit brown in color but green works. (These colors are fillers, brown is copper, sucks the heat out)
50 cons are better dry, 75-100s are wet wheels but you can work with any.
I'd also guess no dresser so you have to indicate it in on the spindle.
Some wheels will come with a stick and you'll need one if grinding very many things.
The wheel will be open when brand new as they have to be dressed when coming out of the press and would most likely get through your part but will load up in the future.
You can put scotch tape on the OD if worrying about your indicator tip. (again not something I have to worry about and we indicate on the diamond all the time).
It will like some coolant. If you have a helper even a old windex bottle with water, a capful of coolant and a few drops of dish soap will help a bunch.

You will get away with just about anything on this part.
Keep your depth light, in the tenth's and you will be fine The wheel, part and machine will complain real fast if you are going too heavy.
With the right wheel, and lots of coolant your machine will take .100 thou. deep 3/8 wide in one pass but you don't try this at home.
Bob
 
Take Stephen up on that offer...
A carbide wheel should be indicated in or dressed on its mount and is a big investment for a one-up job.
It needs to be run with coolant (a bucket and a hose to the wheel would work Ok.)
120gt- 100conc would be the best choice for a general purpose diamond wheel.

Set a shim between wheel and indicator point to save point and true wheel to run .002 or better.

After .002 true you can grind a flat soft steel with one way feed (not climb) to true a little better... Steel sucks out diamonds pretty quick with a .0002/.0003feed and slow full wheel bottom travel across. then clean with green stick. (yes a break wheel dresser is the right way to dress) Should not slow RPM very much, if so then less feed.

Silver solder and braze makes a good a-fix to steel. Must be super clean surface with no finger prints. heat to cherry and watch flow... move a slight and hold still to cool.
*Can the design be made so only the steel needs to be ground?
Green wheel may work for snubbing off thin stock at edge but is not much good for grinding on the flat or wide areas.

A hose held to touch wheel.. grind away hose with wheel to be a close almost touch touch. hung high bucket (can) and a small valve to adjust works well. A box of sorts to catch spray for a one-up or a few. Catch box and vacuum for production.
Coolant 1/4 cup of washing soda to a gallon of tap water OK.
 
Thanks for all replies, and especially Stephen for your kind offer. I'm very tempted, it's been a while since we've visited. But I do like trying these things myself tho, that's how I learn and broaden my capabilities.

So... looking thru the stuff that came with my grinder, I found a small diamond cup wheel, 3 or 4" diam, 150 grit 100 conc. Has 1-1/4 bore, so it will fit on my machine, wondering if I could use this. Should be easy to set up, the 1/2" square carbide chip will be brazed to the end of a piece of 1/2 square steel stock Any reason this won't work? Would I want to feed in and hit the entire face with each pass? How much infeed per pass?
 
If you grind these "guides" flat they will be more cutting tool than guide. It seems to me that for a guide you woulc want a large radius that would indeed guide the band. Grinding a flat surface will make the edge a cutting tool.
 
Cup wheel will cut Ok. It should turn at 5500 to 6000 RPM for best performance (even higher is good but you should stick with RPM label). Cup wheel won’t last as long as a 7” SG wheel because of slow SG speed and less diamond area. But will grind at surface grinder speed. End brazing ½ x ½ might not be as good as notching the steel like a TCT tool bit to give more braze surface area, But still OK. Boil the brazed parts to remove brazing flux that gets glass hard and tears up the wheel. Steel will turn black at boil.

Step angle plate a good fixture for such a job. Snag off any braze and steel you might hit with an oxide wheel as it will tear up diamond wheel and suck out diamonds. Might be good to oxide wheel grind away any steel -.001 or .002 so not needing to hit steel with diamond wheel.

Should run wet to reduce heat build up in part and control of dust. Small aquarium pump ok for a start.. Larger simple pump for production. For production buy a 7" SG diamond wheel as soon as you can.

Infeed you will feel out as If RPM slows that is too much infeed.

For sharp edges you might make a low long V block that sets on the chuck with only perhaps 1/8 inch at bottom of V. That will allow you to set them in with an end block for slide.. You can chamfer grind with using the 7" wheel not the cup.
(move about so not to put a a hole in the wheel bottom of SG wheel)

With the cup you will have to to clamp at angle to have the corner edge face the wheel.. and still not grind steel.
(green stick to clean diamond)
 
Last edited:
We always used a white stick to clean a diamond wheel. New wheels came with one.

Big B

Cup wheel will cut Ok. It should turn at 5500 to 6000 RPM for best performance (even higher is good but you should stick with RPM label). Cup wheel won’t last as long as a 7” SG wheel because of slow SG speed and less diamond area. But will grind at surface grinder speed. End brazing ½ x ½ might not be as good as notching the steel like a TCT tool bit to give more braze surface area, But still OK. Boil the brazed parts to remove brazing flux that gets glass hard and tears up the wheel. Steel will turn black at boil.

Step angle plate a good fixture for such a job. Snag off any braze and steel you might hit with an oxide wheel as it will tear up diamond wheel and suck out diamonds. Might be good to oxide wheel grind away any steel -.001 or .002 so not needing to hit steel with diamond wheel.

Should run wet to reduce heat build up in part and control of dust. Small aquarium pump ok for a start.. Larger simple pump for production. For production buy a 7" SG diamond wheel as soon as you can.

Infeed you will feel out as If RPM slows that is too much infeed.

For sharp edges you might make a low long V block that sets on the chuck with only perhaps 1/8 inch at bottom of V. That will allow you to set them in with an end block for slide.. You can chamfer grind with using the 7" wheel not the cup.

With the cup you will have to to clamp at angle to have the corner edge face the wheel.. and still not grind steel.
(green stick to clean diamond wheel)
 
So... looking thru the stuff that came with my grinder, I found a small diamond cup wheel, 3 or 4" diam, 150 grit 100 conc. Has 1-1/4 bore, so it will fit on my machine, wondering if I could use this. Should be easy to set up, the 1/2" square carbide chip will be brazed to the end of a piece of 1/2 square steel stock Any reason this won't work? Would I want to feed in and hit the entire face with each pass? How much infeed per pass?

Should be no problem.
Small wheel on a normal fixed speed spindle helps keep the heat down.
Infeed is in one/two tenths which is not easy on this in/out knob and you may have to stop and let things cool down with no coolant.
Do not let the the part get hotter than you can set you finger on. It will grow into the wheel and muck you up.
Move fast, don't let it dwell on the wheel.
Cut and make some spark out passes before the next infeed.
100 con is actually a really bad choice for dry grinding on 1/2 inch contact but you can make it work.
Contact length is the killer here, This is not a little flat on an endmill. Any water from a mister or spray bottle will make a very large difference.
Face wheel grinding, which is what you seem to be speaking runs a finish 4X better than OD so your grit is ok but you need spark out passes to get a nice finish.
The wheel entrance and more the exit side at this grit is going to have some chips so if it matters hit those edges on a deburr wheel.
Bob
 
Richard-

As real experts above have outlined, your plan should work if 1.) you clean the wheel, 2.) clean the wheel, 3.) have something running or misting the center of the wheel so it flings out the rim and on the part, and does not need cleaned as much, and 4.) clean the wheel if you can't keep it wet. Having coolant with diamonds and carbide is night and day.

After the face is ground flat/parallel, remove it from the fixture, turn off the grinder, and hone each of the edges on the face of the diamond wheel (on the flattest surface) manually. Turn the wheel a little with each honing motion to keep the wear distributed and cutting face fresh. A coarse diamond hand hone would be as good or better. But the edges can be rounded off fine by hand. Or if you are feeling adventuresome and confident, turn the wheel on and dub the edges one by one, by hand.

Would love to see you. Imagine we both have too much going on to spend the time traveling. Sadly. All in good time, though. :)

smt
 
For a one-up the cup will self dress flat in short order. Staying on thee left of wheel will direct cutting forces down for better holding. You can wear a dust mask. Box in the job a bit to keep diamond does off other things.

Re: Stephen [“Having coolant with diamonds and carbide is night and day.”]

Diamond wheels are best used wet. Yes for cutter sharpening they are often used dry but with that use the wheels wear faster, incur more heat and pressure, and provide a less quality finish. People with carbide grinder experience will attest to this because when the coolant stops the grinding almost stops.

For production of this part you may wish to have a bench grinder to rough in. Perhaps green one side, white the other.
The cup throws dry dust of wheel and carbide or wet with the same in a circle going every direction. If wising the cup on a surface grinder I recommend you make a circle box of sorts to contain this throw of material…perhaps a bottom half cut of a 20 gal steal barrel. Yes you still need a wheel guard..
The surface grinder type wheel directs the coolant one way so is easier to control, runs at correct surface speed, directs cutting forces in one direction and stock removal per dollar is more favorable.
 
I had planned to ease the edges with a slow speed Power Hone that I use for sharpening engraving tools and touching up inserts.

Sounds like the cup wheel will do the trick, but I'm tempted to look for a cheap used flat wheel on ebay to make dust/mist containment easier. I only need to make 4 of these, assuming my design works ok, but I'm sure I'll find a use for the wheel once I get comfortable with grinding carbide. I have a mister that came with a used machine I bought long ago, will clean it up and give it a try here.

This forum is a life saver, there just doesn't seem to be much info online or in books about surface grinding. I will be asking more ignorant questions soon, hoping to grind a skiving form tool for making very decorative ball end nuts for banjos. Thanks again for sharing. And please feel free to ask for advice on the woodworking forum, where I can offer my years of experience.
 
Richard we enjoy the sharing of thoughts so there are few Ignorant questions..Set for 4 is just to clamp part horizontal grind side facing the cup face, held up off the chuck to grind on the down side of wheel and grind away with having stop set so you don’t wreck using long table travel. Start with .0005 feed and work more or less from there. The splash box can just be a wood box around for catching coolant. Using perhaps an angle plate or the like to fixture. Mister or just a 1/16 or so constant shot to wheel center. Still adding a dust mask a good idea as some of the older cups had a fiber in the bonding (pre 70S or so).

With coolant and not grinding braze or steal the cup wheel will last a good long time. as I mentioned 1/4 (to a hlf) cup washing soda and a gallon of water makes a (non rusting) home mix you can dump in the weed bed.

Get that skiving tool done we are waiting for the photos.

Merry Christmas, Buck
 
I just finished grinding grooves in some carbide rings with an old Norton OD/ID grinder... that was quite the learning experience!
I tried a few different wheels that put a nice shine on the rings but didn't remove any measurable material before I found one that would do the job, .00025" at a time. I'd sloooooowly dial it in, making sure it didn't start ringing too much and let it spark out.
Painfully slow process.
 








 
Back
Top