What grit(s) are best for grinding profiles in carbide and HSS?

[TorontoBuilder]

I'm ordering a diamond wheel or two for our 8" bench grinders. One is a slow speed grinder and the other is 3600 rpm grinder on a stand. I can only afford 2 diamond wheels at the moment and they'll have to last a while.

I have plenty of course and medium grit wheels in various ceramic abrasives

So if you can only have two diamond wheels, what grit(s) are best for grinding and polishing profiles in carbide and HSS?

Let me compound the complexity of this issue by stating that I read that diamond wheels are prone to premature wheel wear when grinding steels.

 

[TorontoBuilder]

I doubt I'll grind so many cutters of either type that premature wear is an issue...

I cant afford one set of diamond wheels and two set of cbn wheels. My home shop with wood lathe has cbn wheels for my lathe chisels

 

[TorontoBuilder]

My thoughts are diamond wheels in 320 and 600 grits.

 

[Susquatch]

I don't have any experience to speak of with diamond wheels @TorontoBuilder. It's looking like nobody does or doesn't want to say. You are prolly plowing new ground.

 

[TorontoBuilder]

I don't have any experience to speak of with diamond wheels @TorontoBuilder. It's looking like nobody does or doesn't want to say. You are prolly plowing new ground.

I'll go with what I have selected.

I was sorely tempted though to buy 1000 grit, because that it the recommended lap grit for polishing carbide gravers for had cutting steel but I can hand polish when needed sine I have diamond hones

 

[David]

Diamond Grinding

How to decide if grinding with a diamond wheel is the most cost effective way to grind.

carbideprocessors.com

 

[TorontoBuilder]

Diamond Grinding

How to decide if grinding with a diamond wheel is the most cost effective way to grind.

carbideprocessors.com

thanks.

They throw labour costs into the mix... ours is free, and were not sharpening a 180 tooth plywood saw blade.

The article however mentions something critical... the impact of metal bonded diamonds on brittle carbide. I'm used to carbon steels on metal bonded cbn wheels. Carbon steels are not brittle so no issues.

So that limits sharpening carbides to resin wheels. Resin wheels lack finer grit selections, so the finest wheel is the limiting factor. Have to hone for finer finish

So 320 and 600 are available on amazon sent from china.

 

[Stellrammer]

Depends on your needs, what specifically are you grinding, sharpening edges on brazed tools or regrinding inserts?
180 grit will do most of what you need, certainly nothing over 300 unless you are regrinding wood working carbide blades.
If you are referring to bonded diamond you must be very careful to avoid contact with steel. Steel will destroy your wheel in short order, always make clearances on brazed tools on a carborundum wheel so it does not contact when grinding with diamond. Rough with green silicone carbide then finish with the diamond, I remembered I have a flared cup wheel and a d1a1 wheel, never used them in 10 years, only green silicon and a diamond hone

 

[TorontoBuilder]

Depends on your needs, what specifically are you grinding, sharpening edges on brazed tools or regrinding inserts?
180 grit will do most of what you need, certainly nothing over 300 unless you are regrinding wood working carbide blades.
If you are referring to bonded diamond you must be very careful to avoid contact with steel. Steel will destroy your wheel in short order, always make clearances on brazed tools on a carborundum wheel so it does not contact when grinding with diamond. Rough with green silicone carbide then finish with the diamond, I remembered I have a flared cup wheel and a d1a1 wheel, never used them in 10 years, only green silicon and a diamond hone

I'll be grinding carbide rods to make custom tooling... mostly for engraving. and regrinding existing profiles. And grind tunsgsten carbide rods for tig welding.

I planned to rough shape on silicone carbide wheels as we do now, we have a rough grinder and a finishing grinder. The plan is to make the finishing grinder with both diamond wheels to smooth finish the rough cut tools

 

[Stellrammer]

You’re going to be fluting by hand?, you need a tool and cutter grinder, air spindle and cup wheels, and a motorized rotary head. Chances are you can find a Cincinnati #2 for the price of scrap, cause there is barely anyone left who knows how to use one.

 

[TorontoBuilder]

You’re going to be fluting by hand?, you need a tool and cutter grinder, air spindle and cup wheels, and a motorized rotary head. Chances are you can find a Cincinnati #2 for the price of scrap, cause there is barely anyone left who knows how to use one.

not fluting, at least not until I get a tool and cutter grinder... a table top version not a massive monster.

I'm making small tools for engraving... and use in pneumatic engravers, and custom ground wood lathe turning tools in carbide and in CPM10V and M42 cobalt steel.

 

[Stellrammer]

So you are essentially making d- bits like on a Deckel.

 

[Former Member]

Diamonds for Carbide CBN for HSS. Can you use them on the other, you greatly reduce their life. How much I can't say not enough experience.

My understand though is with Diamond wheels on HSS slow speed is required.

Now unless you have balanced and smooth running spindles don't waste your money.

I bought a Deckel clone for that reason, one of my Diamond wheels is less than a CBN wheel. No problem as my tooling has gone Carbide and other than drill bits HSS but will slow replace them with carbide.

Love Carbide now that I've gotten used to it. HSS is so old school.

 

[TorontoBuilder]

more like this out of carbide rods and bars

but the base shape wil be done using surface grinder and grinding fixtures... so diamond wheel will just touch up the face and polish

 

[Rauce]

I have some diamond wheels I use on carbide scraping inserts and for re-honing brazed carbide tooling. I’ve used the 1500 and 3000 mostly. I bought an 800 or 1000 as well but I’ve never used it. These are ~6” discs that I put on a bench grinder with an aluminum backing plate.

 

[TorontoBuilder]

I have some diamond wheels I use on carbide scraping inserts and for re-honing brazed carbide tooling. I’ve used the 1500 and 3000 mostly. I bought an 800 or 1000 as well but I’ve never used it. These are ~6” discs that I put on a bench grinder with an aluminum backing plate.

I keep looking at low speed horizontal lapping wheel systems but god they're so expensive.

These sound like a good compromise

 

[Rauce]

I keep looking at low speed horizontal lapping wheel systems but god they're so expensive.

These sound like a good compromise

At some point I’d like to make a dedicated set up for them with a lower speed motor. Maybe a 1750rpm DC motor with a PWM control. It would have a work rest that can be angled as well.

For really fine honing you can use a cast iron disc and embed diamond paste in it.

 

[TorontoBuilder]

At some point I’d like to make a dedicated set up for them with a lower speed motor. Maybe a 1750rpm DC motor with a PWM control. It would have a work rest that can be angled as well.

For really fine honing you can use a cast iron disc and embed diamond paste in it.

me too... I have a fractional HP 3 ph motor and will be buying a cheapo vfd.

I use a 1000 grit diamond stone followed by several grades of diamond paste and spray on custom strops bonded to granite for my honing. I use the thickest veg tanned leather so I can cut tool profiles into it into which to add paste for honing curved tools like my carving gouges. I like my woodblock carving tools razor sharp.

 

[Stellrammer]

So that’s why the super fine grits, used Glendo accufinish machines rarely come up, but many people have made their own from DC motors and such. You can use the import diamond plate tools on them or buy Glendo wheels.

 

[Mcgyver]

Rambling muses.

For carbon steel woodworking tools slow speed makes. You don't want to affect the temper and the temperature, where a molecule of abrasive meets one of steel is almost entirely dependent upon the relative speed of the two, i.e. surface speed. Slowly, the temps stay low.

There is probably an advantage in going slowly for diamond and steel (carbon or hss) .....diamond/steel is discouraged as at higher temperatures (again a function of surface speed), the diamond (carbon) gets absorbed into the steel. otoh The late John Stephenson (great guy, internet forum character and machinist) claimed the absorption was baloney....or least it happened slowly enough not to matter. That was after he'd been using a cheap diamond wheel on steel for some time.

But what I don't get, is why one would care about slow for carbide/diamond or hss/ceramic. Some guys just starting scraping get excited about a Glendo (for carbide scrapers) but it never made sense....all it does is take longer.

If you are doing the work on surface or T&CG grinder or maybe a Deckel, you can get a near mirror finsh with 60 grit wheel via sparking out. Of course that goes out the window by hand....I always stone the end on a HSS tool after hand grinding.

I've got a small horizontal power hone, slow speed, which wouldn't be hard to make, photo below. Got it for doing watchmaking gravers. For the shapes John presented it would be ideal. Polish the sides then rig something to hold the cutting face at right angle and away you go.

For carbide scrapers, here's a rotary lap I made. Crappy tire grinder with a couple of cast irons disks. A fair bit of work went into the mounting of the disks; there is a taper hub turned in situ (turning to mate this is a challenge) on the shaft and the disks bolts to that. Keeps things in balance and lets you take a disk off for charging. Cheap to operated....a syringe of 8 micron diamond paste lasts forever. you have to lap the sides of the scraper before silver soldering, but from then, a 30 second touch on the power lap puts a fresh mirror finish on and away you go.

Photos to give some ideas