Models for grinding HSS Lathe Tools

mikey said:
Very cool, Bob! What do you plan to do with it? I assume it is off-road capable, right?
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Plans.....? oh a few parades, military truck shows, already been down to Weare. NH

Very uncomfortable to drive, would need a full heavy load to deflect the springs as is it rides like a buckboard, semi COE gets very hot, so the engine cover needs insulation, found some ceramic felt to replace the asbestos pads.
Yes, it will go anywhere and has pulled out my Massey Ferguson tractor out of many ruts.

Nice for a pleasant back road drive in the Fall..... cruising at 30 to 35 MPH........ definitely not a highway machine so it gets trailer-ed a lot to out of town events. On real rough bush roads you get tossed around a lot.

The reality is the truck was design by the Brits, built in Oshawa Ontario, for the typical Canadian soldier of the time..... 20 years old, lean from the depression at 135 lb and about 5'6"......... and I am a modern Canadian 6'2" and 225 lbs......... you do the math!!!!!

If it had suspenders, I could wear it has bush pants.

Bob C
 
Bob,
I’m so envious, would love to live in a place where I had that kind of room to take on those kind of projects.
 
Gents and ladies ......must remain politically correct.....

Not sure if is off topic for this thread.....if so please redirect me....... remember I am a newbie hoping to learn......

I would like to learn what grinding wheel is best for HSS steel.....most of the grinding wheels that come with the grinders as OEM are fine for general garage use. In most cases I have purchased the softer white stone for my wood turning chisels and it works good on HSS. But there are some series of green and some pink all for a specific purpose........ which is which. The question of grinder speed..... how relevant & significant to this issue. More to the point, metal lathe cutters are now available with carbide tips......... my question is " are there any techniques for honing / resharpening the edge of those carbide bits and what wheel or belt could be used. I just hate throwing away a tip if it can be reused.

IN the past I have used "craftex" hard rubber wheels ( 2 grade course and fine) that did a great job honing the cutting edge BUT had to be installed to run backward away from you....just needed to turn the grinder 180 backward to you and re position the gards..... can't seem t finds them anymore.

Cheers
 
Bob, CBN wheels are intended for grinding HSS and from what we have seen, they do an excellent job of it. They are sold by a number of vendors in the US, like this guy: https://woodturnerswonders.com/collections/cbn-wheels. I suggest you email him to discuss your needs first.

You can also use regular Aluminum Oxide for HSS but I am not an expert on those wheels and will leave that to others.

For carbide, I assume you mean brazed carbide. For that, the green silicone carbide wheels are what you want for that. On the other hand, @JimDawson uses regular gray wheels and maybe he'll chime in.

For honing HSS, I prefer diamond stones for speed. This is more than adequate for most purposes. However, when you need the absolute best edge on a fine HSS tool, it is hard to beat a fine India stone followed by a polish on a Translucent Arkansas stone.

For honing carbide, diamond stones are your best bet.
 
I heard my name being dropped around here :)

Yes, I have a 25 year old Chinese bench grinder that still has the original gray wheels on it. They are really hard utility wheels. I grind brazed carbide tool bits on them all the time, you just have to push a bit harder. It actually grinds pretty fast once it gets red hot. Also works very well for HSS tool bits. I also have a Baldor style tool grinder (from Harbor Freight) with green wheels on it. I do use that for quick touchups and when I need a bit more precision than the bench grinder will do. I also have a Baldor bench grinder with diamond wheels on it. That only gets used for fine work. Sometimes I use my Dremel with a diamond disk for creating chip breakers in brazed carbide tools. I buy only the finest brazed carbide tools that Harbor Freight sells, about $2 each for the AR-8

If I were doing a lot of HSS tools, I would have a grinder with softer white wheels for final touch up. I also use my 12 inch disk sander for HHS tools and drill bits.

I have never finish honed any tool bits, never saw a need to do it.
 
JimDawson said:
I buy only the finest brazed carbide tools that Harbor Freight sells, about $2 each for the AR-8.
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Well, as long as they're the finest then okay, Jim!

Thanks for chiming in. I was concerned about cost and availability of wheels in Canada and I think the common gray wheels would be more easily obtained. I knew you could give us real world experience with them.
 
jlsmithseven said:
To all of you grinding these lathe bits, I highly recommend grinding a chip breaker on the top. I was introduced this concept this year and it works amazing. No more tangling up of long stringy chips or any chips building on tool. They just go on top of the chip breaker and fall right down into chip pan. It's made a huge difference for me.

I've uploaded a picture showing what I mean.
In the red outline, use a stone or grinder to make the end of the tool rounded.
In the blue outline, use the side of a bench grinder to make a slot on top of the tool.
The yellow box is supposed to be a pedestal grinder wheel. Use where the side meets the front edge to do the chip breaker.
Looking at this image, the cutting tool is like you're looking straight down on it from above.

View attachment 247736[/QUO

I cut a chip breaker in this tool yesterday. It definitely breaks the chips but I ended up with big balls of real fine chips building up on the tip of the tool. Like steel wool but aluminum
I think I might have cut a bigger grove than needed, not sure. I’ll grind it flat and try again.
Leaves a great finish either way.
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Jeff, I would be interested to hear if you think chip breakers are worth the time to grind them. They work best with materials that have high ductility - aluminum, stainless, some steels. These are the kinds of materials that tend to string rather than form chips. Some HSS tool users swear by them; some don't.

What say you?
 
I’m on the fence still. The chips were rolling up on top of the tool but not breaking off. I was concerned about them rolling back under the cutting tip of the tool.
I want to try different sized groves and also the placement of the grove in relation to the tip and see if can get the chips to break off without me using my orange stick to knock them off. Grind it flat and try again.
 
Pardon my lack of experience but........ is it not the purpose of the "back rake" angle to facilitate the chips/curls to move away from the cutting edge??

Would it not be simpler to increase the rake angle for certain more ductile material such as Aluminium, Copper, Brass, etc....

I have noticed some very fine/narrow grooves cut behind and near the cutting edges of replaceable square carbide tips...... but assumed they were needed since the back rake is near zero in most cases.

I actually went crazy with my Xmas shopping and picked up some ready made carbide tips in 1/4 inch size today....... the best "kwalitee" made in Taiwan for $2.59 CDN....... curious to see how they will perform. With the early Boxing day sale also got new, fresh, flat, square edged, 6 and 8 inch green carbide grinding wheels for my two grinders.............. existing grey wheels have already been abused and redressed many time by "others" using my grinders.......Darn Xmas spirit!!!!!

Bob C
 
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