Making Lathe Bits Without the "Right" Tools

Now I remember why I live in the desert.

Gunner

"Upon Roosevelt's death in 1945, H. L. Mencken predicted in his diary that Roosevelt would be remembered as a great president, "maybe even alongside Washington and Lincoln," opining that Roosevelt "had every quality that morons esteem in their heroes.""

Yep, after a while snow, condensation, rain and other crap gets annoying.

So do Sidewinders, duststorms,Tarantulas, and scorpions.

I see them so seldom as to make them moot.

Gunner

"Upon Roosevelt's death in 1945, H. L. Mencken predicted in his diary that Roosevelt would be remembered as a great president, "maybe even alongside Washington and Lincoln," opining that Roosevelt "had every quality that morons esteem in their heroes.""

I'd keep on using the tools you are using now. they will involve you in no extra cost and they do the job. if this technique catches on it may end up being the standard way of doing things.

for some reason angle head grinders have a reputation for rough work. with a delicate touch they can do superb fine work. Stealth Pilot

On Sun, 22 Feb 2009 09:42:35 GMT, the infamous Stealth Pilot scrawled the following:

I've had good luck with the 4" x 1/16" cutoff wheels in a die grinder.

?Itemnumber=93389It's amazing how handy this pair can be for so little money.

If you don't have a die grinder, here's a cheapie which lasts:

A very versatile new toolset for under $17? Just do it.

Bite your tongue, heathen. TOOLS! MORE TOOLS! WE WANT MORE TOOLS!

That's very true. I have a Lancelot bit which mounts to my angle grinder. It's a mini-chainsaw on steroids which'll cut a tubafore in half in about five seconds. In the right hands, it can be used to draw eyebrow hairs on a carving. I'd bet that a flap sanding wheel on an angle grinder could do the same delicate things.

-- Everything I did in my life that was worthwhile I caught hell for. -- Earl Warren

Possibly even better would be to use an electric die grinder, Larry.

I've used a lot of air powered tools (like yourself), but running a big air compressor motor of maybe 2 to 5+ HP, to do the work that a 1/4 to 1/2 HP universal motor could do, just doesn't seem very practical to me.

Both versions require proper safety equipment.

The additional advantage of an electric die grinder is that it can be used where no compressed air source is available.

The electric version may require a little more preventive maintenance, but a quality electric die grinder should provide many years of reliable service (and the operator's arm and hand don't need to support weight of the air hose).

On Sun, 22 Feb 2009 22:26:17 -0500, the infamous "Wild_Bill" scrawled the following:

That would work far better than a Dremel.

In this case, where no true power is necessary, you're right. For heavy cutting, air is usually better.

ABSOLUTELY! Those little disks like to come apart on a regular basis. DON'T grind inline with them and DO wear a full face shield over your glasses or goggles.

True.

Jeeze, we're talking about knocking off corners here, not grinding a true-to-life replica of the Statue of Liberty from a solid block of carbide, dude.

A tip for the air hose weight is to loop it around the back of your neck like you were carrying a snake. I do that with power tool cords, too, so my saw cord doesn't stop me in the middle of a plywood cut.

-- Everything I did in my life that was worthwhile I caught hell for. -- Earl Warren

I've tried quite a few ways to rough out lathe bits to avoid burning my fingers or excessively rounding the corners on my bench grinder wheel. For me the 4-1/2" electric angle grinder is the best combination of cutting speed, control, and cheap disks that still do their main job after the edge has been rounded. I find that the weight of a tool holder or drill chuck (or blacksmith's bolt tongs) interferes with grinding the face flat and smooth. There was no point suggesting antique bolt tongs or hand vises that most people don't have and can't buy.

Die grinders don't cut sharp-edged flat surfaces very well. They are good for cleaning up inside threading tool shanks and corner-rounding radius bits and reclaiming large dull taps, but no better than a Dremel. They are the last grinders I'd buy for tool grinding, not the first. I have one for cutting off rusty muffler bolts and smoothing inside corner welds.

A 7" angle grinder cuts faster and cooler with less control. They will cut a rough notch in a lathe bit quickly. I finish it with the 4-1/2" grinder to remove stress risers. Again, not the best first choice unless you weld steel.

I didn't have a large enough compressor to run an air grinder continuously until a few years ago when I stumbled on enough repairable parts to put one together. I judge how well a tool is cutting partly by ear and the compressor is just too loud for that in the shop. I use electric tools indoors and inefficient import air tools only outdoors where there is more of a shock hazard. A 500 Watt electric grinder does the same work as an air tool plus a 2 HP compressor. The GFCIs on my heavily-loaded outside outlets occasionally wear or burn out so I don't trust them.

Jim Wilkins

My experience is dramatically the opposite. I have several 4-1/2" electric angle grinders and a 1/4" air angle grinder:

I only use the air one for deburring, small clean up etc where one-handed is necessary. I use 1-1/2 or 2" pads & even then the grinder can bog down. The electric has far more power.

As usual ... YMMV, Bob

You're definitely correct, Jim, about the 4.5" angle grinder wheels/disks being the most cost effective abrasive for steel, HSS and welds.

My suggestion of a die grinder was about finding/using coarse grits of abrasive.. I don't think there are any mounted points with 1/8" shanks that are any coarser than 80 grit, or possibly 120 grit. There wouldn't be much use in trying to shape a HSS lathe cutting tool with a fine stone.

I've used mounted stones of about 36 grit that are available on 1/4" shanks, and they cut well if they're not cheap facimilies/imitations of quality mounted stones like Norton or other good brands, however the quality ones are not cheap to buy.

The 4.5" grinder disk/wheel wins hands down as the most economical, for fast metal removal. The fast surface speed combined with coarse abrasive provides a fast cutting action.

I don't like buying them as single disks, and I haven't bought the bottom of the barrel cheap Chinese bulk packs. The last box was Metabo, IIRC.. not the cheapest, but no need to anticipate them exploding.

Many portable power tools can provide good or better results when they're mounted as a stationary machine. I haven't made a frame/bracket fixture to mount an angle grinder to a workbench, but it seems as though it could be a worthwhile project.

I wouldn't even consider using a high speed power tool in this way without a foot switch that will shut the tool's power off immediately if an Oh Shit event takes place, or a distraction happens.

Dremel tools, die grinders and flex shaft handpieces are sometimes mounted to lathe toolposts (essentially making them stationary) for precise positioning while being held securely in a clamping accessory. In the same way, making a bench holder for these tools will likely add to their versatility.

Not many tools can grip HSS securely since HSS doesn't conform to gripping pressures. I suppose if silicon carbide granule or diamond dust loaded jaws were commonplace, gripping HSS wouldn't be very difficult.

As I've mentioned before, I don't get burned fingertips anymore since I've been using some cutting tool holders to take the punishment out of grinding lathe cutting tools. They work well either resting on the bench grinder tool rest, or freehand without relying on the tool rest.

I've tried quite a few ways to rough out lathe bits to avoid burning my fingers or excessively rounding the corners on my bench grinder wheel. For me the 4-1/2" electric angle grinder is the best combination of cutting speed, control, and cheap disks that still do their main job after the edge has been rounded. I find that the weight of a tool holder or drill chuck (or blacksmith's bolt tongs) interferes with grinding the face flat and smooth. There was no point suggesting antique bolt tongs or hand vises that most people don't have and can't buy.

Die grinders don't cut sharp-edged flat surfaces very well. They are good for cleaning up inside threading tool shanks and corner-rounding radius bits and reclaiming large dull taps, but no better than a Dremel. They are the last grinders I'd buy for tool grinding, not the first. I have one for cutting off rusty muffler bolts and smoothing inside corner welds.

A 7" angle grinder cuts faster and cooler with less control. They will cut a rough notch in a lathe bit quickly. I finish it with the 4-1/2" grinder to remove stress risers. Again, not the best first choice unless you weld steel.

I didn't have a large enough compressor to run an air grinder continuously until a few years ago when I stumbled on enough repairable parts to put one together. I judge how well a tool is cutting partly by ear and the compressor is just too loud for that in the shop. I use electric tools indoors and inefficient import air tools only outdoors where there is more of a shock hazard. A 500 Watt electric grinder does the same work as an air tool plus a 2 HP compressor. The GFCIs on my heavily-loaded outside outlets occasionally wear or burn out so I don't trust them.

Jim Wilkins

That's nice, and avoids my objection of weight and bounce. It suggests a different idea for the lengthwise vise I want to make to cut or notch small pieces in the horizontal bandsaw. Pipe with fixed and screw-down notched inserts might work well.

These are the antiques I sometimes use:

Jim Wilkins

That's a great old hand vise, Jim.. especially the 2-way V-notches. That would be a very useful machining project, if I only had some 100 year old steel to make it with.

Don't copy its 100 years of wear. The jaws tilt back too much to hold a lathe bit well, the bolt tongs work better. Grinding a lengthwise groove in Vise-Grip jaws might be better.

Jim Wilkins

How would you make that tool to hold bits from 1/8" to 5/16", assuming they don't have to be centered?

Jim Wilkins

Well, I'd take a hunk of pipe that fit the largest tool bit I wanted to hold, drill it and tap it for a couple of grub screws (on one side of the pipe) to hold the square bit against the round pipe wall, and call it good. But I clearly have lower standards than some folks. With a flat point on the grub screws I don't find that the bitstock is prone to moving, despite the lack of any sort of square recess.

If bothering with the square recess, you could bother with grub screws from two sides of the square recess to hold against the other two sides, and flat copper points on the screws to be fancy/nice.

I like it! If you wanted to gild the turd, as is said , you could drill & tap on 3 sides and it would be really secure.

Bob

Nice hand/pin vise you have there Jim. I have a couple, but neither are that big. Very worthy tool to have around for many things. They work good for getting taps started, holding countersink/reamers, drill bits...

I'm not sure that I'd know how to make a universal size holder, Jim, but it would probably need to involve tapered jaws and a long nut, something like a T-handled tap holder.

The problem I would expect to have with a universal size holder would be that the contact area between the holder and the HSS cutting tool would be reduced, and the cutting tool probably wouldn't be held as securely, and likely slip back into the holder while grinding.

The deep recess/broach in the holders I made will hold new full length new blanks with reasonable extension of the HSS for grinding, and also hold shorter sections of HSS securely.

I believe the reason the holders I made hold the HSS effectively is because there is full contact on 2 sides of the HSS cutting tool held securely by the pressure of the clamp block. I think if the contact area of the holder-to-cutting tool is reduced, it's likely the grip will fail.. that's the issue that the holder addresses, contact area.

Unlike most pliers or vise grips, the cutting tool holder's surfaces are parallel and of sufficient area to hold square HSS securely. I have pliers with parallel jaws, and they don't grip HSS securely because the surface area isn't adequate.

If a holder like the ones on my webpage was made for 5/16" cutting tools, a set of flat shims could reduce the hole size to 1/4", and maybe a second thicker set of shims could reduce it to 1/8".

I don't think a couple of set screws would provide adequate holding grip on HSS, but they might. My initial thought process was proceeding along the lines of holding the HSS securely, and that the clamp block would provide a method of adjusting side relief angles as it sat on the grinder's tool rest.

The additional benefit that I discovered was, that the holder gripped the HSS cutting tool well enough that I could apply some serious pressure while grinding, and effectively reduce the time that it takes to grind cutting tools from new blanks.

Resharpening lathe cutting tools doesn't present much of a challenge, but roughing out blanks shouldn't either.

It's my opinion that many new lathe owners are experiencing poor results from trying to grind HSS cutting tools because it takes too long to grind cutting tools from from new blanks. Possibly they're intimidated by the grinding wheel, and most likely they aren't able to apply sufficient pressure to the cutting tool when holding the HSS with their fingers to grind them in a reasonable amount of time. As they try to apply more pressure, they end up burning their finger tips more. Then carbide tooling could start looking like a good option, when it may not be.

In addition to insufficient grinding pressures, they end up glazing the grinding wheel surface, which only compounds the heat and grinding time problems.

If a grinder is set up with the correct wheel abrasive (which I suspect many time it's not), a 1/2 HP grinder should be more than adequate for any lathe tool grinding, IMO.

A grinding wheel abrasive that's too hard won't stay sharp, and the user may not realize that grinding lathe cutting tools doesn't need to be difficult/frustrating or time consuming.

The holders I've made may help a lathe user overcome the problems of heat and insufficient grinding pressure, allowing them to grind their cutting tools in a reasonable amount of time with very few problems.