Power tools

[Mikey98118]

Yes, no, 'what?

The thread size for housing caps (on most rotary tool’s plastic bodies) match up with Dremel. You can change flexible drives and other attachments between many of them. Collet nuts can be a different story. Many rotary tools have interchangeable collet nuts. Some Dremel spindles are apparently smaller, so Collet nuts from other rotary tools may, or may not, fit your Dremel tool, and some threaded accessories, like their fan, aren’t likely to fit on other tools. Yet, their variable chuck will; go figure.

[Mikey98118]

Micro drilling

There are two reasons for drilling, during burner construction; creating inside corners for air openings, and drilling holes to be threaded with taps. The speed chart below should make it plain that finding a good tool for either task isn’t automatic. 1/4” drills come closest to the right speed range, but aren’t likely to provide enough quality in their chucks for micro drilling; adding the right chucks for the task is like paying twice for one tool. Rotary tools have better chucks for micro drill bits, but must be slowed down enough to heat up their motors, to keep from rapidly ruining bits; that will get tricky. Micro-drills are the best compromise, but tend to be weak; as in slow.

    So, as is often the case, avoidance, reduces the pain of the compromises you must deal with. Corner holes for air openings don’t require drill bits at all. Small cheap diamond encrusted rotary file sets. Or 1/8” solid carbide burr sets, will serve the purpose better, and don’t require speed reduction. For the few holes that will be threaded, smaller needle files can do the bulk of the work, so that overtaxed drill bits need only be used to ream the holes larger; this spreads the work of the bit over its whole length, rather than mostly its end. You will still sacrifice the bits, but you can get the job done.

 

Maximum recommended drilling speeds (approximate):

A 1/16” bit’s maximum RPM is 8,500 in mild steel; 4,300 in stainless.

A 5/64” bit’s maximum RPM is 6,800 in mild steel; 3,400 in stainless.

A 3/32” bit’s maximum RPM is 1,700 in mild steel; 2,800 in stainless.

A 7/64” bit’s maximum RPM is 4,800 in mild steel; 2,400 in stainless.

A 5/32” bit’s maximum RPM is 4,200 in mild steel; 2,100 in stainless.

A 9/64” bit’s maximum RPM is 2,700 in mild steel; 1,700 in stainless.

An 8-32 set screw requires a #29 drill bit (0.1360”) for 75% thread engagement, or a 26 drill (0.1470”) bit for 50% thread engagement; 4,200 RPM through mild steel, or 2,100 RPM through stainless steel.

 

Cobalt drill bits are high speed steel with cobalt added, starting with M-35 (5% cobalt); M-42 (8%); both grades come with reasonable prices. The grades go up higher, but so do their prices. Also M51 is tougher than the first two grades, but has no red-hardness. What matters to you is that M-35 and M-42 bits have do “red hardness,” which is very desirable when you are running bits at higher RPM than you should; they are available through Amazon.com for the same money you would pay for regular high speed steel bits at your local hardware store. Why so much more at a hardware store? This is just another case of the ignorance tax at work.

 

Housolution Hand Drill has a 0.6mm (0.024) to 6mm (0.236”) capacity chuck; metal parts are made from cast steel ($23 from Amazon.com). This tool will do as well as a 1/4” drill motor for enlarging holes for threading without trashing drill bits.

 

AUTOTOOLHOME DIY mini hand drill (available through Amazon.com) is an $11 kit, consisting of a keyed chuck, shaft arbor, and a 12V DC motor. You must provide the wiring, and batteries, or wall wart (adapter). They only claim their chuck will open large enogh for a 4mm drill bit; this is 0.157”, which is the diameter of a #29 bit that I use for 8-32 taps; this provides 75% thread engagement, which is only recommended for softer materials, like brass. I use the deeper thread for increased strength, in tubing and pipe walls. With the doubled walls used on some of these burner parts, 50% thread engagement is advised; that requires a #27 drill bit; fortunately, it turns out that this chuck will open much more than they claim for it.

 

[Mikey98118]

Do keep rotary tools dry, whether running or stored. If nothing else, they can be sealed in

In a plastic bag when not in use. If you are planning to build heating equipment, the water in the air well end up dumped out of the exhaust, greatly increasing rust and other oxidative processes in your shop. Don’t expose electrical tools to that by being lazy about putting them away carefully.

 

Do clean the motor housing’s exterior after each use, and blow dust out of air

intakes when needed; immediately after creating a cloud of dust from whatever your working on; or after cutting, grinding, or sanding on glass, ceramic, brick, or concrete. Allowing metal dust to accumulate in tools can lead to electrical shorts. You can buy canisters of dry compressed air from office supply outlets.

    Be sure to blow away debris from around switches; especially sliding switches. Many OEMs deliberately produce tools with stiff sliding switches in the mistaken belief that they are safer. Debris buildup can tip such a switch over the edge, into broken machinery.

 

[Mikey98118]

Do keep tools electrical tools dry, whether running or stored. If nothing else, they can be sealed In a plastic bag when not in use.

If you are planning to build heating equipment, the water in the air well end up dumped out of the exhaust, greatly increasing rust and other oxidative processes in your shop. Don’t expose electrical tools to that by being lazy about putting them away carefully. That goes for machinist tools too.

Winter air is heavily laden with water vapor; super heating it creates a wonderful rust machine.

 

 

[Another FrankenBurner]

If you are going to plastic bag your tools, do not forget a desiccant.  Otherwise, the bag can exacerbate the rust problem.

[Another FrankenBurner]

I have not payed attention but no ozone that I have detected.  I don't have an accurate temperature reading but they are hot enough for me.  

This is a 3/8" burner with an 0.031" orifice running below one psi in a mini forge.

Both the forge and the burner are older designs.  I am currently working on updating the 1/4" burner for a forge this size.  I still haven't built a micro(nano?) forge for the 1/8" burner yet.  

[tinkertim]

Wow Frank!

That almost looks like a spacecraft engine! (Millenium Falcon / Nostromo!)

That is so cool. Me likey a lot!

I'd still be interested in one of your 1/4" vortex injectors to use as a hand-held burner.

Please let me know when they are available.

Keep up the fantastic work, matey.

Tink!

[Mikey98118]

We are all awaiting that, but...either he will have to jump through some serious hoops before marketing, or else live under threat of catastrophic law suits for the rest of his natural life. Why do you suppose so many American goods are manufactured in Asia? When a machine is spitting out hundreds of widgets an hour, whether its operator is paid twenty cents or twenty dollars for that time is irrelevant.

But try a frivolous suit against a Chinese company and they will back them against you. Sue an American company and their insurance company can't wait to settle out of court, and get back to monkey business as usual. After all, they can always raise your rates.

[tinkertim]

Well just scratch Made-in-China on the side and ship-away!

 

[Mikey98118]

Serious hoops? Yes; first you need product insurance; which you can't get without having the product tested and certified by a recognized laboratory ($$$$) Then, you need a patent to keep the locusts from copying what you built and under bidding you. All this forces you to get financing in the form of a backer or big company, because no bank is going to touch your deal...Life ain't easy, when you're living with "the forty thieves."

[ThomasPowers]

And Patent infringements may be the new norm as dealing with international lawsuits is not suggested for any but the deepest of pockets!

[Frosty]

It's hardly worth coming up with a better mouse trap anymore. Lucky mice. <sigh>

Frosty The Lucky.

[Mikey98118]

Of course, in kit form, he would actually have do something wrong, before the vultures could descend

Kits have to be completed by the potential complainant; making an awkward position for lawyers

[ThomasPowers]

It's Friday so: *That* explains "Kit Carson"---ducking liability!

[Mikey98118]

I'm a strong believer in taking responsibility; not in our court system. Being set up and run by lawyers, their first rule is that THEY  have no responsibility; only opportunity.

[Mikey98118]

Run-out

Any rotating tool is meant to revolve around its center. If its spindle isn’t drilled true (centered and parallel to its axis), a rotary tool or die grinder will spin in a tiny circle around its axis, instead of revolving on it, producing heavy vibration. A drill bit chucked into such a tool will also spin around a small circle; this is called run-out.

    But the common cause for run-out in an electric drill is the mandrel connecting the chuck to its motor being machined off center and/or not parallel to its axis. This is the weak point in some micro-drills. It takes vary little run-out to destroy tiny drill bits.  

[Mikey98118]

 

Mounting a safety handle:

A rotary tool can be braced for straight travel (similar to cutting with angle grinders), rather than the typical swinging arm motion (tendency to curve; binding the disc), by mounting a small handle next to its spindle; this provides superb control for cutting. Twenty years ago, 2” angle grinders like the Proxxon’s Long Neck Angle Grinder LHW/E, or the Merlin 2 from King Arthur Tools, were the only power tools that could easily make straight line cuts in burner parts; they were designed for inline motion, and had steel safety guards. A rotary tool with a safety handle mounted can now do a better job, more safely, for a small fraction of their prices.

What has changed, to make this possible? See-through safety guards didn’t exist back then; they do now. When cutting along an ink or scribe line, with the help of a tool’s handle, it is tempting to bend over a tool, to provide the best view; a very bad habit, unless the tool has a safety guard; it’s also frustrating. But you can pace your disc beyond the cut line, and work safely and comfortably, if you can see the line by looking through the guard.

Two rotary tools already have a removable plastic handle (CUBEWAY and Hilda), but they are set up for increased comfort during buffing, grinding, and drilling; not for increased control during a cut.

Caution: Whether or not a handle improves the safety of your rotary tool, depends on power switch location and type; that can’t be listed for every model, since there is such a variety of on/off switch designs. Mounting a handle will increase stability as you cut. But, stopping the tool before lifting a cutting disc out of the kerf  is best, only if the switch type and location allows this, with handle added. if switch type or location makes that impractical already, then no safety is lost by adding a handle. If the switch can be safely used to stop the tool during cutting at present, but adding the handle would change that situation, leave it off; this is unlikely, but possible).

Warning:  Mounting a handle on an electric die grinder must be far more restricted than on a rotary tool:

(1)  Any safety at all requires a power switch with the right location and type. The switch must be easy to operate, without jogging the tool, in the slightest degree.

(2)   The grinder must be run at half speed.

(3)  The cutoff disc cannot be greater than 2” diameter; smaller than that is better.

(4)  The disc must be breakable; a resin-based friction disc, and thinner is safer; it isn’t less likely to break of course, but less likely to fling the grinder around will doing so. Do not employ a grit coated steel disc, or a toothed circular saw blade. when kickback occurs, it is necessary that the accessory to be destroyed, rather than the grinder being flung about near your body.

(5)  The grinder should not be used in confined spaces, or with your body unable to be properly braced, with or without a handle installed.

Safety, is seldom an absolute, except in the negative sense. “Don’t do that” is neat and simple advice. To suggest that someone “do that safely,” is absurd. Whenever you attempt to do anything, risk is involved. Using an electric die grinder, can never be perfectly safe; cutting with one involves substantial risk, at best.

    Why not use one of the new mini-saws, instead; isn’t that what they are for? If you’re cutting on flat surfaces, yes. If you’re cutting off the ends of angles or pipes, the saw still maintains an advantage, so long as you pay close attention. When cutting internal sections into pipe or tubing, no. If you’re cutting into curved surfaces to create equipment shells, no.

[Mikey98118]

Angle grinders

When I wrote Gas Burner for Forges, Furnaces, and Kilns, hand held rotary tools were no longer expensive, but that wasn’t yet true of their accessories. The “newfangled” 4-1/2” angle grinders of the day, were really just re-geared 4” grinders being marketed because their grinding wheels were far less expensive than the new 4” wheels. At the time, these grinders were a little under powered, which made them a lot safer for cutting work than the high-power models being pushed in today’s market.

    Also, the previous text’s smallest burner was ½”, which is the largest size in this book. Times have changed. You don’t need to use an angle grinder to build burners and heating equipment.

    But what about people on a shoestring budget? What about using your angle grinder for cutting into forge shells? High-speed plus high-power still equals high hazard…but hazard levels can be reduced. By starting out with one of the weaker grinders from Harbor Freight Tools, or an old Makita 4” grinder, you can bring power down to the level of a 3” angle grinder (big bucks and hard to find) by reducing it to half speed with a router speed controller; and these are cheap.

    The hazard level can be further reduced by changing out the 4-1/2” grinding wheel for a well-used cutting disc (around 3” remaining); is this a perfect solution? No, but it’s a whole lot better than no viable choices, for building the 1/2” burner. And for smaller burners? Forget it.

    But make no mistake about it; Rotary tools are infinitely safer than electric die grinders or angle grinders.

Please disregard the reference to a present book; this was an excerpt from my book notes.

[Mikey98118]

What, no questions? No,  disagreements? Surely, there must be one or the other out there

[Frosty]

Okay, I strongly disagree with turning an abrasive cutting wheel, of any size, off BEFORE removing it from the cut. Even a longitudinal grinder of the Dremel or die type can generate enough torque too bind the wheel. 

Right angle grinders are especially prone to torquing at 90* to the plane of rotation of the disk, side handle or not it can do you a serious mischief. 

Frosty The Lucky.

[Mikey98118]

What ever made you think I was suggesting it? However, the on/off switch on some rotary tools and die grinders make that very good practice impossible, without creating the the vary accident you are trying to prevent

That's very,not vary Bad Mikey. No cookies for you!

[Mikey98118]

This does bring up something thing new, which is going to make trouble for lots of people. Diamond coated steel cutoff discs that are meant for steel cutting. Unlike resin based discs, they don't shatter from torsion during kickback; leaving all that kinetic energy to flung the tool around. Worse; these disks are available in up to 3" diameters.

Unfortunately, compact die grinders, with the kind of power previously seen only in extended neck grinders have come into the market.

I think these two factors  are going to create some grisly accidents.

[Frosty]

They give me the willies but so do cut off disks in general. I'm not even a fan of a bench hot cut off saw though they are the only thing that works on very thin stock, say tubing. I can baby my band saw through thin stock but I have to stand there ready to lift the blade at thee sound of it starting to bind. 

One of these days I might try an abrasive bandsaw blade though I'm not sure how to pick the grit size.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

Talk about the willies. Last night I had a dream where a cutoff disk blew up in my face. Taking that in consideration, I will now wear a full face shield along with my safety glasses, which saved my eyes in the dream.

[Frosty]

Yeah, you ain't lived until you've taken about 1/3 of a disk off a 9" Milwaukee disk grinder in the chest. It'd been dropped and I hadn't checked when I pulled the trigger. My bad, other guys in the shop used the tools and some were pretty clueless. I was wearing my welding jacket and full face shield so I only got bruised.

Worse still I was violating one of Dad's most often used adages, "familiarity breeds contempt," by getting complacent and using the above 9" Milwaukee to cut angle slots in a piece of pipe to braze carbides into for an asphalt hole saw. 

Everything was going well and I forgot to pull the disk out of the cut before letting go of the trigger. Nope, that heavy beast didn't just stall, it tried to drag me through the kerf while launching itself a good 30' across the shop. My right hand was numb to my shoulder and there was a bite out of the right glove's ring finger. Hmmm I says to myself, I should look at that. Nice size avulsion, from the last joint to a little better than half way up my nail. Didn't get the nail, that's just where it began and across to the center. 3 deep stitches and 7 to close it up.

I get a LITTLE jumpy about letting go of the trigger before pulling the disk out of the kerf.

Frosty The Lucky.