Power tools

[Mikey98118]

I spent thousands of hours running abrasive cutoff saws, with up to 36" diameter blades, and would never consider stopping a blade in the kerf. Nor would I sit inline with the disk. And after my third disk in a row blew apart when it got up to full speed, I never touched a disk that wasn't fiberglass reinforced again. But, chop saws are chop saws. I don't transfer every lesson learned on them to other saws; they have kind of a reality all of their own. I believe most tools are like that; each one has its do and don't, and who to them as try to "do it their way."

[Deimos]

Even little angle grinders can be dangerous, some one off my classmates almost cut his hand off with one because he was using it one handed (great idea) and the blade got stuck in the cut he was making. Launched its way right trough 30% of his wrist. I was always very happy with the pneumatic angle grinders we used in the factory, never had safer tools.

[Irondragon Forge ClayWorks]

Cutoff saws and angle grinders are not the only spinning tool that will get you. Bench grinders are about as bad. I never stand in front of the grinder when turning it on. I learned that a lot of years ago. I turned my 8 inch grinder on and stepped to the side to get the item I was working on.

Just as the wheel reached top speed it came apart and pieces of it flew across the shop leaving holes in the wall like a bullet. If I had not moved, I would have had to do more than go change my shorts.

[Mikey98118]

The problem is the learning curve

[ThomasPowers]

I'm sorry but just the word "Avulsion" gives me the willies!   

[671jungle]

I took an avulsion fracture to the ankle back in a high school fight. The first Doc failed to see the injury. I walked around on it for almost a month before a foot specialist saw the xrays and had to go in for surgery. Power tools scare the heck out of me.

[ThomasPowers]

I have a good friend who has managed to cut off both forefingers with a tablesaw and have them reattached---11 years apart. 

Also two friends who have had serious accidents cutting down trees.

Me, I'm safe---I just play with fire!

[Mikey98118]

Anything with teeth that are traveling fast gives me the willies. Friction wheels and cutoff discs are bad enough. Circular saw blades on rotary tools? That's where I draw the line; let alone on die grinders!

[Deimos]

You do not want to meet my dogs then

[Mikey98118]

I don't want to meet a shark in the water either. Avoidance is good

[Mikey98118]

 

Resin bonded friction discs meant for cutting ferrous metals are fiberglass reinforced, and that should be stated in their sales literature. Why is fiberglass reinforcement so important? Because, without it, discs are too easily shattered, flinging segments at body parts. Also. steel cutting discs have course grit. If you can’t see the grit in expanded views of the product, keep on looking elsewhere.

    Fiberglass reinforced cutoff discs come in a variety of diameters; they also come with various size arbor holes: 1/16”; 1/8”; 1/4”; and 3/8” arbor hole sizes are all common. Each hole diameter requires a different mandrel. Diamond coated cutoff discs used on rotary tools have 1/16” or 1/8” arbor holes; with 1/4” and 3/8” holes on die grinder discs. Common fiberglass reinforced disc diameters that you might use in a rotary tool or die grinder are 1”; 1-1/4”; 1-1/2”; 2”; and 3”.  2-1/2” diameter discs are also available, but not common.

Avoiding cutting problems: When starting a cut, be sure the accessory is already turning; do not start or continue a cut with the tool stopped. Gently lower the disc unto the part surface. Start and stop the cut short of the end of the line, and finish the cut with a small diameter disc, for greater control, as these two areas are likely spots to create kickback problems. If you can, allow the disc to come to a complete stop before removing it from a cut, to help avoid jamming.

    A common cause of kickback is a disc that is moving even a little out of parallel to the kerf (that slit made by the disc in your part); the problem is multiplied when the disc is deeply inserted into the kerf. It is safer to move a disc back and forth on the part surface, beside a scribe line, gradually deepening its grove, and only cutting through the material at the last. Once the disk begins breaking through the part’s wall. Try to only move the disc counter to the direction friction inclines it to “walk” along the part. After you finish all cuts and remove unwanted sections, then start grinding back to the scribed or inked lines with a small stone wheel, or diamond disc.

    Do not use fiberglass reinforced cutoff discs for grinding; it dangerously weakens them; then, the same fiberglass reinforcement that helps protect against torsional forces, ensures that flung sections will be larger, and will therefore hit harder!

EZ lock mandrel and cutoff disks are the safest way for a beginner to cut steel with a rotary tool; they are more expensive than generic cutoff discs, which run in standard mandrels, but considerably easier for a newbie to deal with, for the work needed to build a couple of burners. By the time you use up the disks in one their mandrel and disk kits, you should be well enough acquainted with rotary cutting to take advantage of the more tempting offers for disks and regular mandrels. You will still find yourself reverting to the EZ lock system for tricky cutting jobs.

    You begin by inserting the mandrel all the way into the collet nut on the tool’s spindle, and then tighten the nut. To mount a disk, push the plastic part of the head down against its spring, dropping a disk past the mandrel’s bow tie shaped end piece, and then turn it ninety degrees, to lock it in place.

    You can buy the discs and mandrel in kit form online, and from most large hardware stores. The spring driven locking mechanism is what makes this system unique. It eliminates the usual locking screw, so that grinding and sanding wheels can be used nearly parallel to part surfaces, without interference from a protruding screw head. The disc is positively locked, because there is no screw to loosen from vibration, allowing the disc to spin on the mandrel. But most important of all, the spring allows the disc to move out of alignment, without shattering during kickbacks, by nearly eliminating torsional forces; you can order them online, and they are available from numerous hardware stores.

Separating discs are standard jeweler’s thin (0.025” thick) 1” and smaller diameter emery cutoff discs, which come as part of most accessory kits. They are too brittle to be practical for most steel cutting tasks, but when doubled on a mandrel, they are good for sharpening small drill bits; like diamond coated discs, they are a safer and surer way to cut through the last 1/4” next to a corner hole, than using a larger disc.

Disc mandrels: You don’t want to employ just any disc mandrel for steel cutting. The standard jeweler’s mandrel, which only has a 1/16” standard machine-screw head, was designed for making very short cuts in soft alloys; not for making extended cuts in steel. There are special mandrels with 1/16”screws that have oversize screw heads, threading into oversize mandrel faces; these far outperform the standard minimal screw head variety; you can find them offered through eBay, Amazon.com, and through most jeweler’s supply houses ( input “SEINC rotary tool mandrel” to find them quickly); these mandrels are excellent for spinning the 1-1/4” diameter fiberglass reinforced aluminum oxide cutoff discs, which are handiest for cutting out rectangular air openings on tube burners.

[Mikey98118]

Surface Cutting

When you run a chop saw, or plunge cut with a hand-held circular saw, the last thing you want to do is stop the saw during cutting; more often than not, doing so will cause kickback. The opposite is true when surface cutting through sheet metal products, like pipe and tubing.

    Those OEMs (like Dremel Tools) who bother with thorough safety tips in their rotary tool instruction manuals, all advise the operator to run the cutoff disc back and forth on the part surface, gradually deepening a groove at the cut line, until the disc begins to break through the groove, which is then called a “kerf.” Unlike chop sawing or plunge cutting through parts, the operator is supposed to bring the disc to a halt before exiting the kerf, Why? During a plunge cut, your disc isn’t deeply positioned in the part.

And, unlike other cutting processes, there is very little material for the disc to “walk up,” creating an opportunity for kickback.

    Die grinders are treated the same as rotary tools for surface cutting (my own description for the technique).,

 

[Mikey98118]

Surface Cutting

When you run a chop saw, or plunge cut with a hand-held circular saw, the last thing you want to do is stop the saw during cutting; more often than not, doing so will cause kickback. The opposite is true when surface cutting through sheet metal products, like cylinders and mufflers used for forge shells.

    Those OEMs (like Dremel Tools) who bother with thorough safety tips in their rotary tool instruction manuals, all advise the operator to run the cutoff disc back and forth on the part surface, gradually deepening a groove at the cut line, until the disc begins to break through the groove, which is then called a “kerf.” Unlike chop sawing or plunge cutting through parts, the operator is supposed to bring the disc to a halt before exiting the kerf, Why? During a plunge cut, your disc isn’t deeply positioned in the part.

And, unlike other cutting processes, there is very little material for the disc to “walk up,” creating an opportunity for kickback.

    Die grinders are treated the same as rotary tools for surface cutting (my own description for the technique).,

[Mikey98118]

    Keep it dry or maybe lose it

      Do keep tools dry, whether running or stored. If you only have a three prong plug (like most power tools), it isn’t grounded. Don’t use none-grounded tools around water, or in the rain. Keep your tool stored nice and dry; if nothing else, they can be sealed in a plastic bag, along with a package of silica gel, when not in use. If you are planning to build heating equipment, the water vapor in the air well end up dumped out of the exhaust as super-heated steam, 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.

    People assume that tools aren’t exposed to much water vapor, because there is no movement in and out of their tool vents, when the tool isn’t running; this is wrong. Temperatures rise and fall every day. Heating air expands, pushing air out your tool’s air vents. Then, temperatures fall, and ambient air contracts, sucking fresh air, with its moisture content back into the tool. Day in and day out fresh moisture is allowed to attack the tool; only a little at a time, but it adds up. Months later you want to use your “safely stored” tool, and it starts right up…or maybe not.

[Mikey98118]

    Keep it dry or maybe lose it

      Do keep tools dry, whether running or stored. If you only have a three prong plug (like most power tools), it isn’t grounded. Don’t use none-grounded tools around water, or in the rain. Keep your tool stored nice and dry; if nothing else, they can be sealed in a plastic bag, along with a package of silica gel, when not in use. If you are planning to build heating equipment, the water vapor in the air well end up dumped out of the exhaust as super-heated steam, 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.

    People assume that tools aren’t exposed to much water vapor, because there is no movement in and out of their tool vents, when the tool isn’t running; this is wrong. Temperatures rise and fall every day. Heating air expands, pushing air out your tool’s air vents. Then, temperatures fall, and ambient air contracts, sucking fresh air, with its moisture content back into the tool. Day in and day out fresh moisture is allowed to attack the tool; only a little at a time, but it adds up. Months later you want to use your “safely stored” tool, and it starts right up…or maybe not.

[teenylittlemetalguy]

On 11/13/2020 at 7:30 PM, Mikey98118 said:

It is safer to move a disc back and forth on the part surface, beside a scribe line, gradually deepening its grove, and only cutting through the material at the last.

Mikey- someone was listening...me! Great pointer, makes cutting off so much more controllable. thank you for the tip!

[Mikey98118]

You're welcome; just passing it on.

[Mikey98118]

Freeing up jammed accessories

Collet nuts on rotary tools frequently need to be sharply rapped once or twice with the tool’s tiny wrench, to free up jammed accessories. Unscrew the nut a partial turn, so that the accessory can slide free; commonly, they will revolve, but cannot be slid forward and removed. What has happened is that a collet, which the accessory’s shank (shaft) slides into has jammed in place against the inner bevel of the collet nut, locking the accessory’s shank together with the collet and nut. A gentle tap or two on the end of the nut, will transmit just enough of a shock wave through the three parts, to break free the collet’s grip. Should a new tool come from the factory with the collet stuck in place, unscrew the nut a couple of turns, and poke the shank of an accessory against the collet, to break it loose.

    If you change accessories frequently, you may find relief from this irritation with a brass collet; brass drill bit collet kits, which include 1/8” collets, go for around $2.50 on eBay. Just as some collets release better than others, some collet nuts are better too. Most collet nuts fit most spindles, so switching a better collet nut from a less used rotary tool to your favorite should be an obvious move.

    Some people simply replace the collet nut (and its sticking collet) with a Dremel keyless rotary chuck (make sure to buy this attachment from Dremel; the cheap look-a likes don’t work very long, when they even work at all). How clever is this move? Enough that some rotary tools are starting to be sold with this kind of chuck, instead of a collet nut; nothing succeeds like success.

[Mikey98118]

Freeing up jammed accessories

Collet nuts on rotary tools frequently need to be sharply rapped once or twice with the tool’s tiny wrench, to free up jammed accessories. Unscrew the nut a partial turn, so that the accessory can slide free; commonly, they will revolve, but cannot be slid forward and removed. What has happened is that a collet, which the accessory’s shank (shaft) slides into has jammed in place against the inner bevel of the collet nut, locking the accessory’s shank together with the collet and nut. A gentle tap or two on the end of the nut, will transmit just enough of a shock wave through the three parts, to break free the collet’s grip. Should a new tool come from the factory with the collet stuck in place, unscrew the nut a couple of turns, and poke the shank of an accessory against the collet, to break it loose.

 

    If you change accessories frequently, you may find relief from this irritation with a brass collet; brass drill bit collet kits, which include 1/8” collets, go for around $2.50 on eBay. Just as some collets release better than others, some collet nuts are better too. Most collet nuts fit most spindles, so switching a better collet nut from a less used rotary tool to your favorite should be an obvious move.

 

    Some people simply replace the collet nut (and its sticking collet) with a Dremel keyless rotary chuck (make sure to buy this attachment from Dremel; the cheap look-a likes don’t work very long, when they even work at all). How clever is this move? Enough that some rotary tools are starting to be sold with this kind of chuck, instead of a collet nut; nothing succeeds like success.

[Mikey98118]

Properly securing and balancing accessories

Fully insert accessories into the rotary tool’s spindle, and snug the collet nut; don’t over tighten, or you might strip its threads, or even worse, the spindle threads. There is a good reason that collet wrenches are so tiny; take the hint.

    Accessory shank and collet diameters need to be properly matched. Some accessories that are sold as 1/8” actually have 3/32” shanks (popular for engraving, and nail grooming accessories). An eighth of an inch is 4/32”; 0.125”; 3.2mm (which commonly turns out to be 3.17mm). But, 3/32” shanks will end up loose enough to vibrate their way out of the tool. What to do? Buy a cheap set of brass collets; there will be a 3/32” collet among them.   

    I have yet to find an accessories kit that doesn’t include a little blue, green, or charcoal gray oblong silicon carbide dressing stone; they are used to balance aluminum oxide grinding stones, wheels, and cutting discs, to keep your rotary tool from suffering degradation from excessive vibration. Cheap rotary tools are as likely as not to have spindles, which were machined slightly out of true with the tool’s axis; if you add unbalanced accessories to that, bent shanks and flung accessories are the next trouble that will get spewed up. A few light touches with a dressing stone on your accessory can save a lot of grief.

    It can also help to rotate an accessory (like a brush or drum) a quarter turn at a time, to improve balance.

[Mikey98118]

Properly securing and balancing accessories

Fully insert accessories into the rotary tool’s spindle, and snug the collet nut; don’t over tighten, or you might strip its threads, or even worse, the spindle threads. There is a good reason that collet wrenches are so tiny; take the hint.

    Accessory shank and collet diameters need to be properly matched. Some accessories that are sold as 1/8” actually have 3/32” shanks (popular for engraving, and nail grooming accessories). An eighth of an inch is 4/32”; 0.125”; 3.2mm (which commonly turns out to be 3.17mm). But, 3/32” shanks will end up loose enough to vibrate their way out of the tool. What to do? Buy a cheap set of brass collets; there will be a 3/32” collet among them.   

    I have yet to find an accessories kit that doesn’t include a little blue, green, or charcoal gray oblong silicon carbide dressing stone; they are used to balance aluminum oxide grinding stones, wheels, and cutting discs, to keep your rotary tool from suffering degradation from excessive vibration. Cheap rotary tools are as likely as not to have spindles, which were machined slightly out of true with the tool’s axis; if you add unbalanced accessories to that, bent shanks and flung accessories are the next trouble that will get spewed up. A few light touches with a dressing stone on your accessory can save a lot of grief.

    It can also help to rotate an accessory (like a brush or drum) a quarter turn at a time, to improve balance.

[Welshj]

Do I really need to post the pics of my three fingers of my left hand to prove a gross point of just how much these guys know what they're talking about?

Own, use and respect many rotary type tools.

I've owned a tablesaw for over 20yrs. I've used one since I was 15 in shop class. In all that time- I had one serious- headed to the hospital injury. All it took was a momentary lapse in pressure... and I got off fortunate.

Explaining to the sheriff's office how my fingerprints actually DID change when renewing my chl... yeah, that was fun.

Rotary tools are a thing to be respected... trust us.

 

Admin- suggestion? The twist this thread has taken has some pretty good merit. This section isolation in its own thread, under a tool use/safety heading mebbe?

[Frosty]

Got pics, are they gory? We're trying to put a proper fear of not taking rotary tools seriously aren't we? 

Naw, me either, for some silly reason I never think of taking pics when: bent, folded, spindled or mutilated. 

Frosty The Lucky.

[Welshj]

Yup...

This is after about a week or two. I'll save the during pics from the hospital- but let's just say they couldn't stitch anything, and a nurse spent about 30 minutes trimming... stringy stuff before bandaging.

I was ripping a small pieces of stock off to 1/8" widths. The blade guard up and out of the way so could catch the small pieces as they came out. Stupid- very.... lost focus, wood bound & kicked and my fingernail caught in a nick in the wood- pulling my fingers back vertically over the blade.

Like I said earlier, i got fortunate that nothing worse happened. The middle finger was the deepest, about a 1/4".

I too have felt a cutoff wheel bounce off my chest! This is the exact reason I always remove cutoff wheels from a hand held grinder after use. Also had a pair of jeans ruined, with a nasty leg gash from the same problem.

the worst is a coarse wire cup wire wheel wrapped up in my t-shirt and up my chest. I threw it away that day and won't use one now. Bench grinder mounted wheels only.

[Frazer]

If those cup wire wheels catch on something and the grinder jumps, you better have a good grip on it or that thing will kick right out of your hands. That's (one reason) why OSHA requires a dead man switch on all hand tools on a job site. Many, I'll even go as far as to say most, that are used in the home shop do not. Including mine!  A rotating system gone wild is no joke. Anyone who has heard a cutoff wheel wiz by their ear after exploding is very reluctant to ever get that thing lined up with their face/chest. Or get them wet (unless they are made to be). Ever.

Or seen those videos of spools of heavy wire being rolled up in some factory somewhere... enough said.

Welshj, I'm glad your digits healed up ok. On the plus side, if you ever turned to a life of crime, they'll probably have trouble getting a good print...