Angle Grinder vs. Cut-off Tool

I take apart a lot of little gadgets and I can’t always find ways to get inside them (see dozens of my tear down videos on my Youtube channel). Either the screw heads are stripped, or parts (usually wheels on toy cars) are pressed onto shafts and I can’t get them off, or the thing is glued together and I need a saw of some sort to cut it in half.

I’ve been using a little Dremel tool with a cutting wheel which works great, but doesn’t cover enough distance fast enough, or can’t get deep enough to say, cut off axles that have wheels pressed onto them.

I tried a little reciprocating saw with a fine blade and also a medium blade, but it wasn’t much use.

Reciprocating Saw

So now I’m going to try a different approach — mentioned below. I’ll report back after I’ve used it a little.

I’m talking about two very similar tools — angle grinder and cut-off tool. I’ve learned some differences, a few that I haven’t seen mentioned anywhere else, so I thought I would share what I’ve learned.

Both tools can be used to grind things, or cut metal. Either grinding wheels or much thinner cutting wheels can be used on either. Accessories like hole saws and wire brushes can be used with an angle grinder — I’m not sure if they can be used on a cut-off tool.

Angle grinder

An average angle grinder typically uses 4-1/2″ discs, has a speed of around 11,000 RPM, and draws about 4 Amps. It has one or two handles that are usually moveable to at least two positions. Inexpensive ones have a screw to adjust the safety guard, more expensive ones have a quick-release lever.

Cut-off Tool

The cut-off tool typically uses 3″ discs and has a speed of around 20,000 RPM, at 3 Amps. It only cuts to a depth of about 1″ and doesn’t have any handles. So it’s smaller, but faster, which I assume is the advantage of using this over an angle grinder for cutting things.

Safety tips

Both tools spew sparks and bits of painful and molten pieces from the wheels and from whatever you’re grinding or cutting. Good safety glasses are imperative.

Face shields are just as good an idea as safety glasses. It will keep sharp or molten chips off of your face, or heaven forbid — a shattered wheel flying into your face!

A dust mask and hearing protection can also be very good ideas.

dust mask respirator — Dust Mask / Respirator

ear plugs hearing protection — Hearing protection

leather work gloves — Leather work gloves

And don’t forget that protective gloves ara a good idea to help prevent injury to your hands from hot, flying debris, or if the material or tool get away from you. Gloves aren’t going to stop a cutting wheel, but may lessen injury, and will prevent or reduce injury from a grinding wheel.

December 7, 2017April 23, 2019

Digital Calipers

A digital caliper is a great tool to have around for all kinds of measurements. An example of how I use the caliper: When I want to use LEDs in one of my projects, I like to find a drill bit just a little smaller than the LED without drilling a bunch of trial and error holes. That way the LED will be a nice pressure-fit in the hole and won’t need to be glued into a hole that is oversized.

Here are some at Amazon: http://amzn.to/2BR4MZ0

See much more on calipers in my blog here.

July 30, 2017March 21, 2019

Tin snips make terrific heavy-duty scissors

This style is officially called aviation snips. Actual tin snips are a little different but I like this style better. It has corrugated blades and leverage linkage to the blades that tin snips don’t have.

I have arthritis and cutting thicker things with scissors such as cardboard or heavy cloth, or yes, even tin, is difficult for me. I researched electric scissors but didn’t find anything that looked right. And the heavy-duty ones cost around $100.00 and I wasn’t about to spend that kind of money on scissors.

So I figured I’d try tin snips. Eureka! I love them for all of the above! They even just cut some hard plastic tubing that I didn’t think would work, but the tin snips went through it very easily. It’s easy now for me to cut all those thick things that used to cause me so much trouble. If you are having trouble cutting things, arthritis or not, get yourself some tin snips!

You can probably get them for under $10.00 and they’re fantastic! There are ‘straight cut’ style, and left cut and right cut style snips. Straight cut are best for straight-line cuts and all around use. Left cut make it easier to cut arcs to the left, right cut, easier to cut to the right. I didn’t want to be limited by a directional bias so I bought the straight cut and they’re working great!

I say “no thank you!” to ads like this one for wimpy scissors at really high prices now that I’ve discovered my tin snips!

July 29, 2017

O-ring Drive Belts vs Rubber Bands

For a long time I considered ‘o-ring’ to be the proper terminology for a drive belt in little DIY (do it yourself) animatronic projects. But when trying to purchase some o-ring drive belts, I discovered that the term ‘o-ring’ by itself is technically wrong. O-rings are for sealing things (like valves).

Better terminology when using them to drive things (transfer power from one location to another) is ‘o-ring drive belt’, or even ‘urethane belt’, which most o-ring drive belts are made from. (Rubber bands are made from, well, rubber). (So if you’re searching Google or YouTube for information on o-ring drive belts, you’ll have much better results using the full term instead of just searching for o-rings).

Rubber bands are for holding things together.

Rubber bands do not make great o-ring drive belt replacements, but they can work OK in simple applications.

How to quickly tell the difference between o-rings and rubber bands: O-ring cross-sections are typically round and they stretch some, but not as much or as easily as rubber bands. Rubber bands typically have rectangular cross sections and stretch easily.

Imagine that you have a little hobby toy your are playing with and you are trying to rotate a shaft that is located a few inches away from your drive motor.

If you use a rubber band as the drive belt, the rubber band can ‘store’ energy as it stretches, and then it will finally transfer the power (rotate the shaft) after it has stretched to a certain point. This can make for a very uneven rotation, or it might just slip on the drive or driven shaft before ‘giving up’ its energy and result in complete failure to rotate the shaft at all.

The o-ring drive belt doesn’t stretch like the rubber band so rotation is much smoother. It also maintains its integrity much, much longer than rubber bands, which loose their strength and elasticity fairly soon.

White rubber band, black o-ring shown below.

Here’s a little video I made to show the difference in drive smoothness:

Here’s a page with some good information: http://www.applerubber.com/seal-design-guide/special-elastomer-applications/drive-belt.cfm

And here: http://www.durabelt.com/rubber-band-belts.php

April 24, 2017July 30, 2021

Buying resistors

If you’re going to purchase resistors, don’t get these blue ones if you can avoid it. The color bands that indicate the resistance values don’t show up well enough against the blue background, so it’s next to impossible to read the resistance value on many of them. You often have to resort to an ohmmeter.

They’re OK if you only take them out of their marked container and use them once right away. I’m guessing they’re intended mostly for automated insertion machines on circuit boards that have small insertion holes to save space. But if you use them in a test circuit in your hobbies and then throw them in a box to use again with other loose resisters like I do, you can forget about being able to pick out the value you want again without breaking out your ohmmeter.

Here is a box that I use to toss miscellaneous parts into for easy access for re-use.

Looking for a certain resistor value on these beige ones is pretty easy, but trying to read a blue resistor value in a situation like this is next to impossible in my opinion. That’s why you don’t see any blue ones here — I threw them all in the trash.

And watch out for the ones that have extremely thin leads. All of the blue ones and some of the beige ones that I’ve purchased from China via eBay have had very thin leads that are difficult to handle and they bend way too easily which means they kind of crumple when you try to insert them into test solderless breadboards.

If you’re not sure if you have the ‘angel hair’ leads, get out your caliper and measure them as shown in the video (I measured Angel hair = .013″ lead thickness — Better ones = .020″ lead thickness). It doesn’t look like a big difference, but it is!

Or if you just want to read their value in a circuit you’ve already built, forget it. I got a refund because they were so hard for me to read.

I understand that blue means they are metal film resistors with a 1% tolerance, and the beige ones are carbon with a 5% accuracy tolerance. If you need 1% tolerance you will be stuck with the awful blue ones.

The blue ones are hard enough to read, and cheap enough, where if I had to use them, I’d just throw them away after using them in a test circuit, rather than keeping them in my junk box to use again like I do the beige ones. Trying to stay organized and returning them to their marked container (usually just a plastic bag) is way too much messing around.

I’m happy with 5% tolerance of the beige ones and I stick with them. For most hobby projects using Arduinos, LEDs, relays, etc., 5% tolerance is fine. But just like the blue ones, you have to be careful not to get the beige resistors with the wimpy leads.

I suggest getting the resistors with a beige background and the thicker leads (if the tolerance is acceptable in your projects).

I found beige resistors with fat leads at www.newark.com and www.microcenter.com . I actually got Newark to send me a couple of samples before I bought. Places like Newark who supply to commercial companies will send out samples, but that’s a service intended for companies who buy large quantities. You can try to get a couple of free samples but you’ll probably just have to buy some from most places and hope for the best.

I think I’d just buy from Amazon from now on. It’s so easy to return stuff, I’d pick a vendor with an assortment that looks good and then just return them if they’re the wimpy leads and try a different vendor on Amazon. It’s time we stood up against wimpy resistor leads and said enough is enough! 🙂

If you must purchase the blue metal film 1% resistor kits, this set looks pretty good. But beware, somebody reviewed them and mentioned the same problems I’ve had — thin leads and extremely difficult to read the color codes.