Today I want to talk about one of the most indispensable tools in my shop: the Dremel multi tool. I love Dremel multi tools. I don’t get paid to write that. I buy all my own Dremel tools. Whether it’s Dremel brand or not probably doesn’t matter.
I’ve put together an Amazon shopping list if you want to get started with a Dremel. Its linked at the bottom of the article.
If you want to watch my overview video, click on the play button, otherwise, read on.
This tool is simply a high-speed motor with a small chuck at the end to grip the shanks of various accessories. The combination of high-speed and specific accessories to cut, grind, sand, carve, brush and polish (have I missed any?) makes the multi tool very useful.
As with any cutting tool, the general concept is a harder material can be used to cut or grind a softer material.
This is the third one that I’ve owned in around 15 years. The earlier two eventually quit working, but they lasted me a long time, and, honestly, they were probably abused. I keep buying the Dremel brand, only because I know they will take a beating. I haven’t used a battery-powered Dremel. I’m always using it in my shop, so I stick with a mains-powered version.
This particular model Dremel has a variable speed motor with a spindle and a small chuck at the end. Frankly, I have never run my Dremel at anything less than full speed, so a single speed model would probably be adequate. Dremel’s website does however advise slower speeds for cutting and grinding metals, and slower again for plastics. Most cutting or grinding tools work best at a particular speed range (measured in metres per minute, or some similar velocity measurement). At the tiny scale of Dremel accessories, the tool needs to be spinning very fast to achieve the optimum cutting velocity.
When you screw the collet nut down it squeezes the collet which grips the tool shank. Different size collets are available. This allows you to use tools with various shank sizes. My version of the tool has a shaft lock (the silver button on the side of the black body), and an included wrench that tightens the collet nut. Most of the accessories are nominally 1/8” diameter, however I have a smaller collet and some accessories in 3/32” diameter. If you screw down the collet nut and the cutting bit shank is loose, then you need a smaller collet. You can buy the smaller collets separately.
The benefit of a Dremel multi tool is similar to an angle grinder – dozens of accessories to extend it use. I would suggest it is far cheaper to purchase a kit with an assortment of accessories, rather than purchasing them individually. Here are some of the accessories and a description of where and how you might use them.
The cutting wheels are almost always the reason I take my Dremel out of the case. Use them for cutting small metal stock or parts. Much more finesse than an angle grinder, and faster than a hacksaw. Need to cut down a steel rod? Shorten a small bolt or screw? Trim a couple of millimetres off some metal? Need to get into a tight space? Need to cut a slot in a mangled screw to fit a screwdriver?
You could compare a Dremel with a cut-off wheel to an angle grinder with a cut-off wheel – just on a mini-scale, for mini-scale jobs. Like an angle grinder, the wheels need to be treated carefully. If you bend the discs significantly while they are cutting, they’ll shatter.
The shank that carries the replaceable cut-off wheels is also used for other accessories, such as sanding discs. Buy bulk packs of the cut-off wheels if you can find them on sale.
Grinding stones (or “mounted points”)
I know the article on angle grinders didn’t recommend grinding wheels due to their aggressive nature, but on a micro-scale, Dremel grinding stones are really useful on motorcycle tasks.
After you’ve cut something with the cut-off wheel, there is a chance you’ll need to smooth it.
These tiny stones come in a variety of sizes, shapes and materials. In the Dremel brand, stones are provided in two material types:
- Aluminium oxide (tan colour) – generally used for steel and stainless steel
- Silicon carbide (blue/gray colour) – suitable for glass, stone and aluminium
The large variety of sizes simply give you more options when you have a specific task at hand. Silicon carbide is more expensive than aluminium oxide, but if you only work with steels then you don’t really need silicon carbide. However if you use aluminum oxide on aluminum, you’ll find the stone clogs up with aluminum quickly and becomes unusable.
The only way to address this problem is to use the accessory dressing stone. This stone essentially tears the surface grit from the mounted point and reveals a new, clean surface. To use the dressing stone, carefully bring it to the spinning mounted point and let it “grind” the mounted point.
Obviously this action reduces the size of the mounted point. Eventually you’ll wear the mounted point to a point it becomes unusable and needs to be replaced.
These tiny sanding discs are simply clamped to the cutting shank by the mounting screw. For stripping paint off inaccessible areas, to smoothing small areas, the sanding disc is great accessory. The sanding grit is very fine. This means its most effective when used after other, rougher smoothing tools (such as files, flap discs on an angle grinder, or hand sanding).
The discs don’t last long if you press too hard as they’ll wear the edges quickly and eventually break off around the clamp screw. Use a light touch and let the speed of the spindle do the hard work for you.
The sanding drum spindle consists of a rubber cylinder and a clamp screw. When you tighten the screw, the rubber cylinder is compressed and bulges out to hold the sanding drum.
I’ve found these most useful when I need to slightly enlarge a hole. With very careful motion of the sanding drum inside a drilled hole, you can increase the size a little. Its also useful for cleaning off the rough edges of a hole generated by drilling or using a hole saw. You might also use them for sharpening an edge tool, like an axe.
Many accessory kits come with a threaded spindle and tiny polishing wheels. I haven’t found much use for these outside polishing jewellry. You’ll need a metal polishing compound if you want to use this accessory (California Custom Purple is my favourite all-round metal polish).
I’m not sure where you’d use these on a motorcycle, but let us know in the comments if you have any success.
I’ve picked up genuine and “no-name” accessory wire wheels in brass and nylon. The brass ones are useful for paint removal around irregular shapes like welds – especially if your angle grinder won’t fit in the smaller spaces on the bike.
Like the sanding discs, they don’t last long with heavy-handed use, which is why I had none to photograph for the article! Useful, but if you rely on these to remove a lot of paint it’ll cost a fortune in replacement wheels.
These bits are made of “high speed steel”, which is a tool alloy. They cut very aggressively and are suited to softer materials like wood and plastics. While I haven’t done this, they could be used for careful freehand carving in wood or soft metals such as aluminum.
I bought these expensive bits for a particular job and they paid off. Strictly these bits are ‘Tungsten Carbide”. This material is very hard, strong, stiff and dense. When used in cutting tools, they withstand very high temperatures and can be used to machine through many different steels. This is where they shine.
When working on a 1970’s Kawasaki engine that had been in storage for years, I found the intake manifold screws (steel) were corroded into the aluminum cylinder head. When I tried to remove them, they snapped off. When I attempted to use a screw extractor, it also snapped off in the manifold screw. Many expletives were audible in my shop at this time. I needed to grind away the screw extractor, and the steel screw without damaging the cylinder head. A carbide bit in the Dremel eventually saved the engine. I used it to carefully eat away at the steel screw. I had to use a helical insert to repair the cylinder head, but it was successful. I can’t think of any other way I could have done that repair in my shop.
Carbide bits are not easily identifiable – compared to the many other cutting bits available – so make sure you store them carefully so they don’t get mixed up.
I’ve used diamond-coated bits to engrave very hard materials like alloy steels, stainless steel and even glass. Eventually the diamond grit is stripped from the carrying material, and they need to be replaced. If you are grinding or engraving very hard materials, then a diamond bit might be the right tool.
How could such a small tool cause any harm? Well, they spin very fast, and many of the accessories will make short work of your skin.
Firstly, the workpiece should be firmly secured. If it’s a small part, put it in a vice. If you have the Dremel in one hand, keep the other hand clear of the spinning tool.
Secondly, consider your eyes and lungs. If the Dremel is shooting particles into the air, you should wear some glasses and even a dust mask.
There are lots of additional resources on the internet related to multitools. Test your multitool accessories on some scrap materials before attacking your motorcycle. Once you’ve cut or ground the material away, it’s tough to put it back!
Check out the Dremel shopping list to get started: