Bicycle Mechanics - Dremel Bits in Regular Drill

When cutting cable housing, I've wished I had a Dremel tool. But I could probably just buy some Dremel bits and use them in one of my regular drills, right?

Yeah, they're a bit fragile, though, especially those flimsy thin grinding discs. The drill is a bit tougher to handle. You'll need to bury the trigger to get the rpm up on that corded drill, and it won't be close to that of even the cheapest $20 Dremel knockoff. Cordless typically slower still.

Youu could probably use a mandrel with a cutting disc on a drill. Even though slow and would probably wear the disc out faster, it would work.
My self I don't own a Dremel tool. I prefer regular Die grinders. I have a couple electrics and pneumatics.

Why not just buy a cheap multi tool w/bits, on sale, at Harbor Freight.

The maximum rpm of most drills is 2200 or less, sometimes a lot less. My 3/8" single-speed turns 1200 rpm and my 1/2" variable has a maximum of 950 rpm.

Dremels typically turn 20,000 to 30,000 rpm so they work a lot faster and with less pressure. As Metzinger noted, Dremel bits, particularly cut-off wheels, are fragile and rely on peripheral speed, not pressure to cut smoothly and relatively fast.

Your drill might work but it will be very slow and you will have a tendency to apply too much pressure to hurry things along.

why not just buy a cable/housing cutter? I have a cheaper one, I have done 3 bikes with it now and it still works great. The proper cable/housing cutter is quicker, as well. A quick snip, then open up the inner housing with an Awl or smooth nail, and your done. I always file the end of brake cable housings flat to the housing as well, Everyone should have a file in their home ;)

OK, got it.


Why not just buy a cheap multi tool w/bits, on sale, at Harbor Freight.

Are those any good?

I've never thought of trying this, but I would think using the smaller Dremel bits in a regular drill would be cumbersome. The nice thing about the Dremel is that it's easy to handle so you can be precise.

I've got a two-speed model and it has worked fine for everything I've done with it. I wouldn't screw around with a battery-operated one though unless you plan on using it very often.

Are those any good?

The Chicago Electric cordless 9.6v variable speed multitool is pretty nice. I use that for small parts fabrication in my shop at work. It's held up well to making all the fiddley little bits I make from aluminum or steel scraps. (Robotics/machine engineering shop, not a bike shop; just to clarify.)

When cutting cable housing, I've wished I had a Dremel tool. But I could probably just buy some Dremel bits and use them in one of my regular drills, right?

Yes and No, mostly No.

Owing to their small diameters Dremel bits need to run at very high speed, typically 20,000-35,000rpm to be effective.

Cutting performance is related to surface feet per minute at the cutting edge, so the optimum RPM is inversely related to the diameter of the bit. This is less critical with some operations, such as drilling, or using a burr on soft materials, but absolutely critical to effective grinding or using abrasive discs.

The average bench grinder runs at 3600 RPM and uses a 6 or 7" wheel. The Dremel 1" diameter cut off disc needs to run at about 25,000 RPM, vastly beyond the range of the typical hand drill.

Why not just buy a cheap multi tool w/bits, on sale, at Harbor Freight.


Are those any good?

Whether it's any good or not, here's the way I look at it: If I need a tool, I will generally buy the cheapest possible version of the tool and use it until it breaks. Maybe 2/3 to 3/4 of the time, it never breaks and works just as well as the more expensive tool (true especially for tools you don't use very often). Let's say it does break.... well, while I was using the tool, I maybe noticed features or lack of features of the cheap knockoff tool and now when I go to buy a more expensive, higher quality version of the tool, I know much more about what makes it worth the money. The $20, for instance, that I throw away on a Harbor Freight tool actually paid for itself if I got to use the tool a few times before it broke, not to mention the educational aspect of learning about the tool and what I want in the replacement for it.

Short version: If you get the cheapie and it works fine, you saved a lot of money. If not, at least you know why the name brand version costs more.

Whether it's any good or not, here's the way I look at it: If I need a tool, I will generally buy the cheapest possible version of the tool and use it until it breaks. Maybe 2/3 to 3/4 of the time, it never breaks and works just as well as the more expensive tool (true especially for tools you don't use very often).

That's been the difference I've seen with big-name stuff vs. Harbour Freight brands: Durability. Stuff I use all the time, I get a big-name brand. Even on the off chance it does break, they usually have a decent waranty for replacement/repair, making the extra cost worth the money.
If (when) my $20 portable compresser croaks after a couple years, I'll just go buy a new one instead of futzing around with a repair/replacement if it were a $300 piece of equipment.

Right... but if that $20 POS compressor lasts for 3 years, you're way ahead of the game.

Yes and No, mostly No.

Owing to their small diameters Dremel bits need to run at very high speed, typically 20,000-35,000rpm to be effective.

Cutting performance is related to surface feet per minute at the cutting edge, so the optimum RPM is inversely related to the diameter of the bit. This is less critical with some operations, such as drilling, or using a burr on soft materials, but absolutely critical to effective grinding or using abrasive discs.

The average bench grinder runs at 3600 RPM and uses a 6 or 7" wheel. The Dremel 1" diameter cut off disc needs to run at about 25,000 RPM, vastly beyond the range of the typical hand drill.
I use these cut-off discs everyday as a goldsmith. We rarely run them at 20,000 rpm! We run them at an "appropriate" speed for the material and thickness of the item being cut. These discs can become dangerous if they break and are spinning at high speed. Unfortunately, its difficult to describe how "appropriate speed " is judged. Mostly by experience. It's actually safer to cut the housing with a proper housing cutter and to use the cut-off wheels to trim and true the cable ends, only!
If you don't want to buy a Dremel, there is a universal Flexible shaft attachment made by various makers that will turn a drill press or hand power drill into a suitable flexible shaft unit that can accept these cut-off wheels. (see; http://www.micromark.com/UNIVERSAL-FLEX-SHAFT,6558.html , as an example).
Incidently, a Dremel is considered a poor cousin to a professional flexible shaft unit like Foredom Electric or Pfingst Co. that are used by goldsmith/jewelers and Dental Lab technicians.

I use these cut-off discs everyday as a goldsmith. We rarely run them at 20,000 rpm! We run them at an "appropriate" speed for the material and thickness of the item being cut. These discs can become dangerous if they break and are spinning at high speed. Unfortunately, its difficult to describe how "appropriate speed " is judged. Mostly by experience. It's actually safer to cut the housing with a proper housing cutter and to use the cut-off wheels to trim and true the cable ends, only!

Correct but gold is not steel so the appropriate RPM is going to be very different. Also, there are fiber reinforced cut-off disks available for Dremel tools that are not nearly as fragile or "explosive" as the hard brittle ones but cut nearly as well.


If you don't want to buy a Dremel, there is a universal Flexible shaft attachment made by various makers that will turn a drill press or hand power drill into a suitable flexible shaft unit that can accept these cut-off wheels. (see; http://www.micromark.com/UNIVERSAL-FLEX-SHAFT,6558.html , as an example).
Incidently, a Dremel is considered a poor cousin to a professional flexible shaft unit like Foredom Electric or Pfingst Co. that are used by goldsmith/jewelers and Dental Lab technicians.
The flexible shaft adapters still limit you to the relatively low rpm a drill press or hand drill runs so it's no improvement other than it offers better dexterity.

Those professional tools like the Foredom cost so much that they are completely out of the question for the occasional home user and are massive over-kill for the home bike mechanic.

[SIZE=3][FONT=Times New Roman] Incidently, a Dremel is considered a poor cousin to a professional flexible shaft unit like Foredom Electric or Pfingst Co. that are used by goldsmith/jewelers and Dental Lab technicians.

Really? My orthodontist used to have a Dremel sitting out on his desk at all times. It used to scare me to no end.

buy a cable cutter from home depot or lowes. they do a great job with housing too.

Correct but gold is not steel so the appropriate RPM is going to be very different. Also, there are fiber reinforced cut-off disks available for Dremel tools that are not nearly as fragile or "explosive" as the hard brittle ones but cut nearly as well.


The flexible shaft adapters still limit you to the relatively low rpm a drill press or hand drill runs so it's no improvement other than it offers better dexterity.

Those professional tools like the Foredom cost so much that they are completely out of the question for the occasional home user and are massive over-kill for the home bike mechanic.


Really? My orthodontist used to have a Dremel sitting out on his desk at all times. It used to scare me to no end.

Correct but gold is not steel so the appropriate RPM is going to be very different. Also, there are fiber reinforced cut-off disks available for Dremel tools that are not nearly as fragile or "explosive" as the hard brittle ones but cut nearly as well.


The flexible shaft adapters still limit you to the relatively low rpm a drill press or hand drill runs so it's no improvement other than it offers better dexterity.

Those professional tools like the Foredom cost so much that they are completely out of the question for the occasional home user and are massive over-kill for the home bike mechanic.


I am, more often than not, using these cut-off discs on steel tools. Only occasionally do I use them on actual gold pieces. My comments about 20,000 rpm being needed to cut, still apply- On Steel, I run them at much lower speeds than 20,00 rpm.
The flex shaft attachment was offered as a possibility for those interested in their use and unable to justify the cost of a Foredom Unit. They are also cheaper than a Dremel tool. Notice that I said "Dental Lab technicians" and not Orthodontists or dentists. Lab technicians and jewelers run these tools for continuous periods , often a couple of hours, Your average Dremel will get very hot, in the same circumstances. The real point to my post was that these cut-off discs work better to finish up a housing that was cut by a housing cutter. There are also various devices available to adapt a grinding motor to hold 1/4", 1/8" or 3/32" mandrels that are designed to hold these cut-off discs (Foredom makes one to fit 5/16" arbor- CHA-5; about $25), another for 1/2" arbor at http://www.gesswein.com/catalog/catalog.cfm?cat=8&sub=7&subsub=6&catalog=1&CFID=3088851&CFTOKEN=38217730 (http://www.gesswein.com/catalog/catalog.cfm?cat=8&sub=7&subsub=6&catalog=1&CFID=3088851&CFTOKEN=38217730) This one is a three jawed chuck that can hold a variety of bits and tools
There are lots of ways to skin this cat!