1/4″ Die Grinder

One of my favorite tools

Today I am going to throw out some info about one of my favorite and most frequently used tools.  The 1/4″ die grinder shown here is what I consider to be one of the most valuable tools in my toolbox.  Fitted with a carbide bit, this tool can be used to bore out holes and grind in hard to reach places.  And, unlike some other air tools, these units are really cheap and seem to last forever. I am not going to recommend any brands in this post.  But I can tell you that the grinder shown in the picture above is not made by a major brand.  In fact, this unit was definitely the cheapest one in the store.  But, having gone through several of these in my career, I can tell you that they are a pretty simple device and consequently they seem to last a really long time. There are two significant benefits of an air die grinder versus an electric die grinder.  The first is that the air die grinders are quite compact.  Now there are definitely different sizes available, but I would recommend getting the smallest one that you can find.  Any power increase that you might see from a bigger model will likely be offset by the bulkiness and restrictions associated with larger sizes.  As well, die grinding does not require a large amount of force or power. 

The second big advantage of air die grinders is the variable speed capacity.  As with many other air tools, the trigger will allow the user to control the air flow very precisely.  Electric die grinders do not usually have the same delicate control.  Some of you might ask, why is that so important?  It is important because it allows the user to perform very delicate work if he/she needs to.  Using a very slow speeds helps to perform fine work with less risk of grinding away too much metal.  Slower speeds also allows you to keep the heat generated by the grinding friction down. 

Die grinder with a flapper wheel

Some other benefits of die grinders are that they are quite versatile.  Any cutting device with a 1/4″ shank can be used in them.  Shown here is a 60 grit flapper wheel that is very effective for removing surface rust from sheet metal.  This flapper wheel will also strip paint quite effectively, but should not be used for large areas.  The main benefit of this flapper wheel is that they last a reasonably long time and they leave a very nice finish on sheet metal.  Smooth enough to be primed, but rough enough so that you can be sure the surface is clean.  If you are working with stainless or aluminum, this flapper wheel can be used to create a brushed finish.  It works much better on stainless, but just make sure that you use long, straight passes to achieve a uniform pattern.  If you are looking for a neat and cheap finish, try brushing some mild steel and then apply Tremclad clear right over top.  This creates the look of stainless, at a fraction of the price.

You might notice that the body of the die grinder above is larger than the first one.  It is, but it is not any better or worse than the one that appeared at the top of this post.   I paid under $30 for each of these die grinders, and they both work equally well.  In fact, I have more than one die grinder so that I do not have to change the bits so often.  This might be a little extravagant for some guys at home in their garage, but the point is that there is no reason to pay more than $30 for a die grinder.

90 degree 1/4" die grinder

A couple of final notes.  The die grinder shown here is similar to the one shown above, but with the rotating tool head at 90 degrees to the handle.  These units are handy too, but not an absolute necessity.  The grinder here is fitted with a 3″ roloc TM abrasive arbour and disc.  These small sanding discs are really handy for doing fine work on small areas, or when you need to grind in a tight area.  The roloc TM discs have a plastic threaded anchor on their backs.  This anchor threads into the arbor.  I find that this system is better than the velcro TM type setups as the Roloc TM discs never come off.  However, these discs, as handy as they may be, are one of the most expensive abrasives that you can buy.  I usually pay 2 to 3 dollars per disc.  So use them sparingly.


The indispensible cut-off tool

 Finally, we have cutting discs.  The tool shown on the right is not actually a die grinder, it is a cut off tool.  But there are arbours available that will allow you to attach a 3″ cutting disc into a die grinder.  I am only mentioning it here because this is perhaps the most valuable tool and grinding disc that you can have in your tool box. I will discuss this tool in a separate post, but for now let’s just say that this tool is a must have.
  • 1/4″ die grinders are a very valuable tool with many different cutting heads for different purposes.
  • It has been my experience that even the most inexpensive die grinders seem to last a very long time and function quite nicely.  There is no need to pay more for name brands ($30 and under)
  • Size should be a determining factor.  The smaller the better.  Die grinding does not require a lot of torque 
  • Carbide cutting heads are expensive ($25 or more), but literally last forever,  I am still using the first one I ever bought.
  • Flapper wheels are moderately expensive, but last quite a while and do a very nice job of preparing (not grinding) metal.  ($5 to $10)
  • 3″ Roloc TM sanding discs are handy for tight spaces and for doing fine grinding, but they are expensive.  (under $10 for the arbor $2-$3 for eacch disc)
  • 3″ cut-off wheels are indispensibe.  Whether in a die grinder or on a cut-off tool, this is in the top 5 tools that you need to have if you want to build hot rods.  ( under $30 for the cut-off tool, $.50 to $3 for the discs)

Well, I hope that some of this information is of some use.  Once again, if you have any comments, we are always glad to hear from you.  And remember, tell your friends about howtobuildhotrods.com