Difference between revisions of "Die grinder"
m (Dremel moved to Die Grinder: Thats what they are really) |
(asstd minor) |
||
| Line 1: | Line 1: | ||
| − | ''' | + | A '''Die Grinder''' is a small high speed rotary power tool. Typically these take an array of tools of upto 1.5" diameter with 3.2mm shank. |
| + | |||
| + | '''Dremel''' is a popular make of die grinder, and the word Dremel is widely used to mean a die grinder (of any brand). | ||
| Line 6: | Line 8: | ||
===Drill bits=== | ===Drill bits=== | ||
| − | Upto 3.2mm | + | * Upto 3.2mm |
| + | * Thinner drill bits are very weak, sideways force or movement should be avoided | ||
| − | |||
===Grind stones=== | ===Grind stones=== | ||
| − | + | * Various shapes, compounds & grades. | |
| + | * Use depends on the material and shape of the bit | ||
| − | |||
===Diamond coated engraving bits=== | ===Diamond coated engraving bits=== | ||
| − | For engraving glass | + | * For engraving glass |
| + | |||
===Metal wire wheel=== | ===Metal wire wheel=== | ||
| − | For removing rust & paint | + | * For removing rust & paint |
| + | * For raising 3d grain in wood eg for moulding. | ||
| − | |||
===Metal wire cup wheel=== | ===Metal wire cup wheel=== | ||
| − | As above, but less powerful and more able to get into corners | + | * As above, but less powerful and more able to get into corners |
| + | |||
===Nylon brush wheel=== | ===Nylon brush wheel=== | ||
| − | Cleaning | + | * Cleaning |
| + | * Removal of soft materials | ||
| + | * Removal of loose paint | ||
| − | + | ===Nylon cup brush wheel=== | |
| + | * As above, but less powerful and more able to get into corners | ||
| − | |||
| − | |||
| − | |||
===Cutting discs=== | ===Cutting discs=== | ||
| − | Various compounds and | + | * Various compounds, grades & sizes |
| + | * What they cut depends on compound and grade of the disc | ||
| + | * See safety notes re non-reinforced discs. | ||
| − | + | ===Sanding drum=== | |
| − | |||
| − | |||
===Felt polishing pads=== | ===Felt polishing pads=== | ||
| − | Polishing metal, plastics, | + | * Polishing metal, plastics, |
| + | * Use with polishing compound | ||
| − | |||
===Rasps=== | ===Rasps=== | ||
| − | aka High speed cutters | + | * aka High speed cutters |
| + | * Fast shaping of soft metals, plastics, wood etc | ||
| − | |||
===Sanding discs=== | ===Sanding discs=== | ||
| − | Sandpaper discs are used with a flexible backing pad. | + | * Sandpaper discs are used with a flexible backing pad. |
| + | |||
===Screw mandrel=== | ===Screw mandrel=== | ||
| − | These hold felt pads | + | * These hold felt pads |
| Line 53: | Line 58: | ||
Grinding stones can clog with metal. This can be removed either by a wirebrush or a coarse abrasive. | Grinding stones can clog with metal. This can be removed either by a wirebrush or a coarse abrasive. | ||
| − | When grinding soft metals such as aluminium and copper, clogging can | + | When grinding soft metals such as aluminium and copper, clogging can be a real problem. Rubbing the disc or stone firmly with chalk first may reduce the clogging to some extent. |
==Performance== | ==Performance== | ||
| − | Linear speed of a 1" 30,000 rpm tool is around | + | Linear speed of a 1" 30,000 rpm tool is around 2/3 of that of a 4.5" 11,000 rpm angle grinder tool. Also angle grinder discs & brushes are much more robust. So more speed and force are available from an angle grinder than a die grinder. |
| − | The prime advantage of | + | The prime advantage of die grinders lies in their tiny size, which enables access in restricted spaces, and makes fine work with miniature tools practical. |
They are also generally much quieter than angle grinders, which can be an advantage in some situations. | They are also generally much quieter than angle grinders, which can be an advantage in some situations. | ||
| − | Finally more types of tool are available for | + | Finally more types of tool are available for die grinders than angle grinders. |
| Line 79: | Line 84: | ||
Some machines can be set to reduced speed to enable lower speed tools to be used, some can't. For machines with no speed control there are some workarounds for speed reduction. | Some machines can be set to reduced speed to enable lower speed tools to be used, some can't. For machines with no speed control there are some workarounds for speed reduction. | ||
* Running the tool off a 110v transformer gives a max speed of 110/240 x the usual run speed | * Running the tool off a 110v transformer gives a max speed of 110/240 x the usual run speed | ||
| − | * When no better alternative is to hand, running a lightbulb in series with the | + | * When no better alternative is to hand, running a lightbulb in series with the die grinder reduces the voltage and thus speed. |
| + | ** A multimeter is used to measure the offload voltage and thus calculate max speed. The downside of this arrangement is that as the tool is loaded its speed will reduce at a greater than usual rate as load increases. | ||
* Low voltage tools can be run off a supply of lower voltage to reduce speed. | * Low voltage tools can be run off a supply of lower voltage to reduce speed. | ||
| Line 92: | Line 98: | ||
Speed rating of machine and tool are important, the tool should not be used at above its rated speed. Running over speed can cause tools to shatter explosively. | Speed rating of machine and tool are important, the tool should not be used at above its rated speed. Running over speed can cause tools to shatter explosively. | ||
| − | Cutting discs for these machines are | + | Cutting discs for these machines are often unreinforced, despite the fact that they run at very high speed. This means that if they break in use they can explode. They are also typically very thin, thus having low force ratings, and meaning that a single intergrain bond failure has a greater likelihood of causing disc failure. |
| − | Wire brushes are prone to shedding bristles. These shed bristles come off at high speed, | + | Wire brushes are prone to shedding bristles. These shed bristles come off at high speed, often with sharp points. |
Eye protection is a must with these tools, and one should always stay out of the plane of spin of the tool. | Eye protection is a must with these tools, and one should always stay out of the plane of spin of the tool. | ||
Revision as of 09:46, 10 May 2007
A Die Grinder is a small high speed rotary power tool. Typically these take an array of tools of upto 1.5" diameter with 3.2mm shank.
Dremel is a popular make of die grinder, and the word Dremel is widely used to mean a die grinder (of any brand).
Tools
Many types of tools are used with these machines.
Drill bits
- Upto 3.2mm
- Thinner drill bits are very weak, sideways force or movement should be avoided
Grind stones
- Various shapes, compounds & grades.
- Use depends on the material and shape of the bit
Diamond coated engraving bits
- For engraving glass
Metal wire wheel
- For removing rust & paint
- For raising 3d grain in wood eg for moulding.
Metal wire cup wheel
- As above, but less powerful and more able to get into corners
Nylon brush wheel
- Cleaning
- Removal of soft materials
- Removal of loose paint
Nylon cup brush wheel
- As above, but less powerful and more able to get into corners
Cutting discs
- Various compounds, grades & sizes
- What they cut depends on compound and grade of the disc
- See safety notes re non-reinforced discs.
Sanding drum
Felt polishing pads
- Polishing metal, plastics,
- Use with polishing compound
Rasps
- aka High speed cutters
- Fast shaping of soft metals, plastics, wood etc
Sanding discs
- Sandpaper discs are used with a flexible backing pad.
Screw mandrel
- These hold felt pads
Tool Maintenance
Grinding stones can clog with metal. This can be removed either by a wirebrush or a coarse abrasive.
When grinding soft metals such as aluminium and copper, clogging can be a real problem. Rubbing the disc or stone firmly with chalk first may reduce the clogging to some extent.
Performance
Linear speed of a 1" 30,000 rpm tool is around 2/3 of that of a 4.5" 11,000 rpm angle grinder tool. Also angle grinder discs & brushes are much more robust. So more speed and force are available from an angle grinder than a die grinder.
The prime advantage of die grinders lies in their tiny size, which enables access in restricted spaces, and makes fine work with miniature tools practical.
They are also generally much quieter than angle grinders, which can be an advantage in some situations.
Finally more types of tool are available for die grinders than angle grinders.
Usefulness
How useful are they is a question often asked. Personal experiences follow.
- I rarely use mine, but when I do, nothing else will do.
- I last used one for cutting out some bearings. I don't know any other tool could have done the job.
- They can be used for cutting pipes in awkward places.
Speed
These tools operate at extremely high rotational speed, and one should check that the tools used are rated for the speed of the machine. There are tools available rated at below typical machine speeds, and these should not be used above their rated speed on safety grounds.
Reducing speed
Some machines can be set to reduced speed to enable lower speed tools to be used, some can't. For machines with no speed control there are some workarounds for speed reduction.
- Running the tool off a 110v transformer gives a max speed of 110/240 x the usual run speed
- When no better alternative is to hand, running a lightbulb in series with the die grinder reduces the voltage and thus speed.
- A multimeter is used to measure the offload voltage and thus calculate max speed. The downside of this arrangement is that as the tool is loaded its speed will reduce at a greater than usual rate as load increases.
- Low voltage tools can be run off a supply of lower voltage to reduce speed.
Speed = voltage/rated voltage x rated speed.
This holds true for both mains and low voltage machines.
Safety
The main risk with these machines is explosion of the tool due to breakage at very high speed.
Speed rating of machine and tool are important, the tool should not be used at above its rated speed. Running over speed can cause tools to shatter explosively.
Cutting discs for these machines are often unreinforced, despite the fact that they run at very high speed. This means that if they break in use they can explode. They are also typically very thin, thus having low force ratings, and meaning that a single intergrain bond failure has a greater likelihood of causing disc failure.
Wire brushes are prone to shedding bristles. These shed bristles come off at high speed, often with sharp points.
Eye protection is a must with these tools, and one should always stay out of the plane of spin of the tool.
A second risk results from high speed, tool inertia and absence of guarding. Catching a spinning tool on something can yank the machine forcefully. The machine should be held firmly, hands kept out of the way of the tool, and force on the workpiece should be kept light.
Tools that cause vibration should be retired. These have become unbalanced, and are much more liable to fail dangerously in use. They also put high stresses on machine bearings causing premature failure.