As far as cutting tools are concerned, the drill is the most universally used. However, drills would be nothing without their reamers. An important piece of equipment that, unfortunately, many ignore or are unaware of.
In fact, I have seen many cases of people with drills who do not know what a reamer is. So don’t be part of the ignorance, and take the opportunity to inform yourself about this important piece of equipment.
What is a Reamer?
A reamer is a rotary cutting tool (cylindrical in shape).
It comes from a reaming process, a machining operation, or a chip removal process. It seeks to give a good finish to certain surfaces or enlarge holes previously made and with better accuracy.
The hand reamer with chip removal, or simply reamer, makes the hole with a higher level of precision than any other tool.
In turn, the reamer has teeth or slots carved along its body, which can be straight, helical, or conical and be directed to the left (to make through holes) or to the right (to make blind holes).
They come in different sizes and shapes, are made of high carbon steel, and are many types. Both adjustable and non-adjustable, removable or fixed, and for manual or machine use.
Reamers can be activated by hand by turning them with a wrench. But not just any wrench. I mean, don’t go using Allen wrenches with a reamer, thinking that’s how you’ll move them. To move them, you’ll need a tap wrench.
Parts of a Reamer
They can also be put on a drill, drill press, lathe, milling machine, or reaming machine.
The next thing you need to know is the three parts of a reamer: splines, neck, and shank.
The flutes are basically the sharp end of the reamer. The shank is the tip opposite the flutes, and the neck is the bridge that connects the two parts of the object.
The splines, in addition, consist of a face, a drilling zone, a sizing section, and a tapering zone.
The face serves to facilitate the entry of the reamer into the hole where it is drilled. The drilling zone does the heavy lifting when impacting the surface, and the sizing section serves to guide you in using the reamer to get a hole the size you need.
Types of Reamers
Now that you know what a reamer is, it’s time to learn about the types and functions of each:
1. Manual reamers
The hand reamer is distinguished by having a slightly conical tip, which facilitates the drilling of the reamer on the work surface.
At the same time, the grooves are scattered around the body in an irregular shape so that the body is more stable during the work. After all, the hand reamer tends to slip or have a torsional deflection after much continuous use.
To move them, you should use a standard or adjustable tap wrench. It may sound difficult, but these have a square shape at the opposite end of the bore.
They are divided into adjustable hand reamer and straight reamer.
2. Straight reamers
Straight reamers are used only for making small hole enlargements, which need to meet specific measurements.
3. Machine reamers
As mentioned before, some reamers can be placed in specialized machines, called precision reamers.
In terms of design, these reamers are very similar to hand reamers. They have only a few subtle differences, made to adapt these reamers to the machines.
For example, their shanks do not have square shapes but conical shapes. They also have 45° angle faces.
4. Rose reamers
These have shorter flutes and soften or finish hard-to-cut holes without the holes losing their size.
5. Shell reamers
This type of reamer has grooves along almost the entire length of its body and is used for drilling bearings or other similar items.
6. Floating reamers
They are used to correct any misalignment between the cutting shafts of the reamer and a previously made hole.
7. Expandable reamers
On the other hand, these reamers create holes of different sizes over a limited surface or range. Therefore, they can remove a small amount of additional material by enlarging the hole.
8. Carbide reamers
Carbide reamers have a higher abrasion resistance. They provide a better surface finish and extend the life of the reamer.
At the same time, they are ideal for creating a new hole on its own axis instead of enlarging a previously made hole.
9. Conical reamers
For these, a conical reamer is used.
They are used to make or finish tapered holes.
10. Morse taper reamers
They are mostly used for ship and building construction.
They are used because usually in such constructions, steel plates have holes that were made with drills but are shallow and difficult to penetrate.
This is where a reamer comes in handy, as it aligns the holes and gives them enough space so that rivets and screws can then be placed into the holes in the plates.
11. Machine reamers with helix flutes
These have grooves directed to the right side and are used to achieve smooth, deep cuts with proper shafts in stainless steel and materials with strong surfaces.
Be careful not to use them on soft surfaces, as they have the opposite effect. Instead of giving a good result, they only deform the hole and ruin the work.
12. Reamers with spiral grooves
Unlike the other types, this one is used exclusively for copper and bronze surfaces and holes containing grooves, keyways, or oil channels.
13. Mold reamers
As the name suggests, these are used for the construction of molds and accessories with holes.
For this purpose, they focus on faster drilling. They have only three flutes and high-angle helixes.
14. Reamers with point screws
Speed and Feed
Regarding speed and feed, reamers should be turned at slower speeds (70%) and higher feeds (300% or 400%) than drilling.
It would help if you found that balance because very low speeds will affect the production level, while very high speeds cause the material you drilled to stick to the reamer shafts and surfaces.
How to Use Them Correctly
I realize that for the uninitiated, knowing how to use these screws can be tricky. So I’ll give you a few tips.
- If you are going to use a tap wrench, tighten the handle around the tapered handle of the reamer.
- Start by placing the reamer over the hole. Then move it progressively down and clockwise until it is centered in the hole.
- If you use a tap wrench, the process is the same: move the wrench clockwise until the reamer enters the hole.
- If you’re drilling steel, lubricate the tool with cutting oil.
- But if you are drilling soft iron, do not lubricate the tool.
- Put a screw on the material to be drilled. You can use this as a guide to make sure the hole is perpendicular to the jaws of the screw.
- If you will use a straight reamer, keep in mind that these have a slightly tapered tip. So it will go into the hole without any problems.
- To remove the reamer from the hole, simultaneously pull the tool and move clockwise. Never move counterclockwise, or the reamer will wear out.
- Remember to find the right speed. Going too fast or too slow will affect the reamer and leave an uneven hole.
- With a machine reamer, the feed for reaming is higher than for drilling.
- The ideal speed is usually a quarter of the speed used for drilling the same material.
- Too much feed can reduce the accuracy of the hole and the quality of the result.
- Too little feed can cause glazing or tool wear.
- The feed range varies according to the material.
How to care for them
As a bonus, here are some tips on how to properly care for your reamers.
- Before starting the reaming process, clean the reamers well. This is the only way they will work well.
- To keep them sharp, make sure you point the reamer properly. It would help if you pointed it only in the direction of the cut.
- But if you notice that the reamer has lost its sharpness, you can use a stone to sharpen its shafts.
- Fortunately, though, the blades of some reamers can be replaceable. And by some, I mean the adjustable reamers. So you might want to get one like that.
- Don’t use reamers to remove more than 0.002 or 0.003 millimeters of steel.
- After you are done using them, store them in an area where they will not contact each other or other tools. This will prevent them from being damaged while in storage.
- If you applied the ideal amount of pressure during the job, but the reamer broke, replace it with another reamer. That one probably came defective, and you will need to use another one to finish the job properly.