R9 Machining

Posted: October 10, 2010 in Resistant Materials

Initial knowledge – 1

Current working knowledge – 2

A lot of the machines in the workshop do look familiar and I have had a chance to use them in the past.  I have used the pillar drill, buffering machine, band saw, belt sander, orbital sander, scroll saw and wood-turning lathe at some point in my education.  I feel confident with machining but feel I will need to practice with them once more and fully learn the safety features of the machines and familiar myself with safe practice again before moving into schools next year.  I will use this section to explain the functionality and practicality aspect of the various machines whereas section R12 will be used to show health and safety and risk assessment.

Pillar Drill

I am very familiar with this machine, I used it throughout school and it was one of the first machines I used when making the ball-bearing game mini task.

The pillar drill is a common type of machine drill used in many workshops. It is similar to a bench drill because both machines do pretty much the same thing which is to drill holes in a variety of materials such as wood and plastic.  The pillar drill sits directly on the floor and is useful for working with large and small pieces of material.  Because the pillar drill is larger than a bench drill it can drill bigger holes and as well as a twist drill (standard drill bit) used for drilling hole ranging in sizes from 1mm to 14mm.  It can also accommodate a Forstner bit which is used for larger diameter holes.  It is worth remembering when using this bit that the hole is drilled very slowly so that the bit does not ‘jam’ in the wood and also a hole saw. The hole saw is used for large diameters of hole.  The advantage of  this type of drill bit is that the blade can be changed to give different sizes of diameter.

Minimal effort is needed to operate the drill and the angle of the spindle is fixed relative to the table to allow holl to be drilled accurately and repetitively.

The main parts of the pillar drill are:

  • CHUCK –  The chuck holds the drill bit and is tightened and released with the use of a chuck key.  A chuck will usually accommodate drill bits with a shank up to 16mm
  • ELECTRIC MOTOR-  The motors power is transmitted through a V-belt and pulley system to the spindle and chuck.  The induction motor is rated between 187 and 850 W
  • NVR switch- no volt release switch for safety
  • FEED LEVER-  This drops the drill into the material, it is spring loaded but can be clamped to run the drill at a lower position to enable the user to work with both hands
  • THROAT- The distance between the worktable an column, the larger the better for added flexibility.
  • SAFETY GUARD-  This shields the chuck, it stops loose items getting entangled in the chuck and protects the user from flying debris although with some smaller items it can get in the way.  It would also prevent the chuck going round if the key was accidently left in.
  • WORKTABLE- Cast metal and attached to the column with a cantilever it has a hole in the middle to allow the drill to go through any work without damage to the table.  The worktable can be tilted to 45 degrees on some machines and can be moved to a side to accommodate larger work pieces.  Fences, vices or jigs can be bolted into the slots on the table.

Pillar drill 1.  Locking lever

2. Chuck

3.  Safety Guard

4.  Worktable

5.  Worktable lock

6.  Column

7.  Feed Lever

8.  Enclosed pulley levering

BUFFING MACHINE

The first time I used this machine was making a rather fetching acrylic keyring for my first ever project for DT in year 7.  It is easy to use and I employed it when buffing the edges for my plate rack after I had glass papered and wet and dried the edges of it.  By applying a small amount of polish to the buffing cloth it can produce a fine smooth finish.  It is important to hold the work with both hands as the wheel spins extremely rapidly and you don’t want to send the work into orbit.  It is a fairly straightforward machine to operate and the danger comes from not holding the work tightly.  It is also worth noting that it is wise to use the width of the buffing cloth to polish the work and to move the work in an up and down motion as if you keep the work still it will wear out the buffing cloth.  There is also an emergency stop button on the bottom of the machine that can be foot operated.

BAND SAW

I have used the band saw many a time in the workshop already.  It is an extremely useful machine that allows for the accurate cutting of straight lines in a wide variety of materials.  I have cut large sheet acrylic and smaller pieces on the metal band saw.  I have also used the wood band saw on many occasions for pine, ply and various other woods.  I am competent and confident on the machine but recognize that it can pose a severe danger in the workshop (see health and safety).

Band saws have a serrated metal band that is held in place by two pulleys.  The pulleys allow the band or the ‘blade’ to move around in a circular motion.  The material is fed slowly into the band causing a neat cutting line, it is run on an electric motor and can have one or more running speeds.  For every type of material there is a suitable cutting blade ( as Let me know when cutting acrylic on the wood one, I think the word used was ‘moron’), and therefore the blade can be changed and tuned for the appropriate material.

There are many different types of blades, a regular tooth band is most often used for cutting wood.  A skip tooth blade is best used for cutting pieces of soft woods and a hooked tooth blade is made for cutting through pieces of hard woods. You can also purchase a special diamond blade that is able to saw through pieces of glass. And, there is a hardened blade that can cut through metal. These blades come in varied tooth sizes, tooth shapes and band material.

By using the proper type of blade, you can cut almost any type of material, including soft wood, hard wood, thin steel, copper, conduit, metals, glass, galvanized pipe, and PVC pipe. Once you have chosen the proper band saw blade, and have installed it,  it must be adjusted and positioned on the center of the pulleys. The tension of the blade should also be tight enough to keep the blade from slipping.

The different parts of the band saw are:

  • BLADE-  The band saw blade is a long, flexible band with teeth on one side. A variety of blades are available, including fine-tooth blades, metal cutting blades and diamond blades.
  • BLADE WHEELS-  The blade is wrapped around an upper and a lower wheel. The blade is set in the wheels’  tracks to keep the blade from slipping. The wheels spin to revolve the blade for sawing.
  • BLADE WHEEL COVERS-  The blade wheels are enclosed in a metal cover that guards the blade and other internal mechanisms. The metal covers include doors for access to the blade and wheels.
  • BLADE GUIDE-  A small guide hovering above the table encloses the blade and functions to keep the blade steady as it revolves. The guide includes an adjuster knob for raising the guide up and down to accommodate different material thicknesses.
  • BLADE TENSION ADJUSTER-  Band saws have a tension adjuster knob or screw associated with the top blade wheel. The adjuster is turned for loosening or tightening the tension on the blade.TABLE-  The table is located between the two wheels with the blade running through a slot in the middle. Most tables have a bolt underneath, which is loosened to set the table on an incline for making angled cuts. The table also has a groove for the optional use of a miter guide.

SCROLL SAW

I have used the scroll saw on a number of occasions, again it was one of the first bits of machining I did in the workshop when cutting acrylic for my my ball bearing game.  I used it again to cut the handles out for the sides of my plate rack as I could cut the shaped holes out accurately.  I seem to remember the scroll saw being a popular tool to use in school and it was one of the first electric machines we were allowed to use.   Because of the thin blade it is important to be quite delicate with the material you are cutting when feeding it into the blade.  If you push too fast the blade can snap quite easily and admittedly this did happen to me on one of my first attempts.  It is relatively easy to use but I think the key is patience really.  It only needs a gentle push and when I found that there was resistance from the blade and it was vibrating the material it meant that the blade needed changing.  If any sideways pressure is put on the material you can see the blade bending but it can be quite easy to do so it’s just a case of relaxing the pressure.  The blades range from 1-12 with a 1 being for more delicate cuts.

CIRCULAR TABLE SAW

In the first week Bhav showed us how to use the circular table saw, as yet I haven’t needed to put it into practice.  At school we were not actually allowed to use this piece of machinery and if we needed to use it it was left to the teacher or technician.  Before I used it I had images of me cutting my arm off but if used in a safe correct manner it should cause no danger although its’ potential is evident.  It was fairly easy to use  and would be ideal for cutting man made boards like ply wood and MDF and natural woods up to about 50mm thick.  I found that using 2 push sticks was the safest method as I certainly didn’t want to get my fingers anywhere near the rotating blade.

The table (mounted fixed to the blade) has a fine groove to the left side of the blade where the crosscut angle can be moved. This way crosscuts are easily done. To the left side of the blade the guide fence for rip cuts is attached.   A rip cut is a parallel cut along the board sides, to cut the wood equal in width. Table saws with a sliding table allow the user to move the whole table part – left of the saw blade – backwards and forwards. As the entire table is guided on guide bush rollers even panels of size can be cut easily. Compared to fixed base table saws the sliding table allows to do cross cuts on wider board width.

Metal lathe 

The metal lathe is an extremely useful tool for turning metal. Also like all power equipment it can be very dangerous if not operated with caution. The term used in cutting metal on an engine (metal) lathe is “turning” for obvious reasons as the piece of metal in the machine is being rotated and the cutting instrument (tool) is stationary.

Most engine lathes come equipped with a three (3) jaw chuck but some have a four (4) jaw.

There are three most important elements of using an engine lathe to understand the use of the chuck, the tool post carriage and cross-slide and the tailstock.

The Chuck

The chuck is directly attached to the drive mechanism of the engine lathe and rotates at variable speeds up to as much as 6500 rpm on some machines. To start, clamp the piece of metal to be turned in the chuck, the three-jaw chuck is self centering, however since pieces of metal are not always perfectly straight and level it is recommended that you use a dial indicator to check the location of the piece of metal in relationship to the machine. This can be done by placing the indicator on top of the tool post with the dial stem touching the part and with the machine turned OFF and in neutral position rotate the chuck checking the trueness of the part within one or two thousands of one inch.  This is a precision machine that can make cut to sizes within that tolerance or better. Once you are sure that the part is true, tighten the chuck as tight as you can place the chuck key in each key receptacle on the side of the chuck. Check once more for true and then place the chuck key on the workbench away from all moving parts.  Never, leave the key in the chuck except when using it to tighten the part in the chuck. The key can become a flying chunk of lethal steel if left in the chuck and the machine is started into motion.

 The Tool Post Carriage and Cross-slide:

It is self explanatory that this is where the cutting tool will be located. The cutting tool, for safe and efficient cutting the tip of the tool must be located direct on center of the part in the chuck, too high and the base of the tool will drag on the part deflecting the depth of the cut and too low the tip will tend to gouge and/or cut too deep. If you are not familiar with using an engine lathe, It isrecommended that you use the lower speed of chuck rotation and take shallow cuts until slowly increasing the rpm’s until the tool cuts smoothly and does not appear to heat up, this can be seen by the tip discoloring to a blue tint when no longer cutting. The depth of the cut is regulated by the dial handle on the cross-slide of the carriage, the tool post is mounted here, each line on the dial of the handle of the tool post (small wheeled handle) is equal to either 1 one thousands of an inch or 2 one thousands of an inch. With the part rotating at a moderate speed touch off the tip of the cutting tool near the end of the rotating part, very slowly ease the tool towards the part until it just touches, as witness there will be a very fine hair like shaving on the cutting edge of the tool and back the carriage off from the part (using the large wheel on the carriage) without removing the tool from its position. The set the indicator marks on the dial to the Zero mark.

The carriage moves along the ways (the metal tracks) to and away from the chuck, the cross-slide move to and away from center or the part. There are two other handles (lever like) on the carriage these are the power feed handles. One feeds the carriage toward the chuck at a predetermined speed and the other feeds the cross-slide. To understand the operation I recommend you test these operations without a part in the chuck at the different speeds of feed to get the feel of the action of the machine.


The higher the speed, within reason to the size and weight of the part, and slower the feed combined on most chromoly steels, if you are not sure test speed and feed combinations on a scrap piece of the same metal you will be turning.  Be sure to stop the motion of the carriage before coming into contact between the chuck and tool post, this can damage either or both part as well as being dangerous to your safety.

When cutting metal it does heat up, heat can damage both the part and the cutting tool, the use of water soluble oil mix with water or light cutting oil sprayed on the part is recommended to extend the life of the tool and keep the part from creating hard spot from over heating.

Tailstock:

The Tail Stock is located on the opposite end of the engine lathe from the chuck, mounted on the ways of the machine. The tail-stock has limited uses, the most common is to drill out the center of the piece of steel in the sleeve of the unit you can insert a “Jacobs Chuck”, a chuck like on your hand-held power drill, and can be fed into the rotating part using the wheel at the outside end of the tail-stock. The other general use is for a live center, the cone shaped object with a tapered tang shaft that fits into the sleeve, and the cone portion spins on ball bearing internal mechanism. This is used to fit into the center hole of the work piece holding it firmly between the tailstock and chuck.

Before feeding either the drill chuck or live center into the moving part, be sure to lock down the tailstock into position by tightening the screws at the base of the unit or the tension lever, they come equipped either way.

Cutting Threads:

The thread cutting lever  is referred to as the half nut. On the backside of the carriage you will see a dial with four number and marks, these are you engage marks. It is hard to explain fully but in generalities, for even numbered threads as in ¼ “20” use even numbers for odd numbered threads the odd numbers.  The half nut and the carriage will take off at a high rate of speed. So when threading, do not use high speed, the feed relationship is direct to the rpm’s the part is rotating. Reminder: this is just a general description of the threading process and it is recommended that you seek direct hands on instructions.

Until you get use to the operation of the piece of machinery test at various speeds and feeds. If you get a long stringy cut instead of a chip increase feed until material comes off in chips. Keep the ways and carriage clear of chips from cutting, do not use your hands use a small brush; the chips can be HOT and are extremely sharp and can cause injuries. Always wear Safety Glasses and keep your hands away from moving parts of the machine. These are just the basic safety practices. And as with any shop always keep your work area clear and clean.

I have used this machine for the plumbob mini task.  Unfortunately when drilling the hole I managed to snap the drill bit.  When moving the tailstock hand wheel it was suggested that I turn it just a quarter at a time to avoid doing this again.

Router table

In general, a router table will help you work with stock of dimensions that don’t lend themselves to handheld router work.   I attempted to router the rebates and grooves on the timber for my space saving unit but I found it a little hard to control so I decided to use the table router.  Long, narrow stock, such as that used to make moldings and trim are nearly impossible to work with a handheld router. Edge profiling a few hundred feet of a particular door or base molding could probably be done with handheld router and the aid of special shop-built rigging, but dong so would be an extremely inefficient choice, when a router table makes long runs of narrow stock routine.

Small pieces of stock are also a challenge to work with a handheld router. Handheld work on small parts often involves a difficult balancing act. You have to keep the router perfectly upright on stock that doesn’t do a good job of supporting the router base. To compound the problem, you have to have a way of holding the stock itself in place while you work. A router table leaves both of your hands free to hold on to small parts while the table surface provides a sturdy, flat support for the entire surface of the workpiece.

Trimming the edge of a piece of stock to a flat, smooth, square surface or exactly following the contour of a pattern is one of the router’s specialties. Attaching a straightedge or a template to a piece of stock is one of the quickest and most effective ways to clean up an edge, or to perfectly and repeatably form the arched top of a frame and panel door or any other curved part.
Using a router table for edge trimming and pattern work speeds the process by eliminating the need to hold both the workpiece and the pattern down while you make the cut.

The router table surface supports the workpiece very well. With a handheld router, the door would have had to be clamped down a work-surface in preparation for the cut, and considerable care would have been required to keep the router surface flat on the surface of the wood.

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