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Micro Mesh Pad Storage………
“I have had some Micro Mesh pads for some time and have kept them in a screw top jar together with the colour code and grit information. A while ago we were given a box of Bendicks Crisp Mint Chocolates and having eaten a couple I looked at the box and realised the size of the slots the mints were displayed in was almost the same size as the micro mesh pads and exactly the same number of slots. I re-covered the lid with some brown paper and cut the colour code chart down to fit into the lid and what you see is the result. It keeps them in order and can be easily returned to the correct slot after going down the grits without having them all over the bench” Colin BushellAxminster AWVSL 1000 Lathe Gearbox Maintenance………
Anyone who has one of these lathes may experience noise and or stiffness of operation in changing speeds. The gearbox operates on the DAF
Truck gearbox principle using friction pulleys to change the speeds over a given range using a constant speed motor.
I have experienced both of these problems, stiffness and with accompanying noise being the most recent. To check to see where the noise was
coming from and to eliminate the head stock bearing; I placed a screwdriver on the bearing housing and my ear to the handle. Any bearing noise
will be detected through the screwdriver generally at a high pitch. Fortunately, this was not the case but the noise was evident from the gearbox
area and the operation of the gear lever stiff.
Like anything else close to dust, the gearbox suffers from ingress of dust over time and whilst this isn’t a major cause of noise it nevertheless
doesn’t help with the operation. Here is my solution:
To gain access to the gearbox firstly isolate the power supply.
Undo the securing screws of the cover and put them somewhere safe.
Swing the head stock away from you so that the gearbox faces you.
You will be confronted by the belt and the pullies. Firstly, vacuum out the gearbox and cover. I strongly recommend the wearing of a face mask at
this point and also disposable gloves.
I foolishly removed the belt from the drive/motor end and the plates, under spring tension, snapped shut. Oh no! Initial panic but a few words with
the Axminster Tech team put me right. The pulley plates on the drive shaft were ingrained with dust and therefore their removal was needed to
give the drive end a good clean. To remove them I needed circlip pliers. After all my years, the one tool I didn’t possess was circlip pliers but these
were easily obtainable from the internet. To continue.
5. Grasping the spring on the shaft remove the circlip and place it somewhere safe. The plates on my lathe had closed and therefore there was no
energy in the spring. If the belt is in place the energy presented is present but minimal. Remove spring, retaining washer and nearest plate. Undo
the grub screws holding the back plate onto the shaft, remove the plate.
6. Give the plates and the shaft a good clean. The shaft may require some attention using a 400grit abrasive, or finer, or wire wool to remove any
residual gunk on the shaft.
7. Lubricate the shaft. I used silicone fluid.
8. Whilst the shaft is bare, access to the variomatic shaft (the shaft that drives the live end) is made easier. I made no attempt to remove the pullies
here but cleaned up as best I could in situ. By operating the lever to a high speed position the plates will open up thereby allowing you to apply
some lubrication to the shaft and bearings of the variomatic device situated between the plates and the fixed live end bearing. Ensure that all grub
screws in this area are tight.
9. Replace the drive end back plate to a circlip situated on the shaft close to the motor housing. Tighten the grub screws so that they bight into the
shaft and not the keyway on the shaft. Now comes the tricky bit. Replace the second plate, but do not try to fit the belt at this juncture as you will
never get the circlip back onto the shaft unless you have a gorilla as an assistant. The plates will close together but don’t worry. Return the spring,
retaining washer and circlip.
10. Place the drive belt on the variomatic pulley first and then manipulate the pully over the drive end plates. The belt will be tight but you can get it
to sit on the plates. With your thumbs on the circlip end of the shaft and your fingers and fingernails pull the plates apart so that the belt starts to
enter the gap between the plates. Now put pressure on the belt and it should begin to slide between the plates.
11. If you are lucky enough to have a set of bearing extractors these will probably do the trick however the plates are made of alloy and any undue
force will crack the plates. Seek advice from Axminster first.
12. Taking great care with the cover off, reconnect the power supply and give the lathe a test spin. Operate the speed changes. This is a good
opportunity to observe how this clever piece of kit works.
13. Remove the power supply again and check the grub screws around the operating lever are tight. Being curious I undid and removed mine. The
operation is a simple rack and pinion movement on a square threaded shaft and it transpired that this was where most of the noise was coming
from because of loose grub screws. I replaced the lever and tightened up. (Note: There is a certain amount of backlash between rack and pinion as
it is very basic system)
14. Replace the gearbox cover with the screws, if you haven’t lost them on the workshop floor.
Return the head stock to the datum position, replace the power supply and test run.
Mine now runs like new with a smooth, quiet lever operation and didn’t realise just how bad it had become before I had carried out this
maintenance routine.
I have a tip for the club members as contained in the Amazon link below. I think it will
be of interest.
If anybody uses a tablet computer, of any kind, or indeed a larger smart phone for
Zoom, or You Tube or just reading, …..I have found possibly one of the best stands
around.
The thing that makes it so good is the weight of the base (almost impossible to over
balance) the quality of the manufacture, and the design. It is as good sat beside the
lathe for working ‘with a demonstration’ as it is located on a table in front of you for
taking part in a Zoom meeting.
Another plus is that if you have a cover (that protects your tablet) this stand
accommodates that as well, so no removing your case everytime you want to use
the stand!
Well worth a look!!
Tim Awmack.
Bottle cutting on the lathe
The title is a little misleading. As you know, you don’t actually cut glass, you break it in a controlled way. The lathe is never switched on, it is used as
a jig to enable accurate rotation of the bottle, by hand, while the diamond or carbide tool is applied. The base of the bottle goes in the chuck jaws,
the cone live centre goes in the neck. The bottle is not gripped by the jaws; the jaws and tail stock are tightened just enough to prevent any sideways
movement. The only movement of the bottle should be rotation. I use a piece of non-slip cloth in the jaws as metal on glass feels wrong. It is
necessary to have some sort of block on the tool rest to prevent the tool from wandering sideways as you rotate the bottle. You need to try and get
an accurate unbroken circumferential score-line around the bottle, starting and finishing at the same spot, in one rotation if possible. Because
bottles are never truly round, it’s worth practicing on old wine bottles first, to get used to the amount of pressure needed to create an even score-
line.
The bottle is then fractured along this line by pouring boiling water on it, trying to concentrate the water on the score line. Subsequent rapid cooling
under the cold tap should result in the two halves separating along the line. There is a failure rate, of course. Because the hot water spreads over a
large part of the surface, cracks can appear radiating aware from the desired fracture line. This isn’t always a disaster, as long as the cracks are into
the waste piece. To reduce this, I use rubber bands around the bottle either side of the line to channel the boiling water. These bands need to be a
good 5mm or more thick to be effective. I have a pair of silicone straps that work like cable ties but I haven’t been able to find a source for these
anywhere (they came in a commercial bottle-cutting kit, most parts of which I don’t use).
However, you can make your own bands by piping a thick bead of ordinary bathroom silicone sealant around the bottle as appropriate. You can also
make reusable bands in the same way by wrapping baking or grease-proof paper round something slightly smaller than your bottle and piping
silicone round that. Once it goes off, it will peel away easily to form very elastic bands that can be stretched round the bottle to be cut (see pictures).
The cut edges of the bottle are cleaned up and smoothed using wet and dry sandpaper starting at about 180grit and going up through the grits, up
to 2000, depending on the final use. I also dry-sand the edges, especially when using finer grits, with a sanding pad in a Jacob’s chuck in the lathe.
Wear a face mask, you don’t want to inhale glass dust.
Peter Hatherell
