And so, it's Thursday and my life has been tiled on it's head, so I haven't had chance to post! I'm moving back to Manchester as I currently reside in Nottingham and starting work. So I've been prepping and saying my goodbyes.
Sorry for the wall of text that is about to ensue, I apologise because I am the shy, retiring, extremely English type.
[h=2]Outer casing[/h]A piece of 1m long aluminium pipe with an outer diameter of 38.1mm and an inner diameter of 25.4mm was placed inside the chuck of the lathe with a small amount exposed. From this, the piece was faced off to give a parallel, clean surface to put in the live centre.
When setting up a centre, the tailstock is brought almost up to the work and the handle turned so that the centre is touching the work. The tailstock is locked off, the handle is then brought past the halfway mark and locked off. Locks are used to prevent the tailstock from moving from vibration once the machine is running. The handle is positioned past the halfway mark so that if vibration does occur, it will tighten the work. (Lewtas, 2017)
A live centre was used as a 250mm length of the bar would be exposed from the chuck. A live centre is held in place by friction on a morse taper shank and will rotate with the workpiece. (p.42, Byrne, 1996)
The whole bar was then turned down to 36mm diameter as that would be the thickest point. From there, points that needed to be turned down further were marked on the shaft using a marker. Beyond this cuts of different increments were taken.
Overall cut
| Increments
| Final finish
| Reasoning
|
4mm
| 2mm, 1mm, 1mm
| Shiney but slightly dull
| End cut, could take off large amounts at a time
|
4mm
| 3 x 1mm, 2 x 0.5mm
| High shine
| Was in the middle of the work and therefore needed to be taken off in smaller increments.
|
2mm
| 1mm, 2 x 0.5mm
| High shine
| Experimentation with finish indicated taking off 0.5mm increments would produce high shine.
|
To create the chamfered bulge, the inner size was marked out which should have been 6mm as 10mm by accident. This meant that more had to be taken off and it caused striping in the work. This was buffed off using two grades of emery cloth.
[h=2]Setting up a boring operation[/h]A boring tool was set up on the tool post which had been turned 90 degrees. This allowed for the tool to reach inside of the tube. When turning down the inside of the tube, the direction in which the cross-slide was to be moved was switched compared to normal operations, and therefore special care was taken to make sure the tool was being moved in the right direction. Care also had to be taken when backing away from the work to not move too far, as the tool could crash into the other side of the work.
[h=2]Polished centre bar[/h]The aluminium bar was faced off, drilled and centred in the same way as the pipe as a 250mm long section of the pipe was turned. The pipe was polished used fine grit emery cloth, held across the bar, applying pressure to improve contact between the emery and the bar. This was then cut long using the mechanised hacksaw and faced to the length just short of 180mm. The bar was cut short by roughly 0.1mm so that is would bring all sections together tightly. The bar was then centre drilled, then drilled using an 8.5mm to a depth of 25mm and tapped to M10.
These processes created a centre bar, which was polished to a high finish. It would also be the part that would bring the end components together.
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Also, I have tried my hardest to make my pictures bigger by uploading them using the direct link from imgur, but it hasn't helped at all. If anyone has any suggestions, they would be welcomed.
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Oh, if you click on them they are shown big. I am jumping the gun.