Timer Housing

In the manufacturing of the housing for the timer there are a number of procedures to follow.

The marking out and drilling

The reason for marking out is to identify where the bends are to be located and where there are holes to be drilled. There is an aluminum templet to assist in the marking out. This templet is put onto the plastic and the location of the holes are marked on with a pen. The try square is used to mark on the position of the bends to be made on the plastic. Always check in the booklet to vervify the sizes of the holes and the location of the bends.

The size of the holes are marked onto the plastic and the pedestal drill will be set up to drill the 4mm and 7mm holes. One of the holes is to be drilled 20mm and this is done using a forstner bit which is also set up on the drilling machine. This is a large hole to drill into plastic and there needs to be extra care taken to make sure there is nothing under the plastic before the drill starts.

First bend

When the plastic has been drilled and the short edges have been filed and polished on the polishing machine, the plastic is ready to be bent. The plastic is put on top of the line bender the lever is pulled up. When this lever has sprung back up the plastic is ready to bend. Set the timer is set for 2 minutes as a double security indicator.

When the plastic is floppy and ready to be bent, take it off the maching and put it into the purpose built jig and hold for 30 – 45 seconds to allow the plastic to cool down.

This will give a right angle bend.

Second bend,

This is done in a similar way to the first bend in that the plastic is put into the vice at the line where it has been marked. Note the position of the plastic in relation to the first bend and the location of the holes on the plastic. Make sure that the plastic is put in the correct way.  There may be some confussion as to the way the plastic needs to be bent  so make sure that you have a clear picture in your head as to the way the plastic is to be bent before you bend it.
When the time is up (2 minutes) take the plastic from the bender and band it arount the jig in the same way as the picture. Hold it in that position for a further 1 minute until it has cooled down.
Not the final shape of the bends.

Third bend,

The third bend is done in the same way as the first two execpt there is no need for a jig to be used. The plastic is heated on the line bender where the last bend has been marked (40mm in from the last side).

When the time is up and the plastic is soft it is bent underneath itself and held on the workbench until to cools down. This will take about a minute, it is essential that the plastic is not moved from either the jigs or the final position on the bench until the plastic is cool.

Putting on the sides and bottom.

When putting the sides on you have a choice, you can either use plastic and stick it onto the sides, or you can use wood and inlay it. The plastic stuck onto the sides anc give a very visual look and contrasting colours can be used. The wood is inlayed in the plastic and can also be very visula appealing and gives a good contrast.

More information to follow


5 Responses

  1. Thanks sooo much CTD- this site is gr8 4 the transfer revision!
    How long do you hold your plastic for after it has been bended??


  2. in the par 3rd bend you have put pench should it not be bench :S

  3. MIght want to check spellings.

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