Back to Bed . . .

Sometimes things which should be just a small part of something else turn out be of major significance all by themselves.

I guess that's where a saying we used to have in the IT industry comes from :
"The first part of the project takes the first 90% of the effort.
The last 10% of the project takes the other 90%!"

This lifting bed idea seemed so simple.
What could be so hard?
Some guide rails, some pulleys, a gearbox, a small motor : should be easy.

Then all the small difficulties add up to NOT EASY!

Eventually you remember the other little saying :
"Sometimes the shortest way there is the longest way round."

So eventually I have decided to do it properly.
With chains and sprockets and shafts etc.
The basic structure is there it just needs a few little modifications.
Famous last words. . .

Chain is not cheap. (Not really expensive either but there is not point throwing money away.)
It is like most things there is an optimal size (for manufacturing) ; smaller OR larger than which it is more expensive to make.
After hunting around I found a supplier who had a quantity of the optimal size chain (normally used for go-kart drives) which had been sitting on the shelf for five years and he would be happy to just recover some money for it.
This mechanism will need quite a bit so the whole roll was purchased.


















Then it was discovered that two pieces of chain would not fit past the rollers in the track.
This was suspected right from the beginning so the track was mounted on an upright through which the return side could be fed. Of course, hoping not to need to do this not all the relevant openings were made from the beginning. This left the choice of cutting out all the tracks, making the changes and putting them back in or trying to do them in place.

"Oh well. Let's try it in place first.
I can always take it out and do it the other way if I have to . . ."

First I needed to remove the front part of the track so I could get at the back and cut an opening between the track and the support for the top sprocket to guide the chain over into the support/return tube.
The only way I could really get at it was a 9" angle grinder.
Not my favourite tool - rough as guts!


















Next a series of holes was drilled along the bottom of the cuts (can't get the grinder in there) and the pieces broken out. Of course this will never be seen as it all gets covered up in the final fit out but I couldn't really leave it like that - could I?

























The only thing to reach in there that I could think of was a die grinder with a rotary burr.
This tool is a carbide "round file" which can be driven in a compressed air driven tool like a straight drill. They run at about 10,000rpm and will cut straight through mild steel. They come in all shapes and sizes and can be used for freehand carving in "relatively" soft metal.


















This one did a great job of cleaning up.
Then it was on to the bottom part of the tube where it had to go through a cross brace as well.
A case of drilling a hole through to start and then carving out the rectangular shape.
All of this work had to be done on each of the four corners upside down from underneath.
Like this to start :


















And like this when finished.
(The jagged shapes are just light reflecting off the metal in different ways.)


















Of course all went well until the very last one . . .














I thought these things were solid carbide but it appears that the carbide head is silver soldered to the shaft. Silver solder is good stuff when applied properly giving over 90% of the strength of mild steel. In this case I think it's the "applied properly" bit which was a problem. At around $40 each I think I will be looking for a replacement on Monday morning.
Then its make the sprockets, etc. , etc. etc. . . . . . . .

I think this is the long way round bit (but I wont be happy unless it works reliably and properly).

In the mean time . . . I'm exhausted after all that so it's . . . . back to bed .