leto
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| posted on 1/10/04 at 08:32 PM |
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This the first time I read anything on this forum that actually scared me.
"Drilling the centre of bolts is OK as the centre is actually a nuetral axis."
This statement is not wrong, it is true IF the bots are bended or twisted. If a bolt is in tension or in shear, and most are, there is on “neutarl
axis”, the whole cross section of the bolt supports the load and drilling out the center will make it weaker.
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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I love speed :-P
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| posted on 1/10/04 at 08:41 PM |
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just 2 add something which i will probly regret, wasnt the whole point of holes, used in aeroplanes, 2 a make them lighter, but also, 2 move the
stress points or something?
Don't Steal
The Government doesn’t like the competition
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Cita
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| posted on 1/10/04 at 09:14 PM |
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The pr guys widely misuse the quality of aircraft material to compare their own products.
What those smart guys dont tell you is that for example a helicopter,even the most advanced military one,would fall apart after a few thousand miles
on the road if it would be used like you drive your daily car,if you understand what i mean.
All i'm saying is that it is damn difficult to compare things so drilling holes to enlighten a part is not per definition a bad idea,or for that
matter a good one.
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David Jenkins
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| posted on 1/10/04 at 09:35 PM |
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True - most aircraft have maintenance schedules that car drivers would never want to achieve!
David
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Hugh Paterson
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| posted on 2/10/04 at 12:22 AM |
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Dam-n-blast
Thats it had enough all this article has done is pee me off because that weldings the mutts nutts (not a pun), i thought i had it cracked until I
saw that O well back to horseshoes
Shug.
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silex
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| posted on 2/10/04 at 04:38 AM |
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OK, the engineers out there can argue about holes an swaging and how bad they can be, but you also know that this depends on the direction of force
and how much material it removed and that a well place hole can in fact add stress relief.
Perhaps a simple guide for the non engineers out there should be to ask yourself the following question
If what I drill breaks, could I die or cause serious injury because of it ?
If you think there is a possibility that the answer it yes...........don't drill the hole.
Murphy's 2 laws
1. If it can go wrong it will
2. In case of emergency - refer to rule 1.
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Cita
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| posted on 2/10/04 at 05:45 AM |
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Drilling out parts by amateurs (me and 99% of us homebuiders)would be done for the looks.Most of us,and certainly me, dont have the knowledge to make
a dependable analysis and according to this design the ultimate part which incorporates sometimes enlightening by drilling.
Other things can be done to improve the looks and most of the time this will add weigth instead of remove weigth but what are we talking about in
terms of actual weigth?A few kilograms at the most!Transform this to percentage and you will see that it's neglectable.
Furthermore most of the drilling is done on parts which are hidden so ...
Perhaps it's time that a more knowledgable builder than myself will come up with some sort of list which deals with all these myths like
drilling brake discs-putting extra wide tyres on etc....
I dont think that any of you guys go's to the toilet every time you take your seven out for a drive like Schummi does before every race to win
a few thousends of a second,or dou you...?
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JB
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| posted on 2/10/04 at 06:08 PM |
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Taking a Dump before a race...
I put Ti bolts on my mountain bike and a mate joked why dont I just shave my eye brows and hair and cut my nails to save a bit more!
Jb
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David Jenkins
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| posted on 2/10/04 at 06:24 PM |
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To be honest, I could reduce the all-up weight of my car by 50-60lb without lightening holes anywhere - I could go on a diet!
The heaviest thing on my car is the nut holding the wheel...
David
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cymtriks
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| posted on 2/10/04 at 08:46 PM |
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Holes can be OK if properly thought through.
Take a look at an Elise pedal, it has a network of triangular holes through its width making the lever arm into a little spaceframe. That's fine
if you have Lotus Engineering to tell you that it's strong enough. There must be a few crashed Elises around by now. Maybe these pedals are
waiting in a breakers somewhere to be fitted to locosts.
I have been looking at some shafts for jet engines lately at work. At various places along their length they have holes to allow air and oil to
circulate to appropriate places. Every time there is a hole the shaft has it's wall thickness roughly doubled around the hole. This is not an
accident. We spent weeks thinking about those holes.
I can't think of any part on a locost that I'd put a lightening hole. I don't think it's worth it in most cases. You will have
to drill a lot of holes to make any real difference and either spent a lot of time crunching the stress sums or taken a big risk in the process.
Personally I'd spend the time and effort elsewhere and not take the risk.
The best parts to save weight from are probably the wheels and tyres followed by the hubs and uprights. This helps three times over. It saves unsprung
weight thus improving handling and ride. It saves dead weight thus improving cornering, braking and acceleration. It saves rotating mass thus
improving braking and acceleration.
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