Eternal Rubbing Derailleur

Is this common? My front derailleur seems to creep out of angle till the chain begins to rub more and more when I climb in small gears. It may be fine for 3 weeks and then I have to make major adjustments. It practically ruined my ride yesterday when I had to stop and get my tools out.
I just tried buying a new screw to refit the entire derailleur in case it's slipping.
But it gets worse. Often when doing a refit, I find the shift works fine on the rear derailleur but soon as I shift to the big chain ring there is one hell of a grinding noise. It can take ages to adjust cable tension and angle till the noise ceases.
I have a sora at present but it gives me continual problems. I'm thinking of buying another model.
Again, is this a common problem with front derailleurs?

Is this is a clamp type derailleur? It sounds like the inside diameter of the clamp is just a little bit too big for the seat tube, and you're bottoming out the clamp. Before you go out and buy a new derailleur, try shimming the clamp with a strip of aluminum foil or beer can.

It's fastened by a long screw you tighten with an allen key.
What I try to do is slacken off the cable and then carefully move the derailleur so it's slightly clear of the chain on the smallest gear I have on my bike (on the biggest rear-wheel cassette cog and on the middle chain ring).
The whole idea is there should be no rubbing when I'm on my smallest gear climbing, although I don't mind rubbing on the two last large gears (I don't use these so often).
But i'ts tough. I have real problems with setting this up. Usually I can do quite a good job but it seldom lasts very long. It seems like the derailleur is moving slowly which is why I thought I'd buy a fresh screw and really try and tighten it to the limit.
Are all derailleurs so problematic do you think? Maybe sora aren't so good?

Sora has worked fine for me. Three years on the bike without more than token adjustments twice during scheduled maintenance.

But, since all I have to go on is my experience and yours, I don't know if I am the exception or you are...

Nope. It's just you, Carrera.

With all of the hill work you do I'm going to take a stab at guessing and say you shift quite a bit with the front derailleur. Is that correct?

You may have simply worn it out over the years of use. Mechanical things do wear out over time and the more they get used the greater the likelyhood of them doing so. I live in a very flat part of the World and hardly ever shift out of the middle chainring so my front der. hardly gets any use. Also, only a couple of cogs on the cassette wear as I have no real need to shift frequently.

You may just want to get another front derailleur if it's needing that much adjustment. You may be able to rebuild it but Sora isn't too expensive. You may want to consider moving up to 105 if you shift quite a bit as I'm suspecting. Here in the States you can get a 105 5501 front for $25 plus shipping. For $25 it isn't worth the hassle of screwing around with one that doesn't work properly or needs too frequent adjustment. Put on a new shifter cable while your at it.

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Maybe you have a point. I shift all the time. I may fit a new derailleur now or maybe let winter pass first.
I purchased an allen key set and have a new screw so I may get a tighter fit.
The gears I use most tend to be my very small climbing gears in conjunction with the mid chainring. Then I have a habit of shifting onto the big ring and using the midway cassette sprockets for the flats and slight ups.
That's where I tend to get trouble on the shift and release. I can get grinding on the big chainring or rubbing in all cases.
Really it's the last thing anybody needs when on a serious training session. You have to dismount as the noise is driving you crazy.
Still, at least all of this is easier than changing a timer-belt on an engine - my latest task to perform. Now, I guess bike mechanics seems an easier option.

Sora works fine most of the time. It's bottom of the Shimano road line but it's functional. It is considerably higher quality than the low end MTB components.

You could try a new screw and perhaps put some Loctite on it to hold it in place once it's set up. If that doesn't work I'd consider putting a new 105 on as it's not worth the hassle as stated above.

New screw might not help. If it is clamp-on, the clamp could be distorted from overtightening and bottoming out when you try to tighten the screw further. I agree with Dr. Morbius, try a new FD.

Go fixed or hub gear for perfect alignment and an end to deraillier rubbing misery.

The situation has improved somewhat but this might be a lesson for everyone who had derailleur trouble.
What I did was remove the whole derailleur today and what did I find? The entire inner part of the clamp was caked in grease. I mean, it was thick with dirt, grime, oil and grease.
I imagine there was no way it could clamp on to the frame as there was no surface to grip against.
So, I got plenty of hot, soapy water and cleaned the entire inner clamp as well as the frame where it fits.
The next bit was the usual nightmare. I always have problems getting the gears to run smoothly without chain rub on both big and small rings together. I can start off with no rubbing on the small ring but on shifting to the big cog the noise is horrific.
Just a slight squint of the angle or too much (or too little) height and it doesn't run smoothly.
So, the situation is better now but not perfect. I suspect I have a slightly bent derailleur and will buy another one a bit later on.
On a sad note, yet another training run has had to be cancelled today due to these mechanical problems. I spent the day de-greasing my chain, cogs and cleaning the bike.
But I seem to be constantly held back from getting proper rides and spending way too much time trying to keep the bike maintained.

are you running little front sprocket on the front to little sprocket on the back? and vice versus?

Careera uses his big ring, and runs big to big but won't admit it.

does he really? because that explains a lot.

He thinks that the small chain ring is for wusses.