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  #21  
Old 25th June 2009, 05:29 PM
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geeman geeman is offline
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Well every single piece of mine was cut to the exact size im mm+->0.5mm, and every angle was exact, as i measured every peice several times before putting them inplace. The errors have happened while welding casuing distortion and metal to twist. For example my chassis isnt completely flat on the board anymore, its risen about 2mm after welding in places, but the +-3mm i was talking about is what things like diagonal sizes between welding a square.
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  #22  
Old 25th June 2009, 05:34 PM
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Also i bet some people out there who will read this thread and are making there chassis will go 'oh s###' as they realise theve been working to much larger tolerances than 0.5mm

on a more serious note, i also realise for many having things like magnetic clamps could have made your lives easier, but ive only got 5 g clamps and a set of welding clamps atm, and im struggeling with just those to hold things in place for welding
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  #23  
Old 25th June 2009, 05:37 PM
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Quote:
Originally Posted by geeman View Post


Oh sh... i just made handy andys mistake ive welded u7 wrongly........uhhhhh uhh. Time to get the cutting discs out as my tig welds dont come off easily.

i didn,t actually make this mistake, it almost got me so thats why i said to be careful about U7 as it is easy to get wrong

may i make a suggestion said with all due respect....... slow down a bit.......
yes it is very tempting to get on with it & get it done, i for one have got mine rolling in a fairly short time, BUT if you have the 10mm out at the front now plus the odd 3mm +- here & there by the time you come to fitting your suspension brackets it,ll be a nightmare to get the whole thing to come together, please accept my apologies if this sounds like "sucking eggs" but deep down we all want you to achieve a good build.
i hope you are ok with my suggestion.
stop, take stock of where you are with the dimensions & correct them.
i,m sure each & everyone of us that has built the chassis have made mistakes but they must be put right at an early stage.
best regards
andy
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  #24  
Old 25th June 2009, 06:42 PM
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Ok, after reading all your advice, and to be honest all of you are really telling me the wright thing to do, its just im kind of in the 'denile' stage of thing( ), i went out to recheck everything, check measurements, angles... Here are my problems(ps having a book to hand may be handy, unless you know the diagrams off by heart). atm, the main thing is that u1, u2 dont fit in properly. I tried to figure out why, starting by measuring all the lengths. The only length that i cut that was out were ff2, and ff3, and the longer part for ff2 and ff3)the 290mm bit is about 292mm, but i think this is because the bend in the tube isnt perfect. Ok well what i said originally about ti being 9mm off if wrong, as i realised when i was measuring it i had taken all the clamps of the board as i needed them to hold tr1 and tr2 in place for welding. The meant that the whole thing has been raised by about 5mm and was supported by friction on the wood blocks that were used as guides along the drawings. This means that the front is actually 359mm not 355mm. the gap between u1 and tr1 is around the 4mm. So im nopt sure as to how to lower the frond without redoing the nose. I could also try cutting the bottom of ff2 and ff3 with a cutting disc and then weld that back to ff1 to fix it.

Also i was saying earlier that fitting tr1 and tr2 was very ight and required force as u3,u6,u7 and u8 may not have been welded completely square to the base. So i had to just bend it abit, but i was aware this would happen while welding, so i had only lightly tack welded u3 and u6-8 to the base.

Also the 3mm tolerance i was talking about only really applied to the diaganal between rectangle br7-10 which was just over 805mm rather than 808mm. Apart from this everything else is perfect
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  #25  
Old 25th June 2009, 07:13 PM
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without actually seeing your chassis i think the main cause of the problem is more likely to be as you have said, caused by movement in the chassis from fully welding some of the pieces........ can i ask if you have fully welded BR1 BR2 to BR3 & BR4 ? as if you have then maybe this is why the chassis has been raised at the front ?

if so you might be able to cut the above out & re do them which hopefully will bring things in line for the front frame.

andy
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  #26  
Old 25th June 2009, 07:36 PM
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ok.. umm imm trying what your saying, but first, can someone try and explain to me what figure 4.10 is saying on page 39. It doesnt make any sense to me it may not actually be the dimension problem, it might just be that i cant fit u1 and u as im not sure how they attath to tr1 and tr2 respectively.
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  #27  
Old 25th June 2009, 07:46 PM
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if you place U1 as said in the text in the book square to BR7 then slide the piece U1 along & under TR1 then the top front corner of U1 should be aligned with the outside edge of TR1, suggest you clamp it in place then do the same in opposite hand with U2 & TR2, clamp that as well then look at the diagram at bottom of page 38 you will see that you need to achieve 361mm between the bases of U1 & U2, that is what is most critical for these uprights ( as long as they have been cut to the correct length & angled correctly) as they give the mounting angles for the upper rear front suspension brackets.

one question..... do you have the "first edition" book or the revised edtion thats states it was re printed in 2008?
as this may be relevant.

andy
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  #28  
Old 25th June 2009, 07:51 PM
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I have the reprinted one from 2008 that has the corrections. Umm let me try what you said, ill be back in 5 min
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  #29  
Old 25th June 2009, 08:10 PM
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ok, well i still dont get the diagram on page 39, but i think i shouldnt get so worried as it actually fits, there is only about a 1.5mm gap which can be fixed by lowering the nose very slightly, but im wondering if thats even nessacasy. look at attached pics.
ALso is there a way to attatch pics without uploading them to imageshack or equivilant??





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  #30  
Old 25th June 2009, 08:21 PM
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looking good, did you get 361mm between the bases of U1 & U2 ? ( a little tip..... draw a center line down the length of your build table & scribe the center line on BR7, 10, 11 & 12 ) this will come in handy also later in the build.

how high is the very top of TR1 & TR2 & what is the distance between them( at outer edges) where they meet the front frame? sorry if this means going into your garage again, just trying to work out your dimensions to be able to help if i can.

andy
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