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Post by BigMark on Mar 4, 2005 6:21:34 GMT -5
Hi again all. I have just recieved a cd of images from Stu (Many Thanks Stu)I hope he does not mind me using this image as I have a question on the chassis design. As you will see the sides are flat and double braced, and there are braced corners instead of the bulkhead. Do people think this will give me enough structural strength compared to the curved bulkheads as they would be a lot easier to construct. Opinions please....... Oh to clarify Stu does have bowed out stringer on the sides but I am not sure if these are just for the look.
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Ian
New Member
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Post by Ian on Mar 4, 2005 13:07:40 GMT -5
Looks fine to me...Ian...
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Post by BigMark on Mar 5, 2005 2:39:00 GMT -5
Cheers Ian, I'm just a little unsure as when I ordered the plans from Alan the main thing he said to me was make sure you keep the bowed sides as much of the strength of the chassis comes from there. Any other opinions ??
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Post by BigMark on Mar 5, 2005 11:51:09 GMT -5
Come on guys, I would have thought there would be a load of opinion on this one!!
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Post by MiNiTiCi on Mar 5, 2005 14:29:12 GMT -5
Hi Mark, Intutively - a single curviture structure should be stiffer than a flat panel in torsion? Therefore Alan's original curved side panels make good sense. (and plenty elbow room!) ;D Doug.
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allan
New Member
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Post by allan on Mar 5, 2005 15:06:42 GMT -5
Terrapin curved stressed side panels; for anyone planning to eliminate them in favour of flat sides -DONT They are an utterly fundamental part of the tube chassis. I f you have any doubts, build one of each in balsa wood and do a hand twist check They are one of the "secrets"
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Wayne
New Member
Posts: 49
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Post by Wayne on Mar 5, 2005 16:07:57 GMT -5
Hi Mark I would have to agree with Allan. I would not let the complicated looking design design put you off its really quite simple once you get started the curves are not very tight and easy to roll up. Make the 2 sheetmetal skins first and use these a templet for the tubes once you have rolled them up simply tack the whole lot together. Cheers Wayne
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Post by Jawfish on Mar 5, 2005 16:30:39 GMT -5
Mark, I would think that the bowed out strigers, such as Stu's would be structural, The bulkhead behind the seat is squared, so repeating the process with bulkhead #2, shouldn't cause a problem in regards to torsonal stiffness. I do agree also with Allan to the detrimental effect of not having it. I didn't find the building process difficult, it just a long process. In my case I just beat the tubing with a mallett between some 4*4 to get the desired curved, and using my jig to see the progress every so often, tedious but very good to lower my stress level .
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Post by BigMark on Mar 6, 2005 2:01:06 GMT -5
Well, many many thanks for the responces guys. Looks like I'll be keeping the diaphram design then ;D Fred, you mention bending using 4 x 4, how does this work? sorry if I am being really stupid asking this
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Cita
Junior Member
Posts: 89
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Post by Cita on Mar 6, 2005 4:55:15 GMT -5
Bigmark,i think Fred means that he places the two 4*4 a small distance apart,let's say a bit under a foot,lay the tube across on it and hit the the tube with a soft mallet right in the middle. By replacing the tube a little further to the right and/or left after every hit,you will notice that the tube starts to form a bow. Dont hit to hard and check the shape as often as possible and you will be able to produce an almost perfect bow within a matter of time.
Cita
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Post by Jawfish on Mar 6, 2005 9:08:55 GMT -5
Could not have said better Cita, I actually placed them 8 inches apart Hey Mark don't feel bad, I had no clue how to do it at first, I tried it that way and it worked. You do have to be carrefull to bend it straight, because the tube can twist sometimes, but it just a matter of hitting it back in the proper shape. I'm building the bulkheads for my new frame this week, so I'll post some pictures of the whole process. Noel Idea is very good see Bending tube jawfish.proboards43.com/index.cgi?board=tech&action=display&thread=1110068022 I am going to try it also.
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Post by BigMark on Mar 6, 2005 9:13:59 GMT -5
Cheers for the tips guys. appologies for asking so many questions but as you say fred I have not got a clue about some of this stuff
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Post by Jawfish on Mar 6, 2005 9:27:24 GMT -5
Mark one of the reason for this forum is to be able to learn, from other's experiences.
You can learn by asking questions, but you can also learn by messing things up the first few times, and doing it right after a few trials. I prefer the first method. ;D
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Post by BigMark on Mar 6, 2005 9:47:10 GMT -5
Well all I can say is thankyou to you all. Ah well on to the next question
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Post by Terrapin on Mar 7, 2005 9:23:11 GMT -5
Mark, just for info. Made my bulkheads on MDF formers not unlike those shown above. My bulkhead hole swaging tool (home made from Lignum Vitae) went to a locost builder in Scotland and never heard anything back. Think he may still post on the locostbuilders site.
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