Originally posted by Slimy38
quote:
Originally posted by subjated
If you put BR10 in the right place and put BR3 and BR4 on to it, what measurement is wrong?
I have the book errors as PDF's somewhere, PM me an email address and I can ping them over. However, I will say there are no errors in any of the BR pieces. The front frame construction on page 37 is the first real step away from the book, and that's only to make the suspension mounts sit better.
PM sent
ive done it the other way so br3/4 is on br11 if i join it the other way an put br3/4 on br10 i get the correct 924mm but then br3/4 sit nearly 10mm longer than br11
nick205 - 24/10/16 at 08:14 AM
As suggested, make the chassis and measure/make the tubes to fit. From personal experience CAD (3D included) is very useful, but it is a screen representation of reality. What appears right/wrong on screen is often best corrected in reality.
jps - 24/10/16 at 09:54 AM
Or....
quote:
Originally posted by subjated
obviously i understand in real life i can just cut the pieces of metal to actually fit the gap
!!! :-)
[Edited on 24/10/16 by jps]
Dean m - 24/10/16 at 02:08 PM
Hi.
If there is any measurements or help I can provide just ask as I have my bare chassis on the build table at the minute.
I used a Talon flat pack chassis kit so it all goes together like a 3d jigsaw ( you almost don't need the book 
)
Can I ask are the measurements correct when you measure from br12 to br11 813mm outside edge to outside edge and br12 to br10 1385mm outside edge to
outside edge?
I drew the bottom rails out on my build board before laying down any metal and the measurements where all spot on.
subjated - 24/10/16 at 06:31 PM
thanks for all the replies, im using a 3d cad package to be precise.
in answer to your question dean (thanks for the help of measurements too!), yes those measurements are correct, its just as though the angles of br3/4
are wrong
talon suggests that i "put the computer away and go lay out tube on a build table" but talon himself sells flat pack kits; and if they go
together as well as everyone says i can only assume hes made tweaks along the line.
i shall be cutting my tube at work and welding at home, but if i cut the tube exactly to the book appendix i know for certain it wont fit without some
"modification"
i know full well i can get around this, and im not particularly concerned, just curious as to why it doesn't seem go together properly in a 3d
model since the book states "the measurements in this book are very precise"
if it is my mistake somewhere at least i wont scrap a bit of tube cutting it to what ive drawn and further down the line i can use the model to check
seat fitment (which i plan to fabricate from aluminium sheet) stress tests etc etc has all sorts of useful applications!
plus i can start building yet so this is as close as i can get
Slimy38 - 24/10/16 at 10:21 PM
quote:
Originally posted by subjated
quote:
Originally posted by Slimy38
quote:
Originally posted by subjated
If you put BR10 in the right place and put BR3 and BR4 on to it, what measurement is wrong?
I have the book errors as PDF's somewhere, PM me an email address and I can ping them over. However, I will say there are no errors in any of the BR pieces. The front frame construction on page 37 is the first real step away from the book, and that's only to make the suspension mounts sit better.
PM sent
ive done it the other way so br3/4 is on br11 if i join it the other way an put br3/4 on br10 i get the correct 924mm but then br3/4 sit nearly 10mm longer than br11
Info sent, send me both CAD pics and I'll see if I can tie it in with my chassis.
Slimy38 - 24/10/16 at 10:31 PMI've just realised something. Are you using the profile angles to determine where the tube should lie? If so, that's where the error is. The profiles are to the nearest degree which is about as accurate as a human can cut, and plenty accurate enough to make a weldable joint. But they're nowhere near accurate enough for a CAD program. That would account for the missing distances.
Try and lay things out by the lengths and positions only, let the angles sort themselves out. Use the diagonal measurements to double check, they should be spot on too.
subjated - 25/10/16 at 07:33 PMquote:
Originally posted by Slimy38
I've just realised something. Are you using the profile angles to determine where the tube should lie? If so, that's where the error is. The profiles are to the nearest degree which is about as accurate as a human can cut, and plenty accurate enough to make a weldable joint. But they're nowhere near accurate enough for a CAD program. That would account for the missing distances.
Try and lay things out by the lengths and positions only, let the angles sort themselves out. Use the diagonal measurements to double check, they should be spot on too.
This is as i may have suspected, that answers my question, i could laser cut my tube with a +/- 0.1 degree accuracy which is why i asked, but since the measurements are not accurate enough for that ill set about the old fashioned way!
Slimy38 - 25/10/16 at 08:56 PMquote:
Originally posted by subjated
This is as i may have suspected, that answers my question, i could laser cut my tube with a +/- 0.1 degree accuracy which is why i asked, but since the measurements are not accurate enough for that ill set about the old fashioned way!
Yeah, I'm not sure Chris Gibbs had laser cutting in mind when he wrote his book!Glad to hear you're all sorted though.
subjated - 26/10/16 at 06:17 PMquote:
Originally posted by Slimy38
Yeah, I'm not sure Chris Gibbs had laser cutting in mind when he wrote his book!
a very valid point, should of thought of that!