This weeks objective was to get the new front frame completed, which means a lot more in my case then just cutting some steel as described in a book and welding it together. My car is a custom version of the Haynes Roadster. When I did the first version I was thinking I'd preserve all the essential angle and distances of the (Haynes) book design for the front frame. That was when I thought I might use the classic Locost suspension design. Truth be told, I never liked those simple U-brackets welded onto the 16 gauge members. It never really seemed adequate to me in terms of strength and rigidity even though it obviously does work.
In preserving the original book configuration using my larger chassis materials, I ended up with a compromise in the way elements fit together. The edge to edge match-up of the pieces was not as good as I wanted. I felt I could do better, but would have to give up the precise duplication of the book pattern. That's what I decided to do recently because I have decided not to use the book U-brackets.
File comment: New drawing for version 2 front frame.
New-FF-Drawing.jpg [ 113.09 KiB | Viewed 543 times ]
I originally designed the chassis in one software product, but switched to a new one after completing it. That meant starting over with the front frame design rather than modifying the old one and mastering the new software at the same time. The front frame is a very tricky part. It's very clever in a number of ways, but way too complicated, I think. However, I'm too far into the project to start all over again with something completely new. I needed to improve what was there in terms of the fit for my chosen materials. All of this lead to a lot of delays and rework. However, It's done now and I think worth the effort.
File comment: New Front Frame.
Front-Frame-Assembly2.jpg [ 102.91 KiB | Viewed 543 times ]
File comment: Three quarter view. Lots of compound angles to fit.
Front-Frame-Assembly.jpg [ 77.38 KiB | Viewed 543 times ]
I was able to salvage the original jig I built way back in the wooden mock-up phase. It was tricky to build some blocks that positioned it precisely. I made trial pieces in wood first using my compound miter saw, so I would not waste steel. That revealed that I needed to shim up the top most piece and a little paper and blue painter's tape provided the final adjustment needed on the jig.
File comment: Basic pieces in reworked jig.
FF-Basic-Pieces.jpg [ 114.89 KiB | Viewed 543 times ]
File comment: Working out a precise fit and final jig adjustments using wood mock-ups
FF-Tricky-Bits.jpg [ 85.61 KiB | Viewed 543 times ]
File comment: Excellent final fit-up in steel.
FF-Rework-Objective.jpg [ 72.17 KiB | Viewed 543 times ]
That extra step gave me an excellent fit-up in the steel parts. The pieces at bottom actually fit to FF1 very well. The radiused edge of the bottom FF1 member, and this camera angle, make it look like a larger gap than it really is in real life. There is a fraction of a MM overhang on the backside due to the compound angles and keeping the front edge as flush to FF1 as possible. I just built up a little ledge of weld material to make sure it is well supported.
The cross braces are 3/4”, 16 gauge tube reinforce the area of the front suspension pickups. They're just tacked in place at the moment. I want to do a little more practice welding of thin, round tubes to thicker RHS before doing the final welds.
These kinds of things are an additional factor in my slow progress. First I have to design it, then I have to build it and often I need to master some practical fabrication process before I can complete it 100%. However, I'm not complaining. I've set this task for myself and am really enjoying the challenge of it all. I've also set a high standard for accuracy too, which I'm doing pretty well with. This piece is also my first fit-up of tubing and it went very well with my final result being within 0.1 degree of the drawing specification. Given the subtle. compound angles involved here, I'm quite proud of that.