Post by Neale on Oct 13, 2018 20:16:22 GMT
Couple of screen grabs from Fusion 360 to show the structure. I modified/improved my technique with almost every piece I cut. I eventually (after spending quite a bit of time with needle files squaring out the corners of slots and the bases of tabs) realised that location is entirely on the flat surfaces of the tabs and the rest of the structure constrains sideways movement, so tabs do not need to be a close fit side-to-side in slots. So I ended up making the slots very slightly overlong and rounding the ends, and cutting semicircular bites out of the base of the tabs to give clearance. Makes fitting much quicker and easier - you can see some of this in the exploded view.
What it is supposed to look like when finished:
And an exploded view. This was created by F360 but due to the fact that I had several pieces forming one component, and F360 explodes at the component level, this needs just a little bit of study to see how the bits fit.
Looking at the image, I see that the "explosion" has left some debris in the wrong place. The double-piece vertical pieces should be inside the single piece and not outside. Comparison with the "what it's supposed to look like" image should make it clearer.
I decided to weld it fully (remember - "What could possibly go wrong?") and the assembly is now clamped to the bed of the mill for finish machining. Picture of item to follow - my welding is absolutely dreadful although I did do a few practice runs first. However, my CNC router is all welded steel, and although the welding on that is dreadful as well, it holds together well enough to have been able to machine these steel bits for the model. Grinder and JB Weld are called for and once painted, and given that none of this will be visible once the thing is on the track, I'm not losing sleep over it. I shall probably weld the rear drag box the same way, but the intermediate stretchers will be silver-soldered. The idea of a few strategic tack welds is useful - I'll certainly consider that although I do have ideas on how I can tab-and-slot those as well.
What it is supposed to look like when finished:
And an exploded view. This was created by F360 but due to the fact that I had several pieces forming one component, and F360 explodes at the component level, this needs just a little bit of study to see how the bits fit.
Looking at the image, I see that the "explosion" has left some debris in the wrong place. The double-piece vertical pieces should be inside the single piece and not outside. Comparison with the "what it's supposed to look like" image should make it clearer.
I decided to weld it fully (remember - "What could possibly go wrong?") and the assembly is now clamped to the bed of the mill for finish machining. Picture of item to follow - my welding is absolutely dreadful although I did do a few practice runs first. However, my CNC router is all welded steel, and although the welding on that is dreadful as well, it holds together well enough to have been able to machine these steel bits for the model. Grinder and JB Weld are called for and once painted, and given that none of this will be visible once the thing is on the track, I'm not losing sleep over it. I shall probably weld the rear drag box the same way, but the intermediate stretchers will be silver-soldered. The idea of a few strategic tack welds is useful - I'll certainly consider that although I do have ideas on how I can tab-and-slot those as well.