Ion Systems - Build progress log

[TechAUmNu]

Tried it with one of the typhoon lightweight bots. Very difficult to get a thin strip to bend into a perfect ring and if it's not perfect first time then it's junked as you can't re-roll it.

We don't need a ring though, just sections, so we can probably get away with it.

[overkill]

I figured it was the top & bottom rim armour. Mild steel will definitely cost less, but the reason you don't see it used much is because its not very effective. Is the aluminium plate thick enough to tap a screw in from the side? If you deleted the tabs, and used the spare weight to increase the thickness of the aluminium at the rim, then the ring can be made in one piece and there is just one weld, which will really reduce costs. Having countersunk screw heads on the outside face is a compromise but if the steel ring is thick enough, make the countersink as deep as possible for extra protection. This also allows field replacement without welding, a huge advantage.

Like Garry mentioned, ring rolling is not an exact process like CNC milling. Once those segments have also been distorted by welding on the tabs, you may find that the parts don't fit into the recesses in the aluminium. To fabricate these accurately enough to fit reliably will take a CNCed jig like a section of the aluminium plate. The fabricator may be adding the cost of a jig into the quote.

Another cost is the flush outside bracket; the fabricator will have costed in labour to grind the welds flat. If you can avoid the flush joint, costs will come down.

Is there room to put the bolt in from the inside? avoiding the countersinking in Hardox will definitely reduce costs.

If you have to put the bolts in from the outside, is it possible to use a nut inside? Tapping hardened steel is a real pain and using a nut will cut costs.

That overlapped weld area will make replacement really difficult. If the tabs are recessed and shaped so each segment slides in, then then one end of each segment is trapped under another segment and they will ALL have to be cut off to replace just one. Much simpler and cheaper to just have a but weld between segments.

[overkill]

I just saw your reply to Garry - its difficult to impossible to roll short ring sections, there is usually a length at each end that doesn't go through all the rollers or if the ends DO go through the rollers, they have a different curve. All metal has an amount of spring back when its bent; when you roll a full circle, you usually adjust the diameter by trimming the ends and then weld them. If the segments are made separately, it will be harder to get the curvature accurate.

[TechAUmNu]

Because of the location of the rings, is it going to be that crucial that they are hardox? They are really there to provide a bit of protection for the internals and make the aluminium less likely to bend at the edges if we get flipped. (The bottom one will also help against PP3D...) The main spinner is slightly further out and should take most of the big hits.

We could maybe compromise and do one ring in hardox and the other in mild steel. Then we can start the way up that makes the hardox one take the most beating based on who we are fighting.

The aluminium plates are already machined, they are 15mm. I don't think bolting it in from the side is really an option it will most likely just rip or fracture the aluminium around the bolts. Especially after seeing what Aftershock can do.

The sections will be bent as a long bar then cut up, so we just wont use the ends. Then the tabs are bolted in place on the aluminium and the section is welded to them. Which should stop it deforming too much. The added id tension should also help make the sections flush to the aluminium.

The overlaps are either both under or both over so only a maximum of 3 would need removed, although I agree a butt join would be a lot easier.

We will do the countersinking and threading so it doesn't add any cost, we can probably change the tabs to mild steel without too much loss in strength which will make our lives easier. There is no space on either side so unfortunately using nuts is a no go.

All the welding/grinding/machining is being done by our uni workshop, so its effectively free although they are really slow. The main cost is getting the material in the right shape.