New HW design - Omni Wheels and 30kW spinner

[maddox10]

A piece of hardox 750*750*40 weights 178 kg, and with a kilo-price of hardox being around £3 you're talking up £600.

[TechAUmNu]

A piece of hardox 750*750*40 weights 178 kg, and with a kilo-price of hardox being around £3 you're talking up £600.

OK, so getting some more parts in the middle should significantly decrease the per part price.

[typhoon_driver]

Or the other option would be to do what we did with the middle weight typhoon and either salvage or purchase a piece of metal pipe with roughly the right dimensions and weld some hardox teeth onto it.

[TechAUmNu]

We want to make some kind of spinner protection for our bearing system, so can probably use a lot of the middle for that.

Have you tried tapping holes?

[typhoon_driver]

Tapping in hardox? Haven't done it but I'm aware that the SSAB website says it's possible. Probably need some taps a bit better than a set from silverline etc.

[maddox10]

You can drill and tap Hardox 450 with good quality HSS tools. But those well be worn out after 1 or maybe 2 uses.

Hardox 500 forget it, unless you have full hardmetal tools.

[overkill]

If you tap holes in the ring, you will first need to drill them to the right diameter; waterjetting won't leave a consistently round hole. Like any hard metal, the hole will need to be sized for a lower thread engagement. Saab may have some suggestions, I would guess at 50% or less to save the sap from breaking. Taps designed for hardened steel usually have cobalt and vanadium and an oxide over nitride coating. You will also need a heavy duty cutting oil.

Update: How about making a tapped steel spacer and pressing that into a hole in the ring? If you are attaching armour to both sides , then it can't pull out.

[TechAUmNu]

If you tap holes in the ring, you will first need to drill them to the right diameter; waterjetting won't leave a consistently round hole. Like any hard metal, the hole will need to be sized for a lower thread engagement. Saab may have some suggestions, I would guess at 50% or less to save the sap from breaking. Taps designed for hardened steel usually have cobalt and vanadium and an oxide over nitride coating. You will also need a heavy duty cutting oil.

Update: How about making a tapped steel spacer and pressing that into a hole in the ring? If you are attaching armour to both sides , then it can't pull out.

Nice idea! That sounds much easier than tapping the hardox.

Here is what I have managed to do today.

Dropped to 35mm hardox, and added some 6082T6 tracks/reinforcement for the skateboard wheels to run on.

ring assembly.jpg

[overkill]

Happy to help! In the last CAD render, are the gear teeth cut into the hardox ring? I cant see how the bearings are going to run on the ring's ID if it has teeth cut into it.

[overkill]

Here is an alternative bearing arrangement that I'd like some feedback on:



It uses a pair of 30205 tapered roller bearings, which are very common & cheap. They are enclosed in a stepped roller that distributes force from the ring and keeps them aligned. here are the pros & cons compared to having separate vertical & horizontal bearings

PRO:
* Half as many bearings to mount & maintain.
* The bot can have a lower over-all hight, which offsets the weight of the rollers.
* The armour above the ring can be lower, which offsets the weight of the rollers.
* The ring is much lower, which is more effective against most bots and harder for vertical spinners to damage.
* Less (or no) armour needed under the ring.

CON:
* Increased friction between the ring and the lower shoulder of the roller.
* Might be more complex to assemble.
* The rollers might increase the over-all weight unless the smaller side armour and fewer bearings & their supports offset the roller weight.