Team Eventorizon: Build Diary

[Ellis]

Yes, those numbers are correct. Although I just use online calculators, less room for error.

I would go for a bite offset of 15mm tops. Even an offset of 10mm will give a huge single tooth effect, proven by how 720, for example, has just ~10mm deep teeth and obviously gets good bite. More than necessary and it's just dumping weight into the counterweight - mass which is better off in the sides of the beater.

[Eventorizon]

Its good to know I got it right!

I am probably going to chicken out of the full 'Single tooth' thing and go with the offset teeth because it just makes things easier. The RMI goes up, the air resistance will drop and the counterweight mass can go into stiffening up the weapon itself.

[Ellis]

Having the one side be 5-10mm longer than the other (that's what I mean by offset) will give you huge single tooth benefits and require a minimal counterweight. Be a shame to let the true single toothness go!

[Eventorizon]

Unlike the crazy 37.5mm offset I had on the previous one. I will see what I can achieve in a real single tooth.

[overkill]

Conker will be travelling slower than you calculated. Even the best Lipo cells have a substantial voltage sag under load and you only ever see 4.2V per cell at no load. I get around 3.3V under load from my Thunder power 65C packs so assuming an optimistic 3.5V, Conker has a theoretical top speed of 3.63m/s. I like to factor in a 15% de-rating for friction losses so a real-world top speed of just over 3 m/s is likely.

[Eventorizon]

I never realised the voltage drop was so significant... and I calculated it first time with 3.7v and then thought that I would get poked for it so I upped the voltage.

I have gone with 15mm of bite for now as anything more than 20 left me with a worryingly large overhang which I was concerned would mean another broken weapon.

[Eventorizon]

Looking at this as the new design for Conker 3's weapon.

Conker 3.5 weapon design 01.PNG

The main body will be some kind of tool steel. D2, S7 or another type we are investigating. The inserts are intend to be Hardox or Toolox and held in with Titanium bolts.

A problem with the original weapon was that the arms were too thin. This was compounded by Hardox's fairly low yield strength at around 1000-1300Mpa, in comparison to D2's 1650-2200Mpa. With increased material thickness and a higher yeild strength the hope is that this will mean the weapon will never deform again.

However the tool steels are no where near as resistant to abrasion. The Hardox or Toolox inserts would be able to take the main hits and eventually be turned round before finally replaced.

I may not bother with the tips though as it is more money and both S7 and D2 have proven records with no additional modifications.

EDIT: The mass of the weapon is 2.8Kg for those who want to know. Up from 2.2kg.

[overkill]

Like!

[harry hills]

Why titanium bolts?

[Eventorizon]

Why titanium bolts?

Because I don't want the inerts to come flying off or for the heads to become so damaged I cant remove the bolts. I had a total B**** of a time removing the bolt on the back of C3 which had its hex hole completely removed by 720. Oh, and cos then I have Ti bolts in my weapon

[Ellis]

Surely ti is no harder than a high tensile bolt?

Some support for the turned bits (radius above and below) wouldn't be a bad thing. All of the forces go through those shafts. Also I'd be inclined to make the difference between the offset teeth smaller so you can have more thickness in the main body of the thing. At the moment the hitting edges of the beater are relatively weak: you have reduced width, no radii on the insert cutouts and holes through the lot.

[Eventorizon]

I seem to be second guessing myself today. I take things out thinking that people will say don't bother then I get advised to put them back again :-P

Putting the Radii back on the inside is no issue but adding them to the shafts is a pain not only to machine but it means that I have to make matching spacers to go on either end. Its not that much effort compared to making the weapon but given the shafts on the original didn't bend and D2 is even less likely to bend I don't think its necessary.

[Niels - Team K.a.L.M.]

In the end it's still your machine. Do what you want and take advise where it is needed.

[overkill]

The radius doesn't have to be large; my eggbeaters have about a 1.5mm radius around the shafts and have been fine so far. I also have spacers on the shafts and I just added a simple chamfer inside the spacer to clear the shaft radius - it only added a few minutes to make each spacer.

Cutting the radii around the teeth can be partly done in the waterjetting stage and the pockets for the inserts can be machined out with a rounded edge end mill. I have used a 1/2" diameter cobalt steel cutter with a 0.06" edge radius to pocket S7 steel and the parts have not stress cracked in 6 years. Rounded edge end mills are very durable and outlast regular end mills by many times. My 1/2" end mills cost $34 and are probably the most used cutters I have.

[Eventorizon]

You and all your handy hints Nick! You need to write a book