Metallurgy blah

[Mental Trousers]

Does anyone around here know much about aluminium alloys?? I'm playing around with getting some parts made for my bike and need to know how much I can trim things down. Most parts it won't matter but I really need to know I'm designing some rearsets that won't break. A broken rearset causing a crash would be bad.

[piston broke]

are you able to make the required parts from carbon fibre?

[Grumph]

Most aluminium plate sold for general use in NZ is 5000 series which is quite good enough for our purposes. Depending on the length frame to peg use either 8 or 10mm plate. If you cut the center of the plate out don't make the remaining side strips narrower than say 15mm for 8mm plates or 12mm for 10mm plate.
With anything like this the reqirement is ductility not absolute strength. 7075 or 6061 is available but while very strong both are really too brittle for this type of application. The marine grade 5000 series sold over the counter is ductile enough in my experience to withstand at least one straightening post crash. Polishes well and anodises reasonably too.

[Mental Trousers]

Most aluminium plate sold for general use in NZ is 5000 series which is quite good enough for our purposes. Depending on the length frame to peg use either 8 or 10mm plate. If you cut the center of the plate out don't make the remaining side strips narrower than say 15mm for 8mm plates or 12mm for 10mm plate.
With anything like this the reqirement is ductility not absolute strength. 7075 or 6061 is available but while very strong both are really too brittle for this type of application. The marine grade 5000 series sold over the counter is ductile enough in my experience to withstand at least one straightening post crash. Polishes well and anodises reasonably too.

That is exactly what I wanted to know. Awesome. Have 500 green bling

[Pixie]

Does anyone around here know much about aluminium alloys?? I'm playing around with getting some parts made for my bike and need to know how much I can trim things down. Most parts it won't matter but I really need to know I'm not designing some rearsets that won't break. A broken rearset causing a crash would be bad.

Er...so you want to design rearsets that will break?

[Donor]

That is exactly what I wanted to know. Awesome. Have 500 green bling

I was just about to say what Grumph said - can I have green bling too?

[Mental Trousers]

I was just about to say what Grumph said - can I have green bling too?

If you can authoritively tell me what sort of tolerances I should be allowing for parts (non-moving parts) so that they fit together nicely without jamming or being too loose then that would earn some bling

[schrodingers cat]

I'm more a 'teach a man to fish' sorta guy myself but here is a link with all the answers
http://www.mitcalc.com/doc/tolerance...erancestxt.htm


Tutorial:
1. Open google.com
2. Enter 'Fits and tolerances'
3. Hit 'I feel lucky'

What you don't realise (yet) is that you asked a 'how long is a piece of string' question but soon, if you apply yourself, you will be an expert.




Lots o lovely bling...

[Mental Trousers]

I'm more a 'teach a man to fish' sorta guy myself but here is a link with all the answers
http://www.mitcalc.com/doc/tolerance...erancestxt.htm

Even better. Cheers

[Ocean1]

Unless you know a fair bit about tempering alloys.

Apart from that, I'd vote for 6000 series T6 plate if you can get it, in that temper (T6) it's about as ridgid as any alternative and works well. Some grades are more susceptable to work hardening. Just use a bit of common sense about where to use them.

Knowledgfe pertaining to tolerances relating to any mating parts is available from imperical sources only. If you don't already know then you need to have a bunch of stuff repeatedly fail until you do. If you can post pretty pictures we can make sweeping generalisations and give free professional advice.

[Mental Trousers]

Pretty pictures. Make sweeping generalizations.

Uses M8's and M10's.

[bogan]

big radius on the frame mounts bit, will it look right mounted up? Looks plenty strong though, shift and brake levers to mount on footpeg shaft too I'm guessing...

What gear you got to machine it? usually plays a big part in the design

[Mental Trousers]

The frame mount holes are 8.1mm with a 14mm sunk around it (is that the correct terminology??). It's based on the Rapid Art ones that I pulled off the bike (they were too high for me and my right leg goes to sleep from lack of blood because of damage done to my knee when I was younger).

Brake lever mounts on the peg and the gear lever mounts directly to the gear change shaft on the engine.

[bogan]

The frame mount holes are 8.1mm with a 14mm sunk around it (is that the correct terminology??). It's based on the Rapid Art ones that I pulled off the bike (they were too high for me and my right leg goes to sleep from lack of blood because of damage done to my knee when I was younger).

Brake lever mounts on the peg and the gear lever mounts directly to the gear change shaft on the engine.

counterbore is the correct term (if not the correct spelling) I think.

http://www.carbidedepot.com/formulas-cb-metric.htm

14.5 is recomend diameter, so I'd go with that just to be safe, winding an cap screw into a counterbore that just a little bit too small is a bastard! also the 8.1 is pretty tight, especially if the measurement is off by a wee bit...

[Mental Trousers]

counterbore is the correct term (if not the correct spelling) I think.

http://www.carbidedepot.com/formulas-cb-metric.htm

14.5 is recomend diameter, so I'd go with that just to be safe, winding an cap screw into a counterbore that just a little bit too small is a bastard! also the 8.1 is pretty tight, especially if the measurement is off by a wee bit...

Awesome. Thanks man