How hard can it be?!

[ales17]

It's not a problem if you have to do it 5 times but if he's playing with the position of the engine and he has to change it 10-15 times then ....

If you filter it then I don't see a reason why not reuse it!

[heng47]

I think I'll dump the oil. Won't be starting the engine till Sept at least.
4L of oil isn't expensive, but it isn't cheap either.

Seperate note, I drew up the plans for the front wheel and have encountered a little snag.The wheel spacers are of different length. Does that mean the wheel is not centered in the forks?
I was trying to determine the position of the calipers relative to wheel center when I noticed this anomaly. The caliper mounts look equally spaced on the fork though so maybe 1 of the spacers is supposed to seat inside the fork? The slot for the axle is slightly larger on the left side so might that be a possibility?
I find it hard to believe the wheel is off center.

[TwoStroke Institute]

The wheel is centred they are just spacers, no problem.

Please you have to crawl before you can walk, learning arc welding will lump you in a power of trouble bronze welding/brazing is a cheap simple no frills way to join tubes.If you have John Bradley's books there is chapters devoted to it. All those English frame builders used it and they have zero problems. Just because it is a bit old fashioned but don't dismiss it. Only 3 simpe rules
1. Have no gaps between tubes
2. 'Tin' the joint first
3. Don't over heat the tube

Oscar is correct you will need a tube notcher of some description. You can make a fixture for the toolpost of your lathe, a drill press mounted one or HERE is a download.

But again you will find without a good notcher a lot of time is taken getting the mitre correct, or in the lathe fixture time taken to make that fixture or the money you spend in buying the notcher. You could have the 'fishmouths' made on a laser cutter but you have to know exact lengths and angles for that.


Any chance of a pic of your notcher Oscar?

[Oscar]

Any chance of a pic of your notcher Oscar?

TSI - here's the website page for it: http://www.jd2.com/shop/custom.aspx?recid=4

I bought it direct from JD2, with transport it cost me about $360 from Jackson in the USA to Sydney airport - four different planes! - and then it cost ANOTHER nearly $300 to get it from off the plane to a warehouse 2 k from the airport and customs cleared (no import duty!) Absolute, blind daylight robbery at this end. It's a really serious bit of kit - 32mm steel plate for all the load-bearing bits, not one of those damn tin things Hare and Forbes sell. Needle-rollers for the shaft, the whole 9 yards.

One note though - once you have cut the notch you need to chamfer it a bit to increase the surface area for the weld - no big deal and I find those thin cutting disks, used gently, do exactly the job you need. You can put the chamfer on without biting into the notch. More important if Tigging than brazing, but a good idea anyway.

Heng - I agree totally with TSI - brazing is the way to go, even if you have to go outside your school shop to do it. It'll be worth the extra hassle in the long run - every other option introduces more complexities than this one - and the results will be well strong enough. If I remember correctly, the early Brabham F1 cars were built this way - and they won WCs.

[heng47]

It is VERY hard to find mild steel tubing for sale to individuals in Japan.
Especially those with the 'correct' carbon ratings.

Most steel pipes sold are 0.45%, probably a little too hard?

[heng47]

I've been told that the Modulus of Elasticity for the steels are similar so it probably wouldn't matter. Without any other expert opinion I'm going for the plunge and will try out those S45C tubes.

Will do a mock-up in acrylic first just to see everything fits. My biggest worry is the airbox, as can be seen in this image, not much clearance between it and shock.

[RatsMC]

I have absolutely zero expertise in this area but it looks to me like the wishbones of different lengths and attached at different angles will create a change in steering geometry as it is compressed. Is that intentional?

[heng47]

I have absolutely zero expertise in this area but it looks to me like the wishbones of different lengths and attached at different angles will create a change in steering geometry as it is compressed. Is that intentional?

Not really intentional, but inevitable. The wheel will travel in an upwards arc as opposed to straight (not totally, but for argument's sake) up on normal forks.

Anyway, this project has crash landed as Tony Foale has just informed me that the eccentric on the upper adjustor is not a fine choice to make, or at least the way it is currently positioned.

In his kind words

you need to junk that eccentric adjustment at the rear of the top arm.

[TwoStroke Institute]

Maybe some thing not so ambitious?

http://www.apriliaforum.com/forums/show ... p?t=184217

[Oscar]

I have absolutely zero expertise in this area but it looks to me like the wishbones of different lengths and attached at different angles will create a change in steering geometry as it is compressed. Is that intentional?

A small amount of forward movement of the contact patch under braking will be beneficial in maintaining the trail as the frame pitches down at the front ( the same as unequal wishbones help maintain camber on a car as it rolls due to c/g forces) though just eyeballing it Heng's diagram suggests the change may be a bit more than neutral. Should give very stable braking though on long sweepers the bike would probably tend to open out the line a little.

Heng - glad you got onto Tony Foale - he may not know everything there is to know but his advice sure as hell will help you avoid a lot of mistakes! As for tubing, if you can't get hold of 4130 from an aircraft supply shop in Japan, you can buy it in small quantities from Aircraft Spruce and Specialty in the U.S A.: http://www.aircraftspruce.com/menus/me/index.html

[RatsMC]

Thanks Oscar.

I can also recommend Aircraft Spruce. When I first got down here, I was having trouble finding aluminum of any sort other than 5000 series stuff when I needed 3003. The only problem I had with Aircraft Spruce is that they tend to deal in very lightweight stuff. They may have exactly what you need though Heng.

[Oscar]

If you really want to get some speed across the ground (vs money!), then this mob in Canada have a great service: send them your frame CAD drawings and they'll cut, bundle and post the exact tubes ready to put together: http://www.cartesiantube.com/

My brother has investigated their cost for his aircraft project and it looks quite good - though he's already built up his trial (mule for making the jigs)fuselage out of mild and therefore knows the exact welding sequence and shrinkage allowance for a Tigged frame. By using braze you really minimise (though not eliminate) the shrinkage problem, and the extra cost could well be cancelled out just on the cost of a good tube notcher for a one-off project.

[chakraist]

Maybe some thing not so ambitious?

http://www.apriliaforum.com/forums/show ... p?t=184217

That's very, very cool. I wonder if he wants someone to race it...

edit- just finished reading the post.. it seems he's just fine!

[heng47]

Math help!

Can anyone provide a forumla or equation or something to calculate what the length of the red and orange highlighted rods might be?

[Kropotkin]

Perhaps I'm being a bit too obvious here, but isn't it just a^2 + b^2 = c^2? E.g., if you know the vertical and horizontal offset from connecting point to the end point, surely you can calculate it like that?

[heng47]

It might be, but the sad fact is I haven't done any heavy math like this since I left my Mecha Eng. course midway 10 years ago. And I really don't remember much of it other than the direction that forces travel and 'Hello world'. A little more explaination would be very helpful

[RatsMC]

Krop is right. You have two triangles. If you know the length of any three members you should be able to calculate the remaining two.

Ignore me. I have no idea what I am talking about. Geez, a beer after work and I just start making sh!t up.



Maybe you can tell us what you know about the pieces? Do you have any of the measurements?

[lucy]

Perhaps I'm being a bit too obvious here, but isn't it just a^2 + b^2 = c^2? E.g., if you know the vertical and horizontal offset from connecting point to the end point, surely you can calculate it like that?

It doesn't look like, from the diagrams presented, that any of the internal angles are 90° therefore the Pythagorean relation between the hypotenuse and catheti doesn't exist.

If the internal angles are known or can be measured them simple trigonometry in the form of tan θ = opposite/adjacent should suffice.

[phil]

C'mon Heng mate it's not rocket science....hold on...I guess it is (in our little way)

Without wanting to contradict Lucy it seems to me there is a 90° angle, if so, follow this link for a trig calculator and input all the information you know for all the unkown values.
If Lucy is correct here is another online calculator.

[lucy]

C'mon Heng mate it's not rocket science....hold on...I guess it is (in our little way)

Without wanting to contradict Lucy it seems to me there is a 90° angle, if so, follow this link for a trig calculator and input all the information you know for all the unkown values.
If Lucy is correct here is another online calculator.

You're right; there are some RHTs in the plan view that I didn't see and pre-Socratic methods will suffice for those.

Heng, please put up the dimensions and angles that are known - I'm sure we can figure this out.

[Kropotkin]

Perhaps I'm being a bit too obvious here, but isn't it just a^2 + b^2 = c^2? E.g., if you know the vertical and horizontal offset from connecting point to the end point, surely you can calculate it like that?

It doesn't look like, from the diagrams presented, that any of the internal angles are 90° therefore the Pythagorean relation between the hypotenuse and catheti doesn't exist.

If the internal angles are known or can be measured them simple trigonometry in the form of tan θ = opposite/adjacent should suffice.

I gave up on trig once we got into tans, sines and cosines. A tan is what you get if you go outside, as far as I'm concerned ...

[TwoStroke Institute]

I'm stating the bleeding obvious here but why not just make a 'go-no go gauge' out of flat bar, a telescopic gauge or even stiff wire?

[JanBros]

Perhaps I'm being a bit too obvious here, but isn't it just a^2 + b^2 = c^2? E.g., if you know the vertical and horizontal offset from connecting point to the end point, surely you can calculate it like that?

It doesn't look like, from the diagrams presented, that any of the internal angles are 90° therefore the Pythagorean relation between the hypotenuse and catheti doesn't exist.

If the internal angles are known or can be measured them simple trigonometry in the form of tan θ = opposite/adjacent should suffice.

if the triangle has no 90° angle, you can always devide it into 2 triangles, than both off them have a 90° angle and combining both you(ll get what you need, just takes a bit more calculating

[JanBros]

any news on this project

[phil]

I'm interested also...