Prosthetic and control mods for one handed riders

[Weldangrind]

Regarding the aux starter button, I'd try a generic two-wire kill switch from a dirt bike.

[trixter]

Originally Posted by Weldangrind

Gotta link to the one you bought?

http://cgi.ebay.com/ebaymotors/ws/eB...m=160481211949

[trixter]

Originally Posted by Weldangrind

Regarding the aux starter button, I'd try a generic two-wire kill switch from a dirt bike.

is that a momentary switch? if its not then it wont work the way I need it to. Well it would work it would just be a pain :P Most of the kill switches I have seen are like the qlink red one where its a toggle switch.

[Weldangrind]

Yes, it's momentary. It's a sprung switch that simply grounds the CDI in the original application, but you could easily use a two-wire version for your needs. It's usually the only switch on a dirt-only bike.

Here's what I mean: http://cgi.ebay.ca/Honda-CR250-CR-25...item415901a328

[Weldangrind]

Originally Posted by trixter

http://cgi.ebay.com/ebaymotors/ws/eB...m=160481211949

That's what I had in mind.

[FastDoc]

That's exactly what I did for a starter button on The Dirt Rat. Worked well.

[trixter]

I was going for a ride this morning before planning on going to sleep and I was going a little more aggressive today. The roads are a mix of dirt, gravel and paved. The dirt parts have a lot of pot holes. I got up to 40mph as I was going across the pot holes, just for fun, and I did 2 laps around my house (2.2 miles total) and then stopped at a neighbors house for a minute. I went to get off the bike which requires me to pull the hitch pin out and to my surprise the loop that came with the turnbuckle was bent. This was not a minor bend either, about 45 degrees. I was able to straighten it a little bit so that I could ride home, but that means that a 1/4 inch turnbuckle is just not strong enough. I would be afraid of metal fatigue if I continued to use it.

I will go to lowes later and see what they have that is stronger but not really longer. This also complicates some of the way that I secured the turnbuckle to the socket. Since the socket is a standard 2 litre soda bottle covered in fiberglass I used a 1 inch fender washer on both the inside and outside of the bottle cap. These are almost an exact fit for most bottlecaps (some have exactly a 1 inch recessed spot so the inside fender washer snaps in place). If I go for a larger bolt assembly I will not have as much room for the fender washers. So there may be a larger than anticipated redesign forthcoming.

While no one else should actually do anything that I am writing about here, this is a stern warning about using smaller hardware for the "wrist" at least.

[Weldangrind]

There might not be a problem with 1/4" hardware, as long as the tensile strength is suitable. Most turnbuckles are only mild steel; it would be advisable to search for grade 8 stuff, although I'm not sure about availability. Stainless would be wise due to corrosion resistance, but it is also mild steel (just really difficult to drill through).

[FastDoc]

Weldandgrind,

Can a guy strengthen or temper the steel with heating and cooling? Would there be a downside? :?:

I'm surprised it bent, but this is new ground, a project that is not done very often, if at all.

Glad you enjoyed the ride, Trixter. Opinions may vary, but I think most beginner riders are best off on smooth lightly travelled pavement before going off road. Too many variables. It's like learing how to ski on moguls rather than the bunny slope.

JMHO.

[trixter]

Originally Posted by Weldangrind

There might not be a problem with 1/4" hardware, as long as the tensile strength is suitable. Most turnbuckles are only mild steel; it would be advisable to search for grade 8 stuff, although I'm not sure about availability. Stainless would be wise due to corrosion resistance, but it is also mild steel (just really difficult to drill through).

And I am shopping at lowes. There is no other place in the county that would have anything similar. Lowes only has a few different types in this regard.


Because I am welding to the clevis pin I really could do anything. Bigger regular style bolts and a coupler of some type (which kinda makes it a turn buckle) the problem is getting something that is threaded and has enough thread bite that it is not going to come undone easily. That is why I liked the turnbuckle, I could spin it and it wont easily unscrew (spinning is important for function).

I will go later today and see what they have available. Who knows I may have missed something. Given how well it held up and the fact that the 1/4 inch bolt appears to be the weakest link in the whole system I am thinking a 1/2 inch should be more than adequate. I may have to switch from fender washers to flat washers since the hole will be 50% of the diameter, but its all the same department

Hey its 8:20 I bet they will be opening soon I should head over there now (its 25 miles away).

[Weldangrind]

Originally Posted by FastDoc

Weldandgrind,

Can a guy strengthen or temper the steel with heating and cooling? Would there be a downside? :?:

I'm not sure Doc, and I'll carefully avoid that kind of guidance. I'd hate to see something heat-treated to the point where it became brittle. We all want Trixter to get home safely.

[FastDoc]

Of course. Just asking because this is something I don't know about.

[trixter]

Originally Posted by Weldangrind

I'm not sure Doc, and I'll carefully avoid that kind of guidance. I'd hate to see something heat-treated to the point where it became brittle. We all want Trixter to get home safely.

it was next door, I wrote that after I was home

I am just afraid of future metal fatigue. I got a 3/8 inch turnbuckle to replace the 1/4 inch. I got extra fiberglass to strengthen the socket as well.



Now the bad news, while at lowes I stopped at a bike repair shop that was near by and got a kill switch. I took the starter controll panel apart (xp200) and there was a plastic bit that fell out. Took me a while to identify where it came from but its what holds the throttle cable in place. I think it was already broken but I cant prove that and the only way I would know about it is if I took it apart (unauthorized repairs). The claim is likely to be that I damaged it putting the clamp on (it was on the other end).

So now I need a new throttle grip. Any recommendations? remember I want to shorten the rotation (ie increase the diameter of the plastic part that should have been metal that the cables connect to). I need the outside diameter of the grip to be roughly the same. The clamp that I got will not tolerate a grip that is much thicker. I do not care about style, its going to be covered. I do not care about comfort I wont be touching it.

I literally only need the cheapest but good quality (metal preferred) throttle grip that is compatible with this bike and has a lower amount of turning required.

[trixter]

I called jp motorsports to see if they knew of anything compatible and they said nothing they know if is. So I will try the ninja 250 trick and super glue a thin sheet of plastic on the inside of the throttle tube where the cable goes against. This increases the diameter slightly which in turn means a faster cable pull, which in turn reduces the rotation that is required to go from closed to open.

sigh I wanted to ride a little more although I probably wouldnt be able to until tomorrow now its looking like a few days to a week :(

[trixter]

Originally Posted by FastDoc

Of course. Just asking because this is something I don't know about.

What I know, and it is not much, when you heat metal and give it a temper its really bad to try to do it again. That tends to make it more brittle. I heard this in relation to making a sword, which is why Japanese artisans back in the day would work the metal constantly, sometimes rolling it for days straight until they had it the way they wanted it. Besides I do not have a crucible or a blast furnace to get it to a high enough temperature. The part that bent was threaded as well. It was the "bolt" that was welded to the clevis pin.