[MikeOK]

I will attach a pic of the clamps for my fork. I think I can improve the top clamp.

My question is this: what are the differences in the different aluminum alloys? As in 6061 compared to 7075? Also, do any of you know of a good source for stock- I need a piece 1/2" think and 3" wide, 7" long.

Another ques- how about using a block of carbon fiber for this? I have some composite experience, and any weight I can knock off this thing would be good, I'm just not sure if it would be strong enough to be used as a clamp. Any thoughts appreciated.

 

[KleinMp99]

lol................ http://www.bikeforums.net/showthread.php?threadid=20528

 

[MikeOK]

Usually the engineer types hang around here more, but this time they came through at BF. If anyone needs good info on this topic click on klein's link.

 

[MikeOK]

Using carbon fiber the only thing I can think of that might cause a problem is how to make the pinch bolts. There is a plastic shop near me that occasionally sells factory second carbon fabric for a very fair price, so then you would only have the cost of the epoxy resin, and I normally have a gallon or so of this out in the shop. I have built 3 boats using both the cedar strip and the sewn seam methods. On the last project I built a canoe with cedar strips covered in clear fiberglass, with a kevlar hull bottom. So far the kevlar has been by far the hardest to work with.

An advantage of doing this with carbon is that after the initial expense, I would still have lots of material left over to make all kinds of sexy carbon doo-dads for the bikes

 

[SpasticJack]

I think the pinch bolt area would be an invitation to trouble. I would bet that you would have to bond your uppers to the upper crown for it to have any kind of strength. Think about the only other suspension fork with a carbon crown- RS SID. They are scary enough as it is, let alone trying to use a carbon crown on a more DH oriented fork.

I would pursue other means of lightening your fork.

 

[indieboy]

Originally posted by SpasticJack
I think the pinch bolt area would be an invitation to trouble. I would bet that you would have to bond your uppers to the upper crown for it to have any kind of strength. Think about the only other suspension fork with a carbon crown- RS SID. They are scary enough as it is, let alone trying to use a carbon crown on a more DH oriented fork.

I would pursue other means of lightening your fork.

those forks are fu/ckin sweet for what they are solely intended for and that is XC racing and that only.

 

[ohio]

I'd stick with aluminum. Easier to maintain tolerances, and less chance of defects.

Carbon fiber composites don't fail because of lack of strength, they fail because of inconsistencies in manufacture, usually voids in the matrix. If you're building it by hand, there's a good chance it will be less than perfect, especially if you haven't used the stuff before and the shape is complex.

6061 T6 is readily available and easy to work with.

7075 T? is harder to find, and harder to work with, but MUCH higher strength. There is no downside, other than that it can't be welded, but you're not welding. People often confuse it with 7005, which can be welded and is a little stronger than 6061.

There are some high strength 2000 series aluminums also. Mat'l properties charts are a good place to start, then see what is available from the nearest supplier. Make sure the stock you buy is properly heat treated (T-rating).

 

[SpasticJack]

Originally posted by indieboy
those forks are fu/ckin sweet for what they are solely intended for and that is XC racing and that only.

My point exactly, I would hesitate to go anywhere near a carbon crown on a DH fork. Without the R&D rescources of a big company, it would be all but impossible to make sure a homebrew piece would be up to the task.

 

[indieboy]

Originally posted by SpasticJack
My point exactly, I would hesitate to go anywhere near a carbon crown on a DH fork. Without the R&D rescources of a big company, it would be all but impossible to make sure a homebrew piece would be up to the task.

true, sorry posted late at night n wasn't fully thinking

 

[Thylacine]

You could use 7075 ( Or 6061 T6 ), or CF impregnated Nylon probably. Sounds like a lot of trouble to save 20 grams.