Crimping lower forks

#1
Found old helpful post from Manchester from 2014 on crimping forks, he drilled a 7/8 hole in heavy metal plate, cut plate in half and used the half holes for dies ( he posted good photo if you search crimp forks in this category), but he heated up the fork bottoms and used a vice. Just discovered the lower forks on suspension K&S bikes are basically 13/16th tubing (not 3/4, not 7/8th). My question, if I made the plates like Manchester did (very ingenious), drilled 13/16 hole, cut them in half for the die, would I be able to press .120 wall tubing in a heavy hydraulic press without heat? Any help or info greatly appreciated. Posted similar request on another forum and got a lot of "big ass hammer" directions. which might work, but trying to make really clean, professionally looking fork bottoms.
 

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#4
Thanks. was looking at dies, are about $550 for a set and they do what the half holes do on the metal plates. Guy named Fred at Metal Depot has been helpful, said he could probably round up some 13/16th tubing, not your standard size. So no problem with .120 tubing?
 
#8
it doesnt matter if the hole is bigger than the tubing. In fact it doesnt even need to be a hole you can grind it out. Leave the tubing long so the die presses straight. Its also difficult to keep them aligned. I used 3/8" bolts then get bent. 1/2" or bigger would work better. I found i couldnt get them completely flat with the 20 ton press. Maybe i didnt press hard enough but i heated them at the end. I doubt 7/8" tubing is exactly 7/8" everything is nominal these days.
 
#9
I found i couldnt get them completely flat with the 20 ton press. Maybe i didnt press hard enough but i heated them at the end.
I have found that a B.F.H. (5Lb mini sledge) and an anvil work great to make sure that the crimp is completely flat after flattening with the shop press.

I haven't tried yet, but I was reading that if you wax the dies or tubing before you smash it helps.
 
#10
I have found that a B.F.H. (5Lb mini sledge) and an anvil work great to make sure that the crimp is completely flat after flattening with the shop press.

I haven't tried yet, but I was reading that if you wax the dies or tubing before you smash it helps.
Thank you, yours look great, how did you keep them straight- eye ball?
 
#14
View attachment 241927 View attachment 241928

I've also used 1/2 schedule 40 pipe which has dimensions of .840" OD x .11" wall (real close to 1/8") without any problems with the shop press whatsoever.
Sooooo, looking at your first picture I noticed the blocks that you have your die welded to have "V" notches in them already, ever try those for end crimping?. I believe they come with the press if I'm not mistaken and would probably do a great job, worth a try anyhow.
 
#15
Sooooo, looking at your first picture I noticed the blocks that you have your die welded to have "V" notches in them already, ever try those for end crimping?. I believe they come with the press if I'm not mistaken and would probably do a great job, worth a try anyhow.
I have not tried those, but I am sure they would work. The little blocks that I made are for a specific fork "crush". I wanted the final product to closely resemble the crimps produced on the Ruttmans, Harrisons, and Lil Indians.
 

PatrickCraik

Well-Known Member
#16
Sooooo, looking at your first picture I noticed the blocks that you have your die welded to have "V" notches in them already, ever try those for end crimping?. I believe they come with the press if I'm not mistaken and would probably do a great job, worth a try anyhow.
The blocks with the V notches ARE THE DIES,unless Im missing something. Looks like a simple,effective way to make the fork ends.
 
#17
Yours do look the part and very well I might add, the extra angle in your dies makes the difference, I was just wondering why nobody has tried the "V" notches in those base plates. PatrickCraik, I circled the "V" notch in the press plates of where I'm talking about, seems like a simple way for folks to flatten or crimp their tubing without a lot of fab work and making their own dies.

CRIMP01.jpg
 
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