Honda CB750 Sandcast

Fender Repair

Sam · 11 · 4202

Sam

  • Administrator
  • Sr. Member
  • *****
    • Posts: 397
    • View Profile
Hey everyone,

The original double-cut fender on #410 has a hole from rust in it (small, maybe 3mm wide). It is possible that I will uncover more holes as I remove the corrosion and chrome. My chromer says "just buy a new one, these things are cheap!" Ha! Obviously not familiar with these bikes!

Anyway, what do you guys suggest for repairing a fender? 95% of the fender is fine. I really want to keep the original fender!

Thanks!
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


Steve Swan

  • Hero Member
  • *****
    • Posts: 2705
    • View Profile
    • cb750sandcastonly.com
Probably brazing.  Silver solder would probably not last the long run.  i have a shot bag, a dozen+ hammers and a dozen+ files for moving metal when it's not where i want it to be.


Sam

  • Administrator
  • Sr. Member
  • *****
    • Posts: 397
    • View Profile
Could brazing also be used to fill in the lower spots that were eaten away by rust?
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


Steve Swan

  • Hero Member
  • *****
    • Posts: 2705
    • View Profile
    • cb750sandcastonly.com
i'm not a welder.  but i have one of the best of many excellent welders in the world.

what i would do if i were in your situation, i would take that fender to a good welder and ask him the best approach for repair. 

Keith kmb69 may have some suggestions.  he is our machinist in residence, par excellence.


kmb69

  • Sr. Member
  • ****
    • Posts: 307
    • View Profile
OMG Steve, I don't know if I can live up to those accolades!

I am a machinist, but not a sheet metal guy. Sheet metal guys and good welders are ARTISTS in my opinion. I must say my oldest son is a welder par excellence and he comes in very handy at times but he is not a sheet metal guy either.

Not 100% sure but I think the holes problem can be fixed via micro welding. Requires some significant hand finishing but it can be done. I do not own a micro welder, yet. I can highly recommend Jim French, JMF Precision Welding, in Dacula, Georgia. He is a micro welding wizard and has the latest technology in micro welding equipment. Let him know that Keith recommended his services. The pitting and such can be fixed by copper plating to fill and then hand finishing prior to re-chroming. Extremely labor intensive and requires patience, patience, and more patience but it's doable. Did I mention labor intensive and the patience requirement?



Sam

  • Administrator
  • Sr. Member
  • *****
    • Posts: 397
    • View Profile
Here's a pic of the fender. My chromer got this far, called me up and sent me home with the fender!



My plan it to get the rest of the chrome off in this area of the fender (the back) to see if there are any other issues. Then, I will try to find someone to fix it. Would be great if I could find someone local. Thanks for the recommendation of Jim French. I might give him a call!
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


Steve Swan

  • Hero Member
  • *****
    • Posts: 2705
    • View Profile
    • cb750sandcastonly.com
Keith, is there a difference between "cold" welding and "micro' welding ?

Yes, a good plater, such as the man i use, can "pool" the copper to fill some pretty major defects.


kmb69

  • Sr. Member
  • ****
    • Posts: 307
    • View Profile
Keith, is there a difference between "cold" welding and "micro' welding ?
.....
Probably not, I should have been more specific. I think cold welding involves 2 identical pieces, at the atomic level, of material being welded in a vacuum and is referred to as micro welding.

The micro welding I was suggesting is micro laser welding. It would involve cutting out the oxidized areas to a good material edge and welding in a patch from similar material or a donor fender. The micro laser welding produces a regular looking weld bead just at a very tiny level.



Steve Swan

  • Hero Member
  • *****
    • Posts: 2705
    • View Profile
    • cb750sandcastonly.com
Keith; you said "The micro welding I was suggesting is micro laser welding. It would involve cutting out the oxidized areas to a good material edge and welding in a patch from similar material or a donor fender. The micro laser welding produces a regular looking weld bead just at a very tiny level."

is this the process that is "hyper-focused" in an very tiny area of work that welds at overall low temp of work piece ?



kmb69

  • Sr. Member
  • ****
    • Posts: 307
    • View Profile
......
is this the process that is "hyper-focused" in an very tiny area of work that welds at overall low temp of work piece ?
Yes sir, that is correct.

Fantastic new welding technology.  not had chance to use it yet.  many of the antique guys use it on their 80-100 year old motorcycle repair work.
« Last Edit: February 08, 2015, 10:58:39 am by Steve Swan »