Galvanize & Painted frame - Threaded Holes?

Project60

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Thornton, CO

• Oct 12, 2007

• #1

What is the best way to handle the threaded holes on frame when the plan is to hot dip galvanize and paint the frame?

Option 1:
Put sacrifical bolts into every hole during the galvanizing/painting process. Remove bolts and have uncoated threads for use.

Option 2:
Leave threaded holes open. Retap after galvanizing and paint.

Option 3:
Leave threaded holes open. Retap after galvanizing. Paint over that.



Concerns:

• Does the acid dip/galvanizing process remove material from the steel? If so, wouldn't the thread be weaker as steel was removed (during acid dip) and then replaced with a weaker coating?
• Do I want an uncoated threaded hole? Wouldn't this promote rust? What if I don't use the threaded hole for some reason, I now have an uncoated section of steel.

 

brownbear

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• Oct 13, 2007

• #2

sacrificial bolts, and then retap prior to installing whatever goes in them. Also at that point grease the threads.

it will be a pain to tap out all the extra stuff from galvanizing and painting. Even paint can be hard to tap out.

 

Project60

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• Oct 13, 2007

• Thread starter
• #3

brownbear said:

sacrificial bolts, and then retap prior to installing whatever goes in them. Also at that point grease the threads.

it will be a pain to tap out all the extra stuff from galvanizing and painting. Even paint can be hard to tap out.

Click to expand...

Grease the bolts during re-assembly?

 

Christian

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• Oct 14, 2007

• #4

Hi Projekt60

I did some research into this when I did mine, the best way IMO is to leave the holes open, the also make it easier for the air to escape when dipped, and retap afterwards. That is what I did, i know retapping is a pain, but you are certain that the zink gets the best chance. After retapping I painted the frame and as I went along installing stuff I just painted the bolts over with a brush. Remember that galvanization "creeps" over exposed steel, so the rustproofing effect will creep back in to the retapped holes.

 

Project60

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• Oct 14, 2007

• Thread starter
• #5

So galvanization adds thickness to the metal? I don't mind re-tapping. Did you paint after tapping?

Does the acid dip they do first remove material? This concerns me as you are removing the strength of the steel in the threaded section.

 

CardinalFJ60

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Lafayette, CO

• Oct 14, 2007

• #6

Toyota trails

I have an old TT issue with this info in it...the author recommended putting in sacrificial bolts...and he still needed to heat and crack them to spin them out. I'll try to find the exact issue and post it up.


stay tuned...

 

Christian

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• Oct 14, 2007

• #7

Galvanizatin adds ALOT! it took two to carry my frame out, but three to carry it back in!
About the paint, I have painted the entire frame, and spot-painted where I have scratched the paint when tappingand stuff. This is merely cosmetic, since the zink rustproofes enough! Just think about lamppost. Overhere they are only galvanized and hold forever, eventhough the roads are salted.
The acid only removes rust, I think it is citric acid, which I use instead of sandblasting on delicate parts. It removes only ryst and leaves clean iron.
Btw, just for porn I have used stainless bolts mounting everything..

Using sacrificial bolts sounds wrong IMO, there is the air issue when dipping and the thing with heating and cracking sounds wrong, sorry...