Technical question for galvanizing

[overload]

Hi all,
At the moment, I have been using taps and dies to clean up any threads on nuts and bolts that are welded to the pieces I make and I am wondering if there is any way to cover or protect the threads from the galvanizing process so I won't have to clean them up later?

Cheers!

 

[irondarren]

As far as i know there isn't, Galv involves dipping the item in molten zinc, and protection to threads as far as i am aware would burn off in the process. I could be wrong

 

[Chipper]

Guessing that there's no maskt/protection etc: Landy chassis makers re-tap threads after galving, so if there was a way to mask against galv and survive the pre-clean they'd have it down. As it is, they seem to recut afterwards.

 

[Welderpaul]

There is a product produced by Metaflux called Galvaprotect. Looks like pink cough medicine. It is painted onto threads, allowed to dry, then once it is galvanised, the product can be wire brushed off. Good stuff. Expensive though - a 2 or 3 litre tub is £125 Lasts a good while though. Not easy to get hold of, took our welding supplier a while to get hold of it.

 

[slim_boy_fat]

How about plastic plugs of a size to just fit in the threaded bit? [or is that too silly...... ]

 

[Drains]

How about plastic plugs of a size to just fit in the threaded bit? [or is that too silly...... ]

They might be a bit melty.

 

[brightspark]

fill em up with dental plaster dunno if the galv company would complain ring and ask then chip it out

 

[scott0031]

There is a product produced by Metaflux called Galvaprotect. Looks like pink cough medicine. It is painted onto threads, allowed to dry, then once it is galvanised, the product can be wire brushed off. Good stuff. Expensive though - a 2 or 3 litre tub is £125 Lasts a good while though. Not easy to get hold of, took our welding supplier a while to get hold of it.

I would take a wild guess that its some form of ceramic paint, that might be something to look for 'ceramic based' the worst that can happen is it wont work.

Nothing i have ever heard of that will do the job you want. The only thing i can think of is plug them with bolts, not sure if they would get stuck fast though if the galv manages to get into the thread. Plus it might tend to split away the glav round the hole when removed, something you wont get with clearing out the threads in the traditional way.


Kind regards,


Scott (ward eng)

 

[Omniata]

What about this:

Ceramshield

It's a spray to put on mig shrouds that's supposedly ceramic

 

[Welderpaul]

Here's the stuff. You need to be careful what you put on to protect the threads. Chances are the acid bath will wash a makeshift masking fluid off before it even goes near the zinc.

We've put bolts in holes before now - any thing less than M10 is risky - theres a good chance you will shear the bolt off if it has a good hold. Bigger sizes won't shear but break a big lump of galv off when they come out. We have put bolts in M20 threaded holes before now, they were a nightmare to get back out again.

 

[Hitch]

For male threads, we put nuts and spacer washers on the thread. They unscrew quite easily with a nut runner. Try and avoid whenever possible though, like drilling and tapping, then screwing studs in afterwards.

Female threads, just pilot and drill/tap after galv'ing.

 

[overload]

The bolts I use are 1/2" unc thread and the nuts are 1" unc thread which is a large size considering! Not sure what the metric equivilent is!

Would I be ok to put a 1" unc bolt in the nut and when it comes back,using a thin disc cutter, put a cut around the galvanizing finish where the bolt/screw just enters the nut and free it that way?

 

[brightspark]

a question

is there a lot of bolt.holes ??whatever u put in will have 2 be cleaned out

 

[overload]

is there a lot of bolt.holes ??whatever u put in will have 2 be cleaned out

Absolutely! I already have the correct tap and die, just trying to make life easier for myself! Yeah, there is alot of nuts and bolts lol!

 

[bigbadbugga]

Is there a metal that galv will not stick to?

was just thinking you could make/buy some bolts made from it and screw them in.

 

[Hitch]

Is the bits quite big? Spin galvanising an option...

 

[brightspark]

Is there a metal that galv will not stick to?

was just thinking you could make/buy some bolts made from it and screw them in.

probs wont stick to aluminium or alloy bolts/ galve melts at approx 440 to 450 c
aluminium at about 660c so they wont melt

 

[Hitch]

Probably get stuck in and shear them off though...
Tapping after galv shouldnt be a problem though, its not like you need to tap it twice.

 

[brightspark]

Probably get stuck in and shear them off though...
Tapping after galv shouldnt be a problem though, its not like you need to tap it twice.

id just retap them personaly if there was a large amout he could put tap in rechargeable drill on slow speed and run em through