Galvanising threaded holes.

[dannewhouse]

After advice, last time we did this they advised filling with grease or putting a sacrifice bolt in.
I tried both the. Grease was a waste of time luckily as part that wasn't too bad to drill and tap but took effert to stop drill running off.
Bolts were stuck in, wasn't easy getting them out.

Reading internet, high temperature silicone?
Anyone tried it?
I'm thinking of trying it, M16 holes about 35mm deep.
Can't machine them afterwards.

 

[the-mad-welder]

I was told to fill them with putty. I've never had the need to try it yet though to be honest!

 

[steveR]

Bolt with Copaslip?

Silicone sealant?

Or are they underground/under muck?

 

[shumungus]

As an extreme I'm guessing set of burners and an airline then run a tap down it. Remember to take all the precautions regarding zinc fumes and flying molten metal. There is 1000 degrees of difference between the melting point of zinc and mild steel.
Clogged Threads | American Galvanizers Association (galvanizeit.org)

 

[mx110]

I've copperslipped bolts before and worked OK better than when I've tried to burn threads clean and re tap them.

 

[milkloss]

Get the threads good and clean then maybe try an aerosol of galv spray. Did some on our livestock trailer gates that need patching and it’s done a good job.

 

[dannewhouse]

Just to clarify I don't want galv on the threads just want to be able to use them happy to re tap asking as I'm not towing mi rocks off, last time was very hard to re drill without wondering off.

 

[Andrew]

Last time I did it I copper slipped a bolt and put in. Only put it deep enough to be flush with far side of the material though. Wound out with a windy gun.
Only did this as it was a weldnut.

If possible I’d drill the holes through all and tap after galvanising, the shouldn’t fill up. Maybe make a jig to run the bit through after so it’s easier.

 

[AJR75]

As stated, if they're blond holes they will fill or partially fill with galv or dross. Thro hole if you ca and run a tap thro after galv.

We have used this product with varying degrees of success in the past. Find that it needs applying in several layers and to a fair thickness to be effective:

Metatec Metaflux

Metatec®,Metaflux®,Aromatec®,Aroma's,Gels & Cabinets,Hygeinics, Crystal-Sorb®,Hand and surface sanitisers,Adhesives,Cleaners,Grease,Lubricants,Metallic Coatings,NSF® Products,Porta® Products,Zinc Paste & Sprays BS EN ISO 3549 & 1461

metateconline.com

 

[bkg]

This work ok

 

[dannewhouse]

Is that a thumbs up???
Haha good, hope it does work, sent mine today with fire proof grout/sealant in holes

 

[TechWise]

I've tended to just pilot drill the hole before galvanising then drill to the final size and tap out after the galvanising is done. I have tried tapping in advance then trying to clean out with a tap afterwards but it can be tricky to get the tap started on the same thread again once things are a bit clogged up.

 

[Exfarmer]

If the hole is critical , I would drill undersized and put bolt with nut on. After galvanising cut bolt drill and tap to sizeIf not critical just undersized pilot and let the zinc do its worst.

 

[Hooby Farmer]

Blow the burners through the centre of the holes gently just enough to make it melt run a bolt right the way through and back again.

 

[Classichay]

Grub screws? Just plug all the holes surely to god galv ain’t that thick? Wouldn’t a tap just re cut itself in a drill with the clutch set very low to stop the tap snapping.

 

[itsalwaysme]

Grub screws? Just plug all the holes surely to god galv ain’t that thick? Wouldn’t a tap just re cut itself in a drill with the clutch set very low to stop the tap snapping.

or one of these

SpeedTap™ Impact Taps (307010)

SpeedTaps let you tap threads 10x faster, blasting through tedious tasks. Designed to be driven by an impact wrench or impact driver. Order Today.

holemaker-technology.com

 

[nhr962]

I've seen isopon used with decent success. Takes a little time to get it off afterwards.

 

[dannewhouse]

Just to let you all know I think it worked really well, used 1200 degree fire cement/grout from Screwfix.
Was like silicon when put in.
Looked kind of burnt when they came back.
Holes are 16mm thread, I went in with 6mm hammer drill bit and went around and around till clean.
Hand wound the tapping drill size but this was hardly touching anything.
Put plenty oil in and wound tap in.
If I was in a rush I think the threads would be fine with an oiled bolt.