Armortek

Has anyone ever utilised the trick of using an acid to remove the remnants of broken steel fasteners from aluminium ?

I'm rebuilding the Sherman prototype and due to its lengthy stay out in the Devon weather, several of the bolts in the sprockets have sheared off due to rust.

I've read about using Nitric or Sulphuric acid to erode the steel without affecting the aluminium but would be grateful to hear from anoyone who has actually used this process.

Adrian.

if you can take the parts to a local engineering company a lot of them use a technique called spark erosion which will completely remove corroded metal from alloy threads with out any damage, worth a look through the yellow pages.

Adrian
I have used acid for this and it does attack the alloy as well
spark erosion is a better way to go.
I have also drilled down the screw using a drill with the core size of the thread, eg on a 3mm screw drill 2.5.

Hope this helps

Derek

Adrian,

If you can still get hold of the stub of the bolts to turn them try heat first. Aluminium expands more than steel and it will break the rusting. Obviously be careful not to melt the aluminium.

I use that way to Allan, thou i first use soapwater
on them and it tends to get into the threads it seems.
I got the tip from a old auto mechanic "soak it with a spraycan and let it set, try loosen it after ca 30 mins.If the bolt mooves just apply more soap/water solution and twist it back and forward. If the bolt is really stuck, apply heat with a heat gun or propane.
It usually work great for me i must say.

Regards
Freddie

Hi,

I work on Merchant ships and have this problen constantly.

I very strongly recomend PC Blaster. It seems the best out there. I would try this before heat, adif, or the electric stuff.

Good Luck,
-Brian

Hi Brian,

can you be more specific about the product? Where is it found, maybe some info about it on line for example?

I've found saturating a bolt with a thread solvent spray, or soap helps. Differential heating may help by applying ice to one part while carefully heating another for example. Sometimes a mild tap while doing the above helps to free a part.

Cheers all,

Thanks for all the comments and suggestions

I've been away this week but have received a quote from one of the companies I contacted about spark erosion. The inital price was £20 per bolt but due to the quantity they have said they may be able to do it based on an hourly rate instead, so I'll need to audit how many I need to remove and then take it from there.

I tried Googling "PC Blaster" but got everything from computer speakers to ways to improve my (non-existant) six pack Nothing about rust removal though

<later>

Did you mean "PB Blaster" That gets a few useful looking hits...

Adrian.

Thanks Adrian!

Now I see it is "PB Blaster"