Home Baked Crack Detection

There are a number of techniques of non-destructive testing:

  1. Ultrasonic
  2. X-Ray
  3. Magnetic Particle (Magnaflux)
  4. Dye Penetrant

All have their uses and limitations, but for the home user the Dye Penetrant technique is the easiest and at £30 plus VAT the cheapest. I used Ardrox 996PB. I had seen similar used in the Fleet Air Arm in the 1970s and 1980s.

There are three parts to the kit which comes in aerosols.

  1. Cleaner
  2. Red Dye
  3. Aqueous Developer

My first test was on the Stub axles. The machining on mine is fairly rough which I thought would affect the results of the test, however this was not the case. Difficult though to see a crack with the Mk1 Eyeball.

Step 1:

Thoroughly clean the item with the Dye remover Ardrox 9PR5, then clean it again!

Step 2:

Spray it with Ardrox 996PB and let it stand for a while

Step 3:

Clean it off with a rag moistened with the Dye remover. Do warn your friends and family that you are using this as it looks as though you have cut yourself badly. On the other hand you can play childish pranks! However read the directions as there are dire warnings on bare skin contact and the need for well ventilated spaces.

Step 4:

Spray on the developer Ardrox 9D1B. This is a water based developer that dries to a white powder. The kit I have got seems to take a lot longer to dry than I recall, but we were using it in the Mediterranean at the time. I also put on two coats.

Step 5:

Make a cup of tea as you need to leave it for 20 to 30 minutes for the dye to leach out into the developer. You are looking for a sharp red line and then as time passes it will turn into a dull stain as it leaches further. The pink spots indicate porosity or the turning marks shown the first photograph. No cracks though.

It may be worth breaking an old tile and putting the pieces together with tape to test a known crack to see how the system works. Now, are there any volunteers to polish my stub axles?

Tim Parrott tp(at)tpss.co.uk {please substitute @ for (at)}

Ed’s note: Tim is rebuilding TA2664 and has sent me some ‘House of Horrors’ pictures, one of which is reproduced below. Tim describes it as “a new approach to wiring”.

He’s also found, to name but a few bodges: Bolts instead of brake bleed nipples on the front brakes; engine journals and big ends missing split pins; only 6 bolts holding the sump on (remaining holes had damaged threads).

One thought on “Home Baked Crack Detection

  1. Chris Parkhurst says:

    As well as being a TC man I also have Austin 7 s we all know the cranks on these can break but if you find a crank and have no money then immerse the crank in paraffin then take it out wipe it down ,then hang it by a string and give it a whack with a good hammer if there are any cranks the paraffin will ouse out of any cracks and you can send it to the scrap man.Also a good crank should ring like a bell for at least 20 seconds .Try it with your xpag crank this weekend !

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