Bob- I have experience with the dye penetrant crack test kits, as well as an
acquaintance who does NDT full-time (Non-Destructive Testing).
My take on it- It does a good job with surface exposed cracks-The dye has
to sink into the crack, then you spray it with the developer which causes the
penetrant to efflourese (sp?), at which time you can visually see the crack.
One kit can last quite a long time, it depends more on the amount of surface
area which you need to cover than the number and size of cracks. Be aware that
the part to be tested should be removed from the car and cleaned thoroughly,
otherwise the buildups can mask the cracks (i.e. if they're filled with gup,
the dye can't work it's way in.
My friend's take on it-Since he works with NDT daily, he has access to
techniques that the rest of us could only dream of. His statements on dye
penetrant..."It works well for large , obvious cracks, It's cleaner than using
Magnaflux (the magnetic process) but the results are about the same. I prefer
using X-Ray Analysis because it will show the propogation of cracks which are
subsurface, and their relative intrusion points (Intrusions in the casting are
usually the crack propogation point if they exist). Ultrasound is a good
technique, but it's limitations are the depth of transmission (this is relative
to the power driving the transducer), and the operator 's interpretation of the
resultant graph"
Basically, dye penetrant is basically a low budget, surface crack detector.
It's difficult to use on bolts, and won't show much if the parts aren't
perfectly clean. If you want a small level of asuredness that things aren't
cracking while you have things apart, it's fine. If you suspect a crack (for
example in a head) it's fine, if you have the idea that it will show any crack
that may appear during a race, you're kidding yourself.
Some real info, some personal opinion, take what you want, leave the rest.
BTW I do have a dye penetrant kit in my own shop FWIW
Mark Haynes
RMVR
Bob Spruck wrote:
> After hearing the Flounder's sad story about the steering arm bolts
> breaking on his Bugeye race car, I am prompted to do another crack test on
> my ' 67 Midget vintage race car. This time I want to do it myself since the
> car is not apart as it was when we last checked the critical parts. There
> is a Magnaflux Crack Detector Kit listed on the Eastwood website for $29.99
> (item number 43128). Does anybody on the List have any experience with this
> kit or any others? Is it effective? How many "cracks" can it test? Does it
> store well after partial use? I may want to buy two kits and save what I
> don't use. I plan on checking the spindles and kingpins. Any other
> suggestions? The Eastwood site is www.eastwoodcompany.com.
> Regards,
>
> Bob Spruck
> Sharpsburg, GA
> ' 67 Midget Vintage Racer
> ' '72 Midget Weekend Car
> 4 parts cars in the woods
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