Engineer's blue

Previously peter_maple wrote:

Hi Noccers.

I recently bought some engineer's blue to try and find a high spot on my drum brake where the shoe first makes contact. The blue came in a small tin and had the consistency of Vaseline. When I coated the drum with the blue it remained tacky even after a few hours. I thought it would have dried to a thin film. As I haven't used the stuff before I thought I had better ask for advice from them that know. Thanks in advance for any tips etc. Peter.

hello engineers blue is not meantto dry when your find you high or low spots you can then work on that area if any is left just wipeit off, white spirits is good for these jobs also used doing valve jobs and check to lookfor valves leaking mixed with white spirit, I have a big tin of this stuff from my marine engineering days back in the mid 70s to late 80s on the biggest ships afloat now do have fun withit all , yours anna j

Hi Peter, for that job I use blue chalk powder from builders supplies ,its used on chalk lines.

Peter

I wonder if a marker pen would do it in this case ?

Arne

I use Sharpie pens for all sorts of marking out etc. I keep a nice sharp one for critical things and a worn one for use instead of engineers' blue.

I do have a tube of the latter but it's probably 40 years old and it's lost most of its solvent.

There are two types of engineers blue, One is as you have found, a vaseline type consistency, for finding high spots. The second is like a spirit based dye to coat a surface and then mark out dimensions with a vernier height gauge or other marking device for instance. You would always check your watchmakers eyeglass before use, to ensure the team joker had not smeared the first type around the rim.

"Micrometer" blue if I'm not mistaken.

In the day, I seem to remember that we would use chalk on the inside of the drum to locate areas of ovality and then , after cleaning the chalk from the drum,chalk the shoes to identify high spots.

Drum brakes ... shudder ...

Previously Charles Bovington wrote:

In the day, I seem to remember that we would use chalk on the inside of the drum to locate areas of ovality and then , after cleaning the chalk from the drum,chalk the shoes to identify high spots.

Nothing wrong with a well set up drum.

Indeed -- it's the setting-up part that can be the pain.

Previously ian_soady wrote:

Nothing wrong with a well set up drum.

You could remove the brake plate and reassemble with a spacer, then, if you don't have access to a dial gauge, a sticky pin (thin pointed rod and plasticine) will show any discrepancy, Under a powerful light you should be able to see down to a couple of thou. If the bike has had a frontal impact then the drum can easily go out of true. A friend of mine had one like this and when I rode it and commented, he said he just didn't use the front brake!