Hello Gary,

Any darkish coloured spray paint will give a contrast medium against which scribed lines can be readily seen will do just fine. Matt finish grey primer stops the shine and shows pencil marks as well, helpful in noting hole sizes against location point. However, this part comes later, see next para.

I don't know the castings but with any project involving castings you need a reference face from which other measurements can be taken; it could well be the base on this model. First go over that surface with a coarse file to knock down the lumps and rough surfaces before holding the casting in a 4 jaw chuck to skim it and make a reference face of it. Try to cut under the outer skin to preserve the tool edge without taking off more metal than necessary. As for hollows in the base, they are probably out of site when it is sitting down on a plinth and will have been bridged in the skimming, so they shouldn't be any more than cosmetic.

Now you can paint the other surfaces and mark it all up.

I hope that helps

Regards Brian

The problem with spraying with primer on castings this early is that it is going to attract oil which means that you will need to remove it later before you look to do the actual painting.

Good old fashioned engineering blue works well and as Fizzy says you can also use a permanent marker. I personally find applying engineering blue with a brush faster and less likely to come off on my fingers .

I have never had any problems with my Iron castings rusting prior to machining but then my workshop is fairly rust free: Do you get problems with your machine tools? If not don't worry.

Jo

Hi Gary ,

Castings are often painted before machining for two reasons :

(1) To keep you and the castings reasonably clean during machining – cast iron dust is horribly dirty and gets everywhere .

(2) To prevent oil getting into the unmachined surfaces . Any large ingress of oil will make proper painting at a later stage more difficult .

Traditional paint was ' red lead ' but probably not approved of nowadays !

As for marking out Fizzy has the right idea – just marker pen .

Regards ,

Michael Williams .