Best wheel for finishing A36 hot rolled steel

Doubleeboy

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My new surface grinder is headed my way shortly. One of my first projects after set up is to finish a base for a model engine. The base is done but I would like to get as good a surface finish as possible for appearance sake. Any recommendations for a wheel will be appreciated. I don't mind spending a little money to get a good wheel. I already have a Norton 5SG 46 J on order for my basic wheel, was thinking something a little finer grit would be good for final finishing in milder steels.

Thanks
michael
 
With proper technique, the 46 grit wheel should give you excellent finish. You can go to the 60 grit Norton wheel, but it takes a little more skill to avoid burning. Higher grits are for more experienced grinder hands.
 
It is hard to get a particularly good finish from A36. Believe me. I have a surface grinder and an assortment of wheels and hundreds of pounds of A36, as I would often take home the drops from a shop where I used to work (they never used anything less than 24", and that's almost all I used).

The problem is that it's a junk steel. Great for fabrication and structural use, but never intended for anything more precise or attractive. As it was once explained to me, the main difference between 1018 and A36 is that with 1018 you know what you're getting. With A36 there's just no guarantee that it will be any more durable than 1018, but as it's recycled steel produced in huge quantities with little concern for exact composition or performance the behavior can change not just from one piece to the next but even within sections of the same piece. Reminds me of wood that way, with sudden changes in grain direction (as an analogy).

I suspect that careful technique to get the best finish you can from the SG, followed by lapping, followed by polishing, could probably work. Good luck, and share your results!
 
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