[Crokto]

I'm repairing a few pieces of anodized aluminum and don't want to damage the finish; when holding them in the mill's vise, what's the best way to keep them secure without any scratches or scrapes? My current ideas are to use either my sheet of 1/32" silicone rubber or a few layers of masking tape as interference, but is any of that even necessary? I'm not going to be doing heavy machining, just taking off about 1mm of material in a small area and drilling a hole.

Speaking of drilling holes, I am tapping M2.5 holes in aluminum - blind holes, but I can drill much further than there needs to be threads (I only need about 4mm of thread and I can drill as deep at 10mm). I'd like to power tap using a milling machine, but I'm having trouble deciding between a spiral flute tap or a thread forming tap, I was hoping to get some recommendations or advice.

Thank you!

[Jim Dawson]

Clean steel jaws normally won't scratch anodized parts, if you're careful. A single layer of masking tape would work also, no need for several layers.

I would use a form tap. We use them all the time and they work very well.

[Crokto]

thanks for the tips!