Milling Paint

Are there any issues/concerns with milling a work piece that is painted, e.g. does the paint mess with the cutters, etc?

The paint could get hot and melt and gum up your cutters. I have had that happen. Also, I believe powder coating is pretty abrasive if by chance you encounter that.

Paul

If it's old, there might be concerns with lead.

You might run into a huge problem with the AQMD

I’ve had paint come off from the coolant/cutting oil and chips, especially from drilling. Part looks pretty crappy afterwards.

I think the concerns with lead paint are overblown. I can see problems if people (children) pick up paint chips and eat them so any chips from machining a painted piece should be carefully disposed. If you sand it and breath in the dust, that may be problematic. So, don't do that.

But I worked with electronics starting in my teens and have used lead based solder for over 55 years without any special precautions. It would often rub off on my fingers. I did not lick them: I WASHED IT OFF before eating. I often worked up close and personal with a soldering iron and lead based solder. There is something about that job that seems to bring the vapors from it directly at your nose and mouth. Don't ask me why, it just happens. Even with a fan for air circulation, it still happens. I experienced this over and over so if there was a danger from inhaling a moderate amount of vapors from molten lead, I would be dead by now. Or a babbling idiot.

All you need are common sense precautions: Don't swallow it. Don't breath in any lead dust. Beyond that, unless you are working in a lead foundry or otherwise making lead products all day long, I don't think you need to worry about it while performing normal machining operations.

wheels17 said:

If it's old, there might be concerns with lead.

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drcoelho said:

Are there any issues/concerns with milling a work piece that is painted, e.g. does the paint mess with the cutters, etc?

Click to expand...

I get asked to rework finished parts fairly often. The paint doesn't interfere with the machining so much, but the edges can get a little buggered up if the paint is thick.

The main issue is protecting the finish when the part is on the machine.

You may have to lay craft paper between the part and the table, mask off the part with blue painters tape, be careful with the clamping not to mar the part, machine dry- coolants and oil can absorb and stain the finish. Keep your hands clean and dry, paper the workbench too, if needed.

All or none of the above, depending on what you are doing. There are a lot of considerations when you are working on an already finished part.

If it's going to get repainted when you're finished, just let'er rip.

The depth of cut must be shallow. Otherwise the paint will burn and change color. Usually brown.

EPAIII said:

I think the concerns with lead paint are overblown. I can see problems if people (children) pick up paint chips and eat them so any chips from machining a painted piece should be carefully disposed. If you sand it and breath in the dust, that may be problematic. So, don't do that.

But I worked with electronics starting in my teens and have used lead based solder for over 55 years without any special precautions. It would often rub off on my fingers. I did not lick them: I WASHED IT OFF before eating. I often worked up close and personal with a soldering iron and lead based solder. There is something about that job that seems to bring the vapors from it directly at your nose and mouth. Don't ask me why, it just happens. Even with a fan for air circulation, it still happens. I experienced this over and over so if there was a danger from inhaling a moderate amount of vapors from molten lead, I would be dead by now. Or a babbling idiot.

All you need are common sense precautions: Don't swallow it. Don't breath in any lead dust. Beyond that, unless you are working in a lead foundry or otherwise making lead products all day long, I don't think you need to worry about it while performing normal machining operations.

Click to expand...

Metallic lead is reasonably inert, safe to handle and melt, problems start to show up with the various chemical compounds that absorb to body more easily.
Mercury vs. (di)methylmercury would be the classic example, metallic mercury is not that harmful on occasional skin contact, dimethyl mercury kills you on first skin contact.

I appreciate all the feedback, think I'll try to steer clear of the paint if I can.

wheels17 said:

If it's old, there might be concerns with lead.

Click to expand...

I remember using silver coloured lead paint back in the ‘60’s you could smell the lead and taste it in the back of your mouth as you breathed it in.

Used to have silver hands by the end of the day. Then we were told we could not use it anymore. Occasionally I have come across a similar smell grinding off old parts that need welding.