Making Machined/welded Parts Look Like A Casting

[randyc]

There are two points before I start this short post:

• I wasn't sure which sub-forum to post this.
• Why would anyone want to do this ?
• There are a few reasons and anyone interested in this process will have their own.
• I can't count

Some years ago, I bought a pneumatic "needle scaler" from HF, for about $18 as I recall. This tool is just great for removing rust prior to painting steel parts. It occurred to me that it would also be useful for "peening".

Peening is a useful technique for a couple of reasons besides removing rust.

• Provides a bit of surface hardening and toughness (similar to forging)
• Great for removing welding flux and scale
• Can produce the appearance of a cast surface on the peened part

This is a needle scaler:



It's a formidable looking tool and it works great ! In one situation, I used it to remove the rust from a neglected utility trailer before painting in just three hours.

When I decided that I needed to make some welded parts look like they were cast, I made a slight modification to the scaler. I put some coarse sand and small pebbles in a coffee can and operated the needle scaler against this mixture for about five minutes. The needles acquired a rounded surface, removing the sharp edges.

This is a small clamp, three machined parts welded together, "treated" by the needle scaler. The part is small, about one inch by four inches.

 

[Terrywerm]

Some fellows have had good luck making bar stock parts look like castings by sandblasting them, but your idea appears to work very well.

 

[markknx]

Nice It could also be used to give an aged/ weathered look on steel. Very nice! I used one of these at US steel Gary works a few years back to remove rust from beams on their ore bridge, man do they do a good job. Not as good as the sand blasting they later figured out was faster.
Anyway nice job /idea.
Mark

 

[chips&more]

I have one of those needle scalers. Yes, they are great for "certain things". Since they do move the surface of the metal around. I’m very hesitant on what to needle. I don’t want to warp or cause weird stresses in the metal. Mine takes a lot of cfm of air to operate. Maybe as much as my sand blaster…Good Luck, Dave.

 

[18w]

I have one of those needle scalers. Yes, they are great for "certain things". Since they do move the surface of the metal around. I’m very hesitant on what to needle. I don’t want to warp or cause weird stresses in the metal. Mine takes a lot of cfm of air to operate. Maybe as much as my sand blaster…Good Luck, Dave.

That is one of the useful purposes of a needle scaler, similar in effect to shot peening. It actually helps to remove stresses, especially in welded cast iron repair.

Darrell

 

[Cactus Farmer]

HF has them in two sizes also. I have both and two spare sets of needles. I use one spare set to make punches.
They are tough little pieces of metal ! Also, I have an old regulator between my 90# air supply and my tools. It makes for easy power changes on all air tools. The scaler is less destructive on soft materials when turned down to 40-50 lbs.

 

[randyc]

HF has them in two sizes also. I have both and two spare sets of needles. I use one spare set to make punches.
They are tough little pieces of metal ! Also, I have an old regulator between my 90# air supply and my tools. It makes for easy power changes on all air tools. The scaler is less destructive on soft materials when turned down to 40-50 lbs.

I agree, no need to operate at full shop pressure. You can regulate (pun intended) the degree of finish by air pressure (and of course the duration of the process).

Dang good idea about using the needles for punches !

I also do the same thing as you with multiple regulators. At the top of the photo, the normal compressor regulator can be seen. But the output from the regulators runs through a valve and then tees. The left hand branch provides 90 PSI to wherever in the shop it is needed while the right hand branch has another regulator (bottom of photo). The right hand branch is used for low pressure applications like painting and has no in-line oiler.