I've been doing a lot of needle scaling at work lately -- I let them find out I actually *like* needle scaling. In fact, the needle scaler is my favorite air tool (although several coworkers have threatened to shove it up my posterior due to the noise).

I've been having the tools shed a lot of needles. Sometimes, I'll have three or four drop out in the span of five minutes. Is this normal? I pour a couple drops of Marvel Mystery Air Tool oil into the tool each time I use it. I also gave the disk that holds the needles a coating of graphite last time I replaced a bunch of needles. I'm mostly removing old paint and surface rust. Sadly, I don't fit through the manhole of the boiler currently under rehab, so I can't help with actual scale.

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-Matt Conrad

Matt -

Had one of our guys at Hoosier Valley tell me he was removing old paint from a replacement set of diesel trucks, and the large needle scaler he was using "fell apart".


Les

I've had a couple come out...not a lot. But speaking of noise, the needle scaler is the cause of my partial hearing loss. WEAR EAR PROTECTION.

Having started in the industry over 30 years ago with a needle scaler and graduated to giving instruction in their use and purchasing I can tell you that the material used in todays commonly available versions is less than satisfactory. I can honestly recommend buying a version from Crack Master Carr over anything else simply because it will last longer and give better service. If you have to buy a cheap one, buy 4-6 at the same time so you will have less downtime, and the parts will be interchangeable so you can get the most out of them before they hit the scrap bin and you start over.

We have three scalers in the Car Shop -- two Ingersol Rand 125s and one IR 172 with shorter needles. I usually use one of the larger 125s (the other has donated all its needles at this point), using the 172 where I have to get into tighter corners one-handed. There's another 125 and two even smaller scalers in the roundhouse, I don't recall the model but they're even smaller than the 172.

A few questions:

What do the three settings do on the 125s? They seem to change the spring tension, but I can't tell any real difference in performance.

Can I reuse broken needles by heating and mushrooming the ends? Obviously a full set the same length needs to be done at once.

Am I lubing the tools correctly (air tool oil plus some graphite on the needle ends and holder disk)?

How critical is the spring tension? The tension seemed too tight on one of the 125s and too loose on the 172, so I swapped springs between them, and both seemed to work better.

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-Matt Conrad

Needles have a rounded end and a flat scaling end. It is very normal for the rounded ends to wear thin from constant pounding and blow out. Purchase new replacements, remove the older beaten needles and save them. Insert the new needles and you're good to go. Always use a a few drops of good quality of air tool oil when you start and when you put the scaler away.
Save the older needles, if they're not worn out, as replacements on a late Sunday afternoon.

I've used a Trelawny 4B the last 20 years. If you are going to really use one, you need a good one. They also make larger/smaller.

When I was running it all day, I lubricated it at lunch and took the entire thing apart every day and got all the sticky slime off the needles and carrier. That greatly reduces wear which notches the needle where it rides in the carrier. Broken needles need to be removed immediately to not damage the carrier. Needles lasted 1-2 weeks, the carrier would last a month or two, the sleeves will stress crack. I would sort used needles by length and as the ones I was running broke, I would replace the first few and then change out the whole set when breakage got frequent.

It is brutal work. Wear double hearing protection and anti-shock gloves. Stock lots of consumables. For the last 15 years, I only use it occasionally and am still running off spares. But the sounds and feel take me back to scaling a 100" diameter boiler and four tender/water cars. A beautiful tool.

https://www.surfacetools.eu/en/trelawny-4b-needle-scaler/a3559

In my Navy days, I did a lot of needle scaling. In my railroading days, I did a lot of needle scaling. The best gloves I ever used were ones I used while chipping paint/rust on submarines - they were leather and had a gel pad sewn into the palm. They were made by USA Sewing. USA Sewing, AFIK isn't on that contract and has moved on to kevlar gloves for the Army. I looked up the NSN for those gloves and Impacto is listed as having a qualifying equivalent. I haven't used these but of all their products, the BG650 Anti-Vibration Air Glove is the one I would buy. Not so important for chipping good paint but essential for longevity when chipping rust and boiler scale, the leather construction will last much longer than the knit or synthetic fabrics. You can get a pair for less than $47 on eBay and if this is too much to pay, you shouldn't be doing the work or asking volunteers to do the work. If you can't find the coins to get a pair, it helps to refrain from using a heavy grip - just use your hands to guide the tool and vary the angle while letting the needles travel to impact. If you have a death grip and try to force the gun into the workpiece (audible pitch increases), you're not getting the impact to accomplish the work. Let the tool do the work it was designed to do. The needles are tempered so heating them to mushroom the head will ruin them. Grinding to a sharp point however makes for a good punch or scribe and I always have one in my tool box.
http://www.impacto.ca/uploads/bg650.pdf