Rockwell C Hardness Testing (Who does it?)

[Bloo]

The title says it all. What sort of shop, other than an automotive machine shop, might have this equipment at their disposal?

 

Thanks.

 

 

[edinmass]

Firearm manufacturer will have them. Also, any fabrication shop for boats, and many machine tool shops. They are common and not expensive. We had one in my old shop purchased at a swap meet. We used it to test valves.

[Bloo]

Thanks! How big is the dent? I want to check some water pump shafts, and still use them.

 

 

[edinmass]

Very small. Easily placed where it won’t do harm. It’s easier to just buy some correct material. There are different schools of thought on how hard a pump shaft should be. I don’t have an opinion. 

[Bloo]

I am restoring a pump that uses a bronze bushing on the rear (against the water and packing) and a needle bearing in front for the fan. Specs for the original needle bearing have proved elusive, though modern needle bearing catalogs from Torrington and Koyo who own (or recently owned) Torrington lead me to believe the shaft hardness should be in the high 50s Rockwell C to run on a needle bearing. They also specify shaft finish, though I don't remember the number for that offhand. Fairly polished.

 

I have amassed several NOS/NORS shafts. I don't know how many of the ones I have were intended to run on only bronze. Some may be hardened and correct for the application, but at this time I don't now for sure. One of them has a part number stamped in the flange that implies it might be for this application.

 

If I made a new one, to get to Rockwell 58-59 or so, I imagine it would entail buying drill rod, turning it close to the screwball shaft size (it's not anything standard in US or Metric), having it hardened and then ground. I've not ruled this out, but might have a correct shaft already laying here. I just don't know. Any thoughts are appreciated.

 

Edited December 4, 2022 by Bloo (see edit history)

[bryankazmer]

Contract testing labs do this sort of thing.  Ones that do automotive work will typically be registered to ISO 17025.  An easy test, but there is usually a fee for it.  You might be able to get a favor if you skip the sample conditioning and report.  Where are you located?

[PAV8427]

Take a small file across the corner of the shafts you have. If the file glides across without biting, it more than likely is hardened enough to run. 
If soft, you can case harden. 
Heat shaft to a dull orange color and quench in water.
Measure diameters. Might require some polishing if the shafts 'grow' when heat treating. 

Edited December 4, 2022 by PAV8427 (see edit history)

[Bloo]

5 minutes ago, bryankazmer said:

Contract testing labs do this sort of thing.  Ones that do automotive work will typically be registered to ISO 17025.  An easy test, but there is usually a fee for it.  You might be able to get a favor if you skip the sample conditioning and report.  Where are you located?

Wenatchee, WA

[Akstraw]

You might find that your local engineering college has a Rockwell tester.  That's where I first learned to do the test.   

[edinmass]

Water pump shafts, and water pumps in general are a constant headache. Oftentimes they have been altered or re-engineered and done poorly. I had a customers big boy toy in the shop when the pump exploded and ate the hood, radiator, and associated parts. Long story short, it was an altered pump and obviously done incorrectly. We are talking a 25k failure here. Interestingly I had another similar car at the same time and looked over the pump and it was done in the same way by the same builder. It was an easy up sell when I showed the photos of the other cars failure to the owner of the still intact car. In the last ten years I have had about a dozen pumps done by “professional “ shops for me because I am so busy with other things. About half of them end up leaking sooner or later. Now I only use two sources to do water pump work. They are very good, don’t have comebacks, and are fairly quick. Just don’t ask the price……

 

Modern seal conversations are popular and fine if done correctly. I did my 1936 Pierce V-12 35 years ago and haven’t touched it since. It’s has tens of thousands of miles on it. End play and drive coupler set ups can be problematic. Also incorrect or modified fans that are out of balance can crack with a disaster for under hood. So a “simple” water pump is more often than not complicated. Especially on pre 1936 cars. In general we convert to modern sealed bearings and modern seals if you can machine what you have to work with. It can get complicated fast. Sometimes just rebuilding it in stock configuration is your best option. 
 

Bloo………how about some photos of the pump. 

Edited December 4, 2022 by edinmass (see edit history)

[Bloo]

 

That is the patient in the middle. It is a simple pump. And yes, it was previously rebuilt badly. It was on the car and working fine, but was getting no lubrication to the back bushing. It probably would have failed.

 

This pump was used in production for half a year only, and I am trying to restore it to original condition. Information is sparse and not all the part numbers made it to the parts book. I have managed to identify and collect all the correct parts, except for the giant oil cup that goes on that tall boss that feeds the rear bushing, and I have an oil cup that's probably close enough.  The previous rebuilder apparently reamed the outer bearing bore oversize, but Bhigdog already made me a sleeve to repair the bore. All my back plates are rusted out junk, I'll have to get some of those made eventually.

 

This picture is actually the stuff that came out of the left pump in the picture above, but it's the same shaft, large rear bushing (more or less), fan flange, packing nut, etc. that belong in this pump. Only the needle bearing and felt washers at the front are different. Well that and maybe the hardness and finish of the shaft(?).

 

 

I'm afraid I don't have a picture of all the correct parts yet... soon.... Here is a correct impeller.

 

 

I don't think my pump would have exploded like your customer's did, but the fan worries me. I've wanted to get it magnafluxed as long as I have owned the car. It's construction looks a lot like a certain Hupmobile part that is noted for exploding. I had never heard of one of the Pontiac ones coming apart, but it happened to someone on the way to the Flathead Reunion earlier this year. I've not found anyone to magnaflux locally, so I suppose I'll have to mail it somewhere next spring when I get the car back out. I don't know where to send it.

 

 

[DonMicheletti]

I believe many pump shafts are case hardened and not through hardened.

Case hardening gives a hard, wear resistant surface while preserving the, typically, softer, tougher core.

Through hardening may not be very resistant to shock or sudden loading.

[Bloo]

I agree. I would prefer case hardening.

 

[edinmass]

The grease cup MUST have a check valve, or it will suck air and leak backwards. Looks like a bad idea from new……especially if it’s only a half year pump. You can do crack checking yourself. They have at home kits that work well if you follow instructions. 
 

We call working on such projects…..polishing a turd. When your done, no matter what you do, it’s a POS. If you do a good job, it’s a shiny POS. 😎

I would run a sealed bearing up front, and use use a packing on the back side. Make sure you have some end play….not too much. Also….DO NOT over tighten the belt. On pre war cars the belt should be fairly loose…..

 

[edinmass]

By the way, get water pump grease for the back bushing…….the real stuff Lubriplate sells, not the modern trash most sell.

[Bloo]

These don't use grease they use oil! The bearings are sintered bronze, and there is a reservoir for oil around the outside. The oil soaks through the bronze, There is no hole for it to suck air through or blow water out.

 

Some previous rebuilder put a zerk where the oil cup was supposed to be. I was dutifully trying to cram real Penrite water pump grease in there every few months, but as it turns out, it wasn't going anywhere because there was no way for it to get in. You can see where bronze was smearing on the impeller thrust face because there was no lubrication.

 

The main functional difference of the half-year pump compared to the earlier ones is that it uses a needle bearing at the fan end instead of sintered bronze, and that needle bearing DOES use grease, and a zerk, but there's no water up there. It's still oil and sintered bronze in the back where the water is, it just has a much bigger oil cup than the earlier ones.

 

 

Edited December 4, 2022 by Bloo (see edit history)

[Bloo]

29 minutes ago, edinmass said:

You can do crack checking yourself. They have at home kits that work well if you follow instructions. 

 

Do you mean with dye? The magnetic setups seem to be pretty expensive, although since there seems to be no one around to do it, maybe I should consider getting my own.

 

[edinmass]

Yes, with dye. 
 

Sounds like the pump was broken when new……..

[Bloo]

Well... It's been working fine since I bought the car about 6 years ago.... but I don't know how the needle bearing will hold up. That is the wild card.

 

The last guy converted it back to bronze at the front end, using a stepped shaft and bronze bushing, apparently from a 36 Olds. There was a hole drilled in the bushing for the grease to get through. That end was getting along fine. It probably would have been fine forever if he had put an oiler on the back end, but he put a zerk, and the rear oil reservoir was full of grease, so no lube was getting in there at all.

 

Back then I was unaware of any half year pumps or anything like that. I do read the shop manual and couldn't understand how water pump grease was getting into the rear bushing unless they drilled it, and if they drilled it, why wasn't water trying to come out? A pump came across ebay that matched the pics in the shop manual and I bought it. That's the one on the left up above. It's an early 1936 pump, all sintered bronze bushings, all oil, and basically the same back to 1933. I figured If I ever had the pump off I would just throw that one on, but I took it apart for inspection and discovered it wasn't ready for primetime.

 

[Bhigdog]

Most any machine shop has a RC hardness tester. Only takes a minute. If I had one in my shop I'd do it for free. Tested surface must be free of scale. Will not give surface hardness of case hardened unless pack hardened.

Mcmaster lists any number of hardened and ground steel shafts that might work for you assuming there is not a lot of other machining involved..................Bob

Edited December 4, 2022 by Bhigdog (see edit history)

[Bloo]

38 minutes ago, Bhigdog said:

Will not give surface hardness of case hardened unless pack hardened.

 

So I still won't know then if it's just case hardened? It probably is if it is hardened at all. The modern bearing catalogs say I need this to be high 50s. How can I tell? 

 

A quick check with a caliper says the shafts are 0.487".

 

[Bhigdog]

Common cyanide casing is only a few .001's thick so the RC diamond point pushes right through that and will not give a true reading. OTOH if you get a RC of +50ish that's likely a good reading. The good news is the case only HAS to be few .001's thick for wear. Mcmaster has a .4844 X 6" reamer blank that might work for you. Failing that you could use a .500 prehard rod from McMaster and have it centerle$$ ground to size.

You could also have a steel shaft turned to size and cyanide case hardened which does not add scale.

BTW, .487 is a weird size. Not metric either. Closest is 31/64".............Bob

Edited December 4, 2022 by Bhigdog (see edit history)