How To machine one piece axle box

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hudson
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Re: How To machine one piece axle box

Post by hudson »

The machining of a set of four cannonboxes
for a SAR 4-8-4 steam locomotive was
described as per link:

http://www.northernsteam.com/25NC.htm

Hope this helps.

Best regards,
hudson
flavinny
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Re: How To machine one piece axle box

Post by flavinny »

Dick would have a supplier that could supply about two feet of the DOM tubing you suggested.?
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Dick_Morris
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Re: How To machine one piece axle box

Post by Dick_Morris »

I haven't bought it from them and it's be a number of years since I purchased any, but here is a start https://www.metalsupermarkets.com/search/dom/

My impression has been that their prices are high, but a couple of weeks ago I found a producer price index for steel from the mill as I wanted see what the value of the boiler tubes we bought eight years ago would be today. Since 2014, steel mill products have increased to as high as 350% (fall 2021) and have now settled to "only" $220% of what they were when we made our purchase.
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ALCOSTEAM
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Re: How To machine one piece axle box

Post by ALCOSTEAM »

but if you take steel into the scrap yard they tell you they are not getting anything for it so they can't pay much. The closest yard has a string of gondola's and is loading and shipping as much as I have ever seen.
flavinny
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Re: How To machine one piece axle box

Post by flavinny »

Still procrastinating but getting closer to starting this. I was looking at the webpage suggested by hudson above and it appears they machined the external profiles before machining the bearing pocket. (I am also curious what type bearings they used)
I am thinking of just dusting external surfaces to establish reference points for setup in the lathe. I still have not come up with a plan on how to chuck the casting to bore the first side. The core seems to be fairly concentric but probably not a good surface for the chuck jaws to clamp against. I could possibly take light cuts to clean the bore and face then turn it around to do the other side to dimensions.
My next question is tooling. Any suggestions on where to purchase insert tooling the cut the internal threads (3"x26) at a reasonable price as will probably only be using it for this one job?
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Harold_V
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Re: How To machine one piece axle box

Post by Harold_V »

flavinny wrote: Thu Jul 13, 2023 10:32 am My next question is tooling. Any suggestions on where to purchase insert tooling the cut the internal threads (3"x26) at a reasonable price as will probably only be using it for this one job?
Blink! Blink!
Strange as it may sound, that tool can be fashioned on a pedestal grinder faster than it can be ordered, and it can be made with an old (used) piece of HSS stock.

I have commented often how learning to hand grind cutting tools can set one free. This is a good example of my mindset, made all the more valid by the notion that it would be used only once. Why spend that amount of money when it can be better spent elsewhere, with the added bonus of improving (or getting some new) grinding skill?

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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SteveR
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Re: How To machine one piece axle box

Post by SteveR »

Martin Lewis said that castings were a big time saver, but I think this is only true if you are used to working with castings!

I haven't seen anyone ask the question of "how close the casting is to the final dimensions?" This will have a big impact on which features are machined in which order. For example, if the cored hole is close to the final dimension, you need to make sure that if you start on the external features first, then you have enough excess to put the hole in the right place to the final dimensions.

Best to first determine which features of the casting have the least amount of material to remove to hit the target. These are the most critical and should be done first. Years ago, I machined some iron castings and started by squaring them up. When I was done, I found out that the very first cut was over by 0.1". When I remade the parts, the first cleanup cut had to be 0.025 to avoid having critical features out of spec.

More fun.
SteveR
12x36 Enco Lathe, 9x42 Bridgeport, SMAW, O/A, Miller MIG w/gas, plasma
Not enough measuring tools...
1.5" Allen Models Consolidation on air.
1" FEF in progress
1" & 3/4" LE Projects
Measure twice, cut once, wait - it was supposed to be brass! :)
flavinny
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Re: How To machine one piece axle box

Post by flavinny »

There is plenty of material to work with the core is ~.28 smaller than the finished dimension for the bearing. The adjustment nut is a different story. the LE drawing does not give an ID for the threaded area. I found a calculator online that indicates the thread depth is only 0.021". If this is true, the cutting toll would have a very fine point. Cutting cast iron can be hard on tools even after getting through the crust. The tool getting dull when cutting threads would be a real problem so I would like to use a carbide insert if possible.

https://www.engineersedge.com/calculato ... _15872.htm

I am not sure I am interpreting the output of this calculator correctly the thread depth seems very shallow.
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Harold_V
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Re: How To machine one piece axle box

Post by Harold_V »

flavinny wrote: Fri Jul 14, 2023 9:03 am Cutting cast iron can be hard on tools even after getting through the crust. The tool getting dull when cutting threads would be a real problem so I would like to use a carbide insert if possible.
I understand your concern, but it is highly likely it's misguided. Cast iron, when not chilled or having sand embedded, machines without issue and is NOT inclined to dull tools prematurely. Fact is, HSS on clean cast iron works perfectly well.

Those of us who worked in the trade were expected to be able to fashion our own cutting tools. There was a time where there were NO insert tools available. You can safely assume that WWII was fought without such luxuries.

It is not my intent to tell you how you should work, nor how you should spend your time and money. I just want to refresh your memory that you are NOT bound to use insert tooling---there is a different approach, and it has benefits that can bail you out in many occasions.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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Bill Shields
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Re: How To machine one piece axle box

Post by Bill Shields »

totally agree with H on this (rare)....very few insert tools in my shop.

During WWII there were brazed carbide tools available (came from the Fatherland in the early 1930s ??)...and you still had to sharpen them (giggle)

Jim Stuart was working at Springfield Arsenal during the war -> and he remembers setting a turret lathe on fire because the cutting oil they were using was not up to what was going on....
Too many things going on to bother listing them.
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Harold_V
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Re: How To machine one piece axle box

Post by Harold_V »

Bill Shields wrote: Fri Jul 14, 2023 4:09 pm During WWII there were brazed carbide tools available (came from the Fatherland in the early 1930s ??)...and you still had to sharpen them (giggle)
Yep! And often without the use of diamond wheels. Green silicon carbide wheels were in common use at that time, and the end result from their use left a great deal to be desired. It simply isn't hard enough to create a keen edge, removing unwanted carbide more by chipping than cutting, unlike diamond.

Even in the late 50's, carbide wasn't all that great. It suffered from lack of tensile strength and failed prematurely. Micro-grain appears to be the huge turning point. The carbide of today is a far cry from that which was in use back then.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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