How was this WW2 German Railway Gun Machined?

How big was the lathe that was required to turn the barrel on this German railway gun in WW2??? There were a few hundred comments on this post. Worth reading through if you’re interested in the subject. Below are a few we found interesting…

Top comments include:

• “This page is awesome!! I didn’t expect to see anything like this come up in my feed and now that it has, I am once again in admiration of the mechanical feats accomplished back when people made things happen out of sheer will and necessity.”

• “Aren't prop shafts for large ships about that long? theres some vids on youtube showing massive lathes, of course they're foreign korea i think, the lathe is probably not the issue, just like I think the largest stamping press the germans had at like 5000 tons, I can't remember if they still have it or russians took it, but yeah most things probably repurposed, I don't think the lathe size is the issue, but a setup for the rifflings, that setup for something that large probably doesn't exist anymore”

  • “America got most of the big presses after the war they are still where used to this day from what I’ve have read about them”

  • “Proper shafts of that length are usually shorter sections with flange connections.”

  • “I think it was 50,000 tonnes and it was one of the first things the Russians grabbed”

  • “The only manufacturer of propeller shafts in the U.S. is Erie Forge and Steel in Erie Pennsylvania. Their primary if not only customer is the U.S. Navy.”

• “I manufactured Howitzers for the Army during my career. Barrels for very large guns are not turned on a lathe. They are forged and the bore is finished with broaching. Threads are made with a grinder.”

• There is actually video out there I’ve seen in the past of the Iowa Class battleship barrels being produced at Bethlehem steel.

• “I have seen some documentaries featuring Germanys. Super weapons including the V3 gun developed for firing rounds from the coast of Calais into London. The barrels were over 400 feet long but may have been segmented. German Engineering of that era was futuristic.”

• “I am probably one of the few people still alive that had the privilege of viewing these large steel mills with their equipment still in place. They were huge machines that dwarfed the men who operated them. The lathes were able to bore 40 meter cannons in a single piece. The foundations on their presses went very deep. Some as I remember were filled with carbide to handle the weight. When the mills closed, it was said that the foundations were dug up to retrieve the carbide in the ground, but I can't verify that. I did have the opportunity to buy a borescope from one of them though. It was about 3" in diameter and was 60' long once you screwed all the sections together.”

• “I once did some work at a factory that made bridges, a guy drove his lorry into the factory to drop some steel off and asked where was the milling machine to which the reply came your parked on it. It was about 40m long and 15m wide.”

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Can this be done?

Top comments include:

• “Not sure if you or the customer already ordered pre cut blanks, but we would just get them cut long enough to have something to hold onto and then part or turn the excess off.”

• “Chuck up a piece of aluminum

  Counter bore to fit boss on part

  Use a live center with a plug to apply pressure

  With the boss on the part in the counterbore your part will only slip and not fly out

  Disconnect the foot pedal for the chuck if hydraulic so you don’t unclamp by habit”

• “Used to pressure turn plates all the time. Take lighter cuts than normal. On these I would probably make a pressure plate out of 1” plate and drill a good sized center drill hole in it. Speed the chuck jaws out so they hit the part you are machining about 2/3 of the way out. Adjust as needed.”

• “We had several parts that were "pressure turned" exactly how you described it on manual lathe. Looks like the diameter on the parts in the picture have plenty of diameter to pick up on if the face and diameter are turned in first op and then flipped around and held on finished diameter to complete second side. Had one job that only held on the diameter by .012 so it is possible.”

• “Charge them extra. This is going to be a hassle. The the scariest words to hear "Customer Supplied Material". Tell them to consult with you in future before ordering material”

Question of the Day⁉️

How many threads per inch on an Imperial micrometer thimble?

Top responses include:

• “A question on my high school class I taught. Most got it”

• “25 years ago this was actually a question an employer asked me in an interview. He said a machinist should be able to figure this out. Pretty easy when you think about it.”

• “Good question.... that I've asked hundreds of "machinists". Very, very few knew and most of them couldn't figure it out.”

• “I ask this very question when interviewing potential employees. It tells you a lot about them:

  1. They know how a micrometer works (you'd be surprised).

  2. They know about T.P.I. and threads.

  3. If they don't already know, but can figure it out, they have math skills.”

• “1 divided by .025 = 40.” The machinist trade is based off a screw thread! Some of us are not mechanically inclined, but helps to be mathematically inclined.

  Numbers don’t lie!”

• “Well, it moves 25 thou per turn. And there are 1000 thousandths per inch so 1000/25= 40”

  Join the Conversation Here

Funny Post of the Day 🤣🤣🤣

Machinists with questions or advice 🤔

⁉️ What RPMS do you all use when cutting threads on a lathe? Small stuff.

⁉️What’s the consensus on what a machinist lead position should be paid?

⁉️ Any advice on machining Nylon 6?