Metal tube joint basics

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:


Well-Known Member
Oct 13, 2020
I've never heard anyone say that. It was almost a match for very early Panzers, not the Tiger. Smaller gun with less velocity, much less armor, and slower to boot. In your estimation, what made the Sherman better, aside from numbers?
Total thread hijack, but I'm glad you asked.

A little bit about myself: I served in tanks in the US Army for a bit over 10 years, and became a historian. Also published a couple articles on the subject.

Bottom line: The Tiger I was an incredible collection of specifications which didn't add up to being a successful tank. The Sherman was an excellent Medium tank which did just about everything pretty well, and some things exceptionally.

The Wehrmacht didn't really want the Tiger, but was shoved through the system by chrony capitalist friends of the Austrian Corporal. The problem with the tank were manifold.

The armor was heavy and relatively ineffective, due to not really thinking through how armor was supposed to work. It was literally as thick all the way around, and the armor was arranged in such a way as to optimize the effectiveness of hits. It's weight made it strategically immobile. It was a huge production to move them across the battlefield. The Sherman had well sloped and thought out armor which was only .25 inches less along the front, which is where it really matters.

The 88mm gun, which was the reason for the tank's existence, had to be shortened to fit in a turret. This made it less effective than the infamous flak 88, yet even so, its length and mass made the turret slow and unbalanced, which made it difficult to lay on a target. The turret drive was a nightmare, with the commander having the choice between an electric drive which was jerky and imprecise, or manual control which was glacially slow. The Sherman, on the other hand, had a well balanced gun and a hydro-electric turret drive which had both high speed and low speed settings, both extremely precise, which allowed it to slew quickly and put a first round on target.

Despite its vaunted armor, the Tiger wasn't particularly survivable. Crews burned and died once the armor was perforated, which it could be at all Northern Europe typical engagement ranges (400 yards) at a rate higher than the Sherman. The Sherman, despite its reputation, had the best survival rate of any tank of the war, when hit.

The M4 was brilliantly engineered. The 75mm gun, which is much maligned, could penetrate and kill any German tank at Northern Europe typical ranges (400m). Not only that, but the 75mm had an incredibly effective HE round, roughly equivalent to a 155mm howitzer round. The 76mm gun was more effective against armor, but it's issuance was restricted because (shocked face), the German tank threat just wasn't that important. In fact, in Northern Europe, there were something like 4 Tiger I versus M4 engagements, and the M4s won 3 of them. So the whole "Tiger is worth 10 Shermans" is a myth.

The Sherman was mechanically the best tank of the war, and the second best isn't even close. Engine and transmission changes were simple and easily doable in the field. Germans didn't even consider major field maintenance until 1943, and their designs were poorly engineered to the point where most major maintenance had to be done at a depot, which resulted in the loss of tanks for relatively minor damage/breakdowns.

I'm not the world's authority on this, but among informed historians, the "M4 Sherman is a death trap" myth has been put to rest among those in the know.

This guy knows 100x what I do, and is worth a watch.



Nov 10, 2019
Hillsboro, Oregon
I believe you would calculate the tear-out/bearing of the bolt of the hole of each tube, the tension failure of the x-section of area of the metal each tube, the (single or double) shear of the bolt.. The least value of the three calculations is the tension value.......depending on the span/length of the tube in compression this value may or may not be higher or lower than the compression calculation (Euler calculation) of the tube. Professional stress consultation for a more detailed answer, limit load test or test to destruction for real peace of mind.
Thank you for your time and input!


Active Member
Oct 13, 2020
Southern California deserts....
Here’s a question for the group that’s back on topic: ignoring the method used to cut or form the shape the saddle, what methods do you use to determine the shape of the saddle joint? Thank you.



Well-Known Member
Oct 6, 2021
Eyeball to fit. Hold the tube up next to joints where it will live, mark the tube with a silver pencil, then start fitting.

Align the center line of the tubes to intersect at the same spot to the degree possible - as the general practice as there may be features that require an exception.