M1 Abrams turret fabrication

your correct in that the boring mill was a CNC machine, but you only use the scales (in this case) for positioning. The head does the serious work, and the drives put it position. Similar to a jig bore. When I saw that machine, I’d just set a G&L that was roughly 2/3rds the size. My boss asked me how thick the isolation pad had to be for that thing (mine was 13 feet deep). I’m not sure it could ever have been deep enough!

By the way if you think that mill is big, I saw two plainers at the old American plant in Ohio that could cut three 190" lathes at the same time (lined up end to end), and was capable of doing nine beds on one setup. I once saw a line of 16 SIP jig bores right in a row! (that was way over the top in hard cash!). I hate SIP’s and anything they built. I think it was Northrup where I saw a VTL that had at least a 16 foot table and probably 20 foot. The table was the same hight as the floor (still the biggest I ever saw). Oklahoma City had a plant with a rail line in it that was so long they had to figure in the curvature of the Earth when they laid it! That was just nuts
gary

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tool changers can be a work saving device or a general nightmare. I had 13 jig mills that used 122 switches and prox switches to make one complete tool change from the magazine. The majority of the switches were hidden from sight, and even worse were the prox switches. One small chip of metal could cost fifty grand in less than ten seconds. I would like to think that the boring heads were loaded by hand, as they are probably way too heavy for the tool changer (usually 25lb. or less). Another interesting thing we see in the picture is the evidence of a back cut (the bright metal ring on the bottom side). Probably done with a generating head at the end of the machining operation. Very heavy tooling and pretty damned expensive. Probably uses diamond inserts as changing the insert and then finding size would drive you insane. I think the whole segment of the operation is long overdue from a retool and redesign using the same basic machine. Your looking at 1978 tooling verses something like 2010. I’d start with the fixture

What really suprises me about the lower photo is how they went to all the trouble of boring that ring hole with the turret on it’s side. Been more accurate bore from the horizontal position (but also one nightmare of a machine to build). You always want to start from the earth’s surface and go up if at all possible (locating)
gary

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Next is the GPS mounting surface and the surrounding “coaming”. This took a while to puzzle out based on the limited photos I have.
The mounting lip and surrounding edge was made oversized to help with invisioning its orientation and handling, then cut back to the top of the turret later




The “ coaming” was pocketed out to accept this assembly & orient the two in relation to each other

It was then machined out on the side to represent where the commanders extension passes through & mounts.


Here’s everything made so far in place to check how it’s shaping up.



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when I toured the plants, that part was regarded as top secret. To be exact the entire sighting system was considered top secret as well. Yet they brought the thermo/laser sighting device into work for a shoe & tell one night (Army out of Knox). It was pretty neat, and yet not fully developed at the time (mostly software).
Was stunned at the range it had (probably several miles)

I’d love to have seen the gear generator that cut that ring gear! Probably a solid eight hour cycle (time). Cutting gears was never a great forte for me. I can get by 85% of the time, but that other 15% drove me nuts. Surprised that were not ground as just about everything else inside that hull was
gary

Thanks Gary, I really appreciate the details you’re providing. I’m working on a hull fabrication as well

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Looking at the hull sides - are you going to add on the additional plating (hull thickness) as separate parts?

Yep


Interesting thing is on some hulls the plate is welded on while on others it appears to be one piece with the recesses machined down to thickness .

Top photo is an M1 while bottom is a prototype Grizzly breacher vehicle.

These are screen shots of Egyptian M1A1 production & clearly show a weld seam here


but seems to be a full thickness plate with the recesses machined down to thickness here

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Moving on to the bustle door frame, the rails are laminated .010x.156 & .030x.030 cut to length after drying.



The turret base needed a slot machined to accept the lower rail


I used my lathe as a precision disk sander to get the angles on the side fillet pieces

And here it is closed up checking for fit

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So here’s where you’re hiding out Sean.

Nice work and a very interesting “scene”!

I’ve been in the “lost” Mojo for several months now on my Abrams build on R C Tank Warfare.

Barry

Hi Barry ! Thanks, I’ve been checking in on your project every now & again.

Some new photos have appeared so I’ll have to get back to this





Your average 19–20-year-old tanker will never truly appreciate the complexity of the manufacture and the level of engineering involved in the manufacture of the Abrams tank.

The folks at General Dynamics Land Systems, plus the folks at Lima always get a tip of my hat for their dedication and skill in turning slabs of steel and composite armor into our premier main battle tank.

Agreed, it’s fascinating technology to me.

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My first M-1 was #88. The serial number plate inside the the turret said XM-1, 105MM, GUN, TANK

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Definitely some amazing stuff there when it comes to armored vehicle production. My dad was a machinist for several decades and was always telling me about this machine and that machine. He would love to tour a facility that makes tanks. Fascinating

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some more new (to me) photos.



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Wow, those are all old! 105mm turrets!
Ken

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You can definitely see the evolution of the Abrams, from initial to current production.

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How about some V3 action…
Thought I had more, must have deleted them after I built mine :man_shrugging:t2:



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Thanks for those ! I’ll have a spare A1 turret when I do my ABV that may end up as a stripped down turret waiting for remanufacture.

Just came across this one from the Anniston FB page

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