Sherman gun travel lock

Robert E Morey · Post by **Robert E Morey** » Mon Dec 22, 2008 7:03 pm

I can't let Dale get all the glory with his Sherman, so I thought I'd post some pix of the Sherman gun travel lock prototype I'm working on. Not too slight Dale's superb work, but to prove I do actually work on my Sherman (although only occasionally).

The material is Urethane foam board to test the CNC program. This is the top side program. Now to flip the material over and machine the back side details. Once the programs are proven out, I will machine the parts in Aluminum. I will put one on my Sherman and use the other as a casting master to eventually make a spin cast mold. Stay tuned for a white metal kit possibly later next year (09)?? The "bumps" in the center are the hinge pieces which mount the gun travel lock to the glassis plate. The black lines are epoxy which bonds the three pieces of foam board together.

Happy holidays everyone! Bob

Brian Leach · Post by **Brian Leach** » Mon Dec 22, 2008 7:54 pm

Wow, nice job. I like that you did a test run with the foam.

What kind of milling machine is that we are seeing?

I expect to buy one fr myself and would appreciate any suggestions.

Great work!

-B

Allan Richards · Post by **Allan Richards** » Mon Dec 22, 2008 9:50 pm

Very impressive Bob and a great addition for the Sherman. I've almost compleated the Firefly one which was a lot of work to scratch build.

Robert E Morey · Post by **Robert E Morey** » Mon Dec 22, 2008 10:25 pm

Thanks for the comments guys.

Brian, its a Taig, made near you in Chandler Az. Great little machine, it is very capable if used within its limitations. In my opionion it is way better than Sherline or MaxNC machines. I recommend it over all others. I've made a lot of nice parts with it.

Its always a good itea to prove out and test long programs in foam, wax or other soft matl. This particular program is 180,000 lines of code - just for the top side alone! Better to find a bug in foam than after 12 hours of machining metal. I also run a comuter simulation of the program before machining anything just be sure there are no serious glitches.

Allan, looking forward to seeing your firefly travel lock details, you've done a great job so far. It will be really impressive when painted up.
Bob

Brian Leach · Post by **Brian Leach** » Mon Dec 22, 2008 10:33 pm

Robert,

Thanks for the recomendation. Actually I am going out there this week to take a look at their machines.

I am also looking to get a lathe. Any thoughts?

Thanks again, and of course-Great work!

-B

Dale jordan · Post by **Dale jordan** » Tue Dec 23, 2008 2:20 am

Very Very nice Bob . This is one part , I have been waiting for someone to build as I need one 'soon as' . This will fill up the front plate on my Sherman nicely ... Dale

Robert E Morey · Post by **Robert E Morey** » Tue Dec 23, 2008 5:45 am

Brian,
I'd like a CNC lathe someday myself. The choices in a benchtop model are limited. MaxNC does make a pretty nice looking lathe, but I have not used it and its pretty spendy. Sherline also has one but it is small. I don't believe Taig makes a CNC lathe, but they do a manual one. If I was really wanting a lathe I would shop evilbay for a used EMCO Maier Compact 5 with tool changer if I was in the market for a lathe. You might check Evilbay for a Taig mill, I got mine brand new with stepper motors and control box for around $1680. There's always buy a 7x12 or 7x14 mini-lathe and convert it to CNC as another option.

Dale I agree the gun travel lock is really needed, and I'll keep you posted on the progress. I can't wait to see how the machined alum version turns out.
All for now...
Bob

simon_manning · Post by **simon_manning** » Tue Dec 23, 2008 10:08 am

very nice and very skillfull,keep us posted if you make any you want to sell i would like one.

simon manning

Robert E Morey · Post by **Robert E Morey** » Thu Aug 13, 2009 7:37 pm

Finally got around to machining the Sherman gun travel lock in Alum. Here are a few shots. Now that the Panther is nearly done, I hope to make a few goodies for the Sherman and get it finished up. These are photos of the top side machining. Time to machine is about 5 hours roughing, and 8 1/2 hours finishing. Not exactly what you call "rapid prototyping".

Next steps will be to machine the back side features. The round things in the middle of the piece are the two mounting brackets.

Adrian Harris · Post by **Adrian Harris** » Thu Aug 13, 2009 9:17 pm

Simply stunning Bob

Do you have to change the tool between the roughing and finishing

Adrian

Graham Ord · Post by **Graham Ord** » Fri Aug 14, 2009 9:29 am

Bob
A beautiful piece of work and as an ex CNC machinist I can appreciate the time, effort and skill required to produce it.

Robert E Morey · Post by **Robert E Morey** » Fri Aug 14, 2009 5:50 pm

Adrian,
On the top side machining I did use 2 tools, a 3/16" dia for roughing and a 1/8" dia for finishing. Its actually separate programs for roughing and finishing, so having different tools is relatively easy. One just has the machine return to X0,Y0 after the rough program and then you only have to re-zero the Z axis with the second smaller dia tool. X and Y will use the same zero pt for both programs (rough and finish).

On the bottom side I elected to use the same tool for both rough and finish - the 3/16 dia.

Graham thanks for the compliment! I'm very honored to hear you say that. Your P4 is a marvel of the machining trade, Esp doing most of it on a lathe. Not many people can really appreciate how difficult that truely is. Did you use CNC for any part of that project? I see from the video's it drives superbly.
Bob

Graham Ord · Post by **Graham Ord** » Fri Aug 14, 2009 8:04 pm

Bob
All of my PIV was done manually on my lathe. The only part I did not make was the turret ring gear which I had laser cut.

Robert E Morey · Post by **Robert E Morey** » Mon Aug 17, 2009 6:53 pm

Some recent photos of the gun travel lock finished up and test fitted. I nearly had a distaster on the back side machining. CNC is very unforgiving! In the previous thread I mention that I would use the same tool for the backside machining. Well I program two different tools by mistake (.1875 rough, .125 finish) and nearly ruined the part.

The entire backside was machined .031 undersize on all sides!

But the good news is the part was salvageable, I had to add the washers to the base pivots, but other than that you cannot really tell anything went wrong. It came out ok for the prototype - 1st one in aluminum.

Next will be the barrel hold down piece and hull latch (to hold it to the glassis when not in use).

Jeffrey Goff · Post by **Jeffrey Goff** » Mon Aug 17, 2009 7:27 pm

Hi Bob, that looks fantastic, I am envious of your skill and technology, I tried to remove some alloy using a small mini mill with electronic speed control the cut was to deep, it jammed and it blew its brains out literally, the PC board is on its way back to the manufacture, so I shaped the PZIII mantel ends with a hacksaw and file, at least human manual errors are slight
keep up the good work
regards
Jeff