2 Inch Burrell Governors

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2 Inch Burrell Governors

Post  miller on Sat 18 Jul 2009, 9:00 am

lets take a look at something I've been working on these last few weeks, the 2inch Burrell Governors. these are quite complex sub assemblies considering the fact that they have no real purpose on the 2inch model and are actually dummies.

for those of you not familiar with a governor here is a photo of one from the 4inch model...



and to show a little more detail, a couple of drawings....





we have had the main governor bodies for some time now and have made a start on both the 2inch and 4inch castings....



you may be wondering how we hold these in the machines. well we have made two simple machining jigs. the bodies are located in the jigs in the same way they will be be mounted on the cylinder. the sides of the jigs have been machined square and level, allowing us to lay the part on any side that we require...



but we could not go any further with them until the two bevel gears had been made.
just around Wednesday lunch-time we had the delivery of castings that we had been waiting for, containing quite a few interesting 2inch parts Cool ...



but these are the little fellows that we are interested in, the bevel gears. once these are done we can get back to work on the main bodies. shouldn't take too long, only 100 of each Laughing ...



and this is what needed doing to them, (bare castings on the right and machined castings on the left). they basically needed skimming to a universal length and the hole drilling for the two shafts. i decided to mill around the top of the casting to give me a constant location for the next operation...



so how do we hold something so small ?? one very important piece of equipment for us is the simple Aluminium vice jaw. by using jaws made of Aluminium we can cut custom set-ups to hold just about anything.

looking at the jaws for the bevel gears you can see how a large recess has been cut to allow clearance for the casting. we can then cut a circular pocket in the top section of the jaw that closes around the casting like a collar...



the view from above...



this video clip shows the milling operation. I'm not sure how much you will actually be able to make out, but it gives you a good idea of a typical machining cycle.
three tools do the work.

TOOL 1 is a 12mm end mill that skims across the top of the casting and then lowers down and mills around the body of the casting in a circular motion.

TOOL 2 is a 6mm NC spotting drill that spots the central hole and then de-burs the milled area. you can clearly hear the change in spindle speed between when it's drilling and milling.

TOOL 3 is a 5mm drill that peck drills the central hole. you will have to excuse the squealing as the drill is usually run with coolant at this point. for some reason these brass castings are very sticky and machine a lot more like aluminium.



we will be finishing these in the 4th axis next week !!

another part that's also been done is the Bias lever. you can see it in this photo after having it's 1mm cross hole drilled...



and here we have the work done so far. the main bodies, the bevel gears, the bias lever and shaft, the governor top and ball halves. this is our CNC control model and will be used to make sure all the parts fit together. we are using over-sized split pins to help with our sanity



and now something for you to puzzle over. the ball halves are very small, 9mm diameter in fact, and are simple half spheres. one side of these ball halves needs a 4mm X 0.1mm slot machining across the top for the location of the springs (check back on drawings for clarity). so how do we hold these then ??? and oh yes, there is only 300 to be done Shocked ...



I'll post the answer next week (if it works Wink )

Craig What a Face

miller

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Re: 2 Inch Burrell Governors

Post  miller on Mon 20 Jul 2009, 10:57 am

anyone have any ideas on how i machined the ball halves ???

well i can tell you, it worked Cool 15 at a time in a small brass jig. five rows of three "half sphere" holes with M4 threaded holes correctly spaced between them that allowed me to use cap head bolts as clamps...



with the bolts wound down, the ball halves are held in place and i machined up one row, down the middle row and and back up the other.
all 300 halves done in one morning Cool



should have the bevel gear on the 4th axis tomorrow Cool

Craig What a Face

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Re: 2 Inch Burrell Governors

Post  LilyJack on Mon 20 Jul 2009, 11:32 am

Miller,

That looks like a BALL ache of a job but I have to say, dead impressed with seeing all of that "stuff" there. I didn't realize that the 2" actually served no purpose. An explanation would be nice on this one? <<<First time builder before you fall about laughing!! Rolling Eyes

Best Regards

LilyJack Cool

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Re: 2 Inch Burrell Governors

Post  miller on Mon 20 Jul 2009, 11:40 am

steve is the man to explain on that one, i'll give him a nod in this direction Cool


Last edited by miller on Tue 21 Jul 2009, 9:54 am; edited 1 time in total

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Re: 2 Inch Burrell Governors

Post  Steam Traction World on Tue 21 Jul 2009, 4:30 am

See the relavent topic in the 2" Burrell Section

Regards

Steve

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Re: 2 Inch Burrell Governors

Post  miller on Tue 21 Jul 2009, 9:56 am

thank you Steve Cool

a link to steve's reply.... click

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Re: 2 Inch Burrell Governors

Post  miller on Tue 21 Jul 2009, 12:49 pm

as promised, the bevel gear on the 4th axis machine.


here you can see the 4th axis chuck on the mill...



to finish the bevel we need to cut the three flats and drill the holes to locate the springs....



if we were just milling flats we could machine them in a vice from above, but because the holes need drilling as well, it's 4th axis time.
the gear is held in the chuck using a custom made jig. remember how i milled around the casting to give us a location surface ? well that milled section sits in a recess on the end of this bung and a long M5 bolt locks it all in place...



the milling operation...

once again you can't see very much of the actual cutting (digital camera is not good at filming close up, sorry) but this will give you a good idea of how the 4th axis works.

TOOL 1: 5mm end mill, machines around casting (by turning the chuck) and then cuts three flats.
TOOL 2: spot drill, spot holes
TOOL 3: 1.6mm drill, peck drills holes. holes will be threaded M2 by hand



and the finished part (before on the left and after on the right)



Craig What a Face

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Re: 2 Inch Burrell Governors

Post  miller on Sat 25 Jul 2009, 11:44 pm

it's been a busy week this week and the governors are almost done.

now that the bevels are finished we can go back to the main bodies and finish the machining on them.

here you can see the casting, in the jig, on the machine...



it then goes straight into the next vice to be completed...



with this done the flood gates were opened and all the other parts could be made, mostly on the lathes...



there you can see a Governor with the bevels held in place by some temporary shafts, and yes they do mesh perfectly Cool



and the assembled governor so far...



Craig

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Re: 2 Inch Burrell Governors

Post  hughb on Mon 27 Jul 2009, 11:46 am

Hi cool tred this thaks for the pics and vids

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Re: 2 Inch Burrell Governors

Post  miller on Thu 30 Jul 2009, 10:23 am

no problem, we have some very interesting parts coming up so keep looking, and don't forget to look at the topics for all the other models as some of the machining process will be used on similar parts for your particular kit.

the governors are all but finished now, we are just waiting for some "brought in" parts to arrive such as the small grub screws and the main springs.

you can see the (almost) final assembly below. we have made a mock spring from shim steel to help get it all together...



we have now started work on the safety valves but again, we are waiting for "bought in" parts before we can continue...


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Re: 2 Inch Burrell Governors

Post  miller on Thu 03 Sep 2009, 1:18 pm

well this kit finally got finished, just as i was off on me hol's Cool

most of you will be working on it now, so you can finally appreciate just how small the parts are Neutral (sorry Wink )

there is a good topic on this kit in the main 2 inch burrell section if you need some tips Cool

here a photo of the control model, for inspiration Very Happy ...


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Re: 2 Inch Burrell Governors

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