Author Topic: Steam engine (Tiny vertical w/reverse)  (Read 25537 times)

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #15 on: August 24, 2012, 12:49:06 AM »
This installment will be the machining of the column. It's just over .90 long and .95 wide across the legs. It is also made from 12L14 steel.
I chucked up a piece of 1.00 bar stock, faced and center drilled it.
The next step was to drill it undersize for the crosshead guide followed by a very small boring bar.
I calculated the distance between the legs at the top and bottom and opened the bore up to the required dimension by first plunging to depth with a .25 end mill followed by a drill.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #16 on: August 24, 2012, 12:53:22 AM »
The next step was to put a counterbore into the bottom of the legs for a witness to cut the following taper of 25 degrees. The compound was set over and the small boring bar was also used for the taper.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #17 on: August 24, 2012, 12:56:49 AM »
The diameter of the part was then reduced to 2 diameters, one for chucking in the mill (.625) and one for the lower flange that matches the lower head (.475). With this finished the part was cut off from the bar.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #18 on: August 24, 2012, 01:02:59 AM »
I cleaned the mill table and then mounted the rotary table with the dividing head bolted to it. A test bar was inserted and indicated to get the rotary table parallel with the -x- axis. The handwheel was set to -0- and the part was clamped in the chuck. I didn't show it but the part was rotated and set true using the dial indicator. The next step was to find the center and the end of the part so I put the .200 dia. edge finder in because of the limited space.
With the digitals zeroed I was ready to start cutting.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #19 on: August 24, 2012, 01:08:57 AM »
There's probably several ways to attack the cutting operations. I started by qualifying the width of the legs. By doing this first it left the stock closest to the chuck heavy enough to support the cuts.
The next step was to cut the crosshead window. After finishing this piece I found that I had less to cut with the .125 endmill if I cut the outer crosshead diameter first so that's what I did to the second piece.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #20 on: August 24, 2012, 01:16:02 AM »
I changed from a .125 two flute end mill to a four flute for the finish machining operations.
First was to qualify the width across the bottom of the legs. This would give me a tangent point to cut the 25 degree angle on the inside of the legs. This is why I roughed out this area on the lathe so I wouldn't have so much stock to cut with the small end mill.
With the witness cut I rotated the rotary table and cut the inside of the legs.
Once the angles were cut I put the rotary table to the starting angle and cut the bottom surface of the crosshead guide, sneaking out till I just touched the taper on the legs.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #21 on: August 24, 2012, 01:22:17 AM »
The next steps were to cut the support ribs on the legs. These are .086 thick. I put in a .125 endmill with a .045 radius on the corners. Using the digital readout for all of my tangent points sure makes life easier. I roughed the legs and trunk of the crosshead staying up about .01. I then rotated the part and did the same on the other side. I miked the thickness of the rib and adjusted the quill for my final cut. It looks pretty ugly at this point but once all the witnesses are cut the blending cuts smooth everything out.
Talent unshared is talent wasted.

Offline Don1966

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #22 on: August 24, 2012, 01:26:10 AM »
Gee! George you have been busy. Thanks for the step by step, that is real interesting. keep the photos coming.

Don

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #23 on: August 24, 2012, 01:31:37 AM »
The final machining was done with a .094 ball mill. I set the depth to the trunk diameter witness and then by rotating the dividing head created the circular shape on the trunk.
The chucking lug will stay on so that I can set it up to drill the holes in the bottom of the legs. Once that's done I can part it off and finish face the bottom flange.
I guess at this point I should have taken a picture of the finished crosshead after detailing it with burrs, stones and files but I didn't think until I started putting all this together.
I did set the finished column on the base so you can see that it's starting to take shape.
Tomorrow I'll finish up the second column, remove the dividing head and while the rotary table is still in place I'll do the shifting links for the valve straps.
gbritnell
Talent unshared is talent wasted.

Offline Davyboy

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #24 on: August 24, 2012, 02:16:43 AM »
George, Your work is incredible!  Thanks for sharing with us.  I was wondering, do you work with a print?  And is the design your own, or just the scale? 

Davyboy

Offline Dan Rowe

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #25 on: August 24, 2012, 02:24:38 AM »
George, amazing work thanks for sharing.

Davyboy the prints are here.
http://www.modelenginemaker.com/index.php/topic,569.0.html

Dan
ShaylocoDan

Offline gmac

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #26 on: August 24, 2012, 06:07:09 AM »
Beauty George! Boy it's real easy to loose track of the size of this thing - until you drop another penny  :o

PS - how do you like that six jaw chuck, I've never used one. What diameter?

Cheers Garry  (following closely)

Offline swilliams

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #27 on: August 24, 2012, 10:35:58 AM »
Very educational George

Steve

Online steamer

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #28 on: August 24, 2012, 11:30:20 AM »
Mind boggleing George....as usual!
 :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy:
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline gbritnell

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Re: Steam engine (Tiny vertical w/reverse)
« Reply #29 on: August 24, 2012, 12:23:55 PM »
Hi Garry,
The six jaw chuck is 5" diameter. I found it used and in perfect condition many years ago. It's not so much that it has six jaws but that it's a set-true type chuck, that's the great part. Even though it's very accurate (going from one diameter to another) it can still be tweaked to get it dead concentric. I wanted to buy the other set of jaws for it but they cost a king's ransom.
gbritnell
Talent unshared is talent wasted.