Gallery, Projects and General > Project Logs
Coke Bottle Steam Engine
rleete:
--- Quote from: Bernd on December 28, 2008, 09:14:34 PM ---I've spent over 30 years in a machine shop and I've seen some large pieces, cutters, grinding wheels and such let loose.
--- End quote ---
We have a large surface grinder at work. Yakamoto or somesuch. Anyway, it uses a very large wheel. Something like 24" diameter, about 4 inches wide. I wasn't there when it happened, but the mangled end shield and the repair patch in the wall beyond it is testament to the force of the wheel coming apart at speed. The operator tells me it sounded like a cannon, and he took weeks to get over it.
The end shield is 1/8" sheet steel, and the wheel went through it like a fist into foil. But, it slowed the chunk down enough that it didn't get beyond the first layer of wall (and steel studs) beyond it.
Even more common is the tool coming up. We grind optical panels, often quite thin (.040), and up to 3' x 4' in size. They are solid nickel. So, to hold them we use vacuum chucks. Sometimes the seal lets go, and shoots the tool off the end. It makes a hell of a racket, but so far no one has been hurt.
Bernd:
The saga of machining the valve continues. :dremel:
If the wife asks "What did you do today beside goof off". Don't tell her anything or I'll get a :wack:
Ok lets begin with the pic below. I put layout dye on the part. Determined the dimensions needed, 1/4" in from the side, and scribed the lines.
Next I just touched the top of the part with the cutter. This can be an approximate setting when touching the part. In other words when you hear the cutter touch or see dust chips flying out you know you close enough. Mounted my DRO (dro indicator) and fed the end mill down 1/16". I then visually milled to the scribed line. No need to be with in thousands of an inch, close works here. I guess I'll find out later if close works when assembled. All this pocket does is direct the steam to the proper port. All the can happen is that the cavity is to big or to small. If to big a bit of silver solder and a re-mill. If to small just a re-mill to make bigger.
And here we are. Pocket done and to with in .002" to deep. Close enough.
Next I turned the part over and prepared to mill the slots. First slot is 1/8" wide and up from the bottom 5/32". Here's how I did it. Remember the paper trick I showed earlier? Well here I'm using it again. Works better than edge finder on small machines and work. Touch the side of the part. Half the cutter plus half the part and in the center of the part you are.
Now for the depth setting. It's dimensioned from the bottom. Same procedure as for the sides. Paper, lower till cutter pulls paper.
Mount DRO and bring head up 5/32" and cut slot.
Wal la, slot cut.
Same procedure for the other slot. Touch the solid jaw. Move 1/2 cutter dia. minus half of .531. Mill slot.
Same for depth again. Only this time move 3/32" up. Now I'm beginning to wonder if the cutter will break through to the pocket I milled earlier. Oh, well only one way to find out, cut.
Oh wow, it didn't break through. But I did screw up on the part. I tried to mill the slot with a 3/16" cutter in one pass. That was a no no. The machine chattered and danced. So I decided to take several small cuts. That worked, but something had moved. The cutter didn't look like it was on the center of the slot I had just cut. Closer look, sure enough it had moved. So I moved the table a bit to compensate and began milling again. When I was down to the depth of were I had originally started out I noticed I had a nice step in the side of the slot. Oh well nothing left to do but clean it up and make the next part fit the slot.
More on this at the end. Yes, the slot is also deeper than the first one. That's what the print calls for.
Here is the valve all done. Well I need to debur the sharp edges. The larger slot should be 3/16" or .1875. It turned out to be .204" wide. Next time I'm doing it different. I'll use a smaller cutter and then go bad and widen the slot. Now all I need to do is make the "valve nut" that goes in that slot close to .204". I may even go with .188" and see what happens.
So that's it for the valve. Now I'm going to convert the mill back to a lathe and turn the top and bottom cylinder covers. But that won't be until next time. And who knows when that will be. If the wife lets me live a couple more weeks I might have something by next weekend.
Until next time,
Bernd
sbwhart:
Hi Bernd
Nice job :thumbup:
When your doing work for your own pleasure, and just making one, its easy to make parts fit each other if you don't quite get it right, and you get a great sence of satisfaction.
I've found that when milling a closed pocket like the cavity in your slide valve, a drill put into the corners first, tends to stop the cutter pulling into the corner. Also on a slide valve the width is only critical in one direction.
Have fun
:wave:
Stew
sbwhart:
Hi Bernd
The top and bottom covers can be a bit tricky :zap: to hold, also the critical features for these parts is the small boss that stands out to locate in the cylinder, and the concentricity of this boss with the guide hole for the piston rod, if its not concentric the piston rod will bind. I hope you don't mind me suggesting waiting until you've got your cylinder bored and making this boss to fit. I've just finished my cylinder covers for my Loco:- I'll be posting the photos soon.
Have fun
:wave:
Stew
Bernd:
--- Quote from: sbwhart on December 30, 2008, 01:57:10 AM ---Hi Bernd
Nice job :thumbup:
When your doing work for your own pleasure, and just making one, its easy to make parts fit each other if you don't quite get it right, and you get a great sence of satisfaction.
I've found that when milling a closed pocket like the cavity in your slide valve, a drill put into the corners first, tends to stop the cutter pulling into the corner. Also on a slide valve the width is only critical in one direction.
Have fun
:wave:
Stew
--- End quote ---
Thanks Stew.
Using that small of an end mill - 1/8" dia. - was no trouble in the corners. If this had been a bigger piece I would have done that. I have built an engine with one of these types of valves in it and know what I'm up against.
My problem with this slide valve is I was in a hurry to get it done. Big mistake. Need to take more time to do my projects. That's one thing I'm trying to controll, my impatients in doing something.
--- Quote ---The top and bottom covers can be a bit tricky to hold, also the critical features for these parts is the small boss that stands out to locate in the cylinder, and the concentricity of this boss with the guide hole for the piston rod, if its not concentric the piston rod will bind. I hope you don't mind me suggesting waiting until you've got your cylinder bored and making this boss to fit.
--- End quote ---
Don't mind a bit. I know the procedures but somebody else reading this may not. :)
I actually got a bit of patients. I looked at the print and figured I need to make some close fits so I'll just rough everything out. Then do the cylinder and finally turn the covers to fit the cylinder. I believe they called this procedure were I worked "Methods". Steps to make a part from begining to end.
Bernd
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