Engines > From Plans
Zee Needs Popcorn
zeeprogrammer:
I may as well jump in and start this. It'll be fits and starts and has a high potential of being dropped. But here goes...
I've been enamored by the Cretor popcorn engine for some time.
I've been studying the plans from Stew Hart and Julius. (My version will likely be a slight mix of the two.)
First job has been converting dimensions from metric to imperial. I have some idea about what dimensions are critical but no doubt many parts will be remade.
This model will be a huge challenge for me. Fabricating the governor, whistle, and inlet manifold all represent some firsts (perhaps some seconds) for me.
The crosshead guide looks to be the most challenging.
The 1st picture is an incomplete CAD drawing I'd made some time ago. It's from Julius' plans and still in metric. (I haven't decided to completely model the build version.)
I expect to make the flywheel according to Stew's plans.
The 2nd picture is a CAD drawing of the crosshead guide. Unless there's good reason not to, I expect to make it from 12L14.
But what's got me stumped is machining that transition from the two inner diameters (see red arrow). Thoughts?
Other than the crosshead guide, all other material is brass, aluminum, and stainless steel.
I'd considered doing the guide in stainless (303) as well. But it costs twice as much as the 12L14 and I already have the 12L14. (I worry about rust though.)
If price were not an object, any thoughts on using 303 for the guide?
The guide should be the 1st thing I go after but I'll probably start with some of the smaller bits...mainly to get into the swing of things again and gain some immediate success.
Drat. Here I am developing a project and T comes in with a project of her own that involves me.
We all understand where my priorities lie, right? That is, I like getting fed.
b.lindsey:
Should be a great project Zee. As for shop time, if it's just a matter getting fed, you could always learn to cook. Probably a bit more complicated than that though right ;D
Bill
crueby:
I saw the title and thought you needed to know what kind of popcorn to buy... :Jester:
Looks like a great project, will need to :popcorn: while watching.
I like 303 for good machining and it does not rust like 12L14 loves to. For large chunks, go check the Drop Zone part of Yarde Metals website, they usually have big diameter bar at cheap rates, selection varies since they are offcuts from their commercial sales.
For machining that one section, if you use a boring bar on the lathe, with the narrow end of the crosshead in the chuck, you should be able to do that no problem. Also face the end to the cylinder and bore the guide area at the same time. I would turn the whole thing to rough shape and cut all the sides open first, just in case the metal relaxes any from manufacturing stresses, even a tiny movement would throw off the bore if it was done first. Then do a light finish cut on the contact areas.
:popcorn: :popcorn: :popcorn:
Jasonb:
Set your topslide over before you bore the large diameter using the carrage feed then you can cut the transition with the compound, it's just a tapered bore.
Tennessee Whiskey:
Well I’m glad you are starting another build. I didn’t want you just lounging by the pool and gardening all summer; a man needs a good excuse to go inside for a cool off and one tends not to spend their evening swilling Kentucky rot gut, if they have a build going, well that’s my excuse anyway :lolb:. But here’s my biggest concern: have you been eavesdropping on my PM’s? Just last week I started conversation with two of our members ( unnamed) in regards to my starting of the Cretors Lil’ Popcorn Engine from Myers Castings. I swear, I ain’t lying, you can ask Bill and Tug :lolb: :lolb:. However, I think this is wonderful that we’ll be building the almost same engine, but, you from bar and I from castings. This could be an award winning mini-series :Jester:. Have a great holiday (bet you have been around a lot of “real celebrations” ) in your younger years.
Cletus
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