Author Topic: Myers Stirling Stove Fan  (Read 1383 times)

Offline bent

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Re: Myers Stirling Stove Fan
« Reply #15 on: June 25, 2019, 08:13:33 PM »
Thanks Thomas!

One thing I must say - these castings are of very good quality, both in the soundness/lack of material porosity (knock wood, haven't hit any yet) but also in the dimensional quality - faces are reasonably parallel across the parts (no pattern shift or float/tilt) and bores concentric.  There is one part coming up that has some weirdness, but in areas where it won't matter (they get machined away).  I do sit and stare at that part and wonder how the heck they made the core and pattern...will post photos of it when I get to that step.

Offline bent

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Re: Myers Stirling Stove Fan
« Reply #16 on: October 08, 2019, 04:39:27 PM »
Man have I been busy...or lazy.  Quick update - took the time to locate the base cover on the mini mill at home, leaving enough room between clamps to "touch off" on the machined i.d. and find true center, then bored 9/32 thru, replaced drill with 1/2" endmill and spotfaced the holes (photo below).  It's so much easier to use DRO's for bolt patterns, I'm really glad I installed them.  Oh, and I need to invest in more 3/8" nuts, had to use some spare t-nuts to get the clamping done. :embarassed:

I've also ordered and received a nice little 2" boring head that will let me do some of the more complicated boring tasks at home...but in contemplating (fondling?) the castings realized that two of them need work done on the large lathe at work (because it has a larger chuck), and the drill/mill because it has the required headroom.  But work has been busy, with me being a machinist to make assembly jigs and tooling for a new product, and then doing some R+D...and more to do today...

So maybe later this week I can get some more done?  Will see.

Offline b.lindsey

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Re: Myers Stirling Stove Fan
« Reply #17 on: October 08, 2019, 08:05:30 PM »
You are making more progress than me lately and I don't have the excuse of W*** now. At least it's nice to have the machines at work when you need them though.

Bill

Offline bent

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Re: Myers Stirling Stove Fan
« Reply #18 on: October 16, 2019, 07:46:55 PM »
A bit more done, once again using the work mill and lathe due to lack of headroom and/or swing on the home machines.  The upper piston housing needs to have the i.d. bored, so set it up on some blocks and used a 3" boring head to turn the i.d. (photo 1).  Had to use the side hole of the boring head to get to the 4.3" i.d., which means I couldn't clean up the bore all the way to the bottom.  Will either need to hand work this bit, or just adjust the displacer piston to fit, will decide that later.  After getting a reasonably square/true i.d. datum, I could chuck the part and turn the o.d. of the flange to remove the unsightly casting gate (photo 2 and 3).  Now that good datums have been established, this part will go back to the home mill to get a bolt pattern put in using the dro's, and then bore the power cylinder and displacer piston rod hole.

Photo 4 is just me contemplating the next tricky part - the piece that holds the fan and crankshaft.  Somehow I need to bore out all of the internal casting so the part will fit on top of the piston housing.  Not gonna fit on the lathe, so will need to dream up a jig and means of clamping for the drill-mill.  Hmm... :headscratch:


Offline crueby

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Re: Myers Stirling Stove Fan
« Reply #19 on: October 16, 2019, 08:05:54 PM »
Thats a pretty intricate part, looks more like the trim on an old Dusenberg or something!

 :popcorn: :popcorn: :popcorn:

Offline bent

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Re: Myers Stirling Stove Fan
« Reply #20 on: October 16, 2019, 10:21:51 PM »
I know what you mean, Crueby!  Some days I just sit and look at it and marvel at the person who carved (?) the original pattern, then at the foundry man who figured out how to cast it.

Offline bent

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Re: Myers Stirling Stove Fan
« Reply #21 on: October 17, 2019, 11:45:28 PM »
Well, I decided to jump in and get the fancy standard part started.  After thinking and kicking around ideas with a colleague, I decided to cut a piece of 4" steel pipe we had lying around at work, as it seems to make a fairly snug fit to the part's i.d.  Squared off the end with careful cuts on the lathe yesterday, and tested the fit (photo #1) .

Just needed a notch at the crank shaft end, right?  Yeah, no.  (photo 2).  The fins appear to have warped inwards as they cooled from the casting...or the i.d. of the part is actually tapered along the axis?  Ah, whatever.  Added a strip of polyethylene, and made a c-clamp shoe to fit over the external rib (and a pocket to center the c-clamp swivel end), and voila' (photo 3).  Kinda rickety looking, but it held up well to the shake test, and a couple of whacks with a bit of 2x4.

So, rough-planed the end where it will mate to the piston housing, then shimmed the part in its clamps to get it a bit more square and somewhat even around the rim (photo 4).  The other mickey mouse bit is shown in photo 5, an o-ring was used to stop the c-clamp handle from rattling around during the milling (annoying as all get out until I "fixed" it!).  Finally, in photo 6 you see I've made some marks for the flange and roughed out the center.  Next to bore through the flange with a boring head and make it more circular and sized to fit the piston housing...after finding the center of the rim with a mill with no dro's and really sloppy handwheels... :insane: