Author Topic: Alternatives to milling at eMachineShop?  (Read 3903 times)

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SquirrelHollow

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Alternatives to milling at eMachineShop?
« on: January 21, 2010, 02:32:18 AM »
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I'm up against a wall, with a scratchbuild project.

I'm trying to create a running version of this 1837 Baldwin 4-2-0:

For more info: http://en.wikipedia.org/wiki/Pioneer_(locomotive)

Other than the challenge, I can't tell you why.  I have no interest in CNW, anything having to do with Chicago, or almost any steam from that time period.  It's just something that caught my eye, long ago, and I had to build.  It is microscopic.  In N scale (my choice here), I estimate the cab-to-smoke box dimension at about 1".  The boiler diameter is just over 6mm(0.200").  It's tiny.  It's causing problems... but, I'm enjoying the self-inflicted pain.

I have plans for the cab.  I have my drive worked out.  I have detail parts.  I have wheels and axles for the pilot truck.  I have several sets of driving rods ready for modification, and a few drawings of potential custom etchings.  I've spent a lot of time considering power pickup and distribution.  I even achieved a proper max scale speed of 32mph in testing the motor with a partial mechanism. (Gizmoszone 6mm ~5:1 reduction motor driving a 25:1 worm/worm gear reduction, with a load on it.)

The problem is, I can't find a way to make a suitable "axle bearing" with my existing (or locally available) brass stock.  I've tried rectangles, L shapes, C channels, round tubes, square tubes, and styrene.  Nothing worked.  The materials just aren't up to the task (or, perhaps, I am not up to working with them in the needed manner).

Now, I'm considering having my "axle block" machined.  Local machine shops laugh at me, when I tell them the maximum dimensions.  So, I turned to the web.  The only semi-recommended site I found was eMachineShop.  However, their current quote is at $209 for the first part.  I would prefer saving a bit. (Oddly, it's actually cheaper to include the drill holes, and have it made from brass, than alternative materials and designs I have tried.)

Does anyone have any other recommendations? 

Here is one of several versions of the "axle block" in question:


If needed, the basic dimensions are: 0.350" H x 0.650" (or 0.500") L x 0.250" W. 
Semi-detailed dimensions:
"Top" inside radius is 0.160", stacked (To created locating tabs, 0.015" tall).
Axle pass-thru has a radius of 0.060".
Screw holes are 0.0275" radius.
Worm Gear channel is currently 0.390" L x 0.085" W, and allows for 0.050" radius corners.


You may have noticed, my dimensions don't allow me to model the prototype.  I've had to make enough compromises, that I must loosely base the model on "Pioneer".  Mine is to be called "Pilgrim", but adhere to the idea I set out after.
-Robert

Uintah Railway, Utah Railway.

sd80mac

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Re: Alternatives to milling at eMachineShop?
« Reply #1 on: February 28, 2010, 06:19:22 PM »
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What about having the part rapid prototyped in wax, and then direct-investment casted. Take a look at this company, www.rpwax.com. They make jewelery, but I think they could do what you are asking.

Donnell

SquirrelHollow

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Re: Alternatives to milling at eMachineShop?
« Reply #2 on: February 28, 2010, 10:19:09 PM »
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Thanks for the suggestion, but I already have a member of this forum lined up for the milling.  I'm trying to finalize some dimensions, and find ways to allow looser tolerances.  Once I have the time to complete that task, I'll send the drawing his way.

-Robert

Uintah Railway, Utah Railway.