MLA Main Body

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Next casting I attacked was the main body, I need it done to pretty much work on anything else.

9/13/2015

Setting up to machine the base

The best surface on the machine to use as the reference is the bottom of the main body.  It is also the easiest to prep and is at right angles to pretty much all the following operations.

The casting is bolted to a right angle fixture plate with a really long clamping stud and a couple of nuts.  A couple of shims were forced under the casting where it is closest to the bed of the mill.  This is enough support to allow me to machine the bottom of the machine.  If the surface was going to be visible or required extreme precision I would have bolted a bar between the nose of the casting and the face of the mill table or used a set of hold down clamps on the two bosses on the side of the casting for extra rigidity.  The clamps would have required moving the vice, something I was loathe to do.

I set a couple of blocks at the edges of the casting and laid the torpedo level on top and adjusted the casting to get it level.  While the center of the casting is bulged up the edges should be pretty close to even.  The camera perspective makes it look like the level is crooked, but the bubble tells the real story.

 

Machined base

Here's the casting after facing the bottom.  You can see the shims walked a little bit from where they were in the first picture.  I wish I had an 8 inch face mill, but nobody will see this after the machine is bolted down.  From here the casting will be chucked in my 8" spacer.

This will allow me to drill and tap the table support bosses and the main shaft bearing bore, top cap cover holes and back plate recess.  The body will then be clamped upright on the mill table to machine the file shaft hole.

 

9/19/2015

I switched to the 8" spacer and mounted the casting.  I am using the largest face on the casting as a horizontal zero reference, the torpedo level is accurate enough to set this.  I will face this and it becomes the new reference surface for work when mounted in the spacer.  The scale on the spacer was set and locked at zero before mounting the part.

Seocnd mounting of the main casting

I will then center (R & L in this view)  using the spigot sticking out towards the operator.  After this I will face the spigot, and face and machine the two bosses for the table mounting.  The table bosses will be my new centering surfaces in case I need to un-mount and re-zero the part at a later date.

Cap Face machined

Here is the back cap face and file shaft spigot faced off.

 

Table Mount Bosses machined

The table mount bosses have been machined.  I ran the calculation for the 0.750" end mill and came up with 2.375" in each direction from zero to get a face to face measurement of 4.000".  Came out at 4.0015".  I am real happy with the Shooting Star DRO and my calculator expertise.

In this view you can see the casting core shifted when they poured the housing.  It is about 0.080 to 0.100" offset.  This should not pose a problem.

The next step will be to roll the spacer 90° each way and drill and tap for the table mounting arm bolts.  Tomorrow.... 

9/20/2015

Boring the main shaft hole

I added bracing to support the casting while using the boring head to cut out the rough cast hole.  I bolted an angle plate to the bed and bolted a couple of bars to the now drilled and tapped table mount holes.  A couple of the Vice Grip "Orca Pliers" **  holds it all together.  I bored until I got a clean hole ( 1.155) and then brought it out to an even 1.200".  I am using a piece of 1.250" 932 Bearing Bronze (sourced from McMaster).  I will machine the bronze rod to a interference fit and then drill and bore to fit the shaft in situ.

Boring the Body Cap end of the casting

I rolled the spacer 180° and set up to bore the body cap end of the housing.  My angle plate would not fit under the housing so I offset it and used only one bar.  Still stable enough to get a nice finish.  I am starting to like cast iron, but man is it messy!  I bored this enough to clean up the casting.  Next step will be to counter bore to the specified 3.125" for the end cap and then drill and tap the holes to retain the cap (as of yet un-machined) in place.

9/26/2015

Preliminary assembly

It's getting bigger.....

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**  If you turn them upside down the profile looks like a Killer Whale.  Right side up a Sperm Whale, take your pick...