Friday, April 15, 2011

Small big lathe project

Over the course of the last 5 seasons, the bearing housings on the strut mounts have gotten pretty beat up.  With one cracked, it's time to make new ones.

This part starts off life as 4" diameter stock, and is stepped down to 2".  A 4" chunk of aluminum is reasonably hefty. This piece, 16" long, cost a cool $100.  With the relatively large diameter, the linear speed across the cutting tool is somewhat high, and will load up the machine if the depth is too great.

It sure does look pretty impressive sitting in the lathe, though.

For something of this size, the use of a live center while turning is a must.  The chuck jaws have been reversed, and the part is centered with a dial indicator prior to center drilling.

Then it's just a matter of whittling away- it's going to take about 65 passes. Yikes!


No pictures of the boring steps, but eventually the housing made it's way to the mill for holes and getting squared up.

The DRO speeds up punching holes in the part, as well as the milling operations. Rather than spin in the part center with a indicator, an onsize plug for the bore was turned center drilled.  A center drill in the mill to pick up the center gets within .004" or so of center.  For this part, that's accurate enough for the remaining operations, and significantly faster.

The balance between time and cost comes down to knowing required tolerances for a piece part, as well as the assembled part.

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