[SEL] bore and sleave an engine question

[Curt]

Dave, Craig,
As you know I've machined quite a few of the 1 1/2HP Herc pistons and 
it's 2 hours on the lathe and a couple of more on the Bridgeport doing 
the wrist pin. The worst part of the job is tramming the Bridgeport!
When I did the 1 1/2HP piston, Tommy Berry suggested I put a chucking 
button on the crown to facilitate machining. That has worked out 
exceedingly well as it eliminates one of the chucking steps. This lets 
you turn the entire piston in 1 setup, leaving only the facing of the 
crown. The only drawback is when cutting the ring grooves, as it tends 
to chatter a little so you have to go slow here. A big rubber cork in 
the open end might help absorb the chatter.
Now admittedly the piston size has a huge impact on the machining time. 
The last one I did was the 50# piston casting for the Alamo. I spent the 
better part of a Saturday and the following Monday evening just on lathe 
work. I didn't keep track of the hours but I'd guess 10 hours lathe 
time. I couldn't do the wrist pin bore work on a standard Bridgeport 
(needed 6" of quill travel and lots of vertical room for the part and 
the tooling) so I had to ask a favor of a large machineshop in town and 
they let me use one of their LARGE "Bridgeport" style machines for this 
step. That was a brand new machine to me and between the setup, finding 
the tooling and doing the job I spent the better part of a day there. It 
should have been about 4 hours of work.  That would be much closer to 
the time your buddy estimated. You tend to be a LOT more careful with a 
single 50# casting that when you have a dozen little pistons castings 
available. It's not too traumatic if you kill a little part!
I did document the machining steps for the small piston. I thought I had 
put the machining times on here but I guess not. At one point I 
definitely tracked my time on these as there was a local retiree who was 
going to machine these. I think he estimated $80 each for the machining. 
That never panned out due to his health though. Here is the link on the 
machining steps for the small piston.
<http://www.oldengine.org/members/holland/images/PistonMachiningSteps/Thumbnails.html>
After Portland I'll be machining the first of the 3HP Herc pistons made 
from the patterns developed over the winter. I'll be sure to document 
the time.
Curt

Dave Rotigel wrote:

> The machinist that I talked to earlier tonight (who does this sort of 
> thing on a regular basis) tells me that 15-18 hours would be the norm 
> for taking a piston from "raw" casting to finished product.
>         Dave
> PS, Is it "sleave" or "sleeve?"
>