Subject: Gingery Lathe

From: [email-masked] (Randee Johnson)
Date: 6 Jun 1995 13:02:50 GMT

I am building the Gingery lathe.  The  first two castings of the lathe 
bed were bowed about 1/4 inch...I guess from heat shrinking.  Anybody 
have any suggestions on how to keep it from bowing.

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From: Randee Johnson <[email-masked]>
Date: Tue, 6 Jun 1995 15:13:58 -0400

On Tue, 6 Jun 1995, Mac wrote:

> Hmm...I've cast that pattern at least three times with no 
> deformation of that type; rough surface from ramming to 
> hard or to much water in my sand, short pours etc.
> 
> Is your pattern stiff enough not to bow during ramming?
> 
> Is your cope and drag solid enough to hold the weight of 
> the sand and not bow when you move it to the pour?
> 
The flask is made of 1X4, seems sturdy enough. BTW, I've had all the 
problems above as well.  The last try I rammed up the cope tighter than 
the drag but didnt make much difference.  The pattern is made of 1/4 
plywood, glued and nailed.  Before I pour then next one I will double 
check the points you mentioned.  Thanks

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From: Mac <[email-masked]>
Date: Tue, 6 Jun 1995 16:13:52 GMT

-- 
Mac
Homebrewer and tinker by choice, Computer geek by trade.

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From: [email-masked] (Greg Lewis)
Date: Tue, 6 Jun 1995 20:21:50 GMT

>the sand and not bow when you move it to the pour?

I wimped out and used a CRS bar. Saved lots of work all the way around.
___________________________________________________________________
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From: [email-masked] (Barry Workman)
Date: Thu, 8 Jun 1995 08:10:18 GMT

>have any suggestions on how to keep it from bowing.

I made my bed patterns three times.  Each was an experiment in pattern
making as well as trying out different materials.  I made one from 1/4"
plywood, one from balsa, and one from poplar.  They all worked after a
fashion.  The balsa pattern gave me problems because the grain didn't
seal well and my sand was a little dry.  The plywood one had a varity
of problems.  The poplar is the pattern I kept.  In all cases, I had
no difficulty as you described.  Do you have a good tight joint on
your inner ribs?  Is your pattern true?  When I rammed mine, I did
not use a false drag.  Rather I made a bottom board for the cope to
sit on, rammed the cope, rolled it, dusted, rammed the drag, vented
*A LOT*, rolled, vented, opened, then cut a sprue and riser with a
piece of 1 1/4" OD tubing.  Between the sprue and the cavity I cut a
resevoir to help avoid shrinkage damage.  The venting after the second
roll was to help tap the patten loose from the cope, then a gentle tap
lifted the pattern off of the core prints.
-- 
    - Barry Workman