Subject: Removing rust from a table saw.

From: [email-masked] (Al Amaral - SunSoft PC Desktop Integration)
Date: 1 Dec 1994 19:06:04 GMT

Please respond via email if at all possible.  I don't get to read this
group often...

I've just come into ownership of a 50 year old Delta Unisaw that's been
sitting in a damp garage for most of that time.  The top of the saw, as
well as the sheetmetal cabinet have a bit of rust on them and I'd like
to remove it and restore both to their original glory.

I plan on cleaning up the top with some very fine (400/800/1000) wet/dry 
sandpaper, wet with WD40, or something similar.  I'd like to get the top
to a very clean, shiny surface.  Does this sound like the right approach?
If the top is too badly pitted I'd probably spring to have the top machined
so that it's nice and flat.  What kind of surface can I expect if I do this?
Will it be very smooth, or will it look like a record surface, sort of like
my old Sears saw does...  If it's not going to be FLAT and VERY SMOOTH it's
not worth it to me to spend the money and end up with it being worse than
it is now.   What's the general wisdom here?  How much can I expect to pay
for this?

If I do have it machined, how much would you think would be necessary?  The
rust is just surface rust, nothing deep as far as I can tell.  Maybe a couple
of pits here and there.  I would think a couple of thousanths off the top would
be adequate.  ???  The top is thick enough that taking 1/16" off probably
wouldn't even be noticable...

As far as the cabinet is concerned, I plan on having it sandblasted and
re-painting with the original battleship gray color.  Will sandblasting it
leave it in good condition for repainting?  Should it be protected in some
way between the time I get it blasted and the time it is painted.  It'll
likely be at least a couple of days between the two operations.  Also,
will sandblasting the sheetmetal inside and out leave it too thin in the
end?  This saw weighs in at something like 450lbs and the cabinet has to
hold up this weight, so the sheetmetal is pretty thick already, but I don't
want to end up with it significantly thinner, to the point where the cabinet
fails and destroys the saw.  Will I be OK here?

One other question regarding the motor.  The motor is a 220V, 1phase, 3HP
job, weighing almost as much as I do.  There is a very slim possiblity that 
it may need to be rebuilt or replaced.  I think the problems I saw when I
looked at it were due to the fact that the house was rewired in the past
year or so and I think the electrician didn't realize that the circuit that
the saw is on was meant for 220 and wired it incorrectly.  When I tried
out the saw the motor started up then after 20 seconds or so the breaker 
apparently blew, and the overhead light went dim.  When I turned off the
saw the overhead light WENT OUT!  I didn't see the actual breaker, but
later it dawned on me that the circuit was probably wired on 2 110V 10amp
breakers, rather than a single 220V 15amp or 20amp breaker.  In any case
does anyone have any idea on how much rebuilding this moror would set me back?

Any other pointers on restoring this old beauty would be appreciated.  The
saw was bought new by my wifes grandfather in July of 1945, and he got 50
good years out of it.  I'd like to restore it to as close to original
condition as possible so that myself and my children will get another 100 
years use out of it.  And, yes, Delta STILL has replacement parts for it!

Again, please respond via email if at all possible.

Thanks in advance.

--Al Amaral--
-- 
--------------------------------------------------------------
Al Amaral				[email-masked]

From Bruce Taylor Mon Dec  5 10:42:51 EST 1994
Article: 7869 of rec.crafts.metalworking
Path: bigblue.oit.unc.edu!concert!inxs.ncren.net!taco.cc.ncsu.edu!gatech!howland.reston.ans.net!spool.mu.edu!uwm.edu!caen!crl.dec.com!crl.dec.com!nntpd.lkg.dec.com!tpwosf.tay1.dec.com!taylor
From: [email-masked] (Bruce Taylor)
Newsgroups: rec.crafts.metalworking
Subject: Re: electronic speed control for lathe (update)
Date: 2 Dec 1994 14:22:37 GMT
Organization: Digital Equipment Corporation
Lines: 34
Distribution: world
Message-ID: <[email-masked]>
References: <[email-masked]> <[email-masked]>
Reply-To: Bruce Taylor
NNTP-Posting-Host: tpwosf.tay1.dec.com

Well, I've solved the problem I posted about - electronic speed control
for a lathe - and I thought I'd summarize my experiences before the thread dies:

1. You can't speed control a single-phase induction motor.

2. You can speed control a 3-phase induction motor, but it's damned expensive.
   Basically, you buy a 1-phase to 3-phase converter with pulse stretcher
   from Mitsubishi or Danfoss starting at around $500US. This is (partially)
   offset by the cheap availability of small 3-phase motors.

3. It's easy to speed control a universal (AC/DC, brush) motor with either
   a variac or a commercial solid state unit (basically, a heavy duty
   lamp dimmer) starting at around $150.

4. New 1HP universal motors go for around $350 from Baldor.

5. If you spend a LOT of time on the phone calling motor rewinding shops,
   you can find a used unit for $50-$100. ("Yeah, I had one here last year,
   it might be over there under those pipes if you want to dig it out...")
   You meet a lot of interesting people in your search.

6. These suckers are BIG compared to synchronous units. Built like tanks.
   The only thing that'll ever wear out are the brushes. For lathe applications,
   this is dandy - adds mass and stability to the base. However, they
   are said to be pretty sensitive to heat, so arrange a good air flow.

7. There's a BIG power surge when you turn it on, because it has to charge
   both the field and armature coils - you'll definitely want slo-blo fuses.

Anyhow, that's what I learned. I finally got all the components from various
junkyards for around $100 total, so I'm happy.

				- bruce