Subject: Re: Mill Prices

From: [email-masked] (Paul Amaranth)
Date: 17 Feb 1994 14:30:00 GMT

I got a line on an old Bridgeport the other day.  It's a J head, with a
round ram (not the V-ram currently available).  I couldn't find a model
number, but I might have overlooked it.  It's a little rusty, no
tooling, but looks complete except for a couple of handwheels. Other
than a little surface rust, the ways look pretty good and I couldn't
detect any play in the spindle.  The table looks to be  9 x 42 (I'm
guessing, I didn't have a tape). It is not under power and is not in a
location where it can be connected.  The guy is asking $1250, but I can
probably get him down lower.

A few questions:

First, does anyone know anything about this machine?  I'm not a machinist
and haven't been around a mill for fifteen years or so.  Why the round
ram vs v-ram?  For my hobby-type machining requirements, this is probably
not important, but I'm curious.  Is it an idication of how old the
machine is?  Any other info on this machine would be appreciated.

Second, from the recent discussion, I gather that this is a pretty
reasonable price, although the machine is not in tip top shape.  Am I
nuts to go after this thing?

Are there any specific details I should look for that would tell me
to forget it?

Finally, if I do get it, how do I transport it?  I gather it's around
1500 lbs.  Does a flatbed trailer work?  Or should I just hire somebody
to move it?  They can drop it on a trailer with a forklift, and I have
an overhead hoist in my shop, it's the between part that's the problem :-)

Thanks
-- 
Paul Amaranth  Manager User Services - office: (313) 370 4541 (also voicemail)
(internet)     [email-masked]  |Best error message that wasn't
(bitnet)       amaranth@oakland               |supposed to show up: HODIE
(uucp)         ...!uunet!umich!vela!amaranth  |NATUS EST RADICI FRATER

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From: [email-masked]
Date: 17 Feb 94 08:17:58 -0800

> an overhead hoist in my shop, it's the between part that's the problem :-)

Yes this is an indication of age. The round ram pre-dates the dovetail style
ram. These early machines usually have an M head. The round ram is easier
to knock out of tram I believe but if this machine is in reasonably good
condition it would be fine for lighter hobby use. It should weigh over 2000
lbs. If you are going to move it yourself I would suggest renting a special
lowboy trailer made for moving heavy machinery. Better yet have someone
move it for you it usually isn't that expensive and they are better
equipped to do it. Hope this was of some help.

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:15 EST 1994
Article: 3812 of rec.crafts.metalworking
Newsgroups: rec.crafts.metalworking
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From: [email-masked] (Gordon W J Sorensen)
Subject: Portable homebrewed DC welders
Summary:  How to use an old car alternator and a Briggs and Stranton
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Over the past months I have noted certain elements of the readership that
like to build their own tools. Air compressors, lathes, etc.. Some of this
interest is economic as the cost of buying some of these things has a very
deleterious effect on ones wallet. Others I surmise just like doing these 
type of things. The following is more for the latter group.

Some years ago my ecomonic status was on the tight side and I had need of 
the use of an arc welder. A friend of mine had a portable DC welder 
manufactured by the Scott company. It was very interesting as it was quite
small and looked like a portable standby generator minus the roll cradle.

It certainly wasn't the gas driven Lincoln arc welders that were common to 
contractors in that day (early 80s).  It was advertised at 120 amps DC, and 
it was powered by an 8 horse Briggs and Stranton engine. It weighed less 
than 100 lbs, and it could be carried by one person, though it was it bit 
on the awkward side. Mounted on the engine was a small box about 10 inches
on a side with a potentiometer and Miller type welding lead connectors.
What was in that small box that changed 8 Briggs and Stranton horse power
into 120 amps of DC welding power?

Despite its diminitive stature I knew that you could actually weld with it
as a contractor at work had one and I had personally observed it working.

In the course of using it the belt broke, naturally. Of course this was no
ordinary belt, it was only about 1/4 inch wide instead of the 1/2 inch or
more of a typical "v" belt. I finally tracked down the Scott dealer as this
happened to be a quasi holiday, (Christmas eve day and Christmas was on a 
Saturday). The manager just happened to be working at his store/shop and
while he was no longer the Scott welder dealer, he did have some parts, 
ie,. the belt. 

I drove over to this place and found a small assembly shop, that was making,
you guessed it, portable DC welders of the Scott Welder type.  Being the
curious type I not only purchased a belt, but got a tour of the factory 
and found out what was in that box. Would you believe a Delco alternator, 
some diodes, heat sinks, and a small controler circuit.  The owner 
explained how after he lost the Scott Dealership, how he decided to make
his own. He did some reverse engineering and a lot of messing around in
his garage and brewed up his design which was called an APACHE welder. 

Anyway he bought Delco Alternators from GM with the stators not wound. He
had worked out  the appropriate windings and hired people to wind them for 
his operation. He explained the control circuit and even how he used the 
magneto of the engine to help the self-excitation process get started.

Hot dog, I now knew how to build a welder. I had the engine and Chief auto
parts had lots of Delco alternators.  I bought a rebuilt 60 amp model, no
built in regulator, and took it home. After tearing it apart, expecting to 
find fairly small wire in the stator, I was surprised to find that it looked 
like the same size wire the SCOTT guy was winding into his alternators.  
Great, I won't bother ripping that stuff out, I'll just slide  some 32 guage 
stuff in between for my field windings, throw in a buch of rectifiers, pots, 
capacitors, and viola I will have a welder.

Well the long and short of it is, that you can make a welder this way. 
It wasn't quite as easy as I thought it would be but  I learned a lot about 
3 phase power, Y connection and Delta connection, transformer effects and 
bunch of other stuff. It wasn't entirely  cheap either although my 
home brew machine was less than 1/2 a new one, even if I went out and
purchased a new engine.

A 60 amp Delco alternator is capable of 110-120 amps if it is reconnected
in a Delta configuration. They come "Y" connected.  Basically you buy the
alternator, take it appart, throw out the diodes, and find where the 
3 phases of the stator are tied together and undo that connection. 
In "Y" connection one end of the each of the 3 phases is connected 
together. In a "Delta" connection 2 ends of 2 phases are tied together.

This will lower the output voltage and raise the current by a factor of
1.732 (square root of 3). This will give you an open circuit voltage of
about 50-60 volts and about 20 volts when you are welding.

The alternator has to spin a bunch to do this. You need about a 3 to 1
increase in speed to do this.  This means at 3600 rpm engine speed, the
alternator is doing about 11,000 rpm. Not to worry.  Check out a small
block Chevy.  Depending on the gear ratio, but if you were blasting down 
the freeway in the old days (75 mph) the Chevy was doing 2500-3000 rpm.
The crankshaft pulley is about the size that you are looking for which
means the alternator is buzzing along at 9000 or so rpm.  Stomp on it and
passing gear will get you well above the 11,000 that your welder is running
at.  So the engineers at GM have already considered this form of abuse for 
you.

The existing diodes are too small, so they get canned.  You need at least
25 amp 200 volt PIV diodes. Get 3 stud to anode and 3 stud to cathode.
Fortunately these are fairly cheap, few bucks, bigger is better but anything
past 50 amps is excessive. Mount 3 of each kind on a separate heat sink with
no insulating washers. Electrically isolate the heat sinks and connect your
welding leads to the heat sinks.  One is positive, the other negative.

For excitation I found that the self excitation route was a pain, so I found
a small permanent magnet motor. You need 3 amps at 16 volts. Burdens surplus
catalog has bunches of them.  A simple power rehostat will suffice to 
control the field although a simple power transistor circuit out of a 
radio shack book is a nice touch.

The welder will run 3/32 rod quite nicely and if you push it, 1/8".  It is a
little hard to get the arc started and an arc stabilizer from Burdens would
help.

I still have mine and I made a second one for my brother.  I went so far as
to make a foot control for it and used it with a tig torch. Works pretty
good. I haven't fired any diodes yet. 

Have fun  

gordon

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& My wife says I can have any tool that fits on a peg board.&
& Will peg board hold up a back hoe?                        & 
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From: [email-masked] (Ken Moonitz)
Date: Thu, 17 Feb 1994 20:39:02 GMT

>an overhead hoist in my shop, it's the between part that's the problem :-)

As a matter of fact I bought the same model mill with about the same
set of circumstances with the same problems of transportation.
And I survived all of it.  Don't have the time right now to type the
saga, but you can buzz me if you like. 

	 Ken Moonitz   days- 510-645-5073
		       eves- 510-687-1461

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From: [email-masked] (Paul Jones)
Date: 17 Feb 1994 21:43:38 GMT

>round ram (not the V-ram currently available).  I couldn't find a model
[...]
>an overhead hoist in my shop, it's the between part that's the problem :-)

I have been thinking about this a lot lately.  I would recommend that
you hire a professional equipment mover if you can afford it.

If this is a full-size Bridgeport, it's probably going to weigh a lot
more than 1500 lbs.

I should think you would have to worry a lot about tying it down
properly and protect everything from being jiggled around.

------
Paul Jones,  Motorola MCG                           [email-masked]
1101 E. University Ave.                             Voice: (217) 384-8529
Urbana, IL 61801, USA                               FAX:   (217) 384-8550

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From: [email-masked] (f.w.kerfoot..iii)
Date: Fri, 18 Feb 1994 14:05:45 GMT

>From article <[email-masked]>, by [email-masked] (Paul Jones):

I moved one myself (a V-ram Bridgeport, but the moving issues are similar).
I would say you can do it yourself, if you have some savvy about dealing
with heavy things in general. It will take considerable time to plan
everything properly and assure you have everything you need for things
like holding the machine stationary in the trailer, etc, but it can be
done (I had never moved anything like a Bridgeport before).

> If this is a full-size Bridgeport, it's probably going to weigh a lot

All of that series Bridgeports weigh about 2000 lb (or so the factory
service rep I spoke to said). This applys to the early V-ram machines
as well as the round ram.

> properly and protect everything from being jiggled around.

Right.

Frank Kerfoot
[email-masked]

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From: [email-masked] (Richard Foulk)
Date: Sat, 19 Feb 94 21:40:56 GMT

Please folks,  don't quote a whole big long article just to attach
a couple of lines of response.  It's wasteful and inconsiderate of
the rest of us reading it.

Quote selectively.  Learn how to use your editor.

Thanks

-- 
Richard Foulk		[email-masked]