[TheForge] half round staock

Sun Mar 9 22:51:32 EDT 2014

No Bruce, "air over hydraulic" in no way implies direct air hydraulic oil
contact. I know of two basic air/hydraulic systems. #1 is a compressed air
cylinder that drives a hydraulic master cylinder. #2 is the air motor
driving a hydraulic pump system you describe. No direct air/hydraulic
contact in a properly functioning system. Heck, the sure sign you have air
in your hydraulic fluid is spongy cylinders or snap start motors. The air
compresses till it overcomes the resistance and once the cylinder or motor
begins to move it jumps.

Jer

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce .
Sent: Saturday, March 8, 2014 2:35 PM
To: Blacksmithing List Sponsored by ABANA
Subject: Re: [TheForge] half round staock

Well now you've got me wondering.  What air over hydraulic apparently is NOT
is air over hydraulic!  HF doesn't even call it that -- I think I picked
that up from the local guys.  ("Air over hydraulic" would imply that the air
pressure is impinging directly upon the reservoir of oil, thus pressurizing
it.  That could be incredibly dangerous for reasons of ignition of oil by
high-pressure air, or of sub-cutaneous injection of oil (like can happen
with a paint sprayer).

Rather, it seems to be air operating a hydraulic pump -- it putt-putts away
as you actuate it, just like the little engine that could.  Hence, I rather
expect that's exactly what's going on, but haven't done the homework to find
out.

So I called up the HF manual:
http://manuals.harborfreight.com/manuals/95000-95999/95553.PDF
There's a part (that goes putt-putt) they call the "air motor".

However, they don't give an explanation of how it works, so all of this is
just surmise.

Now, the instructions are pretty clear that these jacks are for lifting, not
for holding.  So Frosty's concerns have some merit in any event.  That may
well be true, however, for ANY hydraulic jack.

Bruce
NJ

On Sat, Mar 8, 2014 at 3:26 PM, Jerry Frost <akfrosty at mtaonline.net> wrote:

> I've wondered how well air over hydraulic cylinders would work inn a 
> forging press. I know they're fast but how true is the 20tn. Rating? 
> There's a difference between lifting 20tns. and a solid 20tn. push. 
> Air is compressible while hydraulics are incompressible so a jack may 
> lift 20 tons but it's going to have some spring.
>
> Don't sweat ugly welds with flux core welders, they're pretty famous 
> for it and I can't imagine what I'd use HF welding wire for, maybe 
> reinforcing in a cast refractory forge liner? Oh wait, if I can't get 
> the needles I trim a stainless steel brush. My wire welder is a Hobart 
> 120 Handler and I use it as GMAW with 75/25 gas and for light welding. 
> For heavy work I have a Lincoln Ranger 9 welder generator. I have a 
> LN-25 fire feed for it with Lincoln's 7018 equivalent flux core wire. 
> I don't recall the actual wire designation because I almost never run 
> enough bead to need the wire, I usually run stick.
>
> My first wire feed was a little Italian import 120v welder designed to 
> use the 2lb. spools but it was an easy mod to mount a spool holder on 
> it's back and buy regular spools. I was really bummed when a cheap 
> part failed and none were available this side of the pond. (grrrrr)
>
> Jer
>
> -----Original Message-----
> From: theforge-bounces at mailman.qth.net 
> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce .
> Sent: Friday, March 7, 2014 1:50 PM
> To: Blacksmithing List Sponsored by ABANA
> Subject: Re: [TheForge] half round staock
>
> Little digging out needed in NJ recently.  It's been mid-30's, mostly.
> I spent some time getting my forging press "on-line".  We made these 
> in an NJBA workshop about a year back, but I didn't have a table for 
> it so never got it up and running before.  It's a wicked thing -- 
> powered by a HF 20-ton air-over-hydraulic jack.  I tested it on some 
> bent stock that was inconvenient (because too long to handle) to 
> straighten by hammer and anvil.
> I've used one to forge a "Damascus" billet.
>
> FWIW, the HF 90-A flux-wire welder (120 VAC -- works off a standard
> circuit) is on sale this weekend only for $80.  Best price I've seen 
> for it.
> I paid about $10 more for mine. It won't replace a big blue, but it's 
> portable and WILL weld fairly heavy stock if you pre-heat the stock 
> (with an ordinary propane torch).  I've been welding 1/2" and 5/8" 
> square stock to a 1/4" plate.  My welds are real sloppy, but that's 
> probably more me than the welder.
>
> One tip -- throw away the crap HF flux-core wire and use a name brand.
> Joseph Fazzio's in NJ advertizes name-brand 10-lb spool for less per 
> lb than HF sells their crap 2-lb spool .  (You'd have to rewind onto 
> the smaller spool or modify the HF welder to hold a 10-lb spool -- 
> which reportedly has been done.)
>
> Bruce
> NJ
>
>
>
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