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Topic: Remove louvre on Master 751 air intake (17 msgs / 316 lines)
1) From: Brian Kamnetz
I need to filter air going into the air intake of my Master 751b so
that chaff doesn't harm whatever is inside. I don't have nylon
stockings around, which is what Ray suggested, so I was going to place
thin cloth under the louver on the air intake. I figured the louver
and the vacuum would hold the cloth in place. But I can't figure out
how the louver comes off. It has a black knob in the center that can
be used to open or close the louver to control air flow, and I assumed
that it was screwed on to a threaded shaft, but I couldn't budge it by
hand, and was too chicken to take a pliers to it.
Anyone know what I have to do to take the louvre off the air intake?
Thanks,
Brian

2) From: Rich
Any filter on the intake will restrict the air flow and increase the operating temperature of the 
element.  This can result in a rapid teminal failue.  Run with the louvers wide open and if chaff is a 
problem place a piece of plain aluminum window screen over the intake.  Just cut out a circle with a 
small hole in the centre that will slip over the knob, it will stay in place.  Chaff will pass through the 
fan and be incinerated going past the element and exit the front of the gun as a bright red comet.  If 
you do not see any comets then you are not sucking in any chaff.  there is nothing to plug in the 751 
series.  If you want to take it apart here is the diagram URL http://www.masterappliance.com/master1_parts.htmlThere are some fragile parts associated with the element.
On Sun, 9 Sep 2007 16:34:39 -0400, Brian Kamnetz wrote:
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3) From: raymanowen
Op Images was a client of mine. As screen printers, they used a number
of these Master heatguns for flash curing multicolor print layers on
small runs. Some of the more creative imbeciles had used three
heatguns for striking devices.
I inherited the three cadavers when Op wanted new HG's from
W.W.Grainger's Tejon St. stock. WWG had the repair parts at the
Chi-town parts depot so I fixed up the three HG's with 1800w 120v
heaters on the two heaters I had to replace. I didn't need many parts,
and fixed all three for <$50 IIRC.
The three new guns cost about $240, but they had them faster than I
got the oldies fixed up.
The radial louver throttles the air more than a sock would, if you
close it down for the highest temperature. Just like your toaster or
convection oven- the minimal air flow and elevated temperatures are
desired.
Screen mesh should work fine, just filter the whole intake area. I
wouldn't try to get it under the louver grille. In that case, a little
chaff would quickly block the small openings.
Cheers -RayO, aka Opa!
On 9/9/07, Rich  wrote:
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-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the
Mighty Wichita (ex- NYC Paramount) WurliTzer- 1976

4) From: Brian Kamnetz
Thanks, fellas. Guess I should scrap the cloth idea and pick up some
screen mesh.
Brian
On 9/9/07, raymanowen  wrote:
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5) From: Rich
If you place the  gun at the correct angle to the bowl no chaff gets sucked in anyway.  Tip is about 2" 
below the rim and 1" away from the near side.  That is a 96 oz mixing bowl.
On Sun, 9 Sep 2007 19:18:55 -0400, Brian Kamnetz wrote:
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6) From: Brian Kamnetz
I don't THINK I'm getting much chaff into the air intake of the
heatgun, but a discussion last summer, and then recent posts, got me
thinking that I should probably take some preventative action.
Brian
On 9/9/07, Rich  wrote:
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7) From: Rich
The design of the Master Appliance model 751 series is such that the only thing that will plug it up is 
something that will cover the intake louver or is non combustable and will block the exit screen.  If 
concerned, a mesh size like the exit screen will function fine over the intake with the shutter wide 
open.  It will raise your operating temperature however.
There is a very large difference in the 751 series design and all of the Chi-Com products.
On Sun, 9 Sep 2007 20:12:09 -0400, Brian Kamnetz wrote:
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8) From: Brian Kamnetz
I think I'm finally catching your drift. If I understand correctly,
the problem in constricting the flow isn't the screen itself, it is
the materials that collect on the screen.
I excel at doing nothing... maybe I'll just continue to do that.
Brian
On 9/9/07, Rich  wrote:
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9) From: Rich
A reasonably open mesh screen, like the one in the front end of the gun reduces the free area by 25% 
or so.  In other words, if the available area at the outlet without the screen is say 1 square inch then 
when the screen is added the available area is REDUCED to 3/4 sq inch or so.  This is significant if 
not included in the original design.  The same will hold true on the suction side.  The screen provides 
some restriction to flow and the crap that collects on it will contribute more restriction.  If you do not 
see red sparks flying out the front end of the gun then you are not sucking chaff into it.  You will get a 
piece or two but the air velocity is low on the suction side for a good reason, keeps the crap out of the 
fan.  The mica surrounding the heating element will flake off and plug the outlet screen.  this is 
something to look for.  Turn on in COOL mode and look for large flakes on that screen.  There should 
be none.  i had to disassemble my gun to get id of them as someone in the past had it apart and had 
played with the mica.  It was making flakes from being creased.
Just look for flaming chaff comets and if you do not see any or only one or two it is not a problem.  An 
intake filter / screen will plug with chaff.  I have a gun location and bowl placement that blows it 
away from the intake and all over the floor.
On Sun, 9 Sep 2007 20:42:23 -0400, Brian Kamnetz wrote:
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10) From: Brian Kamnetz
Thanks, Rich. Next time I roast when I turn it onto cool-down I will
look to see whether I can see any large mica flakes on that screen
Brian
On 9/9/07, Rich  wrote:
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11) From: Rich
Look as soon as you statt it up.  Just go to cooldown fist.  The mica should not flake but it does and 
with the fan off it goes and hides in the back.
On Mon, 10 Sep 2007 13:29:41 -0400, Brian Kamnetz wrote:
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12) From: Brian Kamnetz
Ok, thanks, I'll look on start-up in cool mode. I HOPE there will be
nothing there. I bought this gun new and it has pretty much been
babied.
Brian
On 9/10/07, Rich  wrote:
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13) From: Rich
Should be clear but it is a good idea to look mow and then.  That heat gun is very tough.  It is real 
industrial grade, I can assure you it takes dedicated abuse to break one.
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14) From: Brian Kamnetz
I'm very happy to have stumbled onto this make/model. I was shopping
for a heat gun but didn't know anything, so as far as I knew several
makes/models were more or less interchangeable. Just through
serendipity I stumbled onto the 751b on eBay. I can't remember for
sure anymore, but I think I paid about $35 for the heat gun plus
shipping. Since I devised a way to suspend it (weighing close to 4
pounds, it was a bear to handle by hand), I really like it. Puts out
really even heat.
Brian
On 9/10/07, Rich  wrote:
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15) From: raymanowen
Just don't be a Master Louvre Remover -ro
On 9/10/07, Brian Kamnetz  wrote:
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16) From: Brian Kamnetz
Rich,
I roasted today. I fired up the Master 751b on cool and looked at the
screen over the business end, and sure enough, there were a bunch of
flakes there just big enough that they hadn't blown through the
screen. But during the roast, and after the roast, when I look at the
screen the flakes were gone. So I'm thinking they probably were from
chaff that got sucked into the heat gun last roast while it was
running on cool to cool down after the roast was complete. There was
no sign of the flakes again.
Brian
On 9/9/07, Rich  wrote:
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17) From: Rich
I have seen the same collection of raw chaff that is sucked in during cooldown and general area 
cleanup.  It burns up before the element is up to full temperature.  Sometimes you can see them burn 
when you first start the gun on HOT.  
On Wed, 12 Sep 2007 14:24:43 -0400, Brian Kamnetz wrote:
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