Conference vmszoo::rc

    Jeff,
    
    All yer' assumptions are correct.  I had the identical experience
    using a Royal heat gun...switching to the Top-Flite heat gun
    immediately and permanently solved the problem.  The Royal gun may
    be OK for other coverings but it's no bueno for Monokote.
    
    Actually, I even find the Top-Flite gun a little light on heat and
    have started using a regular industrial heat-shrink gun for applying
    Super-Coverite, Monokote, etc.  You really have to be careful with
    this gun [it gets got enough to melt solder] but you _NEVER_ lack
    for enough heat to do the job.  Just have to keep the gun moving
    and take care not to overheat the material.  BTW, Dave Platt [of
    all people] turned me onto this idea.
    
    Adios,	Al

Jeff,

I guess I'll have to ditto Al's transmition... I used to have one of the 
cheaper heat guns that ya see advertised till it took a walk of the work bench 
and was no longer... yeah, just on plunge did it in!!  I finally bought an 
industrial heat gun that is light weight, durable, and just a "joy" to use!
I'd never use one of the cheaper units again!  The particular brand I picked 
up is a Master-Mite... but I'm sure there are others of equal quality and or 
better.  The one feature I "really" like, is the ability to change the heating
element for the particular job; 340, 475, or 525 watt!! The cooler of the three
works great on the low temp coverings that go over foam, the middle on the 
monocoat and Dacron fabrics requiring more heat, and the last... well I guess
that's good for your household plumbing starting your coal stove, or whatever!!

If your think'n of model'n for a while yet to come, think about a nice heat 
gun!

See ya,

Brian

    Shoot... I just bought a Royal.
    
    I'd like to know if anyone has any particular technique for putting
    on shrink coverings that works well. How do you minimize warpage,
    prevent sags and wrinkles? How do you cover a compound curve like
    the nose?
    
    I've heard that one way to get around the air expansion problem
    is to give the air a path out, like putting small holes in the wing
    ribs for example.
    
    Dave
    

    I had a problem with air expansion on wings until I learned to put
    holes in the ribs and wing tip ribs before covering.  The servo
    well in the wing then allows the inside of the wing to 'breath'
    when it is heated or cooled.  Before I did this, I had a problem
    when I covered the wing with the wing blowing up like a baloon.
    I also had a problem when I left my wing in the car on a hot day.
    I would get to the field with the wing all swollen and then all
    wrinkled as it cooled.  Venting has eliminated this problem completely.
    Small holes (1/32) are sufficient to vent each bay in the wing.
    
    CHarlie
    

    How much money are we talking for one of these comercial heat guns??
    
    Thanks,
    jeff
    

    Jeff and everybody,
    
    I've been working my tail off this week (really!) and just now had
    a chance (I should be working) to check notes.  So, here's what
    I have done.
    
    I have the best success by 1) venting the ribs as mentioned in a
    previous reply and 2) by using the covering iron almost exclusively.
    
    To do the complete job with the iron, I 1st tack the covering as
    per the instructions and then when you normally would use the gun
    I turn up the iron, test the setting with a piece of covering to
    make sure I don't melt it, then I use a rapid motion (for even-ness)
    to shrink the covering.  I find this to be quick and if there are
    any wrinkles this setting works great for working (yes you must
    work at it) out any wrinkles.
    
    You should know that I have done this with Black Baron and Ultracote
    brands only (I love the Ultracote) so I can't say if it would work
    with monocote.
    
    Has anyone tried this method?
    
    Chris
    

    Hi Chris,
    
    Thanks for your reply.  However, the problem with using an iron
    is when you cover solid surfaces (I know Al, another reason to use
    glass/paint).  Using the iron, you actually adhere the covering
    to the surface.  I like the results much more when just the perimeter
    is ironed down.  Then the covering lays over the surface and will
    have a much smoother appearance.
    
    Cheers,
    jeff
    

    Re: .5, Jeff,
    
    I couldn't guess what an industrial heat gun sells for.  I got mine
    by salvaging several broken ones out of the plant garbage and re-
    assembling one good one out of the wreckage.
    
    I'm not even sure where to tell you to look for one but I can't
    imagine them being terribly expensive, perhaps not much more than
    our hobby items.  Maybe the other noter who mentioned the industrial
    gun [I forgot who it was and don't want to bail out of this reply
    to go look] can provide a source and price for you.
    
    Adios,	Al

    Industrial guns sell for $20 to $50 depending upon wattage, 
    multi-heat controls, etc.  The maximum wattage is apt to be 
    about 1000 to 1200; the maximum temperature perhaps 1000 F.
    
    Sears sells guns in this range (please no flames about whether
    Sears has "industrial" tools) (please, friends of the rat, no
    flames about quotes).  I have not yet looked in local tool shops.

>< Note 482.6 by MDVAX1::SPOHR >
...
>    previous reply and 2) by using the covering iron almost exclusively.
...
>    You should know that I have done this with Black Baron and Ultracote
>    brands only (I love the Ultracote) so I can't say if it would work
>    with monocote.
>    
>    Has anyone tried this method?
>    
>    Chris

I've done this with Super Super Coverite, Ultracote, and Monokote.

I use the iron cause I bought an iron and gun in a combo pack.  Then I painted
my flight box and the inside wouldn't dry.  No problem - I just pointed the gun
at it and waited, and waited, and waited.  Nuts to this says I - I'll just
set the gun inside the flight box and close the top - that'll get it hot.

A few minutes later smoke was bellowing out.  I pulled the plug and carried
a flaming heat gun out and sat it on the sidewalk where it continued to burn
for the next 15 minutes.  So ever since I have been covering with the remaining
iron.  Hmmmm - there is a moral here some where.

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

I did a quick review of industrial guns in the Nashua area.  (I'm 
tired of burning wood when removing old paint around the house with 
propane, and I'll need a gun when I get further along on my PT-40.)

Milwaukee 8975     ~ 1400 w,   500 F & 1000 F (switched)   $57-65

Master HG301A                  300-500 F                   $77

       HG501A                  500-750 F                   $77

       HG751B                  750-1000 F                  $84

Black&Decker 9751    1200 w,   ~ 800 F (no control)        $23-30

Emhart # ?           1350 w,   125 F to 1000 F (var)       $50+
    (via mailorder)            12.4 & 21.2 cfm (switched)

Sears 11777          (this one seems to be the B&D 9751)   $23+

      11778          1000 w,   750 F & 1100 F (switched)   $38+

      27112           750 w,   700 F & 1000 F (switched)   $50+
                               2100 & 3000 fpm (switched)

Note that the air flow of the last Sears model is given as velocity 
while the Emhart rating is in volume.  The lower wattage of the Sears 
would imply about half the volume delivery of the Emhart.

None of these prices are really "sales" prices, but most are below the 
artificially high list prices,  e.g. $81 for the Milwaukee.

    I noticed that Sears had one of their guns on sale this week for
    about $20.  I don't know which model it is, but anyone in the market
    for a cheap gun that will get MUCH hotter than the hobby guns might
    be interested in checking this out
     
    Charlie
    

    Dumb questions:
    
    (1) - What heat is required to shrink these films? 
    
    (2) - Can't you buy the "cheap" one temperature gun and vary the
    applied heat by varying how close the gun is to the film? 
    
    Just a thought.
    
    Keith.

    I bought a WE (world Engines) gun & iron. The gun is labelled as
    putting out 1000w. It worked just fine on monokote. heat is not
    controllable (Well it is: Its either on or off).
    
    I bought the iron & gun as a combo & been very happy with it. 
    
    
    I alos have a B&D heat gun. That sucker is *HOT*. Its primary purpose
    in life is to melt paint. I wouldn't use it on film 'cause of the
    high heat and also 'cause the air blower is anemic compared to the
    the other (actualy ith is not too supprising given what it is meant
    tobe used for)
    
    md

    I have a sears heat gun designed for melting paint and jobs requiring
    more heat than shrinking film coverings.  It works fine on Monocote,
    Ultracote, and Super Coverite as long as I am careful not to get
    it too close and to keep it moving.  I have melted Monocote with
    it when I was learning how much heat it can take.  I would rather
    have extra heat than too little.
    
    Charlie
    

    When I worked out the relationship between Wattage, airflow, and
    temperature rise for a heat gun, I obtained a multiplier that seems
    high by a factor of 3 or 5 when compared to the Emhart data of note
    482.11.  Will some one independently look up the constants and check
    my expression?
    
    My expression:
    
    	Watts = 0.35 * T * A           or    ~ T*A/3
    
    		where	T = temp RISE over ambient in degrees Fahrenheit
    			A = flow of air in cubic feet per minute
    
    			assuming nominal sea level, workshop conditions
    
    Emhart data:
    
    	1350 max Watts, 1000 max temperature, and 
    	either 12.4 or 21.2 cfm    then  assuming T = temp - 70,
    
    		W = 0.12 T * A  or  0.07 T * A
    
    What have I done wrong?