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Guillow's de Havilland Chipmunk (Read 4811 times)
Reply #46 - Sep 14th, 2019 at 1:07pm

Dan   Offline
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Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
Today was the day I got all excited about making the final notches in the wing ribs and building a wing! So I thought, anyway. When making a notch in the second W-6 rib, I broke it. Now I need to fabricate another piece. My idea was to trace around the good W-6 with a pencil and then cut around the lines to form a replacement. However, there may well be a better option. Tips, tricks, hints, suggestions, advice...all are welcomed and appreciated.

I didn't stop progress on the Chipmunk, though. The horizontal stabilizer got a little rework done. I cut out S-1 and the two S-3 pieces, as well as the stringer that fit into the notch in S-1. The longitudinal stringer that was joined to the S-3 pieces looked a little crooked, so I made a new one. I also did as alfakilo suggested and ran a square strip where the leading edge of S-1 once was. The two S-3 pieces will be put back into place later.

There are a couple of ways I could deal with S-1. One is reworking the existing piece or cutting a new one out of sheet balsa. The other is making the leading edge setup similar to the trailing edge, with triangular gussets on either side of the stringer. What do the more experienced builders think?

Finally, the fragility of the wing ribs made me reluctant to dump them back into the kit box. Fortunately, I came up with a solution; I originally had this idea in mind for small sections of stick balsa that may still be useful. I put them in cases that originally held disposable vaping devices. The lids can come off pretty easily, so I wrapped rubber bands around them in case an impish cat got hold of them.
 

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Building stick-and-tissue models is a hobby, not work.
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Reply #45 - Sep 13th, 2019 at 9:50pm

pb_guy   Offline
Senior Member
So I'm just a kid at heart.
Youbou, BC, Vancouver Island

Posts: 1591
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My wife is a diabetic, so we have a 'sharps' container for blade disposal. However, just about every bathroom in a store has a 'sharps' disposal bin, so you can use those for blade disposal if it bothers you to dump it in the regular garbage.
ian
 
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Reply #44 - Sep 13th, 2019 at 5:10pm

Dan   Offline
Full Member
Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
Proper blade disposal is something that does not get enough attention! I have a couple of blade banks left over from my days of wet-shaving. When I'm done with a blade, I drop it into the slot, and it's safely away from my pets (and any wild animals that may encounter them after the trash is removed from my property) and the disposal workers' fingers.

Mike, thanks for the tip on cutting curves! I will make sure to cut the inside curve of R-2 first, then the straight lines, and finally the outside curve. I'm taking a break from construction until tomorrow, but I did get a sheet of balsa so I can cut the replacement parts.
 

Building stick-and-tissue models is a hobby, not work.
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Reply #43 - Sep 13th, 2019 at 12:55pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 1156
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Agreed, Mike. I use pliers also and put the old blade into the packet that the new blade came in.
 
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Reply #42 - Sep 13th, 2019 at 12:08pm

New Builder   Offline
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Amherstburg, Ontario, Canada

Posts: 1213
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Dan - AK and Neal are right, most any sharp blade will work. For cutting the inside curves on replacement parts, cut them first as cutting the outside curve first may break the part. Also, be careful changing that scalpel blade, I use pliers as it does not have much area to grab onto and it is incredibly sharp. Now, for something I've never heard any commentary on, disposing of used blades. While they are not sharp enough for our use they are still mighty sharp and capable of inflicting damage, someone down the disposal line has to handle the waste that blade is in and if it does make it to landfill, the animal population may happen on to it. I wrap my blades in several layers of blue tape before disposing of them.
Mike
 

"Skill comes by the constant repetition of familiar feats rather than by a few overbold attempts for which the performer is yet poorly prepared." Wilbur Wright
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Reply #41 - Sep 12th, 2019 at 9:55pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 1156
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Either blade should do the job. It isn't a matter of what works or not, only a matter of what tends to make the job easier. And much of that boils down to personal preference.

I found that despite my many years of model building, I was unaware of a number of things. Folks here went out of their way to expand my store of knowledge and I am the first to credit them with making this hobby one heck of a lot more enjoyable and productive for me. If you have the same experience, then we are all happy campers!!
 
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Reply #40 - Sep 12th, 2019 at 9:54pm

Kerak   Offline
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I Love YaBB 2.5 AE!
Roy, Utah

Posts: 2466
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Hi Dan...all those gizmos and such...all fine items that really help...and you're correct...these models have been built for many years now...with some pretty basic tools.  You'll do alright to just collect things as you go.  Don't forget to pick up a 200 ton hydraulic press...bandsaw, metal lathe...etc. Smiley

Speaking of tools...sharp is the key word.  All things go well when working with a SHARP tool.  You can replace dull blades...but that gets expensive.  So...with that in mind...think about learning to keep those blades sharp.  You can get on youtube for some suggestions and help in that area.  The simplest sharpener is actually a small sheet of fine sandpaper.  No kidding!  Smiley  Of course...there are lots of sharpeners available.  And...clean your blades often...they seem to collect glue, etc.  Wink  These are easy suggestions...that help greatly to enjoy the adventure.  Smiley

Your Chipmunk is a great model to start with...a well designed kit.  You're on the right tract...track...tack...pathe.  Smiley

Neal
 
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Reply #39 - Sep 12th, 2019 at 6:59pm

Dan   Offline
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Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
Lots of neat items on offer! Sooner or later I will build up a fairly comprehensive model-building toolkit, hopefully without straying from the old-school, low-cost approach I prefer.I

I will pick up some of the dollar store emery boards tomorrow. Work on the Chipmunk will resume soon. As regards cutting out the replacement R-2 and S-1 parts: is there a tool that is well-suited for this purpose and should be easy for me to obtain by means other than online ordering? Or will the #11 blade or a razor blade work well enough?
 

Building stick-and-tissue models is a hobby, not work.
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Reply #38 - Sep 12th, 2019 at 8:28am

alfakilo   Offline
Global Moderator
Retired USAF and TWA.
St Louis, MO

Posts: 1156
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This forum and the one at hipppocketaeronautics.com are loaded with help. In addition here are some links and locations where you can find all the goodies folks talk about:

https://volareproducts.com/

https://sigmfg.com/

https://www.wind-it-up.com/

https://easybuiltmodels.com/parts.htm

http://www.bhplans.com/

Locally, visit Wal-Mart, Home Depot or Lowes, Hobby Lobby, Michaels, Harbor Freight, Dollar Stores in addition to your local hobby shop (if you are lucky enough to have one!).

Most models have windows or canopies, so start saving plastic such as milk jugs, food containers, etc to have a stash to go to.

Tom mentioned those highly useful sanding sticks. Also, consider a set of cheap files that come in handy for a wide variety of building tasks. Since we are only using them on balsa, they don't have to be fancy!! For example, from Harbor Freight:



 

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Reply #37 - Sep 12th, 2019 at 3:24am

Dan   Offline
Full Member
Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
The scalpel definitely would not have crossed my mind had alfakilo not mentioned it. I also have plenty of razor blades on hand, both single and double-edge...should have been using those from the get-go.

As for a model Aztec, I don't know of one. This was a real aircraft, made of metal. Re-installing its wings (that's the phrase I should have used) required several student mechanics maneuvering the wing into position and another student mechanic in the fuselage bolting the wing in place. On that very warm day, I was inside the fuselage.
 

Building stick-and-tissue models is a hobby, not work.
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Reply #36 - Sep 11th, 2019 at 11:24pm

Sky9pilot   Offline
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Stick & Tissue
Kelso, WA 98626 USA

Posts: 11447
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As for a cutting utensil you can also us a couple pairs of pliers and snap the single edge razor at an angle for releasing the parts from the die cut sheets or other fine work.  Depending on how you break it...it can be mounted in the xacto handle also.
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #35 - Sep 11th, 2019 at 10:54pm

Rekitus Maximus   Offline
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re-kitter extrordinaire
(in flux) Caribou

Posts: 91
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some one makes a model aztec?
nm I'll go google...

I found the exact dihedral is not a problem
getting the first ribs to the SAME angle is more of the issue...

my first rib of each wing bowed in after I got the wings covered.
that also didn't help...
I told my self to add a couple xtra stringers from rib1 to rib 2
on the next build...

a better solution might be to cover with less stretching.
like damp after gluing on the tissue instead of wet tissue covering.

victor

victor
 

re-kitter extrordinaire
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Reply #34 - Sep 11th, 2019 at 9:41pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 1156
****
 
Dan, what we cut with makes a huge difference at times. Until I joined this forum, I made do with the typical Xacto #11 and never thought much about it.

But, as I have learned, that trusty #11 may not be the best tool depending on what is being cut. I've added two other cutting tools to my work bench...scalpel blades and single edge safety razor blades. These are pretty inexpensive on Amazon allowing me to not try and make do with a dull edge. Here are examples:

https://www.amazon.com/Single-Industrial-Replacement-Scraper-Canopus/dp/B073N7X6...

https://www.amazon.com/gp/product/B0079LWFQK/ref=ppx_yo_dt_b_search_asin_title?i...

https://www.amazon.com/gp/product/B01MPX3JTI/ref=ppx_yo_dt_b_search_asin_title?i...

The safety razor is a good chopper, the #10 scalpel is very good at trimming tissue, and the #11 scalpel is a good all-purpose tool similar to the Xacto #11.
 
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Reply #33 - Sep 11th, 2019 at 8:01pm

Dan   Offline
Full Member
Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
A little more progress was made tonight...I started notching the wing ribs. I had previously made a copy of the patterns, so I started with W-1 and W-2. I cut each pattern from the paper with a hobby knife and lined them up. As those patterns were in an area that a fold passed through, I guided off the leading edge. With everything lined up, I cut the notches and did a quick test fit.

I also tried to make a new R-2 piece using a square of balsa from one of the die-crunched sheets. My efforts were not successful. Tomorrow or Friday will see me making more copies of the plans and picking up a piece of balsa big enough to craft new R-2 and S-1 pieces.
 

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Building stick-and-tissue models is a hobby, not work.
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Reply #32 - Sep 11th, 2019 at 4:43am

Dan   Offline
Full Member
Navy veteran and A&P holder
Detroit Metro

Posts: 145
***
 
Yet again, thank you for the suggestions! I will rework the leading edge and fabricate a new S-1 piece. The two S-3 pieces will be a little easier to rework.

As regards the wings, I will build them in two separate pieces. I've already cut the spars and leading/trailing edges with that setup in mind, and I figure (though I could be wrong) that getting the proper dihedral will be easier that way. Compared to putting the wings back on a Piper Aztec, that should be a walk in the park!
 

Building stick-and-tissue models is a hobby, not work.
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