Carlson Skunk Works

February 28th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

I am now set up to build ribs.

Since returning from Kansas City I have cleaned up my work area in the basement and arranged it for rib assembly. I put a sheet of cardboard over the table top where I will be working and another one on the floor under where I will be working. That way if the T-88 drips it should only drip on the cardboard.

The gussets that I have already cut are in zipper bags on the table behind the rib jig.

I covered the rib jig with a sheet of wax paper to try to minimize the chances of a rib getting glued to the plans. Hopefully I will be working fast enough to avoid that, but it never hurts to be careful.

Now I just need to load up the syringes with T-88 components and work up the nerve to mix a batch of glue.

February 22nd, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

The Skunkworks has moved to Kansas City for this week. I am setup at a Marriott Courtyard near the airport. The primary reason for being here is to attend a class for work, but since I have some long evenings available, I have taken the opportunity to cut gussets from the plywood that I have available. So far things are going quite well and I should have enough gussets ready to allow construction of the ribs to begin once I get back home.

Last Saturday I cut the sheet of 1mm plywood into strips. This week I have been cutting the strips into gussets. There are two main sizes of strips to be cut for the gussets; 105mm and 40mm. The 105mm wide strips need to be cut cross grain and are used for the nose and tail gussets. All of the other strips should be cut with the grain.

I took a walk yesterday at Lowe’s and found a clamp that I had never seen before. It is a 2 inch plastic hand clamp that has a locking mechanism that is very easy to use. There are softer plastic pads on the tips of the jaws that keep from marring the material being clamped. At $5 each I thought they were a bargain, so I purchased two of them.

February 16th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

We have gusset!!! At this time just one, but that means the next step of this project is under way.

Last night I cut the remainder of the spruce pieces for the ribs. My sockpile of parts looks like this:
Rib parts

And another view:
Another view of the parts

Next I moved on to my scarfing sander. Here is the vacuum cleaner that I am going to pull the motor out of:
Vacuum before modifications

Here is the vacuum after I freed the motor from it:
Vacuum after modification

Here are the parts that I will keep and build the scarfing sander out of:
Scarfing Sander Parts

The only issue that I ran into was that when I tried to take the fan off of the motor I didn’t see that the nut used left hand threads and stripped the nut. Now I will have to work a bit harder to get the fan assembly off of the motor. I didn’t have the time or inclination to work on this issue last night, so I proceeded on to cutting gussets.

Cutting gussets should be a fairly easy issue, but I think I will need another sheet of plywood to finish the ribs. I will be able to tell more after I cut a few more gussets. I started with the gussets for the nose of the ribs. I used a spray adhesive to glue a photo copy of the rib nose to a piece of tag board, then cut a pattern from that. Then I cut a strip of plywood 75mm wide. I traced my pattern onto the plywood and nested the pieces to make the best use of the plywood. I was able to get about 24 rib nose gussets from one strip of plywood.

I am using a utility knife to cut the plywood. After all the plywood is only 1mm thick. It takes a couple of passes foir the cut to make it all the way through, but the cut is clean and there is no waste in the form of sawdust. It is a bit tricky to cut the curves on the back of the nose gussets. Making several passes with the knife and being careful seems to do the trick. I was careful to allow a bit extra around the nose of the gussets to ensure that they will cover all of the area that they are designed to cover.

Next week I will be out of town, so I don’t know if I will be able to make much progress if any. I am toying with the idea of taking the plywood with me. If I cut the strips ahead of time and take them with me I shouldn’t draw too much attention bringing it into the hotel 😉

February 15th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

Over the past few days I have cut a few more pieces for the ribs. However, Tuesday night was EAA and Wednesday was Valentine’s Day and our bible study group had a pot luck dinner, so things have been moving quite slowly.

The EAA meeting was well worth the time on Tuesday night. The club calendars were passed out and a full list of members names and contact information was distributed. There was a presentation about aircraft wiring. I setup the TV and DVD player and we watched several of the segments from the Homebuilt Help DVD “912 Competition”. Fred had the Pober spars mounted on a work table and some of the members worked on assembling the ribs to the spars for one wing.

I have been puzzling over how to scarf the plywood joints that will be needed when I assemble the spars for the Maranda. Several Maranda list members offered suggestions and some provided URLs to information on building a scarfing sander ( With this information I have started scrounging for materials to build a scarfing sander. The primary part is an electric motor.

New electric motors run anywhere from $70.00 to $120.00 for a relatively small unit. However, as the horsepower rating decreases the cost seems to increase. The most economical new electric motor that I could find in my area is a 1/3 hp for $70.00. That was too expensive for me. Trying to find a used electric motor was impossible. Then I got to thinking of things that used small electric motors; fans, vacuum cleaners, garage door openers, etc. Goodwill did not have any. The Salvation Army Thrift Store didn’t have any. However, there is a vacuum cleaner store in town and they have used vacuums! I stopped in yesterday and talked to the lady that runs the store and she had an older upright vacuum that has been taking up space for some time. I got it for $10.00! Now all I need to do is take it apart to get the motor. I am good at taking things apart 😉

February 12th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

I cut more pieces over the weekend. The only rib pieces other than the gussets left to cut are A, B, C, M, N, O and P. We are getting there, but slowly.

Purchases of construction supplies last week included a four foot straight edge, some new blades for my utility knife, a couple of large disposable veteranary syringes and a box of disposable plastic gloves. I also got a large 3 ring binder to keep documentation in.

February 10th, 2007

First Sand Casting

Posted by ben in Sandcasting

If you’ve been reading on my other site, I’ve been busy learning about casting aluminum at home. I built a burner which uses propane at high pressure to heat a crucible containing aluminum, and for my first pour, used plaster of paris for the mold. This did not work very well, so I proceeded to move on to sand casting. Today I did my first sand casting, and let me tell you, the results are WONDERFUL!! I am very happy, and excited about the quality of the latest casting. It is still not perfect, but the step forward in switching from plaster of paris to sand was a huge leap.

I’m including some photos here and a couple of videos for posterity.

Sand, drag, and mixing tray Silica sand I???m using for greensand Molding drag

Here you can see me after I’ve mixed up my green sand using approximately 10% bentonite clay and 90% silica sand. I’m starting to ram up the mold here.
Ramming up mold Drag rammed and standing up Mold ready to pour

After pouring, and letting the casting cool, I broke it out of the mold. In this photo it is still very VERY hot, far too hot to pick up, but I couldn’t wait any longer (I had waited about 45 minutes at this point).
First casting using sand

After letting it cool more, and cleaning off the sand, here are some close up photos showing some of the defects in the casting. I’ll be researching what happened, and trying to remedy the problems on the next casting. However, I’m very excited as this casting turned out FAR better than my first!
Close up of casting defects Close up of casting defects Close up of casting defects
Close up of casting defects Close up of casting defects

February 7th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

Last night was more productive. I cut a significant number of pieces of spruce for the ribs. Parts completed to date are F, G, H, I, J and L. I am currently working on K. The vertical rib pieces go quickly since there is only one cut per piece. The diagonals take a bit longer because they require between three and four cuts each. It won’t be long before I start on the gussets!

February 6th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

Nothing much to report today. I did empty another coffee can and added it to my collection. I also recieved the Wicks catalog in the mail.

Chris pointed out that cutting the 1 mm plywood is covered in the GBI manual. Thanks, Chris!

For the record here is a list of the materials that I have purchased to date:
118 – 1/4 x 1/4 x 60 inch spruce cap strips
2 – 1/4 x 1 1/4 x 60 inch spruce cap strips
2 – 1/4 x 1 3/4 x 60 in ch spruce cap strips
1 – 48 x 48 x 1 mm birch plywood
1 – 1/2 gallon T-88 adhesive

February 5th, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

This weekend was busy, but I did manage to get rolling on part production for the ribs. I have cut enough pieces of parts H and K for all of the ribs and have about half of what I need for part L. The parts are labeled starting just behind the nose block and beginning with A and proceeding to P which is just in front of the tail block.

Sunday morning I emptied another coffee can and have added it to my collection of parts storage cans. My recommendataion is that as soon as you know that you will be building an airplane start purchasing all your coffee in one pound containers, either plastic or metal. These are just the right size for storing the parts and they don’t take up as much room as the three pound cans.

February 2nd, 2007

AMF-14H Maranda SN:1026 Construction Log

Posted by Roger in AMF 14H Maranda SN1026, news

The rib jig has been completed! The first set of rib parts other than the gussets have been cut, so if I cut some gussets I could assemble one rib at this point. However, I am going to use this rib as the pattern and duplicate each piece so that I have enough to assemble all of the ribs before doing any of them.

I have attempted to include some pictures with this post. We will see how they turn out.

Rib Jig

The first image shows the completed rib jig with the rib parts on it. This is from the front end with the jig laying flat on the table. When I work on the ribs I keep the jig flat on the table. The spruce for the ribs is in the cardboard box on the back of the table. The pieces that I bent are fairly easily seen. The bent ends are to the left center of the picture.

This also shows the tools that I am using at this time. Rib building is a very nice winter indoor sport 😉 The ribs require only hand tools. I am using a manual staple gun, but some of my friends have purchased pneumatic guns for their projects. My biggest problem with the manual staple gun right now is accuracy, but that will probably improve with practice.

At the far end of the table is my pull saw. In the picture it sort of looks like a butcher’s knife. This is an interesting device. The blade has very fine teeth and is very flexible. A single good pull on the saw will cut through a 6 mm x 6 mm piece of spruce. There is very little kerf, so the waste is minimal. The only issue is that it has difficulty distinguishing between wood, paper and skin.

Rib Jig 2

This is a view from across the room. I was trying to get a better shot of the whole jig, but it doesn’t show up very well due to the angle. It does give an idea of my work area.

Rib Jig 3

Here I set the jig up on its edge so that you could see the whole rib better. One of the spruce stips cracked while I was trying to bend it on Friday last week. I replaced it with another piece and boiled that one a bit longer. However, you can see that I managed to salvage that piece by using it for the bottom stringer for this rib. The broken end is to the left.

Rib Jig 4

This picture has the added coffee can. I have been saving coffee cans, from work and home, primarily to store my rib parts. I have a combination of large three pound coffee cans and smaller one pound cans. The term cans is not exactly accurate, since these are the plastic coffee containers rather than the traditional metal cans.

My approach to this is to label each of the pieces needed to build the rib. In this case the labels went from A to P. Then I labeled the coffee cans from A to P. As I cut the pieces I put them in the appropriately labeled coffee can and when it is time to assemble the ribs I will take the pieces from the coffee cans and place them in the jig at the proper location. The coffee can in the picture contains the nose blocks. I have another one that contains the tail blocks.

After I took these pictures I proceeded to start cutting pieces for the ribs. My approach is to cut the longest pieces first and work my way down to the shortest pieces. This keeps the waste to a minimum. So far I have 16 of the “J” pieces which are the longest diagonals in the rib.

Well, I am going to wrap this up for today and see what the page looks like once I publish it.

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