geep
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Post by geep on Mar 1, 2007 8:45:38 GMT -8
Update time. Over the past few days I've managed to spend a few more hours working on the model. I made a true speep from 1/8" aluminum, revised a masonite template, and started work down the left side of the model. Things I've learned: I've had problems with the clay laminating as I pack it on because the base wasn't warm enough. I found a quick way to test if the surface is ready. Take a ball of warm clay and tap it on the surface. If it sticks, the surface is ready. If it doesn't stick, the surface is too cold. There's a temperature range at which the clay accepts templates best. Too warm and the clay "tears", ruining the surface. Too cold and the templates are reduced to shaving. (The tearing may be partly due to one of my templates not being sharp enough.) Masonite templates work much better than I expected, even in the unsanded condition. Here are some new photos: The new sweep, made from stock in the scrap bin: An adjustable layout square modified to point in layout lines. Transferring the knee cutout shape to the model. The template is placed parallel to the centerline of the table and indexed to a mark on the back of the armature. After marking the cutout line, I slit the clay with an X-acto knife and pushed in a piece of fishing line. After shaping most of the left knee cutout with the template. I came back after the template with a curved rake and cleaned up a bit. I need to make a curved steel so I can remove the chatter marks, my curved rake isn't small enough. A wider view: Next, I need to build a jig to hold the seat relative to the tank as it would be on the motorcycle. The front curvature of the seat is key to the shape of the knee cutout at top at the back of the tank. Then I can finish the knee cutout. I need to fair in the area between the front radius and the top of the tank above the knee cutout. I expected this due to the small curvature of the template. I'll do this by hand and use my profile gauges to transfer the shape to the right side. That's all for today.
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geep
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Post by geep on Feb 25, 2007 23:40:19 GMT -8
Hi Steve, The base is indexed to the armature by the three dowel pins sticking up through the base template. I managed to get most of the top surface roughed in this evening. Here are a few photos of the progress today: I started out by applying a skim coat of hot clay with a spatula. I made this coat about 1/8" thick. My main goal was to force the almost liquid clay into small holes I punched in the foam to key the two together. After the initial coat I reduced the oven to around 135F, put in some fresh clay, and began building out the shape. As I went I tried to bed in the Lucite sweep by taking small cuts in the warm clay with a sawing motion. I ended up sticking .007" feeler stock to the 1/4" masonite template to provide a smoother surface for the sweep to run on. I also found the 1/8" Lucite sweep to be too flexible for the job. Even when used over warm clay it would bend enough to make holding the contour difficult. I also practiced using the finisher and flat steel on the back surface removing chatter marks left by the sweep. The surface ended up glossy, but not flat! Tomorrow I plan to make an aluminum sweep of the same dimensions as the plastic one and try it out. I think a stiffer sweep will make it much easier to create a smooth surface. I also need to sit down with a lump of clay and practice hand surface development. In particular, my finishing technique needs lots of work. Anyway, that's todays work. I have much to learn! ;D John
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geep
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Posts: 26
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Post by geep on Feb 25, 2007 9:25:28 GMT -8
OK, here are some photos of the progress to date: The first photo shows my completed plinth. 1/2" dowels in the base of the plinth key into 1/2" holes drilled in the table on 6" intervals. A few pieces of carpet tape will hold the plinth to the table to prevent rocking. This photo shows the bottom guide template in place on the plinth. I wanted to line it up independent of the plinth, so I drilled clearance holes in the template. The bottom guide template is secured to the plinth with plenty of carpet tape. It will remain in place until the final step of modeling, which will involve extending the base to form a skirt for the mold. In these photos you can see the complete set of templates. In the back you can see the guide templates which will guide a true sweep to form the top surface. The clear plastic template is the true sweep, made from 1/8" Lucite with a radius of 15.25". Also shown is the side guide template to form the knee cutout profile, the curve to bed in the knee cutout profile, the side template, and the new seat. When the shape has been established, the front lip of the seat will be inset into the tank to form a flowing curve from the tank to the seat. After lunch I'm going to begin applying clay. John Oh, do my photos appear dark on your end? I can't really judge the exposure on this monitor.
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geep
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Posts: 26
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Post by geep on Feb 19, 2007 20:11:06 GMT -8
Hi Steve, I managed quite a bit of work on the fuel tank model this weekend. I applied foam to the armature and carved it to rough shape, built a plinth to mount the armature to the table, made side templates from 1/4" tempered hardboard to form the top contour, measured the existing tank, and develped a true sweep to bed in the top surface. Earlier in the week I went to the hardware store in search of Gorilla Glue. While looking for Gorilla Glue I found Titebond Polyurethane glue, which appears to be a functional equivalent to Gorilla glue. What clued me in to the similarity of the products was the color of the glue and the instructions, which were exactly the same. The only difference I could find was the price, with the Titebond product being half the price of the Gorilla product! I see now why you like foaming polyurethane glue so much. The foaming properties allow it to bridge large gaps in the foam work, making precision cuts less important. Not only that, but it cuts MUCH more easily than epoxy. Less hassle too, as there is no mixing required. Thanks for the excellent suggestion! Tomorrow I'm going to smooth out the foam, make the bottom guide template, the side template and the knee cutout templates. Then I'll be ready to begin the real modeling. I'll take some photos shortly. I'm looking forward to seeing the progress on your Corvette foam work. John
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geep
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Posts: 26
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Post by geep on Feb 1, 2007 23:20:05 GMT -8
Hi Steve,
I like a clear, heavy viscosity, 5-minute epoxy made by "System Three". It's great for quickly gluing things up where the glueline thickness isn't important. In fact, I used it to frame in the armature. It comes in 1-quart kits for around $37.
I have passed Gorilla Glue in the store several times, but I've never used it. I'll give it a try when I glue down the foam.
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geep
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Posts: 26
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Post by geep on Feb 1, 2007 13:21:09 GMT -8
Hi Steve, That's the plan. I built an armature that will fit in place of the existing tank. I've marked the centerlines of the armature and the motorcycle so I can reference them on the surface plate. Here's a photo from last week: I still have to add some reinforcement and fill it out with foam. The cutouts are to clear the carburetors, throttle cable, and valve cover. I plan to rough in my key lines with templates, then stand back and see what I have. Then I'll pull out the wires and rakes and fine-tune it. That's the plan anyway. We'll see how long it lasts! ;D
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geep
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Posts: 26
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Post by geep on Jan 30, 2007 10:05:24 GMT -8
Time for another update. I've been busy working on a modeling table, but I do have the 1/4 scale key lines almost complete: I expect them to change once I start the model. Especially the intersection of the top accent line with the front edge of the tank. The drawing at the upper right is the contour for the knee cutout. I still need to make a rear view, but that shouldn't take too long. I may also increase the "scroll" of the knee cutout line in the side view so it intersects the base of the tank at a slightly acute angle. I think the top view flows, but the side view needs a little work before I go full-size on Mylar.
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geep
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Posts: 26
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Post by geep on Jan 8, 2007 15:00:13 GMT -8
Update: I got a package from Chavant a few days ago. In it was the 5 pc. Profilmeister gauge set from along with their advanced modelling video (I already have the other two) and Yamada's book. The Profilmeister gauges are so much better than the garden variety hardware store specials. Can't wait to try them out. The armature is roughed in and ready for foam. I'm reviewing a few different shapes for the tank/rider interface. As soon as I decide what works best I'll begin the full-size key line drawings. Slowly but surely...
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geep
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Posts: 26
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Post by geep on Nov 16, 2006 23:46:32 GMT -8
Thanks for the tips. I'll order a profilemeister set in the next day or two. It looks significantly better than the home depot variety.
Thanks for the clarification on gut lines. I figured that was what Steve was referring to, but wasn't sure. I saw fishing line being used as a guide for wires in Chavant's basic clay modelling video. I'll certainly be using that for the main feature lines.
I'm sure to be asking plenty more questions as I get underway. Should have photos in a week or two. I have to finish up some other things first.
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geep
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Posts: 26
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Post by geep on Nov 13, 2006 23:58:47 GMT -8
Hello, This is my first post, so an introduction is in order. I found styling clay as another tool to use when developing patterns for my composites business. I was looking for a material that would allow me to quickly and accurately reproduce compound curves, while making it possible to revise the pattern if required. My search began with Sculpey modelling clay. I liked the fact that it would become a solid mass when baked, but was unsure about the dimensional stability as it cured. I shouldn't have worried, the body of the clay is so soft that it is impossible to define a shape. This became obvious when I tried a little experiment: Although the shape is resonably well defined, it was impossible to get the sharp features I was looking for. In addition, the soft nature of the clay made holding a tolerance impossible due to flex. I knew that the automotive industry was using clay for modelling purposes, and a few hours on the internet turned up this website and the Chavant company. (Thanks to Steven for the good info on this page.) I ordered a few of their videos, a tool kit, and 60lbs of I-307. Now to my question: After practicing on smaller objects for several months, I have decided to do a full-scale test. For my test I thought a new tank for my motorcycle would provide enough modelling practice without getting overly complicated. I made a few rough sketches of the desired shape. This is one of the rough sketches: The top and rear views aren't critical, because the horizontal plane is governed mainly by the shape of the frame. The details will be governed by what looks good, and how it feels. I plan to rough to my sketches with templates, then revise the shape freehand. Since the tank is symmetrical about the longitudinal axis my plan is to model only one half of the tank initially, using a mirror to show the other half. Once I have the final shape I will model the other half to match. How should I go about modelling the other half to a reasonable degree of accuracy? I would like to stay within +- .030, as I will be taking a mold from the finished clay model. My original idea was to place the half-finished model on a surface plate and use a height gauge to trace the shape onto mylar at various intervals. I could then make templates from the sections to model the opposite side. Are there any other methods that might be faster or more suitable? Am I making this more complicated than it needs to be? Regards, John
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