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1/25 Type VIIC/41 Scratch Build.

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1/25 Type VIIC/41 Scratch Build.

Postby Mylo » Tue Nov 21, 2006 12:04 am

1/25 Type VIIC/41 Scratch Build by Mylo.

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Acknowledgement

First off, I would like to extend my thanks to all those who took the time to post "How to do it" threads on this forum as well as those who consistantly are there to offer assistance. Without you, I would never have attempted what I'm about to undertake. I am as green to this as they come. A special thanks to Steve Neil and Kevin McLeod for their very educational threads on scratch building from A to Z and then some. Gentlemen, it's because of you two in particular that I decided I wanted to spend a ton of time and money to scratch build a sub.......I'm not sure whether thanks are in order or not come to think of it. I hope this thread might inspire other "greenies" to give this stuff a try. Most of the techniques that I use I can not claim as being my own. The only knowledge I have on how to build an R/C sub is from I've read on the Subcommittee forums and it is only through the skills and expertise of others who have shared their knowledge that has even given me enough "know how" to attempt to try. If you see a technique or tool, or material, or whatever, that you recognize as being one that you "invented", PLEASE feel free to step up and take credit. I would appreciate remembering from where I gathered some of this stuff. If you happen to be one of the modelers that I "borrowed" a technique off of, please consider it a compliment. As can be seen, I have included the time in hours it takes me to complete each step. I don't claim to be slow, fast, maticulous, careless, or in between, nor do I care, but I do admit to having zero experience in R/C Sub building with every inch of the way requiring that I "read up" on it or in some other way try and figure out how it's done. I thought this time line might come in handy for other novices who simply don't have a clue how much time goes into building one of these things. Again, a HUGE thanks to everyone at Subcommittee for giving me enough tools to try.

Step 1: Research and Decisions

Time to complete: A year and change.

For me, the decision on what kind of sub to build was easy. It would be a U-Boat, no question. A somewhat harder decision to make was "What type of U-Boat". I knew it would be one of three choices, a type II, type VII, or type IX. (with their respective variants) Since I like all of them equally well, I decided that my choice would come down to the boat that I could find the best plans on. After what seemed like an eternity combing through the net in search of U-Boat data, plans, diagrams, schematics, etc, I decided to order a set of Type VIIc Fritz Kohl Plans after getting some feedback from JWLaRue that they were very good.

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I dug out the credit card, went online, and ordered the plans straight from Germany. I was quickly notified that the plans were on back order and that there was no known date as to when some would become available. *sigh*. My search on the net continued. Six weeks later, I got a notification from Fritz Kohl that the plans I requested were now available. I placed the order for 39,95 Euros. Three weeks later, they arrived in the mail. Nine weeks just to get some plans in my hands. I was beginning to wonder just how long this thing was going to take to actually build. I spent the next two weeks looking over every inch of those diagrams. I was very pleased with the quality. The attention to detail is astounding. I'm quite sure someone could build the actual boat with these plans. I was surprised to see that the plans cover the Type VIIc (1939) and the Type VIIc/41 with different diagrams for each. I decided that the Type VIIc/41 was most thoroughly represented including some excellent cross section diagrams. After some further research, I discovered that the Type VIIc/41 in the plans were of U995 which is on display in Laboe Germany as an exhibit. There are many good current photographs available of this boat as well, which I was happy to find. It suddenly made sense why this particular boat was detailed so well in the plans. I'm sure Fritz himself crawled all over the actual U995 with his tape measure to create them. So, the decision on what U-Boat to model was made, it would be a type VIIc/41. The final major decision remained, what about scale ? My goal with this boat is to not only have it look to scale, but to perform to scale. I also wanted goodies such as a extendable/retractable periscope and functioning torpedoes. I knew that to best accomplish this, the boat would have to be big. I decided that I was going to build the biggest boat that I could feasibly handle by myself and still fit in the back of my truck. I absolutely love the big boats. I decided that 1:25 scale was going to be the one. That puts the Type VIIc/41 model at 8'9". A rough calculation of the WTC that I intend to use (6"x48") puts the weight of the model right around 50lb in order to counter the bouyancy of the WTC. One of the first things I learned about r/c sub building is that, at SOME time, you have to decide that you've done enough research and get started actually building the thing. We all try our best and I feel that the guys that actually get something in the water, have done an incredible job, regardless of whether or not the model is "museum quality". They're all works of art in my book. The decisions made, I was ready to push forward.

A move to a new house put all the sub plans on hold. The new place had a basement that needed finishing. I did that and included my sub work shop into that plan. I was now ready to resume operations at my ship yard to build my Type VIIc/41 after a delay of several months.

I dug out my plans again and began contemplating how I was going to get them to 1:25 scale. The side and top down diagrams were 1:100 scale.

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The most important ones, the cross sections, were 1:15 with only 1/2 the bow, and 1/2 the stern represented on the same plan with the separation right down the middle. In other words, there was only half of each on the same piece of paper. I spent two days at the office photocopier trying to enlarge and resize the plans, cut them out, tape them, etc., etc., etc, to get them to 1:25 but failed....miserably. I ended up wasting a ton of paper and time, all the while getting really frustrated. I decided that I was going to require the services of a professional printer. I took my plans down to a local print shop and told the guy what I wanted. He thought the project was really cool and that the resizing of my plans was the most unique request he's had come through his door. He guaranteed me that he could get all the diagrams I wanted resized PERFECTLY to 1:25 scale and printed on one long continuous length of heavy guage paper with clean crisp lines for the big 8'9" top and side diagrams. As for the cross section, he told me he could cut the joined bow/stern sections down the middle where they join and then create mirror images for the side that was not represented, resize to 1:25 and print 25 copies of each, giving me the templates that I would need to create the hull formers. The miracle of computers to do all this "math" and printing. Now for the quote.......just change under $400 Canadian Dollars .......... *gulp*. I saw no other option....other than to bail on the project all together. "Let's do it" I told him, while in my head all I heard was "...are you nuts ?". Two days later, the work was done. I was VERY pleased with the results. Everything was exactly how I wanted and the quality was better than I expected. The scale on everything was a perfect 1:25. ( I measured....AND...I WAS going to take them back if they weren't bang on). Like everything else in this world, good quality and craftsmanship is expensive. All told, with postage, exchange, taxes, the works, I have $475 Canadian dollars invested in plans alone. .....so.....what was a finished boat going to run me again ? ....a million bucks ? Funny thing is, I was tickled pink about my new 1:25 scale U-Boat plans, I wanted to hang them on my wall.

With the plans drawn up and money spent, now I was committed to this project. I set up my 4' X 9' work table and laid out all my wonderful new plans on it.

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I had purchased a few power tools specifically for this sub build project. A 9" band saw, a table saw, and a 6"/1" sander combo as well as some odd's N' ends hand tools. All these tools are of your "cheap" brands (No DeWalt or Makita here) as the work needed to be done is really light duty. I believe in total I spent well under $500 on the tools I thought I would need for this project. I am a believer in that the right tools make the difference between being frustrated, and enjoying your project. Since I prefer to enjoy my hobbies, I chose to spend a few bucks on tools.....which, ....I'll have to build more subs with :) With tools and plans ready to go, and I was good to start on this endeavour. The bank account was already starting to feel the hit.

Step 2 : Model Stands

Time to complete: 4 hours.

Total to date: 4 hours.

The first thing I decided to do was build a couple stands to hold the mold plug / boat once it was built. I wanted one stand to hold the hull upright, as a model is "normally" displayed, and I wanted a stand to hold the hull laying on it's side, in the event I needed to do this down the road for whatever reason. I knew that working with a hull of this size was going to be awkward so I wanted to minimize any problems the best I could. I figured building the stands first was a good idea. I used one of my 1:25 hull cross section copies as a template and cut the supports out of 3/4" plywood. I used a total of 4 supports for each stand that are roughly 20" apart. The edges of the supports that make contact with the model were lined with door weather stripping. The contruction of the supports took longer than I anticipated, making sure that I was cutting the proper contour at the specific distance took some measuring, and re measuring, ...cutting, ..and recutting, throwing pieces away and starting over. I wrote the experience off as good practice on my band saw as well as the importance of being maticulous with the measurements.

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More progress to follow.

Due to the fact that I started this project on October 20, 2006, I have quite a bit of progress done on it already. I will be adding a few "Steps" to this thread on a daily basis until I get to where I am currently in the build.

I hope thread is of interest to novice and experienced builders alike.

Mylo
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Postby U812 » Tue Nov 21, 2006 4:10 am

Mylo.

This is great. I will be watching and offer help if needed. you are a brave man. U-boats are not an easy first sub. But your approach (as is documented in this thread) will give you a great boat.

I'm very glad to hear that Kevin and I (plus many others) contributed this projects forth coming.

steve
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Postby TMSmalley » Tue Nov 21, 2006 8:21 am

Great start Mylo - you had patience and did your research on the prototype before starting.

Also
The contruction of the supports took longer than I anticipated,


You have revealed a truism that few scratch model builders ever talk about - it nearly ALWAYS takes longer than you think it will.

The other one is that it always COSTS more than you think it will! :D

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Postby gantu » Tue Nov 21, 2006 1:41 pm

Hi Mylo

would be good to build her in two section for better transport :?:

Gantu
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Postby Mylo » Tue Nov 21, 2006 2:17 pm

Steve, Tim.

Yes, I have already learned a lot, now it's time to put my education to practice. FIRST thing I figured out, make an educated guess on how long it will take to complete a phase, then triple it. Second thing, make an educated guess how much that phase will cost you, then triple it.

Steve, your type XVII thread was the first one that I "stumbled" onto here at Subcommittee while I was searching the net for an r/c sub kit. When I saw your thread I thought, "You mean, guys actually build their own subs from scratch ?" I thought it was a very cool idea and ever since, the gears have been turning to build my own sub. That was over a year ago.

....and now for more.

Step 3: Building the Master Formers.

Time to complete: 16 hours.

Total to date: 20 hours.


On the side view of the plan it indicates where the actual ribs were located for both the pressure hull and the outer hull/superstructure. I decided that I would use the actual rib locations of the outer hull for my hull formers, the question remained, which ribs and how many ribs/formers would I make. After literally examining the side profile for hours (not part of the build time), measuring, calculating, I concluded that I could model every 4th rib. Using a former width of 1/8", this left EXACTLY 3" between every forth rib. I would use extruded styrofoam 3" thick in between each former that I made, and that would recreate the hull in perfect scale. Every 4th rib seemed to be a good compromise as well between having enough ribs/formers to accurately replicate the complicated shape of the hull, and not actually making EVERY....SINGLE....RIB (130). I was quite happy with this discovery. After another hour or so gawking at the plans, I selected the following ribs to model:

-15, -13, -9, -7, -4, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 55, 59, 63, 67, 71, 75, 79, 83, 87, 91, 95, 99, 103, 107, 111, 115

Couple things of note on the ribs. The "negative" ribs indicate the ribs of the outer hull which are aft of the pressure hull, hence the negative numbers. Number 0 is where the pressure hull begins. As well, right in the middle, the rib #'s change from even to odd starting at rib #55. This is because in the plans, there is a rib 54a. In other words, rib 55 is still 4 ribs away from rib 52. This numbering scheme is part of the Kohl plans and not of my doing. In addition to that, I felt the neccesity to include a couple extra ribs at the stern in order to get more detail on shaping that area of added comlexity. I included ribs -7 and -15 and will simply have to shave down the extruded foam in order to squeeze it in between these formers that are tighter together than the 3". Finally, ribs 44, 48, 52, 55, 59 are all exactly the same which would mean I would only have to build one master for these 5 ribs.

I spent a ton of time on this phase of planning as I knew that getting things right at this stage was crucial, everything else depended on it. I have a paranoia of getting halfway into a project only to discover that I have to restart it due to not thinking things through thoroughly enough at the start. I lost count how many hours I spent looking at, and measuring my plans. I was very happy with my decision to get excellent plans and go the route I did in terms of getting them enlarged and resized. Huge money but.................... it was already starting to pay off. I had no illusions that this sub would be cheap from the get go.

Now to build the master formers. I decided I would build masters to build the actual formers from after realizing that if I simply built one set of formers from the paper templates, all that time and effort (and expense) would be lost once the formers were destroyed in the plug making process. If I kept a set of masters, then, I would always have them and could make another set of formers very easily if the need ever arose or in the event I needed them in later stages of this sub build.

I started by taking my paper plan copies of the cross sections and carefully.....and tediously.....cutting along the line that represented the particular rib I was after. This was a challenge to say the least. There are so many profile lines so closely together, I had my magnifying glass out and was working with the precision of a brain surgeon under my work table lighting. Had my vision been anything less than 20/20 with a 4X magnifying glass, I don't know if I could have done this. The process was very slow and required a very steady hand. I cut one rib/former out of each paper copy of the cross section so that I would have the longitudinal reference lines that the Kohl plans have, on every former. The importance of this will come up later. As a result, I threw a lot of wasted cut out paper in the garbage, particularly on the small formers. My head, neck, and back was killing me by the end of it.

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Once the paper templates were cut out, I positioned them on 1/8" hardboard to see how many I could get on a 2' x 4' piece. Once I had them laid out, I drew lines where I would cut the hard board into individual pieces for each former so that they would be manageable with the band saw, then took all the paper templates off to cut. Once all the individual pieces were cut out (my table saw made very quick and easy work of this), I spray glued (Elmer's) the paper templates to their respective pieces, pressing them down flat with another piece of hardboard. I then left them to dry (2 hours).

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On returning 2 hours later, I used my bandsaw to cut out each master former, using the paper template that was now glued on top as a guide. At first, I was trying to be bang on with the band saw and cut EXACTLY up to the paper. I found this to be very difficult, my band saw skills not being the best. I quickly discovered that if I just use the band saw to cut "pretty close" to the paper, I could then use my 1" belt sander to bring it up flush to the paper with precision. This technique worked wonderfully as the sound of the sanding would change juuuuust a little when I was nicking the paper, letting me know that I had sanded the former exactly up to the paper template. The rest on the sander ensured that I was sanding at a 90 degree angle as well. It was fast (relatively) and allowed me to shape the 1/8" hardboard perfectly to the paper template glued on top. I was pleased with the accuracy I was getting.

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To get all the formers and extruded foam lined up to create a one piece plug, the "Plan" was to use a spine board to hold the formers in alignment as well as an 1/4" index rod ("ready rod" / threaded rod) that would run the length of the longitudinal axis. This rod would ensure that the formers were anchored at the right hight on the spine board. This rod would also act as to compress the formers and foam together to hold them securely in place. This would be done by threading nuts onto the rod every 4th former. In looking at the cross sections, I concluded that if I put the index rod where the longitudinal axis was marked on the plans, I would have a "spine" that ran.......right down the logitudinal axis of the sub, which, I thought would be the way to go. I discovered that if I was to drill holes on the master formers in the EXACT locations where these lines merge at the tip of the bow and stern on each paper template, I would be able to insert the index rod through these points, which would perfectly align the formers. This was possible only due to the reference lines drawn on the Kohl plans. The result would be formers that were alligned to precision on the spine board. I would use my drill press to drill these holes using a wood bit that has a very sharp "tip" on it. I would lower the bit slowly and place the tip of the bit RIGHT where it needed to be, then drill the hole out. I took a lot of time and care with the drilling of these holes, the accuracy of the former allignment, and therefore the shape of the hull, depended on these holes being perfect. Very hard to explain, I hope the photos are of value.

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The former masters were now completed. I was now ready to build the actual formers using the masters. I felt good about the fact that I had the masters to work with and would still have them long after the sub was built or in the event I had to remake another former. They MAY come in handy in the sub building process as well. They took a ton of time, effort, and precision to build, it would have seemed a shame to have them destroyed in the plug making process if I would have used them as the formers.

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Step 4: Building the hull formers from the masters.

Time to complete: 10 hours.

Total to date: 30 hours.


I don't know why I did this, but I did. I purchased some 2" extruded styrofoam and some 1" stuff ( I could not find 3") in order to be able to put the two together to get 3" stuff, which is, as I mentioned before, the exact distance that I needed between formers. This really isn't very complicated math. What I did was, I decided to put the two pieces together and measure them, to see if they actually were 3" in total. Nope....go figure. 2" + 1" DOES NOT = 3" It DOES = 2 7/8" Now, if you're insulating a house, this likely doesn't matter, but if you NEED 3" in between formers on an R/C sub that you are scratch building, 1/8" off is HUGE. Since there was going to be 39 formers in total, losing an 1/8" on EACH would have put the sub 4 7/8 " shorter than it should have been. In 1:25 scale, that's a scale 3.125 metres (10'), it's no longer a type VIIc/41 as far as I'm concerned. ...THAT's what I mean by "HUGE". It put a wrench in my entire design plan of using 1/8" former widths. However, I quickly realized that since I needed another 1/8" of thickness to make up for it not being there with the foam, I could use 1/4" formers instead of 1/8" formers. Again my ruler and calculator came out and I measured and remeasured. I was right, the 1/4" formers would work great. It turned out to be a blessing that the foam was 1/8" too thin, because I preferred the idea of having the formers 1/4" thick over 1/8" thick, a little more "meat" to work with. I was VERY thankful that I decided to measure the foam before building the formers. If I hadn't, I would have built a ton of 1/8" thick formers that would have been useless for this design.

Using my masters, I traced out all the formers I would need on 1/4" hardboard. Medium Density Fibreboard (MDF) is usually my material of choice to do stuff like this, but I couldn't find it in 1/4" thickness (on the particular day that I was shopping for materials) so I opted to use the hardboard, which is really close to the same thing....only harder. It still cuts and shapes very nicely. Using the exact same technique that I used to make the masters, I made the formers, numbering each one as per it's represented rib. When drilling out the index holes on the formers after marking with the master, I took the master off and simply used the tiny mark in the former to place the bit and drill the hole. I did not want to simply drill the hole out while marking with the master on as I did not want to damage the indexing hole on the master. The holes on the masters were in the EXACT right spot and EXACTLY round, they needed to stay that way if they were going to be of any use in the future.

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Once I was done using the masters to trace and mark, I secured them all in order on their own index rod. I did this not only to keep the masters all nicely together. The complexity of the hull shape demanded that a lot of time be spent on the construction process up to this point. This thing was not a "tube" by any stretch of the imagination. I knew that taking on a U-Boat for my first scratch build was quite a bite to take, so I was prepared for things to take a lot of time, and to make a few mistakes along the way. I only had to redo 2 hull formers due to screwing up, adding about 1.5 hours as I had to completely redo the paper template as well. Thankfully, I had a few "spares". I considered this a success.

By some lack of brainpower, I neglected to cut the spine board slots out of the masters. After some further thought, I decided to use 5/8" malamine as my spine board instead of my initial thought of using a piece of 3/8" plywood that I had lying around. I concluded that the plywood simply wasn't rigid enough, even though I wanted to "cheap out" and use materials that I already had. I also decided on malamine because I suspected that the finished surface would be easier to locate the formers onto. I had drilled the index hole for the spine board slot cutout in the master former 3/8" thinking that I would be using 3/8" plywood. Since I would now be using 5/8" malamine, the holes would have to be redrilled to 5/8".

To cut the spine board slots out of the formers, I measured 5/16" from either side of the centre of the 3/8" index hole that was drilled in the former. In total, I would have 5/16" on each side making for a total of 10/16" (5/8"), which is the width I needed to cut the slot to fit the spine board. Using a square, I marked the lines on the former where the spine board slot would be. I would use these same lines as a guide to place my 5/8" drill bit when I redrilled the index holes.

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Much care had to be taken with these measurements and redrilling. Once the 5/8" index hole was drilled, completing the spine board slot was just a matter of cutting down the two marked lines up to the hole. I used my table saw, a steady hand, and a keen eyeball to do this. I was lucky to get them all done without losing a finger as I had to take the guard off for such small pieces. In all, the technique worked very well as all the formers fit nice and snugly onto the spine board. The malamine board was a good choice for this purpose instead of plywood.

I had placed the formers onto the spine board without the foam to test fit the formers and spine board slots that were cut into them.

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Once on the spine board, the index rod was threaded through by chucking one end into my drill and tapering the other end with a grinder so that if it needed to "find" the index hole, it could do that. The index rod threaded through without any problems, finding each hole easily. As the rod was being threaded through, it was making teeeny tiiiiiny alignment corrections to 3 or 4 of the formers. Once the rod was completely through, the formers were in perfect alignment and very solid on the spine board. After the formers were in alignment, I could see where a couple of the formers needed just a minor sanding to bring them into symetrical form with the others, which was primarily in the centre area of the saddle tanks where the formers are all the identical dimension. The keel section was also sanded down a little to flush up this area nicely.

........more to follow.

Mylo
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Postby Mylo » Tue Nov 21, 2006 2:23 pm

gantu,

I thought a lot about doing just that, building the hull in two pieces.

....but....I chose to go with the entire length. My hull halves will be in top/bottom configuration and not two sides. I was really interested in having these two pieces intact.

...besides, I own a pick up truck.....she fits in the back just fine. :) and while in dry dock at my house, I have already planned a nice little place for it in my garage so, crating around this 8'9" thing isn't going to pose much of a problem.

Mylo
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Postby Mylo » Tue Nov 21, 2006 2:32 pm

Steve,

I forgot to mention, by all means, keep a watchful eye over my progress and feel free to comment. I take criticism very well. As is obvious from my resin / foam "situation" that I posted in the r/c thread, I don't have much of a clue on what I'm REALLY doing.

This comment goes for all you builders out there as well.

Thanks,

Mylo
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Postby raalst » Tue Nov 21, 2006 3:36 pm

Mylo,

do you take off a few mm from the formers to allow for the thickness
of the GRP ?
Regards,

Ronald van Aalst

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Postby Mylo » Tue Nov 21, 2006 4:19 pm

Ronald,

I gave that very consideration a LOT of thought in the early planning stage as it stands to reason that the hull is actually going to be slightly larger than the formers. I decided to go with the accuracy of shaping the formers exactly to the 1/25 plans instead of "shaving" a couple mms to compensate. I was not confident in my ability to "shave" all the formers, removing the exact right amount of material all the way around the entire former, and then have to do that 38 more times for the others. Nor did I want to have plans that were 1:26.9887895 scale. Since I am using the same plans to make all the master components, which are equally going to be glassed and casted, they are all going to be equally larger. In effect, my final Type VIIc/41 will be 1:24.887458972345 scale. I'll call it 1/25, if someone wants to get their micrometer out, they are more than welcome.

Excellent question though. I hope my answer makes sense.

Mylo
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Postby JWLaRue » Tue Nov 21, 2006 7:03 pm

Mylo,

Very nice work! I do not believe that I have seen anyone show some of the steps that you have documented. I look forward to the follow-on installments.

Perhaps we can get you to turn this thread into an article for the SubCommittee Report at some point? Lot's of folks would benefit!

-tnx,

Jeff
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Postby Mylo » Tue Nov 21, 2006 7:27 pm

Jeff,

I would be honoured to have my build thread in the Sub Report. (Did my poem ever make it to print.....don't know if you remember the one I submitted to you about r/c sub guys at the helm of their boats. In my absence from subs, my subscription to the Sub Report expired so I wasn't able to see. I fully plan to renew as I'm obviously in this "sub thing" for the long haul. I enjoy the issues very much by the way). Again, I have to stress that I'm a novice and encourage any builder to fully research any techniques or materials, and not assume any of the things that I'm doing are by the book correct.

I'm hoping my "step by step" log with the "time to complete" will be a help to other new guys who have never done a build. I know I personally spent a ton of time researching this kind of thing and was constantly asking builders how long a certain phase took them, just to give an idea of complexity more than anything.

Stay tuned......

Mylo
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Postby Mylo » Tue Nov 21, 2006 10:48 pm

Step 5: Cutting out the extruded foam.

Time to complete: 4 hours.

Total to date: 34 hours.


As mentioned, the design of the hull construction included that 3" (now 2 7/8") of extruded insulation foam be situated in between each former. I decided that I could cut out the foam to shape the contour of the LARGER former it was next to. As long as I cut it to the larger one, I would then have to TRIM AWAY the excess foam to get the shape of the hull once all the formers and foam were put on the spine board. IF I cut the foam the shape of the smaller former, I would have to ADD material to get the proper hull contours. .....I preferred to trim / sand away. Using the former as a template, I traced the outline onto a piece of foam. I then stacked the two pieces (1" and 2") together and used the band saw to cut out the shape, being careful to hold the pieces togther so that they didn't slip apart and create a cut that was not uniform on both. It is not important to be precise at this since there is going to be final shaping once all the formers and foam are on the spine board. This step is done so that the rough shape of the hull can be seen and as well, to reduce the amount of sanding and shaping required after assembly on the spine board. Sanding and shaping extruded foam, as we know, ....is a less than desireable thing to do due to the mess it creates.

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I had some 1" foam lying around (blue) that I thought I would use for this project. Trying to use common sense, I thought that if I used 3 layers of foam that were each 1" thick, I would get 3" of thickness. So, I cut out some stern foam sections using my old blue foam. Due to my "surprise" with the pink foam being 2 7/8" total, I thought it would be wise to measure how thick 3 pieces of 1" foam actually were. This may come as a shock, but 3 pieces of 1" foam measured to be exactly 3" thick. "Normally", this would have been good, but since my discovery with the pink foam being 1/8" thinner than expected, the formers were increased in thickness to 1/4" from 1/8" to compensate. NOW....these formers were too thick for the blue foam.........that I had decided to measure AFTER I cut them all (bone head).

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The blue foam was not going to work and so I had to scrap all my cut blue foam pieces and cut the pink foam instead. EASY fix at this point, taking only an extra hour to cut the pink foam. Not so easy if this would have been discovered later. Back to the band saw for another cutting session.

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Step 6: Drilling out the index rod holes in the foam.

Time to complete : 1 hour.

Total time to date: 35 hours.


Doing that was simply a matter of using the former with it's recently drilled out indexing holes as a template to mark the foam with a scribe where the holes would have to be drilled out of the foam in order for the indexing rod to pass through as well as the area that would be cut out for the spine board slot. It was not important that these holes be precise, that was the job of the former, not the foam. I cut 1" holes in the foam using an auger bit (largest bit I had, which happened to be hardened steel and titanium.....plenty strong enough for foam I would say). I wanted the holes large enough so that I could move the foam around to adjust it once on the spine board and indexing rod through the formers. Once the holes were drilled out, I cut the spine board slots out with the bandsaw by cutting up to the drilled out hole on both sides.


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My original plan was to have 2 indexing rods, which is why the foam has three holes drilled in them. One for the spine board slot, the other two for indexing rods. I later decided that the extra indexing rod was not going to be required. The allignment of the formers on the spine board was not in question. I had measured and remeasured them many times. They were in perfect alignment on the spineboard with the use of just one indexing rod. (which really only adjusted a couple formers just a hair.....but I guess that's enough to warrant it's use).


......more to follow.

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Postby Mylo » Thu Nov 23, 2006 9:29 am

Step 7 : Mounting formers and foam onto the spine board.

Time to complete: 6 hours.

Total time to date: 41 hours.


I started with rib #55, right in the middle. I placed this rib on the spine board and inserted the index rod through the index hole. I then threaded on and tightened a nut on both sides, securing the index rod from moving. I then placed the corresponding foam pieces on, then another former, then foam, then another former, and so on, putting gorilla glue in between every layer so that everything would be glued tightly. Every fourth former, I would thread on a nut to the index rod and snug it up to the former. This would apply just a little pressure to keep everything tight. Once the glue dried, it would be essentially one big piece. There had to be 8cm (I realize my measurements bounce back and forth from Imperial to Metric. I try to do as much as I can in Imperial measure, but sometimes it's just easier to use metric as the measurement works out better) from centre of former to centre of former, and I was able to ensure this by adjusting them on the index rod. Due to my wonderful planning :) .....putting the 2 7/8" piece of foam in between each former meant that there was exactly 8cm distance from centre of former to centre of former if I put just a liiiiiiiiiiittle squeeze on the foam by tightening down the nut on the index rod. The process went slow, but well. Everything remained solid and aligned. I included an additional short index rod at the stern area to add extra support. This rod only passes through two formers and is only about 7" long. The last rib on the bow was #111. All other shape forward of this point would be shaped as one piece out of MDF. The same thing for the stern. Every rib aft of rib # -13 would be shaped as one piece out of MDF. This was done due to the fine/thin contours of these areas as I suspected that getting that precise with foam would be impossible.

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Step 8: Making the bow and stern tips.

Time to complete: 3 hours.

Total time to date: 44 hours.


I would use 3/4" MDF laminated together using Gorilla glue. Once left overnight to cure (this stuff needs a long time). I was then able to work / shape the pieces.

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The basic outlines were drawn on the bulk material using the master formers as well as some paper templates that were made from the plans. Once all the markings were in place, it was off to the belt sander.

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I simply shaped the piece using the belt sander and then used a sanding sponge to finish. A little at a time, and then check, ....then repeat. I had to do the bow tip twice, and the stern tip 4 times before getting them to the point where I thought they were acceptable. EACH piece took about an hour, before I decided I didn't like it and threw it out to start over. The big hassle was waiting another night for another "batch" of bulk MDF to glue. (I was smart the second time around and made 4 of each so that they would all be dry the following day). These two little pieces consumed a HUGE amount of time to make, only due to my inexperience. After being satisfied with the tips, they were Gorilla glued directly onto their respective former. The bow tip was glued to rib #111, and the stern tip glued to rib -13. After all the time spent on these two pieces, I was happy with the results once on with the rest of the formers and foam.

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......more to follow.


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Postby Mylo » Thu Nov 23, 2006 11:03 pm

Step 9: Rudder Masters.

Time to complete: 1 hour.

Total time to date: 45 hours.


Since I was thoroughly practiced with the belt sander from the bow/stern tips, I thought I would make the two rudders. I traced a paper template off the plans. I then cut two 3" x 4" x 3/4" MDF pieces. The templates were then taped to the MDF pieces and marked. Once marked, I roughly cut the shape out with a band saw and then finish sanded up to the marks with the 1" sander, in much the same way as the formers were made. The centre of the block is marked with a line all the way around in the middle as a guide. I then shaped the rudder using the belt sander with the foam sanding sponge to finish sand. MDF is very good material for this purpose.

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.....more to follow.

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Postby Mylo » Fri Nov 24, 2006 12:00 pm

Step 10: Shaping foam to formers.

Time to complete : 4 hours.

Total time to date : 49 hours.


Step 10 was fun because I could start to see the shape of the hull as I worked away. I just had to "reveal" a little bit more, until next thing I knew, it was 1:00 AM. I started with my foam board rasp to knock down the heavy excess. I was uncertain as to how well this was going to work. As it turned out, it worked really well IF I used the rasp against the grain of the formers. In other words, working the length of the sub, which was the natural way to do it anyway. The rasp was very effective at removing excess foam material yet it glided easily over the hardboard formers without damaging them due to the light pressure I was using. I was especially thankful at this stage that I needed to use the 1/4" hardboard formers instead of the original plan of 1/8". The extra thickness of the formers certainly didn't hurt at this stage with the rasp having to pass over them.

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After the bulk foam was rasped away. I used 80 grit sandpaper on a sanding block to smooth the foam right down to the formers. It's important to get the foam all the way down to the formers in order to maintain the scale and accuracy of the hull. The formers are exact, so the foam needed to flush up to the formers. I had to use my razor knife to scrape/chisel away some excess glue that had seeped out between the foam and the former during the process of mounting the foam and formers to the spine board. This was no major task.

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Once the glue was removed, the sanding took the foam down to the formers quite easily. I used an assortment of sanding tools to get into all the many nooks and crannies with the focus being to get the foam down to the formers. As can be imagined, the rasping/sanding process was very messy. Those statically charged little foam particles get EVERYWHERE. If I had a hot wire foam cutter, I likely would have tried that on the excess foam. But since I didn't, and I had a rasp, I went that route. Again, it worked very well, but does create a mess. During the sanding process, the area around the stern turned out to to be too thin to shape to the former contour due to a short indexing rod that I installed in that area to give it a little extra support. I suspected that this would happen. I will be shaping a piece to fit that area out of MDF, glue it in place, and sand to fit flush against the former. With the combination of the spine board, the index rod, and the glue between foam and former, the plug was as solid as one piece, even though it was actually 117 pieces in total counting all the formers and foam pieces. I "eyeballed" the plug many, (MANY) times up to this point to make sure it was straight and true (I find that sometimes, the eye is the best measuring device) as well as running a straight line down the keel. So far, so good.

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Step 11: MDF detail parts.

Time to complete : 4 hours.

Total time to date : 53 hours.


Due to some particularly thin contours of the boat, I wasn't able to rasp/sand the foam into the desireable shape without the foam disintegrating. I fully expected this to happen. In these areas, I fabricated pieces out of MDF to substitute for the foam. These areas included the rear stern section that is really thin, the tapered stern section of the keel, as well as a couple areas on the fore deck. Add to that the bow and stern tips, and a total of 9 pieces were made out of MDF (4 separate pieces made up the skinny stern part to fit in between the formers. Many of the pieces took 2-3 tries as their shapes were "tricky"). I just marked the pieces using the formers already in place and then essentially molded the parts "free hand", taking a little material at a time, then checking, then "eyeballing", checking, sanding, checking.....repeat. The process was time consuming but, .....I saw no other option. The final result turned out nice. MDF is a wonderful material for forming / shaping / sanding. Once I had fabricated and mounted the parts, I let the quick dry "arts & crafts" glue set up pretty good, and then finished the shaping of these areas with my rotary tool / sanding wheel. ............I wonder if anybody has ever made an ENTIRE plug out of MDF ? I would consider this, but I would imagine that the weight would make the plug just that much more difficult to maneuver given a model of this size. As it is, my foam plug complete with spine board weighs about 25 lbs, with the bulk of that weight being the spine board. The foam and formers are really quite light, which is nice when I have to move the thing around.

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More to follow.

Mylo
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