1949 Chris-Craft 19' Racing Runabout by gjdale - FINISHED -Dumas - 1:8 Scale - RADIO

[thomaslambo]

Hi Grant,

 

Great choice for a build, I'll be following your log with great interest.

 

This subject is right up my alley, as I've been racing Fast Electric (FE) boats for years and still hold three NAMBA National Records.

 

I love the Dumas Chris Craft models and it's just a matter of time until I build one.

 

The electronic components are really straight forward and fairly easy to install, you just need to make a decision very soon on your setup as several of the components take up quite a bit of room and need to be considered in the build (e.g. batteries, controller, motor, steering system, drive shaft, receiver, ect.)  

 

I know Dumas has setups for some of their boats but many FE people consider their power systems somewhat outdated and a bit over priced.  But in many cases they have plans for the installation so that may be of help.

 

Have you made any decision on the electronics?

 

Ok, here is an edit; I see the kit has running gear included (this is a good thing), now you just need to choose your electronics (motor, controller, battery and radio and receiver).  If you get the correct RC gear you won't need to run the antenna outside the hull as it's wood and won't interfere with the signal between the radio and receiver (no ugly antenna showing).

 

Good luck,

 

Boyd

Edited March 31, 2015 by thomaslambo

[gjdale]

Thanks very much Marc and Boyd. The reason there hasn't been an update in a while is that I've been sorting out plans for running gear and electrics/electronics, inlcuding making a working steering wheel, and lights that can be switched on remotely. I've been guided by some very helpful folks on the RC Groups forum, as well as by an exceptionally helpful guy who owns the last remaining real hobby shop in captivity here in Canberra. Consequently I've been slowly acquiring a variety of additional bits and pieces, and as Boyd correctly points out, I need to sort out their positioning in the boat before restricting access. I received the last of those components yesterday, so should be right to proceed. All I need now is that other priceless commodity - time!

[thomaslambo]

Sounds good, I've spent many hours on RC groups and you're in good hands   

[Remcohe]

Hi Grant,

 

Great project. To defog the instrument panel 'glasses'  you can dip them in Future Floor Polish or an equivalent. Aircraft modellers use(d) this to make the canopy's clear.

 

Remco

[gjdale]

Thanks for the tip Remco! I'll have this project back up and running fairly soon. There's just been a short delay while I do a minor re-furbishment on another model to remove 15 years worth of dust and debris while she sat uncovered all that time. I bit the bullet recently and had a proper display case made, so it was time for a spruce up. This shouldn't take very long...............famous last words...............

[Turatopgun]

Hi Grant. How many builds do you have going at once? This boat is going to look good and is a classic boat, absolutely beautiful.

Phill

[mobbsie]

Now I wonder what that boat could be, gonna look good in a case mate.  

 

Being an ex-navy guy I have no doubt you have given a great deal of thought about Weight, Displacement and Stability, also if you will need any ballast.

 

I'm really looking forward to see this boat come to life mate.

 

Be Good

 

mobbsie

[gjdale]

Thanks Phil and Mobbsie,

 

Phil - just the one........for now. The re-furbishment doesn't count!

 

Mobbsie - you know very well what it is my friend, but for others who may be wondering, it is the Armed Pinnace - the very same vessel that Mobbsie is currently building. I built this mainly in my cabin at sea a very long time ago but never quite got around to getting a case for it. When I had the case made for the cross section, I decided to have one made up for this one too.

 

Oh, and that quick re-furbishment............yeah, about that...........

 

Seems I couldn't help myself. You see the gun carriage and sled were made from plywood in the original kit, and I had all this lovely timber left over from the Bomb Vessel cross-section, and I had to take them off to clean them anyway, and I've got all these really cool tools now, and, and, and,.............

 

Carriage is now being re-made in Swiss Pear. It might be a few more weeks before resumption of play on the Runabout........

[Thistle17]

I am building this model with my grandson. I have been a model builder off and on all my life however this one has its challenges.Among the sagas with this kit is the baffling method to trim out the rub strake (bumper) where the deck meets the sides. I bought some perfectly scaled Stripstyrene molding to apply. I have tried several methods to apply "foil" to the molding to make it look realistic but because of the curved nature of the hull from stem to stern it is not easily applied off the hull and then attached afterwards as the metal foil just doesn't stretch going from straight (off the hull) bent curved to apply to the hull. I gave up on the thin stuff from the hobby store and am using heating duct foil as it is a bit more formidable. Got any thoughts? Thanks.

[gjdale]

Hi Thistle,

 

What a great project to do with your grandson! Regarding your problem, I bought some aftermarket stuff from MACK products (http://www.mackproductsrc.com) to replace the kit supplied part. I obviously haven't used it yet, so can't comment on how good it is. If you haven't already found them, there is a very good RC forum (http://www.rcgroups.com) where you will find a number of build logs for this boat, some of them quite outstanding. Like MSW, they are a very friendly and helpful bunch.

 

For anyone else following this build, I hope to re-commence work on this next weekend.

[Thistle17]

Thank you"gjdale". What a great site you recommended. I have tried the thinner chrome metal sheets(that they offer) and I found that the "foil" was so thin it easily abrades. So I don't think it will hold up under use. I also found if CA glue comes in contact it either tarnishes the foil or seems to eat at it. Never the less it is a great site recommendation. Thanks again and as you carry on with your build I will be watching.

[mobbsie]

Hi Grant,

 

About time you resumed work on this little boat, spiders have taken up residence mate.

 

Looking forward to some long awaited progress my friend.

 

Be Good

 

mobbsie

[Thistle17]

We tried a slightly different approach on the lower rub rails of the model this past weekend and it seemed to work reasonably well. I have a roll of shiny aluminum heating duct sealing tape that is about 4 inches wide and comes in rolls starting at about 25 feet. We rolled out a section that had no crinkles in it and lopped it off. We then cut srtips about 3/8 inch wide. We applied the strips (which has adhesive on the reverse side) to the Stripstyrene 1/2 round molding. The half round was .125 in (3.2MM). The foil forms a "U" shape overlap over the molding. We then carefully sliced the excess off the back of the molding with a brand new razor blade. Any excess was scrapped off the back using the razor blade as a scrapper. It was then burnished and applied to the hull with med viscosity CA glue (brushed on). Imagine that it worked!

 

With any problem you have to break it down and determine more acceptable methods. Even as I age I seem to have to learn that lesson over sometimes. Its on to the upper rub rail but the difference here is I will mock up a hull contour to address the inflexible nature of the foil. I will report back on its effectiveness.

 

One last note the Stripstyrene only came in 13 in length so they have to be joined with a scarf joint. Any surface anomalies can be lightly sanded to smooth out the joint. This is required for the upper deck rub strip unless a better source can be found.

[gjdale]

It’s been a year since any progress has been made on the Runabout! What can I say, work, life, and another modelling project all conspired to put this project on hold. But we’re back now and ready to continue. I’ve spent the last couple of weeks trying to get my head back into the project with all the additional modifications I wanted to make and trying to remember where I was headed. Some small progress has been made though.

 

First up was the Rudder Block and Rudder Tube. Fairly straight forward and shown here epoxied in place.

 

 

The Rudder itself was next. The kit provides a brass blank for the Rudder and a short brass rod for the Rudder Post that is pre-split to slide onto the rudder. All that is required is to radius the corners of the Rudder and silver solder the Rudder to the Rudder Post. I gave the Rudder and post both a good sanding first to remove any coating prior to soldering, and again after soldering to remove residue and excess solder. I polished it up with successive grades of sandpaper, although it has since tarnished somewhat. I will clean it up again in due course – haven’t decided yet whether to paint it the same colour as the bottom of the hull, or keep it shiny brass (in which case I’ll polish it up and clear coat it).

 

 

Next up was to cut the slot in the hull for the drive shaft, and to shape and install the engine mount blocks. Cutting the slot was a little nerve-wracking, but turned out to be quite easy – drilled a hole at either end and then used an Exacto knife with a saw blade to cut through the Sintra and Butterfly Keel.  The kit provides balsa for the engine mount blocks, but I decided to replace this with something more substantial to screw into. I used some offcuts of pine that I had in the workshop and cut/sanded these to shape. They were then epoxied (with a liberal amount of epoxy) to the base of the hull and the frame immediately forward of them.

 

 

And here’s a close-up of the Engine Mount Blocks:

 

 

The Engine Mounting Brackets were then bent to shape around the motor, screw locations marked and drilled, and then the motor re-inserted and clamped down to test the mounting arrangement. The screws were then loosened off and the motor removed.

 

 

At this point, it was necessary to deviate from the kit instructions as I planned to install a “working” steering wheel – that is, to set it up such that it turns when the rudder turns. The idea for this, and some of the technique were “borrowed” shamelessly from couple of other builders on the RC Groups Forum. It involves installing a servo with a spline-mounted gear wheel, and some plastic link chain to connect it to the drive shaft of the steering column.

 

After several days of thinking about exactly how I was going to do this, I decided that I would cut an “Access Panel” in the frame. I then made small platform for the bottom of the servo mount to sit on, and I epoxied some nuts to receive the Access Panel Cover. In this picture, you can see the Access hole, the platform and the epoxied nuts.

 

 

The servo itself needed to be mounted at an angle to ensure that the Servo gear and the driveshaft gear remained in the same plane. Having measured the angle of incidence from the plans, I constructed a small block sanded to the correct angle on the Byrnes sander, and mounted the Servo on this. This assembly was then epoxied to the fore side of the Access Panel Cover (this step was completed with the panel in place to ensure the correct location of the servo mount)

 

 

Here is a view with the Access Panel Cover now in place.

 

 

Also in the above photo, you can see the steering column driveshaft (the brass rod) and the steering column sleeve (the shiny silver thingy).

 

Finally, the driveshaft gear was fitted, the chain measured to length and fixed (the links are really easy to snap apart to add/remove links), and the two gears connected. In the photo below, you can also see where I cut a bit of a scallop in the top of the keel to ensure there would be no interference with the chain.

 

 

And finally, a shot from above showing the whole assembly in place.

 

 

I originally made the access panel with the thought that I might be able to access the setup should a part fail. However, I now think that it will be impossible to replace things through that hatch as there is no access from above once the decks go on (at least not without adding an access hatch, which the original boat didn’t have). So, once I’ve proved it running, it will get sealed up inside the boat forever!

 

Next step will be to build a number of shelves/racks to house the electronics. Again, I’m departing from the standard kit here, so want to make sure I get all of this sorted before I close up the hull any further.

[mobbsie]

Hi Grant,

 

Some good progress there mate. All seem to line up nicely, I particularly like the addition of the steering wheel.

 

Have you decided where you are going to place the Battery Pack and Speed Controller, bearing in mind the speedo will need to be kept dry and easy access to the battery needs to be painless and with the boats stability in mind.

 

Be Good

 

mobbsie

 

PS

Catch up soon mate.

[gjdale]

 

Have you decided where you are going to place the Battery Pack and Speed Controller, bearing in mind the speedo will need to be kept dry and easy access to the battery needs to be painless and with the boats stability in mind.

 

I have a cunning plan.................

[gjdale]

Time has been at a premium lately, but some progress has still been made. I started making shelves and racks to house the electronics but soon concluded that I would need to install the drive line before I’d be able to complete that task.

 

I made a mount for the rudder servo, following the lead of some other builders and making a more secure arrangement than a simple Velcro attachment. I fashioned a hold-down strap from some brass sheet, and used some captive nuts to make it easier to insert/remove multiple times.

 

 

 

I have decided to replace the drive shaft and stuffing box. The drive shaft supplied was slightly bent, and as I’m using an “after-market” propeller, it made sense to just replace it. Also, based on advice from Pat Matthews in his book “Mahogany in Scale”, I decided to replace the stuffing box with a larger diameter brass tube and some sintered bronze bearings. All this meant that I would need to cut a new thread on the new drive shaft. Thinking about how to go about this, I came across an excellent video on YouTube (https://www.youtube.com/watch?v=MmGzzZEFSJU) on machining a Tailstock Die Holder for the Sherline Lathe. It seemed to me to be the ideal solution to my problem, so work on the model came to a temporary halt while I spent a couple of weekends manufacturing my Die Holder. The video is excellent and there is a link to purchase the drawings (for not very much at all). I have to say though, I did not find it quite as easy as the video suggested – the presenter is obviously an experienced and skilled machinist (unlike me).  Anyway, here is my completed Tailstock Die Holder.

 

 

I’m very pleased with the end result. The body of the Holder is machined from Aluminium and will take a 1” Die in one end, and a 13/16” Die in the other. The short end of the steel central shaft has a No. 0 Morse Taper to fit the Tailstock of the Sherline Lathe. Okay, now I’m ready to start work on the model again!

[mobbsie]

Nicely done mate, good idea with the servo clamp. Will your mounting plate have an adjusting slot so minor alignments can be made when fitting it into the boat.?

 

I understand why you have made your Die Holder and you have achieved a good piece but, surely a simple Tap & Die with the part your working on held in a vice would have achieved the same result.

 

Please don't think I'm being critical, I'm not, I'm no engineer so I'm just asking the question.

 

NOW, stop messing about and get back on the boat

[mtaylor]

Mobbsie has a point about the die holder. I was wondering the same thing.  Also, won't the lathe spin too fast for it to work and still get the required feed speed?   Beautiful machine work on it though.  

[gjdale]

Thanks Mobbsie and Mark,

 

Mobbsie - the mounting plate does allow for some adjustment.  As for the Die Holder - I wasn't confident of being able to cut the thread accurately/square, hence was looking for a way to achieve that.

 

Mark - the lathe doesn't spin at all for this operation, it's all done without power - just using the capability of the lathe to align things properly. The head stock (with a collet holder) will hold the stock piece, and the Tailstock Die Holder will present the Die centred and square to the stock. The Die Stock is then rotated by hand, or with the assistance of some tommy bars (you can see the holes for the in the centre section of the holder). Because the Die Stock is mounted on a central shaft, it is able to advance itself as the thread begins to cut.

Edited May 15, 2016 by gjdale

[Rustyj]

Nicely done Grant. This is all new to me and very interesting.

[aydingocer]

Nice going Grant, watching your build log gives me motivation to continue every time when I feel troubled with mine. I'll keep following all the way!

/Aydin

[popeye the sailor]

glad to see you've resumed in this build.....nice bit of progress  

[Hsae]

Thanks Mobbise, Mark and Ben.

 

A minor update tonight......

 

 

 

 

Construction: Gauges continued

 

 

The plastic is not quite as clear as I would like, so not sure yet whether I’ll go with this in the end.  I have another alternate method to try yet……..

You could try to spray the plastic with "Future" (Pledge Floor care) this will enhance the look.

This is an old trick from plastic modelers to create a "glas" look for clear plastic.

To glue it in place you can use Micro Kristal Clear (from Microscale Ind.). It is a flexible clear liquid plastic adhesive. I used it also for removing light scratches.

[captainbob]

It's always a design challenge when adding radio equipment.  You're doing a fine job.

 

Bob

[Gerhardvienna]

Hi Grant

 

Just flew over this report, I`ll stay tuned

 

Regards

Gerhard

[gjdale]

Drive Train

 

Progress continues, albeit very slowly! My new stainless steel drive shaft arrived and I was ready to cut the 5-40 thread with my brand new self-made die holder………or so I thought……. I was having trouble getting a thread started and being completely new at this, I decided to pop in and have a chat to my new best friends at the local machining supplies shop. Blinding Glimpse of the Obvious #347: using a carbon steel die to cut a thread on stainless steel is probably not the smartest move known to man…. Doh! However, it might work once or twice before the die destroyed itself, they told me.  By the way, that’s a nice looking die holder you’ve made there, they said, but it’s missing something…….it needs another hole tapping to take a tapered grub screw to open the die up a bit. That way, you might stand a chance of getting your thread cut. Doh!

 

Back home, tapped another hole, tapered a grub screw, forced open the die a little (actually as much as I could), and after some Herculean efforts managed to complete a test run on a piece of brass rod of the same diameter. It took two passes, but once the first one was done, the second went much more easily. Okay, so much for trials…onto the real McCoy now. Once again forced the die open as much as possible and with even greater effort managed to cut my thread, again using two passes. Tested with a standard nut and all was good. Feeling very pleased with myself, went to take the die out of the holder, and it came out in two pieces….. Needless to say, I am now the proud owner of a (very expensive) HSS 5-40 die.

 

With that vital task completed, I was able to assemble the drive train. In this picture, you can see the drive shaft screwed into my after-market brass propeller and protruding through my new stuffing box with sintered bronze bearings. You can also see the brass strut that is silver-soldered to the stuffing tube. This replaces an ugly plastic skeg provided in the kit.  The rudder is temporarily mounted to check for clearance between prop and rudder.

 

 

At the other end, the motor has been temporarily mounted and a dummy dog-bone has been used to create a rigid assembly. After this picture was taken, I subsequently decided to shorten the stuffing tube by about 5 mm in order to bring the motor further aft in its mounting, to provide additional clearance in front of it.

 

 

At this point the stuffing tube was tack glued in place with epoxy and once set, the running gear removed and the stuffing tube permanently set in place by filling the slot around it with a mixture of epoxy and micro-balloons (a polyester filling compound).

 

Electronics Housing

 

Then it was time to make up some shelves and racks to hold the various electronic components. Space is very limited and with the extras that I am adding to this model, the positioning of the equipment needs to be carefully thought through. Fortunately, someone else has been there before me and I have basically followed his placement.

 

In the next picture, you can see the two side-racks that will be inserted and glued in place shortly. Inside the engine compartment, you can see the Battery shelf at the aft end, a mounting to take the fuse holder on the port side, and the tray for the Electronic Speed Control (ESC) in the forward cockpit compartment (it will be under the front seat).

 

 

And finally, here are a couple of shots with the side racks dry-fitted in place.

 

 

 

It’s now time to fit the underplanking on the sides of the hull and start closing this baby up!

[mobbsie]

Hi Mate,

 

An expensive lessen learned me thinks, although it achieved what you wanted it to do I'd have thought it would do more than a single job.!!!!!!!!!!!!!!!!!!!!!

 

Drive gear and shelves are looking good mate, should keep everything neat, tidy and accessible.

 

I have one suggestion if you don't mind and that's to put in some kind of protection for the prop, I see the prop is below the bottom of the rudder and is open to damage. Don't want to bend that up in shallow water or objects below the surface.

 

Enjoy your planking job mate.

 

Catch up soon

 

mobbsie

[Gerhardvienna]

Hi Grant

 

Maybe I`ve overread this, how large will she be?

Drive assembly and rudder look good!

 

Regards

Gerhard

[mtaylor]

Superb work, Grant.   Hmm.. damaged tooling.. expendable... crap happens.  Yeah.. that's it... crap happens.   At least you got the threads turned before finding out about the disaster.  But I do feel your pain.