[Brent Gair]

I just finished a fairly simple scratchbuild. At about 6.5" long (1/72 scale), it microscopic by my standards . It's a Crew Exploration Vehicle based on the proposal for a new, all purpose spacecraft capable of manned flight and resupply.

The small size is the result of some rather small barstock that I used for thew initial machine work. This model represents a change from previous scratchbuilds in that it only has one wooden part (main crew module). The rest of the model is plastic and aluminum.

I'm putting two links here depending on whether you want to see just the finished product or if you want to see the early fabrication process.

Start here to see three pictures of the finished model (Hit "next" from this link to see the two subsequent pictures):

http://groups.msn.com/Margaret6547/miscellaneous.msnw?action=ShowPhoto&PhotoID=35

If you want to start with the early photos, start with this link which takes you to the lathe work on the rocket nozzle (if you keep hitting the "next" button, you will eventually hit the pics of the finished model):

http://groups.msn.com/Margaret6547/miscellaneous.msnw?action=ShowPhoto&PhotoID=30

NOTES:

Rocket nozzle, docking collar and main hatch are turned from 5/8" aluminum.

Main crew module is turned from basswood.

Service module body is made from ABS pipe which was trued on the lathe.

Small parts such as thruster housings and conduits were also made from ABS pipe.

Paint is all lacquer. Crew module further buffed with Silver Leaf Rub 'N Buff.

The crew module is removable such that it can be incorporated into other models such as a lunar lander...a feature expected to be incorporated int the real CEV.

 

[John P]

I would call that model "simple and to the point"
Very nice!

 

[Brent Gair]

Thanks John P.

I'm trying to do TWO things in scratchbuilding...one of which I've accomplished and one of which I haven't accomplished yet.

One thing I've wanted to do is move away from solid wood construction. There's nothing wrong with wood but, as certain parts gets larger, there are problems of weight and long-term shrinkage. When things get larger than 2" diameter, that's an issue.

I also want to move away from the vehicles that have a purely round cross section. I'm perfectly capable of building more complex shapes as seen in my big ship models. But my sci-fi stuff tends to be round. As you can see here, this model is a bit of a step backwards because it has more round parts than anything I've ever built! At least my other scratchbuilds had wings and fins.

 

[Chris Ford]

Very nice!!! Looks like your somewhat of a master on the lathe. Well done :thumbsup:

 

[Mel Williams]

Brent
That looks good! I would like to see some pics of your tooling and how you cut your nozzle. I have thought of useing my lathe to make rocket nozzles but you have done better then I was even thinking of. I had thought of just useing plain cone shapes.
Once again good job!
Mel W.

 

[Brent Gair]

Brent
That looks good! I would like to see some pics of your tooling and how you cut your nozzle.

At this time, I would like to thank MSN for losing my website and all of the scratchbuilding pictures I had posted. That's why the above link is in my Mother's name. MSN screwed up my password about 6 weeks ago...their system also screwed up when I tried to get a new password and my personal site went offline about a week ago. Of course, that's where I had 60 pictures of scratchbuilding and tooling posted!

I have two lathes-one for metal and one for wood work.

The metal working lathe is a real little gem. It's a Taig lathe which I got from Lee Valley Tools. There are a lot of Taig sites on the net. Do a google search and look for "Nick Carters Taig Lathe Pages". He's a dealer and he has got links to every conceivable bit of Taig info.

The Taig Micro Lathe II lacks some of the features of some other small lathes but it has a reputation as an extremely tough machine capable of working to greater tolerances than most small lathes.

I've only had the Taig since mid February of this year and literally learned EVERYTHING I know about how to use it from the internet. I grind my own tool bits from 1/4" square tool steel blanks...and I even learned how to grind them from the 'net.

My basic nozzle making procedure is this (keeping in mind that I've only ever made TWO nozzles so I'm not an authority on the subject!):

I started with some 5/8" diameter aluminum barstock that I bought at Home Depot. Hacksawed about 3" off the bar and mounted in the four jaw chuck. That Taig 4 jaw chuck is a real nice tool with hardened steel jaws. I centered it in the chuck using a dial guage on a magnetic base. The great thing is that this kind of equipment is now very cheap. You can get the guage and base set for about $35.00 (would have cost about $150.00 20 years ago!).

I faced the end of the aluminum piece to make it nice and flat (not really necessary in light of the subsequent machining). Then I drilled a hole (about 3/16" or so) right down the center for the entire estimated length of the nozzle (7/8"). This is another area where the lathe really shines. You can mount a chuck on the tail stock which is equipped with a ram. Drilling with a tail stock is a joy...straight, true, perfect (puts the drill press to shame). I then turned the end of the aluminum down to make that mounting boss as you can see in the first picture.

Next came the real business part of the nozzle itself. I had a drawing of the Apollo Service Module nozzle for basic reference (my nozzle isn't a copy but I wanted to make sure the proportions were realistic). First, I determined how long the nozzle should be and them I used the parting tool to cut a demarcartion groove into the barstock (again, that first picture shows the demarcation line where the shiney nozzle ends and the dull barstock begins). Also note that I ground my own parting tool based on info found on the net. I further used the parting tool to remove metal and make a VERY ROUGH stepped cone. The parting tool isn't designed to move left or right so I just kept digging at the metal.

Once I had a very ugly cone, I used a pointed cutting tool to slowly smooth it into a bell shape...one hand cranking the tool radially into the metal while the other hand cranked axially along the length of the nozzle. Bell shape complete, I went back to the parting tool and made some cuts to locate the raised ribs (just eyeballed the location). The pointed cutting tool was again used to clean out between the ribs thus giving the ribs a raised profile. Since the pointed cutting tool has a slightly rounded tip, I actually used a HAND HELD NEEDLE FILE in order the sharpen the corners of the ribs where they meet the nozzle. With that done, I finished the exterior with some silcon carbide sandpaper and oil to remove any tooling marks. Final finish was some metal polish. I removed the nozzle by cutting it with the parting tool and then doing the last millimeter with a hacksaw.

With the exterior done, I turned the nozzle around to hollow out the interior. That's where the mounting boss is handy. Not only does the boss give you a place to mount the nozzle on the model, it also gives you a place to mount it in the chuck without touching any of the fine finshed surface.

Hollowing out the interior is the one area where I think I've made some innovations. Since I had already drilled a long hole when I first started, that hole is now accessible at the large end of the nozzle. My personal invention (?): I mount a .5" , 45 degree chamfering carbide ROUTER bit in the tail stock and ram it into the nozzle. This cleans out a lot of metal and lets you get a boring bar into the nozzle. I use the boring bar to clean out a portion of the nozzle but your can only do so much because, obviously, as you get near the neck of the nozzle, it becomes way too small to get a boring bar into the tiny space. So I do the final internal shaping with a burr, free hand on a Dremel tool as the nozzle spins in the lathe. Good quality steel burrs (also purchased from Lee Valley Tools) make very short work of the aluminum.

Let me end that very longwinded reply by saying that a cone would sure be easier! I have the accessory top slide for this lathe which can be set to a specific taper. Set the angle you want and start cranking...you have a simple cone. My nozzle was complicated by the curving bell shape and the raised ribs.

But it is EXTREMELY satisfying to manufacture parts from scratch. I must say that since getting the lathe, my desire to build plastic kits has waned.

 

[Dr. Brad]

I'm with John:

Nice, simple, clean. I'd be very proud if I'd made that!

Brad

 

[PerfesserCoffee]

Very cool! Very inspiring!

I've got something I'm in the process of putting together from odds and ends (very few if any actual model kit parts) that is similar in that it is also near future real-space looking sci-fi. I'm going with a Soyuz/Apollo/2001 Discovery meld with multiple engines and lots of greeblies.

 

[Brent Gair]

I'm going with a Soyuz/Apollo/2001 Discovery meld with multiple engines and lots of greeblies.

One aspect of scratchbuilding that I still have to tackle is casting. I hope to start experimenting with that soon. I'll probably use some cheap, crappo stuff until I figure out the basics.

It's that "multiple" engine challenge that is making me look at casting. Building ONE rocket nozzle is fine. But it's clearly not going to work if I want to build a project with 4 identical engines. Not only does it take a fair amount of time to machine something like that nozzle, but it's largely a matter of aesthetics rather than specific measurment and that makes it hard to repeat two identical pieces.

 

[PerfesserCoffee]

It's that "multiple" engine challenge that is making me look at casting. Building ONE rocket nozzle is fine. But it's clearly not going to work if I want to build a project with 4 identical engines. Not only does it take a fair amount of time to machine something like that nozzle, but it's largely a matter of aesthetics rather than specific measurment and that makes it hard to repeat two identical pieces.

I've nothing against casting but I don't want to do it unless I have to and even then it's a bear. All I'm doing now is using the caps from Lucas transmission stop leak fluid which I've used far too much of lately (before having to take the car in for repair ANYWAY! ). They make perfect nozzles. A source of tanks/engines to put in front of the nozzles are two 1/2 inch PVC pipe caps glued together with a small piece of pipe between to align them. After that, a little solder or thick copper wire bent to proper shape for hoses and I've got a good little engine started and as many multiples as I have pieces for.