Joined
·
169 Posts
I thank Russell for posting pics of my car, but to set the record straight, the '39 Maserati Streamliner pictured was carved out of conventional balsa wood, which, as others have mentioned, is difficult to cut cleanly because of its softness. I think Russell is remembering the sequel, a '55 Maserati Streamliner. Unfortunately, I don't have any pictures of it, but it was indeed fragile, and was destroyed at a subsequent Marconi race. I still have the pieces though, and have plans to eventually reassemble it for a resin casting. Copied below is a posting on the old Slots DL describing the trials and tribulations I encountered while building the car. One very important caveat about Balsa Foam: aside from its demonstrated fragility, it also is corrosive to most metals!! After a few weeks the chassis looked in worse shape than the body.
[Oct. 2001]
Well, after seeing some of the competition on the Marconi site, I figure it would be better to offer my excuses in advance, rather than after the race.
I thought I would try carving another body this year (just masochistic I guess), and decided on doing the '55 Maserati streamliner raced by Jean Behra at Monza. Although the car never won a race, I was drawn to its sleek shape -- especially the rear fins (hey, I grew up with Plymouths and DeSotos in the 50s). There are no plans available that I am aware of so I used standard F250 specs for the wheelbase and track. The balsawood I used for last year's car was a real pain to carve because it was too mushy and tended to depress rather than slice cleanly. I decided to try a phenolic resin foam product appropriately called "Balsa-Foam" that is easy to carve and doesn't have any "memory" or bounce back. It is available in 7, 12 or 20 pound densities so I decided to use the medium weight. I couldn't find appropriate sizes at the retail dealers, and the manufacturer had a $100 minimum order, so I decided to glue up two 1" slabs to form the block. I did this with real balsa last year without problems and I also like having a built in center line as a reference. Problem #1, the glue line was much harder than the foam itself and difficult to sand down evenly. Problem #2, the foam is corrosive, requiring care in cleaning edge tools (I found out the hard way). I'm hoping it will not have the same effect on the car's running gear. Problem #3, since it is foam, it is a fairly coarse material and full of little air bubbles -- some of them larger than others -- and required lots of filler to achieve a smooth surface. Problem #4, I tried using thinned down "lightweight" spackle as filler, but it stayed gummy. When sanded it tended to roll up into little balls, which played havoc with the already very delicate foam material. I eventually applied full-strength spackle with my fingers over the entire surface of the car, let it dry to plaster hardness, and then sanded it all down again. Problem #5, when cutting a recess on the inside for the nose screen (made from an old electric shaver foil) I managed to poke my knife all the way through the nose -- aarrgh! more putty. Finally got the body more or less shaped and primered -- on to the chassis.
I wanted to keep it as simple as possible so decided to use a brass pan configuration. The hardest part was bending and drilling the axle bracket. I needed some nice wire wheels and Nincos seemed to be the best choice, but I didn't like the press-fit. I decided to do as Rocky suggested and tapped them for 5-40 threaded axles. Problem #6, all well and good, except the wheels were not round. I trued them as best I could but they still hop a bit under hard acceleration. Since I still do not have a chassis jig, much of my assembly methods are done "free-hand" using clamps and vise grip pliers to hold everything together. Problem #7, have you ever soldered a front axle tube with the wheels and axle still inserted to check clearance? Have you ever done it with nylon wheels? It is not a pretty sight. Okay, finally got the chassis rolling after stealing and tapping the wheels off another Ninco car. Tried fitting the body but needed to trim out most of the backing material behind the rear wheels. Problem #8, I dropped the body on the chassis to check clearance, noise etc. Couldn't resist doing a lap around the track when CARAMBA!?!?!, something jammed and the whole tail end snapped off! It looked like a lost Mickey Thompson car! After letting my heart calm down and fortifying myself with liquid restorative, I mustered up enough courage to examine the damage. Fortunately the break was clean so I CYAed it back together, touched up the crack with spackle, resanded, primered, etc. Problem #9, when fitting body to chassis and drilling holes for the mounting screws I applied too much pressure and again managed to snap the f*&%#ing tail off. By this time I was beginning to think the car was not meant to be. Decided to try one last time with Titebond glue (aliphatic, phenolic -- sounded close enough to me), again followed by the spackle, sand, primer routine. This seemed to be stronger and the rest of the car was finished without incident, although trying to paint a checkerboard pattern on Jean's helmet while holding the driver and magnifying glass in one hand and the pen in another was pretty damn awkward.
The car uses a Lil Ripper motor and is probably overpowered and ill-matched with the 45ohm controller, but I will leave it to the driving pros to sort out. Was building the car worth the gray hairs? I think so, especially since it is a car not available elsewhere. Being able to say you built the car your self provides a great deal of satisfaction, and I highly recommend trying it to everyone. Will I do it again next year? You must be kidding. How many more streamliners are there anyway?
mp
[Oct. 2001]
Well, after seeing some of the competition on the Marconi site, I figure it would be better to offer my excuses in advance, rather than after the race.
I thought I would try carving another body this year (just masochistic I guess), and decided on doing the '55 Maserati streamliner raced by Jean Behra at Monza. Although the car never won a race, I was drawn to its sleek shape -- especially the rear fins (hey, I grew up with Plymouths and DeSotos in the 50s). There are no plans available that I am aware of so I used standard F250 specs for the wheelbase and track. The balsawood I used for last year's car was a real pain to carve because it was too mushy and tended to depress rather than slice cleanly. I decided to try a phenolic resin foam product appropriately called "Balsa-Foam" that is easy to carve and doesn't have any "memory" or bounce back. It is available in 7, 12 or 20 pound densities so I decided to use the medium weight. I couldn't find appropriate sizes at the retail dealers, and the manufacturer had a $100 minimum order, so I decided to glue up two 1" slabs to form the block. I did this with real balsa last year without problems and I also like having a built in center line as a reference. Problem #1, the glue line was much harder than the foam itself and difficult to sand down evenly. Problem #2, the foam is corrosive, requiring care in cleaning edge tools (I found out the hard way). I'm hoping it will not have the same effect on the car's running gear. Problem #3, since it is foam, it is a fairly coarse material and full of little air bubbles -- some of them larger than others -- and required lots of filler to achieve a smooth surface. Problem #4, I tried using thinned down "lightweight" spackle as filler, but it stayed gummy. When sanded it tended to roll up into little balls, which played havoc with the already very delicate foam material. I eventually applied full-strength spackle with my fingers over the entire surface of the car, let it dry to plaster hardness, and then sanded it all down again. Problem #5, when cutting a recess on the inside for the nose screen (made from an old electric shaver foil) I managed to poke my knife all the way through the nose -- aarrgh! more putty. Finally got the body more or less shaped and primered -- on to the chassis.
I wanted to keep it as simple as possible so decided to use a brass pan configuration. The hardest part was bending and drilling the axle bracket. I needed some nice wire wheels and Nincos seemed to be the best choice, but I didn't like the press-fit. I decided to do as Rocky suggested and tapped them for 5-40 threaded axles. Problem #6, all well and good, except the wheels were not round. I trued them as best I could but they still hop a bit under hard acceleration. Since I still do not have a chassis jig, much of my assembly methods are done "free-hand" using clamps and vise grip pliers to hold everything together. Problem #7, have you ever soldered a front axle tube with the wheels and axle still inserted to check clearance? Have you ever done it with nylon wheels? It is not a pretty sight. Okay, finally got the chassis rolling after stealing and tapping the wheels off another Ninco car. Tried fitting the body but needed to trim out most of the backing material behind the rear wheels. Problem #8, I dropped the body on the chassis to check clearance, noise etc. Couldn't resist doing a lap around the track when CARAMBA!?!?!, something jammed and the whole tail end snapped off! It looked like a lost Mickey Thompson car! After letting my heart calm down and fortifying myself with liquid restorative, I mustered up enough courage to examine the damage. Fortunately the break was clean so I CYAed it back together, touched up the crack with spackle, resanded, primered, etc. Problem #9, when fitting body to chassis and drilling holes for the mounting screws I applied too much pressure and again managed to snap the f*&%#ing tail off. By this time I was beginning to think the car was not meant to be. Decided to try one last time with Titebond glue (aliphatic, phenolic -- sounded close enough to me), again followed by the spackle, sand, primer routine. This seemed to be stronger and the rest of the car was finished without incident, although trying to paint a checkerboard pattern on Jean's helmet while holding the driver and magnifying glass in one hand and the pen in another was pretty damn awkward.
The car uses a Lil Ripper motor and is probably overpowered and ill-matched with the 45ohm controller, but I will leave it to the driving pros to sort out. Was building the car worth the gray hairs? I think so, especially since it is a car not available elsewhere. Being able to say you built the car your self provides a great deal of satisfaction, and I highly recommend trying it to everyone. Will I do it again next year? You must be kidding. How many more streamliners are there anyway?
mp
