21 replies to this topic

[Jairus]

Chassis is built up from brass rod and a cut up steel womp chassis.... this is the first mockup.


Mounts for the wing attached.


Rear bumper.


Finished chassis, elapsed time: 8 hours to this point.


Final mockup.



Time to fuss with the driver and other details, Onward and upward!

[James W]

Hey! I only see a couple of Monogram parts!

[CB]

Very cool looking Jairus ---and you get to watch it go round & round too!

[MrObsessive]

Excellent solder work Jairus!

I always have trouble keeping the adjacent joints from coming apart------which type of solder are you using?

I was thinking about soldering the inner frame in a Mercedes 300SL down the road as to why I'm curious...........

[Jairus]

It is called "Stay-Brite" and comes with acid flux. Very important to clean all joints with hot water and kitchen cleanser as the acid will start rusting steel and blacken the brass.
The solder is 5% silver content and flows beautifully with a good 100 watt Inland iron. Still need to sand some of the joints and then most of the chassis will get a nice gloss black paint. The rear bumper and side bump rails will be cleaned, polished and receive a coat of clear.

[Jairus]

Okay, JAMES.
Here's the driver...

[Jairus]

Got the frame painted this morning.
Since the name of this build is "Sprintcar" went with a 9/33 gear ratio.


With wheels and motor carefully installed.

Time to turn attention to the body work and related details...

[Jairus]

Got the driver and some of the steering gear installed along with the side pipes and foot shields.

[Dr. Cranky]

Super cool, J. I think you are one of the few people I know who is cuckoo for slot cars, and I can totally see why!!!

[jbwelda]

great work jairus!

hey bill: the secret to soldering and not undoing adjacent joints is to use a big enough iron that you can heat the area locally hot enough to flow the soldier without keeping the iron in contact with the piece long enough to let the heat migrate beyond the joint youre working on's area. i used to try to use a pencil iron for soldering brass tube like jairus is doing but it would never work out well because i would end up undoing joints as i did others. then someone more familiar with the tricks said that little iron will never work, use you bigger gun. i didnt think that would really help but sure enough it did...hold the trigger down long enough to get the element red and then apply to the joint and pull away as soon as the solder flows.

i will let jairus correct me if he has some other secret (heat sinks help too) but otherwise try out what i say and see if it works for you, it did for me. with that big clunky tip though there is a bit more cleanup but if youre careful it is minimal.

jairus seeing that makes me want to build more slots even though our track went down!

[Jairus]

You are exactly correct!
I use a 100 watt "Inland" iron and just have to touch it to the joint for 3 to 5 seconds for the solder to flow. For heat sinks I use metal alligator clips... but mostly I have been doing soldering for so long that I know instinctivly now what joints to do in what order to avoid something falling off.

[Art Anderson]

One thing to consider is, too, that ordinary lead/tin solder melts very easily, and heat travels down brass rod or tubing at Interstate Highway speeds (or so it seems). With solder, it's the lead content that makes it melt at lower temps, the lower the lead percentage (and higher the tin content), the more heat it takes to break a previously soldered joint. I've even found 90% tin, 10% lead solder at that "Lobby" place, along with all manner of low temp silver solder at Radio Shack.

That said, there are some options. About 5 years ago, there were introduced a number of manufacturers started coming up with hand-held (in the palm of your hand!) butane torches. I have one of these, the Micro-Jet Solder It ™, which uses as its butane tank a refillable version of the ubiquitous Bic lighter (but without a flint). This can be filled from Micro-Jet's own refill cans, or the Ronson butane refill cans available most places. The flame pattern is about that of a small pencil, and it's hot enough to use high-silver content silver solder. One of the real advantages of using silver solder is that this solder takes about 20% more heat to melt out a previously soldered joint than it does to solder it in the first place. The Solder-It uses a thumb trigger to light, just press the trigger, and a pelouze igniter lights it up, SNAP. Let off the trigger, and it goes out.

Now, if you really want to get crazy, there is an old standby, that's been on the market for perhaps 40 years or so, the Microflame Oxygen-Butane Torch. Don't let "Torch" scare you off. The flame pattern on this is about the size of a #2 wooden pencil point, and it is "bright blue hot" (about 4000 degrees hot). This torch uses butane and oxygen from little steel cylinders that are just like the CO2 cylinders available for home cocktail bartending. The kicker is, of course that this torch does use a fair number of these cylinders pretty quickly, at the rate of 2 oxygen cylinders to each butane bottle. However, the real advantage of this one is, it can be used to braze (join with molten brass), which gives a joint as sturdy as the material around it (Jairus, that would be perfect for a sprint car chassis that is gonna take a lot of tumbling, bouncing crashes!) Back some 30 years ago, when I was at the height of my passion for replicating cars from the various starting fields at Indianapolis, I bought one of these units, and after a few tries, proceeded to scratchbuild some 6 or 7 Indy car chassis, from the tubular chassis era.

So, there are some options. Also, if using a soldering iron and lead/tin solder, a lot of strength can be achieved by "fishmouthing brass tubing or rod stock before making Tee joints, and with a bit of tedious (but very beneficial to the model) work, drilling 1/32 inch locating holes in the sides of 1/16" tubing, then using some 1/32" brass rod stock to make locating pins (just insert into the joining butt end) will also make for pretty solid joints.

Lots of options for soldering small model parts, even chassis.

Art

[MrObsessive]

Thanks for the info Art! At my job we use various types of solder, since I train people to do micro surface mount soldering from time to time.

I've used various "eutectic" solders for different electronic operations at work, but when it comes to soldering frames such as Jairus did, I've always seemed to have trouble.

Here's the type of soldering unit I use.............



I have various tips (chisel, round, etc.) to use for different jobs------the tips are 600° for lead solder. (I hate the lead free stuff! )

The heat sink idea I almost forgot about, and I know I have some somewhere in the house. Don't look for the soldered 300SL frame anytime soon............I'll need to practice a bit before I try it on a model!

[Jairus]

Final mockup before sending out to the painter. All plastic parts and pieces come from the Monogram sprintcars (1988). All plastic pieces will be epoxied to the brass and steel frame pieces to ensure secure mounting. However, this in-no-way avoids damage after a crash!!! Body panels will be protected by being mounted within the parameter of the space frame but the wings will shed for sure. Not much can help that... unless I make wings from aluminum.

[James W]

Good looking build Jairus, sorry about the whole 'Monogram' thing.

So where are you going to have it painted?



I have to just say that I have seen many of Jairus' finished slot car builds and they are fantastic pieces of work. His knowledge of the history of slotcar construction is fantastic. I give him grief sometimes, but highly respect his ability. To see these slotcars in person is a treat. The hand made chassis are works of art. And yes, the paint jobs, which he dose himself, are first rate. Check out his website sometime.

Edited by James W, 07 January 2009 - 10:04 AM.

[Ragnar]

Thanks for the info Art! At my job we use various types of solder, since I train people to do micro surface mount soldering from time to time.

I've used various "eutectic" solders for different electronic operations at work, but when it comes to soldering frames such as Jairus did, I've always seemed to have trouble.

Here's the type of soldering unit I use.............



I have various tips (chisel, round, etc.) to use for different jobs------the tips are 600° for lead solder. (I hate the lead free stuff! )

The heat sink idea I almost forgot about, and I know I have some somewhere in the house. Don't look for the soldered 300SL frame anytime soon............I'll need to practice a bit before I try it on a model!

Get yourself an Ungar Handle for screw in elements and an Ungar 33 Iron clad Tip, Some thin guage silver solder, what I use is .055 Dia., You can find the Iron, 33 Element/tip, and the solder at commercial Electronics Web Sites. You will also need a good hot acid flux like the ones sold by welding supply houses, a wet spung made for cleaning your soldering iron tip, and a stand for your iron.

Before soldering use an emory board to clean up and score the areas to be soldered, then brush on your flux to these areas just before you put your iron to them, always heat the solder joint and then apply the solder to the joint after it is good and hot. Be careful not to get flux on your skin as it can cause a nasty acid burn, and be carefull with that Iron at over 1000 deg.s F it will melt right throuh fingers, etc,. You want a joint with just enough solder to cover it, and the solder when it hardens should be very shiney, if it isn't you have a cold joint the will break apart. After soldering clean the chassis first with baking soda and a little water to neutralize the acid, and then with warm water and dish detergent. Use this method and practice making good joints, like everything else you need practice to train yourself to solder properly.

CHEERS!
Tom

Edited by Ragnar, 26 September 2009 - 10:14 AM.

[Ragnar]

Final mockup before sending out to the painter. All plastic parts and pieces come from the Monogram sprintcars (1988). All plastic pieces will be epoxied to the brass and steel frame pieces to ensure secure mounting. However, this in-no-way avoids damage after a crash!!! Body panels will be protected by being mounted within the parameter of the space frame but the wings will shed for sure. Not much can help that... unless I make wings from aluminum.

Jarius your chassis looks as good as your paint jobs, Nice Work!

CHEERS!
Tom

[chris4q]

Just finished painting this Sprint car and unfortunately the decals were real bad so I had to have a plan "B". I decided to go all out for a fantasy car. Marlboro came to mind so I went for it.

Below is a description along with pictures showing how the sprint car was built up by Jairus using a Monogram 1/24 scale kit and of course the final painted car. We did make changes to the car. Instead of using velcro for the front and top wing we ended up using strong magnets because they held the wind much better and if the car ever came off the track the parts come off with no problem. Jairus also reinforced the front of the car by extending the brass rod frame. As you can see in the pictures the car comes apart pretty easy so you can have access to the chassis and motor.

I think if we ever do another sprint car we will go with a metal top wing and that would make it last a good beating on the track.

The finished car

[Jairus]

WOW!

That really turned out nice Chris, thumbs up all the way!

[Ragnar]

That is a sharp looking Sprint car! You did a great job on both the body and Chassis!

CHEERS!