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tube chassies


dalepadgett

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ok, what do you guys use to cut your tubing? i have the old mitre box and hand saw and still get crooked cuts...

also, how many fishmouth thier ends?

if you dont paint the chassis body color, what color do you use?

what is your glue of choice?

do you use rod or tubing?

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Ted,

I know your question was aimed at Joe about locating front suspension points, etc., but I wanted to show you what I'm doing on my Fairmont suspension. I'm going to pick up my thread from back in August on this shortly and will include some of these pics, but wanted to show you how I'm establishing those points, as long as the thread pertains to this subject. I'm sure others will have different ways of doing it.

I measured the diameter of the front tires I'm planning to use, drilled spindle blocks that match the tire centerline and so the spindles are parallel to the ground, determined track width and fore/aft location within the wheel well opening. I then glued the spindle block to a styrene base. Once the block was in place I could set the caster where I wanted it. The upper tubing ties into the firewall and was dictated in large part by the shape of the aluminum tinwork that is integral with the tube frame members, which I had to fuss with. I am going to work on the lower mounts next, but haven't gotten that far yet.

post-7285-0-76299500-1354208579_thumb.jp

post-7285-0-10757500-1354208589_thumb.jp

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Here's the link: http://www.modelcarsmag.com/forums/index.php?showtopic=62293&hl=fairmont

As I mentioned above, I'm planning to get back on it very soon. Chores at home, some misguided eyeballing on my part, and a couple of discussions with fellow modelers have caused me to go in a different direction than originally intended, but I'll leave that explanation to the thread when I get back to it... LOL

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Scott - excellent suspension build and descriptions. My mind is spinning with ideas.

As far as my question about the front geometry, it was open to one and all, as I'm sure everyone has their own procedure.

I like your description above about setting up the car and adding the wheel to determine the spindle location. That makes sense.

What determines the angle between the top and bottom mounts which gives you the caster? I remember the old FED rails had quite a caster and when turning, the front wheels almost looked like they were on a 45 degree angle.

This thread should almost be in Tips, Tricks and Tutorials. Maybe even 'stickied' after that - this is going to be great.

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Hey Ted. Thanks for the feedback. I actually got in touch with Dave (comp1839) and asked him what type of caster is typical for a doorslammer. He replied in the area of 8-10 degrees. I'm trusting that that spec hasn't changed too much over the past 30 years. LOL Because of my PE drawing, I have a CAD program, so it was simple for me to draw the template angle I was shooting for, then simply print it out, cut it out, and lay the template against the front edge of the strut to set the angle. The spindles have a slight interference fit in the spindle blocks so they hold the angle pretty decent. Since I took the pics, I've actually added upper mounts to the splash shield/tubing assembly. (I'll explain more of that when I resume my Fairmont thread.) The next step, then, will be to build a front crossmember-gusset assembly to set the final width of the rails and triangulate the forward rails. I am going to cast the splash shield/tubing so I can remove the temporary fixture holding the frame rails at the angle I was needing. I have some scrap floor pans that I'll probably sacrifice one of them to the cause and glue a completed resin forward rail assembly to the pan so I can work upside-down with the body to see what the heck I'm doing with the lower control arms. My plan, barring any goofs, will be to add some type of locating nub to the frame rail that will serve as a locator for my foldable chassis tabs, which will accept RB Motion rod ends. I've developed a lower control arm "wishbone" that will tie the bottom of the strut body and both sections of control arm together so they're integral with each other. Those will be shown in my Fairmont thread at some point in the future...

Thanks Tom. I'll try to get back to that real soon. I'm starting to feel like I'm digging out... LOL

Edited by futurattraction
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Hey Ted. Thanks for the feedback. I actually got in touch with Dave (comp1839) and asked him what type of caster is typical for a doorslammer. He replied in the area of 8-10 degrees. I'm trusting that that spec hasn't changed too much over the past 30 years. LOL Because of my PE drawing, I have a CAD program, so it was simple for me to draw the template angle I was shooting for, then simply print it out, cut it out, and lay the template against the front edge of the strut to set the angle. The spindles have a slight interference fit in the spindle blocks so they hold the angle pretty decent. Since I took the pics, I've actually added upper mounts to the splash shield/tubing assembly. (I'll explain more of that when I resume my Fairmont thread.) The next step, then, will be to build a front crossmember-gusset assembly to set the final width of the rails and triangulate the forward rails. I am going to cast the splash shield/tubing so I can remove the temporary fixture holding the frame rails at the angle I was needing. I have some scrap floor pans that I'll probably sacrifice one of them to the cause and glue a completed resin forward rail assembly to the pan so I can work upside-down with the body to see what the heck I'm doing with the lower control arms. My plan, barring any goofs, will be to add some type of locating nub to the frame rail that will serve as a locator for my foldable chassis tabs, which will accept RB Motion rod ends. I've developed a lower control arm "wishbone" that will tie the bottom of the strut body and both sections of control arm together so they're integral with each other. Those will be shown in my Fairmont thread at some point in the future...

Thanks Tom. I'll try to get back to that real soon. I'm starting to feel like I'm digging out... LOL

holy noodles, Scott........talkiing about getting it right!!! ........ i eyeball it and glue.........

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LOL. If I was doing all this only for myself, I probably would be a bit more relaxed in the way I approach it, but since I want things to be as close to "right" for anyone interested in eventually buying any components, I feel like I need to make the extra effort to make things as "kit like" as possible. Oh - I fishmouth almost exclusively - any place that the joint is visible. As far as tubing or rod, It depends on what I'm building, what dimensions are available, and how it's all going to fit together. In the thread on my Fairmont, I originally used thin wall 5/64" (.078) brass tubing, with 1/16th tubing telescoped inside it. The new forward chassis I'm building is made out of similar diameter styrene rod made by Plastruct. I'll try to detail the "why" of my change in direction when I post on my Fairmont thread, but suffice it to say, I changed media because of what I was trying to accomplish. I almost exclusively use CA glue. I need to broaden my gluing horizons because I know I could have better control of certain situations if I were to use slower setting adhesives. Another area to grow in, I guess... LOL

Edited by futurattraction
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Lots of great ideas and craftmanship in this thread. Ted , When i setup my frontend i did it opposite of what Scott did. Scott's is a little more technical than what i do ( I don't mean that in a bad way) When i did mine i used alot of reference pictures to start, then from there i used the scaled down wheel base and pretty much aligned the wheels to the body for my liking to make it look right, For the width i again went off the body and sat the front wheels where i wanted to my liking, Once i figured that out and since i allready had my struts from Jim (micronitro) i mounted the wheels and tires and built a little Jig on my chassis table to hold the front wheel exactly where i wanted it. As far as the caster i just leaned the strut back to what i thought looked good going off pictures, once i had all that stuff aligned i built my lower A-arms and upper strut mounts off that. Don't get me wrong i do alot of measuring but i also do alot of eyeball engineering. I love this thread, lots of great ideas and techniques.

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ok, what do you guys use to cut your tubing? i have the old mitre box and hand saw and still get crooked cuts...

also, how many fishmouth thier ends?

if you dont paint the chassis body color, what color do you use?

what is your glue of choice?

do you use rod or tubing?

Al, I use the miter box also. Key is slow cuts and don't force it let the saw do the work, For fishmouthing i use a triangle looking file to get a line started maybe a 1/32" deep then used a round file to do the rest until i get the fit that i want. As far as glue i use Tenax7r and zap-a-gao CA, for the aluminum parts and some styrene parts that i need more time to position i used 30min. epoxy. for the chassis i use all Rod in sizes .060", .080" and .100" , keep in mind though i'm working in 1/16th scale. everything applies for 1/25th also except the rod sizes.

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... As far as the caster i just leaned the strut back to what i thought looked good going off pictures, once i had all that stuff aligned i built my lower A-arms and upper strut mounts off that....

Joe - I'm glad you said that because I figured that's exactly what I'd do. I don't think I'll have working steering anyway, so you wouldn't be able to tell if it's off.

I'm experimenting with fishmouthing, but I like your technique.

As long as we're discussing chassis building, if Thumper is here, I'm wondering why his PDF chassis tutorial ends so abruptly. Did I get the short version? If I remember correctly (and I'm the guy who can't remember what I had for breakfast) he was discussing the rear chassis construction and then it stops.

I'm with everybody else - this is a great thread?

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i usually start with setting the wheelbase, then the track width, then the spindle height. doind the same for front and rear. i use MDF as a chassis jig a screw my little mounting plates to it on the appropriate centerlines. how elaborate or un-elaborate you want to be is your choice. i use alot of lig and mounting plates because i have fat finger syndrome. the mountings keep me from screwing up what i'm building.

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There's lots of different ways to skin a cat.

When i'm doing brass work, i use a magnetic jig.

I usually torch solder my frames, and it works well. I print out the plans, and use extremely strong rare earth magnets to hold everything down to a steel base plate.

jig1.jpg

Full Article I wrote on the subject:

http://www.dirtmodeler.com/?p=412

Edited by DirtModeler
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  • 1 month later...

HI GUYS,

WHEN BUILDING A TUBE CHASSIS FOR A PRO MOD, PRO SPORTSMAN ETC, DOES THE FLOOR TIN GO IN FROM THE TOP, OR FROM THE BOTTOM UP? OR IS IT PERSONAL PREFERENCE?

They go to the bottom, I know on Promods and i assume most pro classes the floor on the drivers side needs to be steel welded directly to the chassis. The center and passenger side can be carbon.

Goto this link lots of great reference pictures.

http://www.facebook.com/pages/R2B2-Race-Cars/171401982899540?sk=photos_stream

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C'mon Joe, with all of that information at hand, how am I going to give the excuse that I didn't know any better?

What a load of information there! I go to their site and even Liked them on Facebook, but I haven't seen that many photos at a time.

Thanks, Joe

Edited by TedsModeling
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C'mon Joe, with all of that information at hand, how am I going to give the excuse that I didn't know any better?

What a load of information there! I go to their site and even Liked them on Facebook, but I haven't seen that many photos at a time.

Thanks, Joe

No problem , You Have a PM

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