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Al Schwartz
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3,396 Posts
Discussion Starter · #1 ·
I needed a sidewinder chassis for one of my projectsand decided to try some of the ideas that Chris Briggs has put forth on his web site:

Chris' site

-and I wanted to try out a new mnin-torch that I bought that uses MAPP gas for a hotter flame than propane:



The front and mid-rear sections of the chassis were cut as one from 0.062" brass and then separated after the slots for the pivot and torsion springs were cut. The front axle carriers are also 0.062" brass and were brazed (with my new torch) into extensions of the torsion spring slots. I did this so that there would be no chance of subsequent soldering steps loosening them. The guide carrier is 0.062" steel (I don't like it when things break!) and the cross brace is another piece of 0.062" brass, both of these parts attached with Sta Brite solder.

More details and the rear section when I find the memory stick from my digicam!

EM

and, no "Hybrid" does not mean that there will be a miniscule I.C. engine to supplement the electric motor.
 

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Alan Tadd
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4,039 Posts
That looks to be a cracking chassis Allan, can't wait for the rear end.

Do you think you could achieve a similar effect with a single fixed piano wire torsion bar?. I have considered trying this but I'm not sure the required strength to hold the two parts of the chassis together could be achieved.

Regards

Alan
 

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Al Schwartz
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3,396 Posts
Discussion Starter · #3 ·
As I understand it (and, remember, my chassis designing experience is more of the "carve it from a solid block of aluminum and nothing will move" school), the problem with a single central torsion bar is that it will not only twist but flex in the vertical (and horizontal) plane, giving the chassis sort of an internal "roller coaster" aspect. In this case, the central pivot is a piece of 1/16" drill blank, soldered to the rear section and enclosed in a 3/32" OD, 1/16" ID tube that is soldered in the front slot. The torsion bars are 0.03125" music wire, attached only at the ends by soldering them into short pieces of 1/16" tube and then soldering the tube, in turn, into the slots. It twists easily but has essentialy no flexibility in the vertical plane.

EM
 

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376 Posts
Hi Em

Very nice work..... clean and neat... you do a better job than I do


When working with brass that thick I find the torch is really the best way to go.. It and take forever to heat up that much brass to get a good flowing solder joint..

I keep everything in the jig so that all the parts stay where they belong...

please keep us posted on how the rest turns out......

Chris
 

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Russell Sheldon
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2,855 Posts
Excellent workmanship, Al. Hopefully you're building it for the yet to be announced World Proxy Can-Am Series.

Also take a look at Larry Geddes' similar chassis, winner of the 2002 Marconi Proxy.





Kind regards,

Russell
 

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Al Schwartz
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3,396 Posts
Discussion Starter · #8 ·
Here is the rest of the story - a bit delayed and not yet mated to a body. I like sidewinders but they do have one little problem - set up. It is easy to adjust the gear mesh on an in-line - just slide the crown or bevel gear on the axle. Anglewinders also allow for a bit of error - the spur can be moved on the axle for fine adjustment of mesh but sidewinders allow no such fiddling - the center-to-center dimension of the motor shaft/ axle combination "is what it is" I know that there are "work-arounds" - like soldering the motor in after the mesh has been set (too many years of heat-sensitive Alnico magnets makes me shudder at the thought of appling an iron to a motor) or mounting the motor on a slotted bracket and then bolting it down but I decided to take the easy way out an let someone else do the work for me. Slot-It, TSRF, Cartrix and others make sidewinder motor- axle carriers that are accurate and inexpensive. For my first attempt I chose a Slot It part. It was cut off, the sides of the molding filed down to give a flat surface and a piece of 0.125" thick aluminum cemented in with a high-strength metal filled epoxy (JB Weld) After curing overnight, the main chassis and the motor pod was placed in my chassis jig, upside down and the previously drilled holes in the chassis transferred to the motor pod. these were then drilled and tapped 2-56 and bolted together with Nylock nuts added for insurance.



The whole assembly seems quite solid and, with the aluminum block cemented along the back edge as well as the bottom, the stresses on the plastic (glass filled nylon?) part are well distributed.



The wheels are modified BWAs with Ortmann tires - the rims need their final trimming so as to not stick out beyond the tires.

I have just finished a second "drive module" using the aft end of a TSRF chassis. It works just as well. this opens the possibility of an easy "engine swap" type tuning for different tracks - the Slot-It for shorter tracks and the TSRF for tracks where a higher top speed will be an advantage at the expense of being a bit over powered in the twisty bits.

Why "sideways" - I slipped in sideways using a short cut to avoid the critical motor - axle set up.

Any why no body? - A bad batch of resin left me with three moldings all of which turned to sticky messes after painting - new resin is in - to be continued.

EM
 

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EM

Very nice work..... how does the chassis set up seem to work for you??
I have used the fly motor pod for chassis also and they are quite nice and easy to work with.... I have not thought of the TSRF motor section but will be looking one over...

Chris
 

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Al Schwartz
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3,396 Posts
Discussion Starter · #11 ·
I am very pleased with the chassis behavior, Chris, especially considering the narrow rubber*. It grips well and is very predictable. The Slot-It motor seems a little light for the task (it's a heavy chassis) so - while waiting for the next body to cure, I'm going to try something a little hotter.

EM

*correction - the tires shown are not Ortmanns - they are EJ 15s
 
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