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Al Schwartz
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Somewhere on my 2 TB hard drive there are some JPEgs of this process but I can't find them at the moment. It is simple enough so that I'm going to try a description.

There are a variety of reasons why one might want to make a home built rear bracket instead of using one of the many available on the market. These include feeling cheap, realizing on Thursday night that the race coming up on Saturday with no time for purchase and delivery or, in this particular case, wanting to experiment with offsets.

Now in the ordinary course of events, making it rear bracket is a simple process. Mark off a motor bearing hole, mounting holes, bend lines and axle bearing holes then drill and bend.

Ah, the bending process. These bends must be precisely equidistant from the motor mount and exactly square with axis through the axle holes. Lacking a bending brake with adjustable stops, I find this process both tedious and fraught with the opportunity for error. It is too easy for a minor problem in lining up the bend line with the clamping system to yield a part that will have a car leaning to one side or proceeding down the track crab wise.

Here is what I do: starting with a strip of material of appropriate thickness and length (I prefer to work in steel - is stronger, lighter and, because it is a poor conductor of heat allows for soldering on detail bits without having the whole assembly fall apart), I lay out a center mark for the motor bearing and then the motor mounting holes. I scribe lines equidistant from the center for the bend lines and a second set of lines, also equidistant from the center, for the axle position.

The holes for the motor and attachments and the axle are drilled in the routine fashion. Then I lay out and drill two holes on each of the bend scribe lines. They should be as far apart as is practical but the distance is not critical. It is important that the starting points be marked precisely on the line. The only requirement for the diameter these holes is that one has at hand a couple of pieces of straight wire half the diameter of the hole to be drilled. In my case, I typically drill a 1/8 inch hole and use 1/16 inch wire.

Bending time - put the wire through the holes and drop the part into whatever clamping system is to be used. (I routinely use a pair of vise grip pliers with extended jaws designed for metal bending) check that the part is resting evenly on both wires, clamp and bend. The geometry of the resulting bends will be symmetrical and square with the long axis. Once the bend is well started, you can pull out the wires and finish the bend which, of course, will need to be checked with a square.

One of the other advantages of this "roll your own" system is the opportunity, if the part is destined for an open wheel car, to do some additional drilling while the material is still flat to provide anchor points for rear suspension detail.

EM
 

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Kevs Racing Bits
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2,617 Posts
Fantastic Roland, now I'm definitely getting that scroll saw
 

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Alexis Gaitanis
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2,398 Posts

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Premium Member
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469 Posts
It's easier to get a piece of U-channel used for windows and sliding doors. There are many sizes and the bending is always exact. Just mark the holes and drill add any rod holes you desire. Material is a little difficult to solder if required but low temp no/low lead solder will work best. This will help. http://www.wikihow.com/Solder-Aluminum

I use U-brackets in plastic chassis in a 4 rearing setup. 2 original and the 2 in the bracket. You can experiment by using loose tolerance bearings in the plastic holders. Like this brass one.
http://www.slotforum.com/forums/uploads/14...3393_497654.jpg


Jimmy
 

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Was made for this proxy. http://www.valdetaro.com/marconi4/p2003-class-e-results.htm It was detuned with less magnets and was untested on Carrera track hence the mediocre showing. The concept is solid but needs to be carefully tuned for each track. I've never made a faster magnet car but with today's equipment I probably could. With full magnets it probably could have won but hindsight is 20/20. With the Neo motor magnets and full traction mag setup the downforce is over a kg.

Here's a short write up from my old tuning article:
I. This next setup was made because of the continuing increase in speeds for high downforce racing. Magnet cars present a basic problem. They need to have enough downforce to hold them through the turns yet not have so much that they overwhelm the motor. Up to now the general feeling was that the lighter the car the better for magnet cars since the more mass a car had the more magnet downforce that was required to keep in on the track in the turns. The fact is that this may not be completely true. What if the weight added was in the motor area which would make available double the torque of a similar car of lighter weight. This would allow a doubling of downforce at a weight cost of only a third of the original weight. The result a greater magnet downforce to overall weight ratio. In an effort to keep everything in the plastic chassis arena a car had to be chosen that had a strong enough chassis to take the extra torque and weight of the duel motor setup. The FLY Porsche GT98 Race version was one such choice. Motor choice was two FK-130s slightly modified. Gears were Sonic 64pitch and tires were PPR supertires for Slotit rims.
ii. The motors were moded as follows:
1. Ball bearings were installed in the can and "endbell". This was done to reduce vibration and friction as well as to allow the rear motor armature to be spaced slightly so that there was more shaft available out the endbell end. This latter item was needed so that there was enough shaft to attach the pinion joint to.
2. Neo-magnets were used to replace the stock motor magnets. They were aligned and spaced to give the best performance. These magnets were used for two reasons. a. To give better torque/braking and b. to give the car more magnet downforce to the track.
3. The bottom of each motor can was cut out to expose the magnetic field of the motor magnets.
4. The motor brushes were aligned so that they provided better comm contact. Epoxy was added to each brush leaf at the joint with the brush holder to add more spring tension to each brush assembly and to reduce float.
5. Each armature was balance checked and hand balanced as necessary.
6. The motors were reassembled and armature spacers were added to reduce slop to a minimum.
iii. The next thing that had to be done was to build up the two motor drive train.
1. The two motors were attached together by a long pinion gear that picked up the rear of the motor shaft on the rear motor and the front of the shaft on the forward motor. Motor armatures were aligned so that the poles of both motors were exactly aligned. This was critical since any misalignment would have caused allot of vibration at speed. The shafts were then soldered to the pinion joint.
2. The complete setup was run in a jig and the motors were checked for any alignment problems. The shaft joint was cut down to reduce mass.
3. At this point the decision was made to use a motor "U" bracket to strengthen the drivetrain so, this was added and the rear axle assembly was built up minus the wheels, outer axle bearings, and alignment spacers for these two items. Ball bearings were used to reduce friction.
4. Next, the gears were run in using auto rubbing compound on the mesh. The gears were polished and after running them in with the compound they were cleaned completely and lubed.
iv. Now the chassis had to be modified to take the duel motor drive train.
1. First, the drive assembly was placed on the underside of the chassis so that the chassis could be marked for cutouts to allow the duel motor setup to sit in the chassis.
2. The chassis was then cut and the duel motor was fit to the chassis.
3. The rear axle bearings were mounted on the main chassis and the drivetrain was centered in the plastic chassis.
4. The chassis was set on a flat surface that was covered with wax paper.
5. The drive train was completely centered in the plastic chassis and Epoxy was placed around each motor so that they were both attached to the plastic chassis. A level was placed on top of the two motors to insure that they were both perfectly aligned vertically.
6. After the epoxy set up the rear wheel/tires were added and the drivetrain was run to make sure everything was still aligned.
7. All the other parts of the chassis were added I.e. front axle assembly, TSRF guide, and motor wires.
8. Pockets were made for downforce magnets and the chassis was trimmed all around the outside so that it did not interfere with the car body except at the three screw attach points.
9. The chassis was now ready for track tuning.
v. The chassis was fairly well balanced and no forward downforce was needed because of the front motor weight and the motor magnets' fields. This car had a brutal amount of torque which enabled the use of about a kilogram of magnet Downforce with no great degradation in top speed. These FK motors have lots of torque already but the addition of the Neo motor magnets really put the torque off the normal scale. The only draw back to this setup is weight. The car is heavy so when it does let go the ballistic impact is very great and usually results in a lot of destruction. This design was run in the last Marconi race, slightly detuned, and the car did quite well. Further it was run at the first ever race in Athens, Greece and finished well ahead of every other cars. At the time of this writing I have one car of this type still running out of four originals. It has allot of track time on it and isn't as fast as it used to be but even in it's degraded state it remains the fastest magnet car in my fleet.
Jimmy
 
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