Question : What are the pros and cons of copper tape vs. braid for home built tracks?
When building a routed track, save yourself some future aggravation and do it right the first time with braid for the electrical contacts instead of sticky backed copper tape. If you're talented enough to build the track and route the slots, it's not that big of a deal to rout the extra groove for the braid. Once you do the main slot, you're 70% there anyway. I've built tracks both ways and copper tape is a headache, especially after it ages. It will split, corrode, tarnish, curl, wrinkle and the connection is not as good.
Just remember when setting up your routing equipment for depth and the like, you always want to have a test piece to do first, even if you think it's correct, it may not be. The test wood is the only way to make sure. Once you get it set right, you can do the whole thing. Preparation is everything. Make sure to allow for whatever adhesive you are using for the braid. This will account for a millimeter or two. I used hot glue on my 110' road course in 1986 and have yet to see any of it, anywhere even begin to lift. Never a problem. It was laid right on the bare wood. Don't paint under the braid. I laid down about a 1/16" diameter bead in the center of each braid groove and then came back later and laid down the braid with a big plumber's soldering iron with the tip ground to match a guide flag with a shallow rudder. You will need two people to do this. Remember to try not to stretch the braid around the corners. Lay it down flat and give yourself plenty to work with otherwise, it will pull up later on. Make your braid grooves wide enough so that the braid will not hang over the main slot. This will cause the cars to pull it up eventually. I always try to keep the braid just a hair away from the slot. If you do this and keep it as close to track level as you can and not too high, it will last almost forever. Hope this helps .... [Michael D. Zimmerman Sr.]
I agree with just about everything Zim says about tape. Routing the recess for braid is no work at all - the main problem is acquiring or making a piloted rabbet bit to fit in the slot. Any machine shop could make one up for you but I followed a tip by Pete Sardella and made my own. I took a flat bottomed carbide-tipped 3/4" rabbet bit and simply drilled a 1/8 hole in the bottom. This was soft enough and no trouble to drill using a press. I soldered in a short piece of axle for the pilot and voila -- worked great ! If you use standard 1/4" wide braid, the 3/4" width of the bit is just about right to give a little space between the braid edge and slot. I glued the braid using contact cement and have had no trouble at all with it lifting. The glue was a bit of a pain to apply to the braid (I used a squeeze bottle and small spatula to spread it on), but once dry placing the braid was easy, and didn't require a soldering iron with special tip or even two people to do it. But whatever method you use, I can only amplify Zim's advice.......preparation is everything. [mp]
We have had that problem, too, with finding the correct bit to use. We gave up on that fairly early and came up with a homemade plate that bolts to the bottom of our router. It has a 1/8" pin on each side of the center shaft of the router. These are set as close together as possible so as to not have problems cutting too far to the inside on turns. It works very well so you need only to install a standard 5/8", 11/16" or 3/4" bit, or whatever you are using. There are many methods to do the job correctly, it is just what seems right for the individual. I have always taken advice from numerous people on everything I do, then condensed it into what I thought was right, added in my own stuff for good measure and went with it. Bottom line is, if you can work with your hands and you put your mind to it, you can do it, and do it in a manner that works the best for you. [Mike Z]
Question : How do you set up and adjust the braid on the slot car guide?
I remember something being said about how to 'properly' prepare pickup braid but never saw the discussion. I thought I would share what I recently discovered. I have been using a brass wire brush (like a toothbrush, comes in a three-pack with steel and plastic for about $2 to clean and separate pickup braid. It removes the oxidation (dirt) and unbraids the ends of the braid, which , I think, is what is needed for good contact. I also have been using Marvel Mystery Oil penetrating oil. I think that's the name. It comes in a red plastic bottle with black printing. They make a regular oil also, but the penetrating oil is the one. Just the smallest amount on each braid very infrequently does the job. It really works well on older corroded braid after the wire brush. Be careful not to get too much oil on the track this way, although it did 'recondition' my old Revell track. Another trick I have been using that I discovered for HO cars and works great for larger scales, is to use duct tape to clean the tires. Just unroll enough to reach back around the roll of tape and reattach to itself, then roll your tires clean. A few laps will clean a dusty track and I have never found any sticky residue on the track with even the cheapest duct tape. Depending on the tire, you may find duct tape is too aggressive. For example, to me it appears that duct tape actually pulls bits of rubber from a Ninco 70140 tire (rather than just removing the dirt) leaving the tire with small pits. I find that packing or masking tape is sufficient to remove the dirt but does not harm the tire. I find that for built up dirt on guide braids that electrical contact cleaner removes the grunge. An ordinary Pink Pearl eraser can then be used to keep the braid clean. I use a pin to pick apart the end of the braid to make it more pliable and hopefully provide better contact. The oil is Marvel Mystery Oil and can be found at most auto supply stores. I t has been a slot racer's friend for many years. [Tom Moye]
One last chance to offer my certainly uninformed and probably ill-advised comments to the tripod discussion. Conventional wisdom states that 1) front wheels are irrelevant except to act as outriggers in hard cornering, and 2) chassis weight should be born by the guide shoe. Obviously there should be adequate weight to maintain brush to braid contact and keep the guide in the slot. It seems to me though, that applying the full weight to the guide, i. e., having the front wheels NOT touch, would tend to increase friction and slow a car down. Theoretically at least, wouldn't having the car's weight partly supported by the front wheels (assuming they are round) reduce friction and thus increase overall speed ? Having the weight roll rather than be shoved or dragged I think was discovered to be the way to go several thousand years ago. Of course, Rocky or Al would remember that time better than I. [Michael Paschal]
Again, why this is a problem ... 1) Tracks are rarely smooth enough to have the braid in PERFECT contact the whole way, acceleration, and brush tension lifts the front of the car ... wheelie. Every track irregularity lifts the wheels AND the braid. 2) With the wheels on the track they WILL steer you out of the slot. See all this is predicated on the idea that the guide shoe is just a piece, actually keeping the guide permanently in the slot is the SLOT CAR part. 3) Friction: sort of not the right term, actually friction goes up with less contact... eg a Knife blade. The guide is pretty low drag, the braid as well. Simply, the whole thing becomes irrelevant if you are not making good contact. Look at this, how about pulling the spring tension off the motor brushes. Drag will go down, speed will go UP. Try that! same with the guide, it runs better with the right amount of pressure on the contacts. But believe what you want. I would be happy to have someone prove me wrong. [Fate]
Last night I was working on a chassis for the upcoming Las Vegas meet Pre-1965 front-engined Le Mans car (with no magnet) and I decided to fit one of the new Slot-It guides for a routed track. I like the forward positioning of the guide post and the eyelet attachment for the wires. The sheet steel chassis that I was butchering has a stamped guide hole - too big for the Slot-It post and too thin to provide accurate positioning. I popped an axle bearing out of a defunct Pittman 703, bored it 3.5mm, turned it down to fit the chassis hole and soldered it in place - perfect fit. With the chassis in running order, I wanted to test it. My Scalextric track will not accommodate the guide as I expected. Before cutting down one of the Slot-It guides to use as a test system, I decided to try one of their plastic track guides. These have a slotted snap-in post like the typical Euroscale car. It snapped in perfectly ! I now have a system that appears to satisfy two important criteria : The forward post maximizes the effective guide base while keeping the guide under the nose and the compatibility of the two versions allows me to convert from plastic to routed track in a matter of minutes.
Return to FAQ Page
|
|
|
