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Copying this topic from the old site. Thought it might still be of use to those wanting to convert to wood...
Baby, Don't Fear the Router
Here are some lessons I learned routing a few mdf tracks. These tips might help you avoid some of the mistakes I made:
1. Use a new router bit. On my second track I used an upward spiral bit because the guy who used it to rout his track before me preferred it over a straight, double-fluted bit, which is what most guys generally use. The upward spiral bit removes material from the slot as you rout. That's all well and good, problem was the bit had already routed through 240 linear feet of mdf prior to my using it. It took some effort to push the router through the mdf and the slots were a bit ragged. It was easily fixed with a little sanding but when I changed the bit for a brand new double-fluted straight bit the router cut clean and without effort. Why make yourself and the router work harder? A new bit will cut through mdf like a hot knife through butter. Whether upward spiral or double-fluted straight, use a new bit. It seems that a router bit is good for about 240 linear feet or one 4-lane, 60' circuit.
2. If using a lexan strip such as the ones Luf sells online- http://www.oldslotracer.com -be sure to use straight nails to hammer it in place. Nails that have even a slight bend in them will tug the lexan strip in one direction or another resulting in slots that are wavy.
3. A plunging router will eliminate slight nicks in your slots at the point where you begin routing. If you do not have a plunging router balance the router on the bit so that it is plumb and level and against your guide fence and give the switch a little blip to drill a hole as straight and plumb as possible at the correct distance from the guide fence.
4. Rout across the seams of adjoining sheets of mdf. This will ensure that your slots line up perfectly at the seams.
5. Always rout with the guide fence to the LEFT of the router as you PUSH the router. (If you are pulling the router towards you then the fence will be to your right). The router will wander away from the fence if you push it in the wrong direction.
6. Rout banked turns flat and then bend into shape after routed. Remember the degree of arc will increase as you form the bank so that a 180° turn may end up being 185° or more depending on the angle of the bank. After banking, check the slot width. It may decrease very slightly. Hand sanding the slot with medium grit sandpaper is usually all it takes to bring the slot width back to where you need it. And it's always a good idea to give the slots a light sanding after routing anyway.
7. When using a pin jig to rout equidistant parallel slots make sure that the slot the pins travel through is clear of dust and debris. You don't want the router to unexpectedly stall because the pins hit an obstruction in the already routed slot. The torque of the router will kick the router slightly causing small nicks at each point where the router is stalled.
8. An alternative to using a pin jig is to use a Sintra strip in the already routed slot to act as a guide fence. This will work only if the radius of your router base is equal to the lane width you desire. If I were to rout another track I would use the Sintra strip versus a pin jig. The jig I used was a home-built version made of wood and attached to two steel rods that directly attached to the router with set screws. I realized as I attempted to close the loops on my slots that the wood portion of the jig was slipping ever so slightly along the steel rods resulting in slight lane width variations so that the starting and ending points of my slots did not flush up.
9. To calculate necessary track width multiply the desired lane spacing by 1 less than the number of lanes, add another 1/8" for each slot and another 8" for borders (In turns you'll want a minimum of 5" for an outside border and a minimum of about 3" on the inside - you may be able to get away with less than this depending upon the turn, but this is a good general starting point for a 1/32 scale track). For a 4-lane track with 3.5" lane spacing this will be a 19" track width [(3 X 3.5") + (4 X 1/8") + 3" +5"]. The more room you have for track width the greater the flexibility you will have in your routing. A track width of 16 or 17" in the turns is restrictive for a 4-lane circuit with 3.5" lane spacing.
10. Bondo is great for fixing routing errors. Be sure to apply enough so that it sits above the level of the track since Bondo shrinks as it cures. If you scrape the Bondo so that it is flush with the track surface while it is still wet you will end up with a depression where the slot is and you will have to apply a second coat. So apply a little more than necessary and sand down to track level once dry. You will know you have sanded to the track surface when the line of Bondo looks to be the same width as the slot it is filling. It's a good idea to scrape excess wet Bondo from the track surface away from the slot to minimize sanding later. To avoid a thin, unsupported strip of Bondo at the edge of a slot being repaired you may want to over-rout the area to be filled and then rout one or two fingers perpendicular to the error to serve as anchors. Once filled, sanded and painted the repair will be invisible but it will be much stronger than a thin sliver of Bondo clinging to nothing but the edge of the slot. Another anchoring method is to over-rout the error and then to drill 1/8" holes to just shy of the bottom of the mdf and filling the holes with Bondo.
11. Durham's Rock Hard Putty works great for filling small nail holes and screw holes. It is water soluble, easy to work with, and gives off no harmful fumes. It doesn't work as well as Bondo for fixing routing errors because it's quite brittle and therefore there is some risk that it will chip either when you rout it or later when the track is in use.
12. Luf's tape laying tool is a great time-saver but I found that the tape would sometimes try to cut straight across the inside of corners. To prevent this, I applied a couple of self-stick felt pads to the base of Luf's tool. This burnished the tape as I was laying it and prevented it from wandering inside the corners. Afterwards, I burnished the tape again with the curved edge of a Bic lighter.
13. You reap what you rout.
Baby, Don't Fear the Router
Here are some lessons I learned routing a few mdf tracks. These tips might help you avoid some of the mistakes I made:
1. Use a new router bit. On my second track I used an upward spiral bit because the guy who used it to rout his track before me preferred it over a straight, double-fluted bit, which is what most guys generally use. The upward spiral bit removes material from the slot as you rout. That's all well and good, problem was the bit had already routed through 240 linear feet of mdf prior to my using it. It took some effort to push the router through the mdf and the slots were a bit ragged. It was easily fixed with a little sanding but when I changed the bit for a brand new double-fluted straight bit the router cut clean and without effort. Why make yourself and the router work harder? A new bit will cut through mdf like a hot knife through butter. Whether upward spiral or double-fluted straight, use a new bit. It seems that a router bit is good for about 240 linear feet or one 4-lane, 60' circuit.
2. If using a lexan strip such as the ones Luf sells online- http://www.oldslotracer.com -be sure to use straight nails to hammer it in place. Nails that have even a slight bend in them will tug the lexan strip in one direction or another resulting in slots that are wavy.
3. A plunging router will eliminate slight nicks in your slots at the point where you begin routing. If you do not have a plunging router balance the router on the bit so that it is plumb and level and against your guide fence and give the switch a little blip to drill a hole as straight and plumb as possible at the correct distance from the guide fence.
4. Rout across the seams of adjoining sheets of mdf. This will ensure that your slots line up perfectly at the seams.
5. Always rout with the guide fence to the LEFT of the router as you PUSH the router. (If you are pulling the router towards you then the fence will be to your right). The router will wander away from the fence if you push it in the wrong direction.
6. Rout banked turns flat and then bend into shape after routed. Remember the degree of arc will increase as you form the bank so that a 180° turn may end up being 185° or more depending on the angle of the bank. After banking, check the slot width. It may decrease very slightly. Hand sanding the slot with medium grit sandpaper is usually all it takes to bring the slot width back to where you need it. And it's always a good idea to give the slots a light sanding after routing anyway.
7. When using a pin jig to rout equidistant parallel slots make sure that the slot the pins travel through is clear of dust and debris. You don't want the router to unexpectedly stall because the pins hit an obstruction in the already routed slot. The torque of the router will kick the router slightly causing small nicks at each point where the router is stalled.
8. An alternative to using a pin jig is to use a Sintra strip in the already routed slot to act as a guide fence. This will work only if the radius of your router base is equal to the lane width you desire. If I were to rout another track I would use the Sintra strip versus a pin jig. The jig I used was a home-built version made of wood and attached to two steel rods that directly attached to the router with set screws. I realized as I attempted to close the loops on my slots that the wood portion of the jig was slipping ever so slightly along the steel rods resulting in slight lane width variations so that the starting and ending points of my slots did not flush up.
9. To calculate necessary track width multiply the desired lane spacing by 1 less than the number of lanes, add another 1/8" for each slot and another 8" for borders (In turns you'll want a minimum of 5" for an outside border and a minimum of about 3" on the inside - you may be able to get away with less than this depending upon the turn, but this is a good general starting point for a 1/32 scale track). For a 4-lane track with 3.5" lane spacing this will be a 19" track width [(3 X 3.5") + (4 X 1/8") + 3" +5"]. The more room you have for track width the greater the flexibility you will have in your routing. A track width of 16 or 17" in the turns is restrictive for a 4-lane circuit with 3.5" lane spacing.
10. Bondo is great for fixing routing errors. Be sure to apply enough so that it sits above the level of the track since Bondo shrinks as it cures. If you scrape the Bondo so that it is flush with the track surface while it is still wet you will end up with a depression where the slot is and you will have to apply a second coat. So apply a little more than necessary and sand down to track level once dry. You will know you have sanded to the track surface when the line of Bondo looks to be the same width as the slot it is filling. It's a good idea to scrape excess wet Bondo from the track surface away from the slot to minimize sanding later. To avoid a thin, unsupported strip of Bondo at the edge of a slot being repaired you may want to over-rout the area to be filled and then rout one or two fingers perpendicular to the error to serve as anchors. Once filled, sanded and painted the repair will be invisible but it will be much stronger than a thin sliver of Bondo clinging to nothing but the edge of the slot. Another anchoring method is to over-rout the error and then to drill 1/8" holes to just shy of the bottom of the mdf and filling the holes with Bondo.
11. Durham's Rock Hard Putty works great for filling small nail holes and screw holes. It is water soluble, easy to work with, and gives off no harmful fumes. It doesn't work as well as Bondo for fixing routing errors because it's quite brittle and therefore there is some risk that it will chip either when you rout it or later when the track is in use.
12. Luf's tape laying tool is a great time-saver but I found that the tape would sometimes try to cut straight across the inside of corners. To prevent this, I applied a couple of self-stick felt pads to the base of Luf's tool. This burnished the tape as I was laying it and prevented it from wandering inside the corners. Afterwards, I burnished the tape again with the curved edge of a Bic lighter.
13. You reap what you rout.
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