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Turntable Choices
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[quote]QUOTE: <i>Originally posted by NYCentral1</i> <br /><br />...I like that 90' Walthers, but what about this wobble problem?..[/quote] <br /> <br /> It's a real challange to build to work reliably, but it's not impossible if you can do some fabrication. <br />The Walthers and Heljan kits use the same drive. I built a Heljan TT, but not as the instructions show, and it works fine. Lot of modelers say the Walthers / Heljan TT's are junk. If you are not careful in the assembly, then yes it is junk. The instructions are a little more than an exploded view and I deviated from the instructions discarding the part with the gear on it and made my own driveshaft so I can remove my bridge (see photo 1). I also modified the electrical pick up for the bridge track (see photo 1 & 2). The drive coupling is my own fabrication (see photo 1). <br /> <br /> One very important step in the assembly is the lower bearing plate. The bridge hight has to be just right. The trucks on the ends of the bridge (I scratch built mine) should ride very lightly on the pit rail, most of the weight should be carried by the bearing. The Heljan kit has a lower bearing plate that glues into the center hole of the pit. That has to be positioned just right (I found that out too late and had to use a .010 shim from a generator pully on an old VW bug to raise the bearing). The bridge is attached to the upper bearing plate and my drive shaft is attached to that. The shaft has to be centered perfectly as possible. I did that by slipping a brass tube through the factory hole, to use as a locating tool and slid the new drive shaft over that. Once the driveshaft was attached, the tool is removed. <br /> <br /> I also mounted the electrical pick up differently. I seperated the two wipers and mounted them on the ends of square brass tubing and attached to the wooden base. They wipe the brass rings which are mounted on the drive shaft and connected to the bridge rails. I made the driveshaft out of brass tubing and insulated it from the power pick up rings with heat shrink tubing. The rings are made from brass tubing also. I found it was easier to solder the feed wires to the rings before installing them and then solder those wires to the bridge feeders. The connection of the motor side of the driveshaft was made from of the guts out a [url="http://www.allelectronics.com/cgi-bin/category/755200/Eurostyle.html"]Eurostyle strip connector[/url](see photo 2). On the other end of the connector I made a "T" from round brass rod which fits into a slot cut into the driveshaft. The bridge assembly just lifts up to remove and clean any debris that might fowl the bearing. <br />The polarity is corrected by a MRC power reversing module. <br /> <br />photo 1 <br />[img]http://img.villagephotos.com/p/2006-2/1148725/ttdrive2.jpg[/img] <br /> <br />photo 2 <br />[img]http://img.villagephotos.com/p/2006-2/1148725/ttdrive1.jpg[/img] <br /> <br /> <br /> If you want the bridge to turn smoothly, you have to be very careful with how the bridge rides on the bearing. The trucks on the end of the bridge must be free wheeling and aligned correctly. Build the basic bridge structure, but without gluing down the track. Dry assemble the basic bridge assembly / pit / drive parts (without glue) to see how everything fits in the pit. Note the rail hight too. Take into acount the weight of the locomotive and the sag of the plastic pit too. Plastic pits flex and will sag a just a wee bit. It can benifit from bracing or support (see photo 4). <br /> <br /> In fact you might want to build a stand or jig to hold the pit up while you work on it. Just cut a hole in a piece of plywood and put short legs under it. <br /> <br /> If you plan on building a roundhouse too, both turntable and roundhouse should be built on the same platform or base. The turntable comes first, then the round house base and tracks. Makes track alignment easier than to try to put a turntable in after the roundhouse is built. <br /> <br />photo 3 <br />[img]http://img.villagephotos.com/p/2006-2/1148725/ROUNDHOUSE9r.jpg[/img] <br /> <br />photo 4 <br />[img]http://img.villagephotos.com/p/2006-2/1148725/ROUNDHOUSE7r.jpg[/img] <br /> <br />finished TT <br />[img]http://img.villagephotos.com/p/2006-2/1148725/TURNTABLE0R.jpg[/img] <br /> <br /> <br />
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