For you competitive T-Jet racers out there, here is an article about preparation of the top gear set... particularly if you are using a mass produced out of the box gear set as opposed to a precision CNC machined set like the ones you can get from RT-HO. When preparing a car for racing you basically need to think about four things... alignment/squareness, friction, current, vibration. This sounds pretty simple from a high altitude point of view, but, these things are intertwined in every part of preparing competitive T-Jet. If you are interested in how it pertains to the top gear set with respect to friction then click on the read more link below. |
First, before we get started I would like to thank Scott Udave for sharing the following information. This info is a combination of a friend of his that was a jeweler and Scott himself who polishes brass professionally. Had I not posted the original article with some errant information on social media he would have never shared the following information. I am appreciative of Scott's information.
The following statement is what started it all. "The first thing I do to a mass produced gear set is de-burr the gears using my Dremel and brass wire brush wheel. I do not want to use anything harder than the brass gears therefor the brass brush wheel." This is where I found out NOT to do this if at all possible because it leaves scratches on the face of the teeth that causes more harm than good.
Lap the gears, yes. When the gears have been lapped and worked in together, then polish the wear side of them.You want to remove the burr on the bottom of the gear surface that rides on the top plate. You also do NOT want to remove any brass from the top of the gears because you want to keep them as thick as possible so they run square with the next gear. Next, never polish the idler hole or gear axes hole. It's a wearable surface let's not speed that along. Let the gear wear to the top plate.
The following statement is what started it all. "The first thing I do to a mass produced gear set is de-burr the gears using my Dremel and brass wire brush wheel. I do not want to use anything harder than the brass gears therefor the brass brush wheel." This is where I found out NOT to do this if at all possible because it leaves scratches on the face of the teeth that causes more harm than good.
Lap the gears, yes. When the gears have been lapped and worked in together, then polish the wear side of them.You want to remove the burr on the bottom of the gear surface that rides on the top plate. You also do NOT want to remove any brass from the top of the gears because you want to keep them as thick as possible so they run square with the next gear. Next, never polish the idler hole or gear axes hole. It's a wearable surface let's not speed that along. Let the gear wear to the top plate.
Before I start polishing I like using the Brasso as a start. It cleans and brightens the gears at the start. But that's just me. (FYI guys thats about the only sentence remaining from the original article) :-)
The following information concerns polishing. This is where Scott's knowledge as a professional polisher of brass comes into the picture. On only one side of the gear (the side that will ride on the gear plate) you will need to swipe it across 400, then 800, then 1200, then 2000 grit sandpaper. At this point is should be a mirror. If you would like to go further then finish with 2500 grit. Remember only on one side (keeping the gear as thick as possible). Also be sure to polish the gear on a hard flat surface using a single layer of paper (No folds).
Scott then indicated that he had polished gears as thin as the rules allow and those gears did not run as well as the gears that were kept thick. This was because the thinned gears would not run on a flat plane. It created a compound angle which means compounded friction.
Scott then proceeded to politely state that the author of the original article might of meant well but basically did not know what they were talking about. That author was me and after reading his reply on social media he was correct. All that said, I have learned from this and it will make me a better T-Jet builder... after all that's what this hobby is all about!!
Thanks again for sharing Scott Udave!! Much appreciated!!
Happy Polishing!!
Thanks again for sharing Scott Udave!! Much appreciated!!
Happy Polishing!!