DoVoMonOgel

Title says it all :-) Could not find any posts leading to any source or alternative Ideas on how to replace the tiny Carbon Brushes in the 6-Wheel train motors. Those little thingys are only some 3*1.5*2.5mm or so when new. They are only "clicked" into their copper contact arms, which in turn are hard-fixed to the left and right motor body weight blocks. That fixture could easily be undone and replaced by a small screew if need be... i.e. if anyone knows of readily made copper+brush parts that can go in place of the originals. Anyone??

Cleary on top, not teethed I'd say. No teeth on the inside of the straight beams, and it speeds up on those straights.

Did as dr_spock suggested. Not a very accurate way of getting the numbers, as the "source lines" printed by rolling the gear are so short. It *might* be 15degrees going by the worm. Is that a common value!? Going by a plastic and a brass gear wheel, I'm not entirely sure, might as well be something like 18 degrees. Will have to dig deeper/harder into worms and gears and common "pairs". Read somewhere (not sure I got that right, though) that angles aren't necessarily matching to allow (or prevent) blocking and/or optimize the line of contact between worm and gear. So might there in fact be some few degrees "delta" intentionally? Any experts around?

Hi all. I have about 5-6 open (now "screw-able" ) 7865s and on two of their shafts I have brass bevel wheels (and on the motor shaft brass worm gears in all cases). All other shafts have white plastic bevel wheels. I never saw any photos of brass bevels I think, and could not g**gle it. I didn't pay much attention and had one brass and one plastic shaft combined in one motor. After a large number of rounds I noticed that one shaft was rotating freely. Opened up and damn! the worm gear running on the brass bevel was completely f*cked, nothing left of the spindle. The bevel looks undamaged. So, the brass bevel is a worm-killer. But ... it must have come out of one of my motors, I definitely have not bought them and swapped them on. I must have cross-swapped the brass shafts out of that source motor into the other motors at some point. I *believe* the brass ones may have come out of my very first motor (with fixed, non-removable pin on top), received in 1983 with my beloved 7740 under the tree. That one lost a worm gear in abt. 2014 when my little one tested her strength against the train, holding it in place while it was at full ahead. (After that my misery ("addiction" in psychology I guess) started, as a replacement Motor had to be sourced, doubling the track length when coming with a lot of extra track . . . don't ask how many more meters, trains and motors there are today, just don't ask please (and don't tell my wife!) :-))) ) The other brass bevel shaft sat in a red motor safely stored and hardly ever run since I fixed it - luckily. Will swap that one out for a plastic one immediately to not risk more worm gears. The question is: which types of 7850 came with brass bevels, and is there a difference then in the worm gears that came with them? I'm afraid there might be a mismatch from plastic bevel matching worm gears versus those that originally were in that brass bevel motor. I can't check it any more, as that original motor took damage to the commutator- fixed ring plate later on, and donated it's remaining worm gear to another motor. "All a mess" , sorry. Also, does anyone have the correct specs for the bevels (plastic ones more importantly) and the worm gears? I never saw any modulus or ratio figures. Bevels have 18 teeth in both variants, and overall dims are easily measured. But detailed teeth and worm geometries not. It is not a modulus of 0.4 on the worms, I know cause I guesstimate that and got hold of two worms with that ratio, but they are different. If we had those numbers... Or, if we had alternative similar matching pairing of bevels and worms available from the hobby train sector... swapping worms and bevels off the lego shafts is doable. Only the parts need to be found. Anyone of you experts? Have a great day! The white one has obviously suffered and isn't usable any longer. Not sure when and where that happened.

Have not found anything on ali yet. 1 lead (and some 2 lead) worms, but not 3. For the interface of plastic gear wheel on shaft, I measured again on the one shaft I have without a gear: The shaft is 3.25 mm where it has no teeth. And on the teeth I measure 3.45 mm. So they are actually teeth with groves in between, not only groves. Hence, the bore in the gear should be 3.25 (-0.00/+0.05) I'd say. Then it would slip on easily along the shaft, and the teeth can cut into the bore to give perfect grip. If this cracks the wheel quickly, one can carefully pre-extend the hole slightly, or source gears with a 3.30mm bore next. Need to find someone who can make those wheels. Have some guys with "normal" 3D printers around, but will need to give them a model file to start with. What I can't measure is the helical angle of the teeth, it's not a "straight" "spur" gear. Not sure how to work that out accurately, will have to dig into it later.

Removal is easy, if you have reason to remove, then the wheel is already damaged in one way or another, so cracking it off is just fine. Getting it on might be a question of well-controlled force and maybe some cooling (freezer for 10 Minutes?) of the shaft and maybe careful warming (60C?) of the new wheel. "Interference Fit" should already do the rest of the job. When the replacement gears are e.g. Nylon and their bore is 1.95mm with the shaft being 2.00, the nylon would sit tight alread and the groves might add to the fit. First hit on g**gle tells me we don't have to reinvent the wheel here, literally :-) and given Bühler made the groves for us no need to roughen the surface. Still not found any source for the worms. Not sure if what shapeways could do is the right level of precision after reading about their min / max dimensions for printed + polished brass. Needs to be polished to ensure it runs smooth against the (nylon?) wheel. Maybe we have to head over to some other model builder forums for some input...RC racing or train guys maybe.

For the quest for the worm and wheel geometry: I took some measurements of the plastic gear wheel and the brass worm the other day. *Please* do scrutinize, question, correct! I'm not that familiar with worms :-) Gear Wheel (plastic, white; won't deal with the brass ones much more as I somewhat fear them now) n = 18 teeth D = 8 mm (outside / addendum / tip diameter) d = 3,2mm (inner diameter on shaft; measured the shaft itself; believe there's not much difference as the actual transmission is by tiny teeth on the shaft onto which the plastic worm wheel is pressed) face width of the teeth: 4 mm base width of the wheel on the shaft: 8 mm Modulus: m = Outside Diameter/(Teeth+2) = 8/(18+2) = 8/20 = 2/5 = 0,4 => this should then also be the modulus for the worm, which is harder to measure accurately Brass Worm 3-start worm (3 worms/screws/teeth on the cylinder); can be seen best when looking along the shaft axis at the flat face of the worm gear L = 6 mm D = 5 mm (outside diameter) d = 2 mm (inner diameter; likely rather 1.95mm given the interference fit; I measured the shaft outer diameter) approx. 1,66 windings for each worm along the 6 mm length (not relevant I guess) Modulus? 0,4 as for the worm wheel above, right? Otherwise they wouldn't fit. Transmission would then be 18(Wheel)/3(Worms) = 6 => 6 Turns of the higher speed motor shaft giving one turn of the wheel(s). Can anyone crosscheck, verify, confirm or correct this please so that we don't have wrong numbers in the world.

I wouldn't want bevel gears from metal ever again given my findings, as I believe the pairing brass-worm-gear vs. plastic-bevel-gear is "safer". If one would have suitable plastic bevels available from other sources (not sure if 3D printing is fine enough to produce such delicate structures with sufficient precision?), they would be the "sacrificial" part in the combo and are (relatively) easy to replace. Replacing worm gears is way more complex and risky. If the motor itself drops or you slip with your tools you may damage the commutator disc, and that's more or less it then (there is a guide in German here on how to steal such a disk (and commutator) from a different kind of motor, but that's quite a job). So the motor itself with the brass worm gears is the "holy grail" to be protected by all means I'd say.

Solved, kinda. These have arrived yesterday. The small end can be carefully reduced in width so that it fits into the holes in the copper holder arms. The brush itself is rather high / thick compared with the original, but there is enough room below + above the motor shaft so that they fit in without further effort. And: IT WORKS.

Thanks for the links. Yes I had seen those threads before asking (at 1000Steone, too, yes indeed). But there is nothing in those helping with the "brushes", no mention anywhere (I could find) where someone found replacements for these tiny fellas. I've now ordered some larger ones on eba..., will see if I can carefully reduce them to get them in... tbc. Party time now over here, have a good one!

@legolux1973 "Freakin' awesome" (mildly put) :-) Did you by chance share instructions or a "Set inventory" for this lovely MOC? Our little "June" over here is so into her doll world, and me into my trains ... that she definitely needs one like this :-) On Flickr I only see one or two poster shots like the one above, are there more detail pics anywhere? Found your account on afol.lu, but not this set there . . . anywhere else to look? PS/OT: your remake of the famous yellow castle is absolutely magnificent!

Hi everyone. 12 Volt enthusiast here. All my "normal" trains run on 12 Volt, even with PF train motors (Horizon Express becoming a true express; 10277 heavily modded, running on two normal PF train motors... etc etc. But that's for another forum & time). First things first. Credits: Most of what I show here is not my inventions. There's been some 12V MRs around before, but I really didn't find too much of it to be honest, despite many hours of searching and following traces. When I get some more time I should make a list of things I took from you other inventors out there who developed what I based my work on. Big t-h-a-n-k-s to all of you and your countless hours of paving the way. Intended to publish my 12 V Monorail work for ages, never got round to do it. Been working on this for about 4 years on-and-off, taking lots of ideas from all the great contributors here and elsewhere, and trying to combine their solutions for a 12V high-speed boogie-based 12V MR, using standard and common parts as far as possible. Not entirely "pure", maybe a few "illegal" details here and there. But the latest prototype is back to "pure original unmodified" parts (except for the cabling). Rail geometry may need the one or other cut power rail though, settled for the blue 70s stuff as it's cheap and hey, who else does red-blue tracks :-) ? Below is just one pic of the "snake train" I more or less settled with. I went through about 20 different arrangements of motors, power pickups (some "self-made" experiments but in the end settled for the good old 12V pickups from the 70s/80s), bogies, gearing. Using PF train motors, various wheel arrangements, 9v block motors (settled for them, cheap stuff, robust, can take 12V apparently "forever", heavy, leading to good traction); tried PF motors, too, but don't like them as much. Overall, aims were: Speed Speed Speed Make the functional internal stuff of the trains 4 wide, to get the trains 6 wide (plus a bit maybe, but generally 6w), and be able to work on the technical internals while keeping the fuselage more or less the same to develop both independently or re-use what had worked okay. hide the bogies as much as possible. So after many tries over the last years, I now have a "snake train" approach working quite well. Snake train double power pickup boogie, first car, and first dual-engine powered bogie. There's a driver sitting in front of the bogie actually, but he's part of the fuselage that slips onto the depicted internal module. Here's a front/rear car cover. Plates on the sides and at the ends of the cars with studs to the sides not fancy, could be tiles eventually. Function first... 20220606_183955 by Tolv Volt, on Flickr Another working approach is a "locomotive-pulled" train, like in conventional trains. Two bogies powered by two vertically mounted 9v block motors with some top-gear. Eats up more energy, not as fast as the snake approach, and the internal structure tends to "bend" through after a while. Could be fixed by designing a fuselage linked fixed to the internals instead of the "slip-on" cover approach used for now. Not really following this road at the moment. 20220606_185900 by Tolv Volt, on Flickr So much more to do... make more robust track (it's all quick and dirty "function first"), especially pillars. As my test track had to somehow fit onto the underlying 12V layout, there's no space for more than 2x2 brick pillars leaving the entire track a bit shaky. And inclined curves eventually, to tilt the trains inwards. Switches... have some prototypes setting out the general geometry. Fine tuning and motorizing them should only be a question of time and technic pieces. Rotating 2-way switch 20220606_192853 by Tolv Volt, on Flickr Want to see stuff in action? https://vimeo.com/tolvvolt Plenty more pictures (all quick and dirty for now; tons more on my phone...) on Flickr. [Edit: removed the embedded photostream here after adding pics on Flickr not directly related to this snake train solution] Looking forward to many adopting 12 Volt MR challenges :-)