Source of Maxon/Faulhaber 4:1 Gearheads

[mike_lawyer]

Just as an FYI, there is a guy on Ebay right now selling over 100 Faulhaber 3 volt 1024s with 10/1 gearheads with 16:1 ratio for $10 each.  You read that right, ten bucks each.  You would only need to remove one stage from the gearhead to make it a 4:1.

I bought 5 of them at that price.  I figure I can tinker with trying my hand at cutting them down.

[metalworkertom]

Just as an FYI, there is a guy on Ebay right now selling over 100 Faulhaber 3 volt 1024s with 10/1 gearheads with 16:1 ratio for $10 each.  You read that right, ten bucks each.  You would only need to remove one stage from the gearhead to make it a 4:1.

I bought 5 of them at that price.  I figure I can tinker with trying my hand at cutting them down.

That's a good price ! You can use a Zener diode on the 3 volt as Max has demonstrated. I'm working on cutting some down as I have time working out methods.

[mmagliaro]

I saw those (on eBay).  That is a great price  Be aware those are 24mm long motors, so kind of long for N Scale.
One cool thing is the motors in that ad have a back shaft.  You can barely see it in the photos.  But on the motor you can see the "K380" option in the part number, which is listed on the data sheet as the option for a 1mm diameter back shaft.   You can't put a gearhead on the back, but you could put a flywheel, if you have room.

[mike_lawyer]

I saw those (on eBay).  That is a great price  Be aware those are 24mm long motors, so kind of long for N Scale.
One cool thing is the motors in that ad have a back shaft.  You can barely see it in the photos.  But on the motor you can see the "K380" option in the part number, which is listed on the data sheet as the option for a 1mm diameter back shaft.   You can't put a gearhead on the back, but you could put a flywheel, if you have room.

Yeah, I was purchasing them just for the gearhead.  1024 is too long for the motor. 

[SkipGear]

@mike_lawyer  Thanks for pointing those out, picked up 3 to play with, I have plenty of 1016 and 1219's to mate up to the gear box. In the meantime I have roughly a dozen 12mm 104.4:1 gearboxes. I decided to cannibalize one to see if anything could be made of it...I may have something. Max, how long is the 4:1 cut down box?

Nose to tail, this one is will be about 15mm and I can cut some gears down and get it to around 11-12mm long I believe. It is just a hair under 4:1. Haven't done the math, just counting a mark on the input gear relative to the output. There is probably a some additional reduction between the motor gear and the input gear though. I have 3 528:1 gearboxes that are the same diameter but the output end is half the thickness of this one. I may dig into one of those to see what can be made.

[mmagliaro]

Tony,
The 10/1  4:1 gearhead is 9.7mm long.  That's what their data sheet says, and I just double-checked with a caliper to confirm it.  When I have cut these down, that's how I know where to cut.  I just measured that much on the larger case, put a score mark, and then cut it off as close to that as possible.

@mike_lawyer  Thanks for pointing those out, picked up 3 to play with, I have plenty of 1016 and 1219's to mate up to the gear box. In the meantime I have roughly a dozen 12mm 104.4:1 gearboxes. I decided to cannibalize one to see if anything could be made of it...I may have something. Max, how long is the 4:1 cut down box?
...
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[mike_lawyer]

Tony,
The 10/1  4:1 gearhead is 9.7mm long.  That's what their data sheet says, and I just double-checked with a caliper to confirm it.  When I have cut these down, that's how I know where to cut.  I just measured that much on the larger case, put a score mark, and then cut it off as close to that as possible.

Max -

Do you use a lathe to cut these down, and if so, what lathe would you recommend?  Or do you use a drill press?  Just trying to figure out which tools I need to cut these down.

[mmagliaro]

Max -

Do you use a lathe to cut these down, and if so, what lathe would you recommend?  Or do you use a drill press?  Just trying to figure out which tools I need to cut these down.

When I did them before, I used my vertical mill.  But I really used it like a lathe turned up on its end, meaning I chucked the gear case in the head and then ran a cutter horizontally into it to cut it off.  But for any more I do, I will use a lathe as it will be much easier (and I have one, hooray).  I own a Grizzly 8 x 16 lathe.  I've had it since April of last year and I'm really happy with it.  I has plenty of power for "bigger than train" work, and after a little tweaking, the run out and vibration are low, the precision is good, and it's easy to use.  I'd guess I've used it about 100 times and nothing's blown out or broken on it.  Can't complain.

[metalworkertom]

I'm using a Sherline that was used. You need some way to indicate the motor so it running as true as possible in the lathe Chuck. I'm using a dial indicator. A boring bar that will go in a 7 mm hole approximately , that's the gearhead ID before the recess is cut to size for the threaded insert. A parting cutter and whichever cutting tool you use for removing the threaded insert. I'm using plug guages to check my ID as I cut. Still making adjustments on this lathe and making repairs needed to cut true while practicing the boring operations.

[mmagliaro]

Well, I just did one of these on my lathe.  I used a plain old high speed steel tool bit to gradually peel off the outside of the case around the threaded insert until the back end of the case was gone and the insert just dropped out.  I used the same HSS cutter to cut the end of the case off so I ended up with the required 9.7mm length.  I have a boring bit set and one of them was small enough to fit inside the case, so I chucked that in the tailstock and used that to cut out the inside of the back of the shortened case until the threaded insert would fit.  I measured with calipers to get close, and then I just bored out a few thou at a time until the threaded insert would push in snugly. 

It took me about 90 minutes from nothing to a finished 4:1 gearhead working really nice on a 1016 motor.  But the worst part of the job was washing and brushing out that gear case after all the cutting.  You can't have one particle of metal left inside there anywhere or it will find its way onto a gear tooth and jam the whole thing or make it run rough.  I just use a clean brush, acetone, and keep washing and wiping off the brush on a clean paper towel.

I ran the gearhead case in the lathe just in a plain old 3-jaw chuck.  And while those aren't often the greatest for precision, I've fiddled and tested this one with a piece of 1/2" precision drill rod in it until a dial indicator shows only about .0015" runout, so it's plenty good enough to do this job.

Final result was a gearhead that will start up at only about 0.25 volt in both directions, and with a current draw at 12v of about 30 mA.  That's the same as a factory 4:1 gearhead mounted on this same motor.  That's the best way, I think, to know you've really got it right, when it can run as slow and draw the same current as factory.

It is DEFINITELY easier to do this with a lathe than it was the last time I did it in the vertical mill.  More accurate, too.

Oh, one final thought.  The only thing I bungled was the cutting speed for the boring bit.  I should have run it really fast to minimize the damage to the rear edges of the teeth inside the case.  But I didn't think about it and only ran it at about 500 RPM.  I had to scrape out the end of each inside tooth with an Xacto point to clean out the metal flash left behind.  Next time, I'd go more like 1500 RPM.

I'm happy enough.  I'm not a pro machinist and I pulled it off.

If I'm feeling industrious, maybe I'll do another one and make a video of the whole operation, step by step, so people can see what we're talking about.  ... Just promise me that the real machinists out there won't pick on me too much for being such a rank amateur.

[SkipGear]

I picked up some of the 16:1 motor/gearboxes that Mike mentioned earlier and they arrived Friday. I've been contemplating a way to take them apart without initially cutting them down.

My idea is find/make a tool that threads into the gearbox in place of the motor. Then slip the gear case into another tube/pipe and slowly wiggle the two apart with a side to side motion. The problem is replicating the fine pitch of the motor mount thread.

[narrowminded]

My idea is find/make a tool that threads into the gearbox in place of the motor. Then slip the gear case into another tube/pipe and slowly wiggle the two apart with a side to side motion. The problem is replicating the fine pitch of the motor mount thread.

I know a guy.

I could look at a sample and if it's viable, probably make that tool.  Are they assembled with glue or such that they just won't press apart?  I ask because it might be possible to make a collet type grip for the barrel/ body end and then just press the two apart... maybe.   A potential problem with this idea might be that the clamping force of the collet would increase the press fit on the end piece.  Also, are there plastic internal parts to those gear heads that wouldn't stand some heat or are they all metal?

[metalworkertom]

I know a guy.

I could look at a sample and if it's viable, probably make that tool.  Are they assembled with glue or such that they just won't press apart?  I ask because it might be possible to make a collet type grip for the barrel/ body end and then just press the two apart... maybe.   A potential problem with this idea might be that the clamping force of the collet would increase the press fit on the end piece.  Also, are there plastic internal parts to those gear heads that wouldn't stand some heat or are they all metal?

I don't think there is any plastic in the gearheads. These are things I had also considered. Really only useful if there is reason to save that amount of gearhead body with the internal gear cut into it.
I'll send you a few Monday or Tuesday for you to play with.

[SkipGear]

No glue, just press fit. The main reason you can't just pull them apart is nothing to grip on. Threading into motor mount seemed the simple solution. Wasn't sure about gripping the body but a collet should keep it from deforming.

Pressing it out would save a lot of debris from getting in the gears.

It would also then give you a way to maintain or pull things back apart if you missed on your original modifications. Im really big on serviceability. No gluing motors in, nothing that you have to break to take things back apart.

[narrowminded]

Without re-reading everything, I thought there was mention that if the case could be cut without losing too much length then a second gear head might be able to be assembled from one double planetary set .  It took a new end cap or maybe both ends but the biggest problem was losing the internal gear length if my memory is correct.  And maybe instead of a plain collet friction grip, a groove could be cut at what will be the parting line when cutting the body length and a tool that inserts into that groove for a grip without compressing the shell.  Even if no effort was made to try to salvage a second piece the groove idea might be legit.  This is why it would be best to see one.  The options will be more evident with one in hand.