I decided to mount the drive system onto the frame to see how loud the gear noise is and how much vibration there is. I am quite pleased to say that the noise is minimal and so is the vibration when running at fairly low speeds (there will be no reason to run the blades faster - they look great at low speeds).
Here is the latest video. Again, the recording makes the gear noise seem to be louder than it actually is. Click on 'Watch on YouTube':
I now think that all the fuss about getting the drive system to run perfectly smoothly was unwarranted. I did need to make the adjustments to the gear alignment and slop, but the remaining noise and extremely minor chatter seems to be inconsequential.
Cheers!!
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Attuvian1You say that the noise lasts for a half second at two and a half second intervals. It makes me wonder if there is a local irregularity on both the worm and the worm gear. Being that the worm surely makes more revolutions per second than the gear, I'm wondering that the differential is such that after 2.5 seconds of operation at a given speed, an ever so slight irregularity on the worm "catches" up to a troublesome few teeth on the gear until sufficient turns occur that they fall out of sync with each other until the "mating" of these two particular portions occurs a few seconds later. This might account for the non-continual, but regular interval growling. I would imagine that the frequency of the growling is directly porportional to any variations in the steady speed at which you are operating the mechanism. I also suspect that at a given speed, a little math based on the gear ratio could verify or predict the frequency and duration of this noise if it is traceable to what I suggest.
Hi John,
I totally agree with your conclusions, but I think the problem will work itself out.
I have been running the drive system for about two hours tonight and the noise level and the length of the chatter are noticably reduced. I'm hoping that a few more hours running time will eliminate the noise altogether.
Here is how the drive sounds now. The recording makes the sound more pronounced than it really is (pardon the shaky camera):
I would be interested in hearing opinions about how serious the problem is. Should I be worried about the long term life of the drive system or not? Keep in mind that the plow is a novelty item. It probably isn't going to get a lot of running time, and it will have sound.
Thanks,
Dave,
I will immediately admit that I am not well-versed in drive mechanics, gearing, and what-not. Having excused myself, however, my noggin keeps churning on what may be going on with this chatter. Hear me out and reply accordingly, all.
You say that the noise lasts for a half second at two and a half second intervals. It makes me wonder if there is a local irregularity on both the worm and the worm gear. Being that the worm surely makes more revolutions per second than the gear, I'm wondering that the differential is such that after 2.5 seconds of operation at a given speed, an ever so slight irregularity on the worm "catches" up to a troublesome few teeth on the gear until sufficient turns occur that they fall out of sync with each other until the "mating" of these two particular portions occurs a few seconds later. This might account for the non-continual, but regular interval growling.
I would imagine that the frequency of the growling is directly porportional to any variations in the steady speed at which you are operating the mechanism. I also suspect that at a given speed, a little math based on the gear ratio could verify or predict the frequency and duration of this noise if it is traceable to what I suggest.
Only a theoretical shot in the dark here.
On the other hand, I would think that if this is indeed the source of the problem, you would have noticed some change - at least in the sound level of the grinding - based on the wear-in going on.
John
OvermodTry puttng a little thick EP grease into a 'hypodermic' injector lubricator, and force it laterally into the bearings. This should provide the right measure of 'hydrodynamic centering' to eliminate shaft walk or chatter as 'the cause'.
Hi Overmod,
I'm not exactly sure what 'EP' grease is but it sounds like it could answer the question of whether or not the bearings are the cause of the chatter. I have syringes but getting the tip of the needle into a position where I can force the grease into the rotary blade shaft bushings will require removal of the blades. I'm a bit reluctant to do that because I have them balanced pretty well right now. If I do decide to remove the blades I might just as well replace the bearings and the shafts and start fresh. However, after thinking about the situation, the bearings are probably not the problem. See my next paragraph.
OvermodIs the noise periodic with the rotation of the worm gear/worm wheel (as I suspect from the description)?
Yes. At medium low speeds (I'm guessing about 3 volts) the chatter occurs about every 2 1/2 seconds and lasts for about 1/2 second. That suggests that the bearings are not the problem. If the bearings were at fault the chatter wouldn't likely occur so regularly.
Overmod Are the teeth on the worm wheel slightly angled to match the 'twist' of the worm -- if so, look at the profile of the teeth one by one to make sure one or more of them hasn't been damaged...
Yes, the teeth on the worm gear are slightly angled. Both the worm and the worm gear came from NWSL from their .3 Mod gear selection so I'm assuming they should be compatible.
I have looked at the teeth on both the worm and the worm gear after they were thoroughly cleaned and scrubbed. There was no damage. I could see where the brass teeth on the worm gear were starting to get polished after a couple of hours run time.
PruittThe compound should be a bit noisier (I think) while it polishes and laps in the teeth.
This was a lot more than 'a bit noisier'. I thought the gears were about to smash themselves to pieces. I did use the compound very sparingly. In fact I used a smaller amount then the amount of grease that I would normally apply.
I think I made three mistakes. The first was not having the gears properly aligned. That was just sloppy workmanship when I built the gearbox. The second was not having enough thrust washers in place to eliminate the end to end movement of the drive shafts. The third was trying to add oil to the polishing compound in an attempt to smooth the operation out. The oil allowed the polishing compound, which had now turned into a slurry, to work its way into the thrust washers and the bearings but it didn't make much difference in the amount of noise.
PruittOr you might not want to go back in the direction of lapping / polishing compounds at all.
That's exactly what I intend to do. Now that I have the gears aligned properly and I have eliminated the end to end play on both shafts, it runs fairly smoothly. There a little bit of chatter, but as I said in an earlier post, I think that is due to sloppy bearings after I reamed them with a drill bit to line them up. I have another set of bearings on order but before I replace the existing ones, I'm going to run the drive system for a few more hours.
Thanks for your advice.
hon30critterThe other problem with the Dremel compound was that I had a heck of a time cleaning it out of the thrust washers and bearings. In fact, I had to disassemble the whole thing to get everything clean.
It sounds like maybe you used too much of the compound. If you apply it sparingly (like you would grease), it shouldn't migrate to the washers and bearings. You only want it on the worm and gear teeth, not on the shafts and bearings.
The compound should be a bit noisier (I think) while it polishes and laps in the teeth.
I heard decades ago that using something like Pearl Drops tooth polish will accomplish the same thing less aggressively than lapping compound does (it's designed to go in your mouth).
Or you might not want to go back in the direction of lapping / polishing compounds at all.
Mark P.
Website: http://www.thecbandqinwyoming.comVideos: https://www.youtube.com/user/mabrunton
Try puttng a little thick EP grease into a 'hypodermic' injector lubricator, and force it laterally into the bearings. This should provide the right measure of 'hydrodynamic centering' to eliminate shaft walk or chatter as 'the cause'.
Is the noise periodic with the rotation of the worm gear/worm wheel (as I suspect from the description)? I don't remember if you said there were multiple threads on the worm. Are the teeth on the worm wheel slightly angled to match the 'twist' of the worm -- if so, look at the profile of the teeth one by one to make sure one or more of them hasn't been damaged...
After close to three hours of running the gearbox is still making an odd sound every few seconds and I think I know why. When I was reassembling the gearbox the second time, the rotary blade drive shaft bearings weren't perfectly lined up. The missalignment was very slight but the drive shaft wouldn't slide through smoothly. Instead of adjusting the position of the bearings I decided to just run a 5/64ths drill bit through the two bearings. The drill seemed to be very close to the diameter of the 2mm drive shaft so I figured that it would be okay. Therein lies my mistake, I think. I believe that using the drill bit enlarged the openings in the bearings too much, and now the drive shaft is chattering because of the excess space. I have ordered replacement bearings in case the problem gets worse. Right now its not too bad.
PruittThis may be a few days too late, but if you're still running the mechanism to let it wear in, try adding a bit of lapping compound to the gears and worm. It will greatly help everything "wear in."
Hi Mark,
I tried using Dremel's polishing compound but it caused the gears to make an awful noise. They definitely weren't happy. I think the Dremel compound is a finer grit than what I remember of the lapping compound from my engine rebuilding days.
The other problem with the Dremel compound was that I had a heck of a time cleaning it out of the thrust washers and bearings. In fact, I had to disassemble the whole thing to get everything clean.
After I realigned the drive shafts and added a couple more thust washers, it runs fairly quietly, but I'm going to let the mechanism run for a few more hours. Hopefully that will smooth everything out. I have ordered a delrin gear the same size as the brass one that is currently installed. If the gears won't quiet down I will try using that.
Thanks for the suggestion,
Hey Dave,
This may be a few days too late, but if you're still running the mechanism to let it wear in, try adding a bit of lapping compound to the gears and worm. It will greatly help everything "wear in."
Water Level RouteGood luck Dave! I can't wait to see this thing fully assembled and running.
Thanks Water Level Route. Please be patient. There is a fair bit left to do.
Not much new to report. I got the new side panels that surround the rotary blades cut out, but other that that all I have been doing is staring at the plow trying to figure out how to do things. I want to be able to remove the shell that is behind the rotary blades, but I think the areas around the blades will have to be permanent. I don't want to risk having part of the body come loose where it could fall into the rotary blades when they are running.
More later,
hon30critterWish me luck!
Mike
I went back at the gearbox again tonight to try to eliminate the odd noises. All I did was add another thrust washer to the worm shaft. The change made a small difference but there is still some occasional minor rumbling. It happens every 10 seconds or so, so apparently there is a spot where the worm and the worm gear aren't meshing perfectly. I'm not going to worry about it. I will run the drive system for a couple of hours to see if things improve, but if they don't, the noise isn't bothersome enough to justify more fiddling.
Of course things are never as simple as you would hope for. After installing and removing the worm gear a few times, it lost its ability to lock onto the rotary blade drive shaft. I solved the problem by knurling the section of the drive shaft where the worm gear sits very slightly, and then adding a tiny amount of Loctite to the hole in the gear. The knurling wasn't so large that the shaft wouldn't go through the bearings, but the gear is now solidly in place. Getting the gearbox to work properly has definitely been a story of a few steps forward and multiple steps back. Am I upset? Not in the least! It's all part of the game.
The next step will be to change the parts of the shell that surround the rotary blades. The existing ones are too big now because I reduced the width of the rotary blade veins. Part of the process will be to incorporate the fixed blades on the front of the plow into the shell assembly. That will require a lot of trial but hopefully without too much error. Wish me luck!
I had another go at the gearbox tonight. The gearbox wasn't running smoothly, particularly at slow speed. When I was running it to break it in, it was making clunking noises every few seconds. It sounded as though the gear teeth were catching on each other.
I knew that I didn't have the rotary blade drive shaft perfectly perpendicular to the worm, and after closer examination I realized the the worm gear was slightly offset from the center of the worm as well. Apparently that combination of misalignments (read sloppy workmanship!) was causing the rough running. I took the gearbox apart and made a small adjustment to the position of one of the bushings for the blade drive shaft, and when I put it back together I adjusted the number of shims on either side of the worm gear to center it over the worm.
It has now been running for an hour at a fairly slow speed and it is much smoother and quieter. It still makes the occassional odd sound but I attribute that to the brass worm gear not being properly worn in yet.
The drive system is capable of spinning the blades at fairly high speeds but I don't intend to operate it that way. I think there would be too much vibration. The blades look better at lower speeds anyhow IMHO.
doctorwayneIf you'd rather do it yourself, I can send you some sheet aluminum. It's .020", and very easy with which to work. I usually score the dimensions using either an X-acto or a utility knife, then flex it to detatch it from the sheet. I use tin snips to make any cuts necessary for folding the form.
Hi Wayne,
Thank you very much for the offers. If I do decide to make castings I think I will work with the 0.005" brass sheet that I have on hand. The weights will be one-offs so I'm not worried about using up the forms.
Before I do any casting I'm going to see what I can come up with using the lead sheet. I have a reasonable amount of experience working with it as is evident in these critters:
Thanks again,
In most cases, I try to balance the added weight, especially in locomotives, but it's also advantageous in most rolling stock, too.If you can find some space inside the plough, and are able to measure it, I should be able to cast some weights for you. If you'd rather do it yourself, I can send you some sheet aluminum. It's .020", and very easy with which to work. I usually score the dimensions using either an X-acto or a utility knife, then flex it to detatch it from the sheet. I use tin snips to make any cuts necessary for folding the form.
There's a thread HERE which pretty-well covers the process.
Wayne
Attuvian1Well, as far as weight is concerned, you have some flexibility. Even with counterbalancing the blades. I'm continually amazed at where modelers afix weights, even to shells. First began to notice this creativity in some of Dr. Wayne's photos. Custom shaped, no less.
Now you have me starting to think about where I could stash some weight without detracting from the appearance. One place that came to mind immediately was the firebox. There is a sizable amount of space behind the electric motor.
Doctorwayne's skills at adding weight are amazing. I have lots of brass sheet that could be used to make forms. Mind you, he uses aluminum to make his forms so he can re-use them. Using brass would be a one shot deal.
I also have a sheet of 1/16" lead which I have used in several of my critters. I could replace the stytrene floor with that.
hon30critter I do have an alternative. That is to remove the 0.040" styrene floor panel and the metal weight which I'm guessing is about 0.060". However, I think that removing the weight would be folly. If anything, I need to add more weight to counteract the mass of the spinning blades. If I go that route, I will start by removing the styrene floor only.
I do have an alternative. That is to remove the 0.040" styrene floor panel and the metal weight which I'm guessing is about 0.060". However, I think that removing the weight would be folly. If anything, I need to add more weight to counteract the mass of the spinning blades. If I go that route, I will start by removing the styrene floor only.
Well, as far as weight is concerned, you have some flexibility. Even with counterbalancing the blades. I'm continually amazed at where modelers afix weights, even to shells. First began to notice this creativity in some of Dr. Wayne's photos. Custom shaped, no less.
Attuvian1Just thinkin' out loud: is Goop too runny to apply to both sides of a felt pad for sound deadening?
I actually have a product that is called 'Glooz-It' which was originally developed for shoe repairs. It is a fairly thick gel and it doesn't 'run' when put in place. It forms a very solid flexible bond when cured.
The issue with using something like a felt strip to deaden the noise is that it will raise the drive mechanism up above the floor. That will put the rotary blades too high. I have already raised the height of the drive mechanism by adding the reinforcing C channels along the sides of the driveline frame. The difference isn't very much (maybe 0.025"), but if I add more height I'm afraid that I will mess up the appearance of the plow.
The first step, once I get the blades running true again, will simply be to hold the drive system firmly against the frame and see how much noise it makes. I'm going to work on that tonight.
Just thinkin' out loud: is Goop too runny to apply to both sides of a felt pad for sound deadening?
I hate plastic glazing, too.
Attuvian1I suspect that you're cresting the hill and most of the stuff left will be fairly straight forward.
Hi again John,
I'm not so sure. There is a lot left to do. The next major step will be to mount the drive system onto the frame. I'm worried about noise transfer if I bolt it down tight so that might take some experimenting. I might just use 'Goop'.
I also have to add power pickup to the wheels and then figure out where to hide the decoder and the speaker(s).
After that there will be a ton of detail parts to install, paint, window glazing etc. etc. I may forego the window glazing if I can't get the Ngineering glass slides cut properly. I hate plastic windows.
Attuvian1There is a real interest in this project. That following is reflected in te number of hits for the string!
Half those hits are probably me looking to see how many hits I have!
Thanks, Dave. There is a real interest in this project. That following is reflected in the number of hits for the string! I suspect that you're cresting the hill and most of the stuff left will be fairly straight forward.
Attuvian1This may have been covered somewhere earlier in this string, but are you going to install a decoder?
I am indeed going to install a decoder, and I want to include sound. There are a couple of YouTube videos of the Cumbres and Toltec rotary steam plow working under load and the sound is pretty good. I already have a Lokprogrammer and I have lots of Loksound V5 decoders on hand. All I have to do is learn how to transfer the recordings to a decoder.
Attuvian1I'm also curious about the max operating revolutions that might have applied to the prototype - presumable operated from the cupola.
The prototype rotary blades operated at about 200 rpm. It amazes me to think of the forces generated considering the fact that the veins were solid steel 4 1/2" thick.
Yes, the prototype would have been controlled from the cupola, but I'm not sure how the controls worked. Overmod suggested that there might have been mechanical linkages to the throttle, etc. There had to be a crew inside the body of the plow as well. Obviously they needed a fireman and I believe there was an engineer who saw to the adjustments on the plow's engines and boiler.
The operator in the cupola also had to communicate with the locomotives. The Cumbres and Toltec units used steam whistle signals to issue commands to the locomotive engineers. I'm not sure what the prototype used, but using whistle signals would add to the sounds considerably.
I tried the Dremel polishing compound this afternoon and I wasn't happy with what it did to the gears. The compound seemed to be fine enough, but when I applied it to the brass worm gear, the gearbox started to sound like I had poured coarse sand into it. I suspect that the mating of the gears is rather tight and so the grit was preventing the teeth from sliding against each other. I only ran the gearbox with the compound in it for about 30 seconds before I decided that it wasn't the right thing to do. I will let the gears wear in over time on their own.
Cleaning the gunk out of the gearbox was a bit of a challenge. I couldn't get my usual cleaning brushes into all the nooks and crannies so I stole a rather nice long bristled brush from my paint brush collection and used that. I also ran the drive gears in a tub of alcohol to get as much of the grit out of the bushings and thrust washers as possible. Its drying as I write. Once all the alcohol has evaporated I will apply Labelle lithium grease to the gears and 10wt Nano oil to the bushings and thrust washers.
While I was doing all of this I noticed that one of the rotary blades was wobbling again. I thought I had sorted that out but apparently not. I had used Loctite red to anchor them in place. I'll have to figure something else out.
This may have been covered somewhere earlier in this string, but are you going to install a decoder?
I'm also curious about the max operating revolutions that might have applied to the prototype - presumable operated from the cupola.
Thanks guys.
I have ordered some Dremel polishing compound to help break in the gears.
That's impressive, Dave! Mechanism looks very well balanced.
Very nicely-done, Dave.
Dave, that is awesome!
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."