......

Thanks Bernd, I will look forward to watching this build. 

The build

It'll take a bit of time, but it will get done. I can't believe I've actually still have an interest in it. I usually never finish because another interesting project caught my fancy.

Bernd

Nice to see it works

I had originally thought you would turn of 1/2 of the thickness of the plastic, epoxy in a brass ring to make up the difference, and then turn out the inside and replace it as well.  That would use the original plastic as the insulator, locator, and attachment point.  Out of curiosity, why would you turn the ring off instead of just cutting it off?  Did you turn some sort of registration lip/hole?

I'm the same way, which is why I have umpteen different projects going in multiple scales.  At least now they're (mostly) all related to my prototype.  Like you, I'm trying to behave and see a project through from start to finish.

This should be interesting!

Now, if a guy wanted to take that turned ring and cut gear teeth on either the inside, the outside or around the top of the ring, could that fellow use a mill to accomplish that for himself?

I gotta agree with Ken, I sure do like the shiny stuff!  There is something about the addition of the machined brass or even aluminum...it just looks better.

Gear cutting requires

some relatively expensive extra bits for a mill. A dividing head or rotary table come to mind. You have to rotate the part accurately, one tooth position at at time, then sweep a shaped cutting wheel across to form the tooth.

There are hobby machinist magazines that have had all sorts of DIY extra tool making articles,  that can save a bunch of money, if you are willing to buy the basic tools and put in the time. 

The why's

@ Ken, the reason I did it that way is the fact that the wall of that turret is very thing, approximately 1/16" or less. What you suggested would have worked if the whole turret had been a solid piece of plastic.

I counter bored the bottom for the brass ring to fit in. I'll take another picture to show that.

@ Kevin, a mill will not do it for inside teeth, what is needed is a gear shaper with special ground cutters for the specific style gear cut.

@ Andy, your wrong. You need a gear shaper. A much different machine. Here's how I know this. I worked for a major machine manufacturer that produces gear cutting machines around the world. I worked there for 30 years. If your interested do a google search on Gleason Works. Now if you have nothing constructive to add to this conversation I'm asking you nicely to not comment. I will delete your posts if you get out of hand. Mr. Fugate take note of my statement.

Now back to modeling.

Bernd

Enjoying the modeling

How much force can the spindle of a mill handle?  The reason I'm asking is that you could cut inside teeth with a broach (basically a gear-shaped rod with the end sharpened, or even a single tooth shape - I know you know what it is, but I'm explaining for others who may not) by pressing it down into the brass slowly and repeatedly.  It's not the fastest or perhaps the best way, but it saves on tooling costs.

I also have to agree with Andy on one thing - the hobbyist magazines, web sites, and forums are excellent sources of DIY information and ideas.  There is a lot that can be done cheaply if you're willing to invest more time and have a good understanding of the tools.

Back to the subject, though.  I dind't realize the material was that thin.  Makes perfect sense now.  I presume that there is nothing on the inside of the turret, so the internal dimension is not critical, correct?

Would it be useful and/or possible to redesign the mating portion on the cab floor?  It looks to me as though the two halves of the floor must be assembled around the turret in order to engage the lip.  It seems to me that it might be easier to make the floor a solid piece, and screw down through that into a brass ring which fits around the one you just made.  I don't really know if it would make a difference, but I was thinking that it might make the addition of mechanical and electrical bits a little easier if the floor could be a single piece.

More pics

Here's what I've done.

First to answer your question Ken, about removing the plastic turret part. Here's a picture that will clearly show the counter bore for the ring to sit in. I used the procedure I showed in the first picture to be able to center the ring better.

I turned another ring/tube to fit inside the outside ring. I then took HO scale 6" X 12" strip and pushed in between the two rings. It's holding pretty good. I think I may fill it with epoxy to make one solid unit.

Here's a top view with the floor attached.

Next I need to remove the portion shown so I can get at the inner ring for mounting wipers. More on the wipers later.

With one side attached.

I'm going to have to notch the sides slightly as marked so I don't get a short.

View from the other side.

Lets see if I can answer Ken's question about shaping teeth. Yes you can do shaping on a mill manually by pulling down on the quill handle. It depends on how big a bite you take out on each cut as to whether the quill will handle the pressure. The same can be done in a drill press. A full size tool in the shape of a gear to be used as a broach could work if you can find a broach of the size you need. If your well versed in machining you could make you own broach, but it would not be cost effective since you need a lathe and a mill. A single tooth broach wouldn't work because of tooth profile. You need to rotate both tool and part to get a tooth shape that would match your pinion. Gear cutting is a little more complicated than people think. The only gear easy to cut in a home shop atmosphere is a spur gear, followed by a helical gear.

Yes Andy is correct, there are many web sites and magazines out there. But by the time you study all that is involved with making a gear you wouldn't ever get your model railroad built. What I'm showing here is knowledge gained over many years to working in this medium. As far as a mill being able to cut an internal gear. I really don't think so, but as it always is if you look hard enough you'll probably find somebody that has done it, but at what cost.

Yes, you are correct. The internal dimension needs to be big enough to be able to fit the motor for rotating the turret.

At this point for the first crane, no. I'll have to take a closer look to see what you're suggesting is workable.

Bernd

Just advising what Sherline offers

I'm not in the low cost hobby gear cutting business, but Sherline is:

e.g. extract from their accessories pages

About The gear tooth cutter is included with the purchase of the indexing attachment and can also be purchased separately. It looks much like a small fly cutter and includes a 1/4" high-speed steel tool blank that you can custom grind to the particular gear tooth shape you need. The cutter can be used in conjunction with both the indexing attachment and rotary table. The #1 Morse taper on the shaft is held in the spindle with a drawbolt and special washer.

This is an economical alternative to round commercial involute gear cutters. Also, grinding your own cutter shape, while somewhat time-consuming, offers unlimited possibilities for matching existing gear tooth shapes when making replacements for gears with broken teeth. Simply use your existing gear as a pattern when grinding the cutter shape. With a little practice and skill, good cutters can be ground on a regular bench grinder.

READ INSTRUCTIONS FOR CUTTING GEARS ON AN INDEXING ATTACHMENT

(Click on your choice.)

MODERATOR NOTE: This post was accidentally marked as spam - but we have restored it. Please do not use the spam link to throttle other members who you may not agree with. However, when posting to someone's else's blog thread, if they ask you nicely to stay on topic, please respect their wishes. The moderatators have restored this post because it is NOT SPAM even though some may consider it controversal.

...

Andy would you please start another thread on gear cutting so you won't clutter this one up with your pabulum. Being the gentleman you are I'm sure that won't bother you.

The Sherline can only cut external gears Andy not internal. Reread Kevin's post. 

Bernd

@ Kevin

Sorry for not answering this one correctly. We've had a bit of static on the thread.

Yes, you could do all three. But I have to ask why a gear? It would make it harder to mount the motor in my opinion. Take a closer look at the how the miniature motor mounts at present. You'll see there's not much room for a gear drive. Although it could be done. Using the motor body with the shaft solidly attached to the frame they way Geoff did in his article is about the best way. Using gearing would only make it more complicated in my opinion.

Hope that answers your questions.

Bernd

Actually

I agree with you on your opinions and experience in gear cutting.  We do have an overlap in industrial experiences and possibly even training..

It is Bernd's blog

This thread is Bernd's blog, so we should respect his wishes as to posts. While I appreciate some debate about construction options, apparently not everyone does, so if anyone has an alternative view, go start your own thread please.

Thank you Joe

I'm hoping something like this will inspire more visitors to join. I realize that some of the techniques used are a bit out of reach for some when it comes to machine tools. I'm willing to work with those who ask the question "do I need a lathe or a mill to do this". There are alternatives to doing things. Remember Geoff showed how he did it with just manual tools, no lathe or mill was involved. I'm showing that one can go a bit further with machine tools and that it's not that hard to learn if some one is willing to show and answer questions on how to "questions".

So feel free to ask questions. I'll try to find you an answer.

Now back to the turret series.

Bernd

Functionality?

Bernd,

What function does this add to the crane, now that you've tried it?  I can see that it makes getting power to the boom a little easier (the reason for my original suggestion), but does it add any useful weight, or make the mechanism smoother?  More durable?  I can imagine all sorts of things that it might do, but it would be interesting to hear what it actually does.

Also, how about using a sheet of paper as insulation to prevent a short?  It might be easier than notching the motor frame.

On second thought

Looking at the design of the turret and cab floor again, I withdraw my former suggestion of making a mating brass ring.  It looks like it would be a lot simpler and more practical to remake the cab floor out of brass, and secure it with a plate on top.  It might be practical to make that plate slide over the other, so that the entire cab can be slid into place and secured with one or two screws on the end, using either a dovetailed edge or small lips on the bottom.  I'm not sure if the benefit would be worth the effort, but it does look like it might make a little more room inside the cab.

In other news, I note that using brass screws up through the bottom of the floor will make routing power from the trucks nice and simple.

added function

The first function was to get the power up to the cab a better way. I think you'll get the picture once I add the electrical wipers. That's what drove this design. The added benefit was that if properly made to fit the cab floor it would move much smoother than on the plastic, even after careful smoothing of the mating plastic surfaces, and it does. Another benefit is the fact you are adding more weight to the center of the whole car. Giving it a better center of gravity. I don't think durability is a factor here for the amount of times the crane would be used, personal opinion.

Little late now. I already have the inside ring made. I think a sheet of paper between the two pieces would be a bit hard to do. Don't get me wrong, I think it would work. the only thing would be you would need to bolt the inner and outer ring down. Eight holes instead of four. What I've done works pretty good and filing it with epoxy will make it one piece.

A little late for that. I don't think they make a lathe that will put plastic back on. (that's a joke folks. No need to try and find an answer on the net)

I can try this on the fourth crane I have. I think I understand what your saying. Instead of a brass turret ring. Leave it plastic but make the floor our of brass and the portion that slips around the lip of the turret ring. It defiantly will make more room. The only think that would need to be re-engineered would be the winches. That one will be down the line a bit.

Ok, it's back the the original crane. I'm going to add the power pickups next. Might as well get as much done in the cab before moving on to the boom. I'm contemplating on making a brass boom for the purpose of weight to counter balance the winch motors. I'm also looking into developing an electronic drive control that will interface with a decoder to drive the motors. That will be the last project on the crane.

Bernd

I'm not explaining myself well, I think

Paper insulation - I was suggesting that a sheet of paper between the brass plate onto which the winch motors are mounted and the two concentric brass rings.  That would prevent the winch mounting plate from causing a short.

Brass floor - I wasn't suggesting this instead of a brass turret ring.  Rather, the two would work in conjunction for a machined brass on brass rotating joint (conveniently transmitting power without the need for a separate wiper).  I had originally suggested adding some sort of brass ring to the plastic floor, but looking at it again I wonder whether it would be more trouble than it's worth.  If someone were going to the trouble of re-engineering the model to this extent, it would be simpler to just completely re-engineer it to fit the needs at the time.

I like the way you've made the concentric rings.  They look good, and I expect they'll be a significant improvement over the stock model.  By the way, how many of these cranes do you have?  Are you going into the crane rebuilding business?

Paper Insulation

Ah, understand now. I thought you meant between the rings.

Two problems here Ken. You never want two similar metals making contact in a rubbing action. They will gall. Second is that you need two separate circuits to bring power into the cab. A brass floor would short out across the two rings.

I have four cranes. My thought was to build them all up and put them on e-bay so the New York, Vermont & Northern can buy rail to start the railroad. That was one of the reason for my comment on decoders. I'll use NCE for testing to make sure what I've done works and is of solid construction. Who knows, by the time I get them all done I may have changed my mind and keep them all.

Bernd

Internal Gears

Andy and I got into a bit of a tiff on this subject. I have found a video that might explain better on internal gear cutting. Here's a video that shows some what of how an internal gear is cut.

Just in case you'd like to know.

Bernd

Video

Thanks for posting the video, excellent information !!!