Bell Machining

[GoldenSpike53]

Hi, Guys!

Well, I've made some progress on my tender frame, but I have to wait for my lathe motor to be repaired (I'm awaiting a capacitor) and some tooling for my mill before I can proceed. So in the mean time...

...I recently purchased a bell kit from Allen Models, and thought that would be a fun project to tackle. But I have a couple of questions.

I managed to get the bell down to a fairly bright finish, but it's not as smooth as most I've seen. How do you polish the brass down so it has a really smooth, ground down appearance and that see-your-face-in-the-reflection shine? I haven't applied any Brasso yet, but
I figured I'd need to get the surface a bit smoother first. I know Brasso is an abraisive, so will it work if I just go for it? Or is there some intermediate step I should take?

(BTW, I "turned" the bell by placing the mounting stub in the drill chuck of my mill, then turning the mill on and applying first some emory cloth, working that to a 150 grit, then I went to some waterproof sandpaper at 220 grit. I know I can get the waterproof paper at smaller grits; they just didn't have any at the hardware store I went to. Should I go to a smaller grit first before trying
the brasso? When I worked with plexiglass a few years ago, we went up to 600 grit to get a nice, smooth, polished glass look to the cut edges.)

Second question: I have the bell attached to the rocker arm, so next I have to drill/machine the holes for the two shaft sections that go through the mount into the rocker arm (with the bell detached, of course), and on one side of course also attaches to the actuator arm. These shaft holes need to be on the same axis or the
bell won't rotate but will bind. The mount is a fairly complex curvature. What sort of jig or process do I need to be able to drill these holes and keep them centered and on the same axis all the way through? I thought of cutting out a wooden block to fit between the sides of the rocker arm to prevent it from flexing as
it's drilled, but I'm at a loss as to what to do to work the mount frame.

There are also two short pieces of support shaft left at the widest part of the mount. (It comes with two shafts, one between the shaft hubs and the other between the widest point where the sides of the
mount bow out.) I used a dremel tool with a cut-off wheel to cut through these support pieces, but that won't get inside the curve of the mount. Is there a dremel attachment that would work to clean that up, or would it be preferable to clamp the mount down to the
table and mill those out?

Any suggestions by successful bell builders? ;D (BTW, this is 1-1/2" scale, like my loco....)

Thanks!

Dale Dennis

[liamlocomotive]

I machined my bell from solid brass on a lathe with a hydraulic tracer. So, I really can't comment on polishing a cast bell except to say take your time and work your way down in abrasive size until you get the desired finish. Maybe start with a smooth half round file to get most of the "pimpliness" off the surfaces. Once you get it smooth with abrasive cloths and Scotchbrite (red); use a buffer to finish the outside if you want a mirror finish on it. And shoot it with some gloss laquer to keep it shiny.

To get the yoke drilled in line, you will need some kind of fixture to hold the yokes so you can index them to drill both holes in line. If you're careful, you can probably drill them with out flipping them 180 degrees. Depends on the tooling you do have. I have a collet indexer that I would use to hold a spud to hold the yokes.

I would drill the hole in the swinging yoke for the bell (which it sounds like you've already done). I would then make a spud to be a neat fit in that hole and use a nut to lock the yoke on the spud. I would then eyeball the yoke as best I could to get things even. Then, I would carefully drill the ends individually using the indexer to get each side and then maybe ream them through from one side. It's easier to do than describe....

The stationary yoke would be mounted on a piece of square stock in the center. I would line everything up as close as I could and drill one side and flip the fixture over and drill the other side. Obviously, I'm thinking of doing this in a milling machine....

A drill press could be used, but would need some way to make sure you didn't lose your locations....

Andy Pullen

[pockets]

Goldenspike, work your way up to about 3000 grit and get one of those cheap polishing kits from Home Dee- Pot. I use my die grinder, regulated down to about 35-40 pounds. A healthy drill motor will work. This is how I do it.

Hi, Andy.

Greg B.

[liamlocomotive]

Hi Greg/pockets....

[GoldenSpike53]

Thanks for the feedback, guys.

Andy, I'm not sure what you're referring to when you say "spud". I grew up in Idaho, and we pulled spuds out of the ground....

If you could describe what you are calling a "spud" or give me a reference to something I could look at, that would help. ;D

I sort of understand what you mean about indexing the holes, assuming not drilling straight through, but the problem appears to me to be that you have to index all three axes to get the shaft holes truly lined up.

Would it be problematic to use a long drill bit and drill straight through?

BTW, the only hole I have drilled in the swing casting is the hole to attach the bell itself in the center top. The rotation points are not drilled yet. Also, I'm working with a mill/drill, so I'm learning about its pluses and minuses. I've been cogitating a way to mount a laser pointer to the head so I can make an index line or string to realign the head when I move it up and down. One step at a time.

Should I drill the holes somewhat undersize, then use a reamer? would that insure good alignment? (That would mean getting a reamer; one more piece of tooling I haven't gotten just yet....)

If I was able to square off a block of wood perfectly, then make a couple of "shelves" for the respective end pieces to fit on that would hold them the correct distance apart and allow me to rotate them exactly 90 degrees, I would hope that would line things up pretty well, so long as the castings themselves are acurately placed on the block and can be held in place somehow.

Thanks, Andy; I seem to learn something new every time I post something.

And thanks to pockets also for his advice; I'll look tonight for what I can find in finer abraisives. 3000 grit seems pretty small, but I guess that gives you the mirror finish. Any suggestions on where that kind of stuff might be available? Locally, we've just got Home Depot and a couple of hardware stores like OSH. I'll start looking in those places. I'll inquire about red Scotchbrite, too. When I worked on the plexiglass stuff, I went to the local Tap plastics, but that was in a different locality. I'm sure Sacramento will have something if I can't find what I need in town.

Well, lots more to figure out. We just keep on workin' at it!

Dale

[pockets]

Stick around, Dale. You can learn a lot from Andy....I have.

Try a body shop supply house for the really fine wet/dry and use it with a light oil. Something like 3 in 1.

Just a thought...If you have the top mounting hole drilled, stick a bolt through it ( use soft washers inside & out ) and run a nut down just snug. Chuck it up in the drill chuck that came with your M/D. (don't grab a bolt by the threads in a good chuck and yes I know, we've all done it.) Run at slowest speed and sand away. Use a light touch, a lot of oil and it won't be long till it starts to gleam.

Another thought: Wrap that wet/dry around a piece of sponge, natural if you can get it. Any good bodyman will tell you that when you sand with your finger tips, you're just making grooves. Those will NOT look good on a polished bell!

Hope I've helped.

Greg B.

[liamlocomotive]

That's a really good tip about the sponge, Greg. Thanks. See, I learned something from you today. I knew I would.

Hi, again, Dale,

A "spud" like I'm talking about is a short length of steel or aluminum or brass held in a chuck or vise with a diameter to fit the hole in your part with either an internal or external thread to hold your part so it can be machined. It could be as simple as a chunk of square stock that is drilled and tapped to hold your yokes. You will be better off machining as close to the center line on the steel. Once you get the part set so you are comfortable drilling both "eyes" in the yoke on center and in line; all you will need to do is drill from one side, flip it over and drill the other side.

Drills will wander in a long hole or if you try to drill one side of a yoke and drill through the other side in one setting. That's why I'm suggesting you drill from each side and then ream through. The reamer will follow the hole that you drilled.

You will need to get some reamers. Buy only what you need when you need it. Use a drill size under the reamer size. 99.99% of the time a drill bit will cut an oversize hole. Anywhere from .0005" to .010" oversize. A good rule of thumb when using reamers is to drill .010" to .015 undersize and then ream. With the smaller sizes; the number drills are helpful here. With larger sizes, rough drill the hole, bore and then ream. And another rule of thumb is to run the reamer at maybe 1/6th the speed that you ran the drill bit. But, increase the feed.

I've used hardwood for fixtures. You will find that you will be doing alot of "set-up" to make just one part. Sometimes hours can be spent setting up to do a 5 minute operation. Take your time.

I have some pictures of my freight car wheel turnig operation that need to be scanned so I can post them. I show the spud that I turned them on along with the finishing operations. Hopefully, I can get that done very soon.

Andy

[GoldenSpike53]

Well...

I've made some progress on the bell itself.

I placed it in the mill chuck and started working with a medium emory cloth. I used a long strip, and just held the cloth around the back of the bell while it turned and moved it up and down slowly to cover the whole area. I moved up to a 220 grit emory cloth, then to a 400 grit wet sandpaper, a 600 grit wet sandpaper, and finally a 1500 grit wet sandpaper. After the last one, I took the bell off and polished it with some Brasso. It has a pretty good shine to it!

I haven't tried to do the holes in the yokes yet; I received the starting capacitor for my lathe and wanted to get that running again if I could. Fortunately, the replacement capacitor solved the problem, and I'm off and running again. Working on the tender wheels.

When I feel comfortable with my set-up for indexing or holding the bell yokes, I'll give that a shot and let you all know how it goes.

Dale

[pockets]

Goodonya, as they say.....

[smokebox]

I hunt deer with a black powder rifle and this year I noticed that my powder measure looked awful
It was green and had several pits from the mix of powder and finger oils.
I lightly chucked it in my 3 jaw chuck and hit the juice, then with a " paper towel" put on some Blue Magic metal polish.
This stuff is not suspossed to be abrasive and the maker claims it is safe on all metals( mag wheels also)
The thing that makes this important to live steamers is that it leaves a silicone film to "protect" the finnish it did not remove the pits however the finnish was so bright it did not matter!!
And after several very lucky deer this season alot of finger oil and also alot of powder (the real stuff, not pyrodex or other junk) it is still very bright!!
I think this stuff would work great on a bell for the live steamer, anything bright for that matter. Give it a try!!

[pockets]

Andy,
When and where are you gonna post that wheel turning thingy?

Regards,
Greg B.

[liamlocomotive]

Hi Greg,

I've got to get my camera to "talk" to my computer. There's a problem in my machine. I'm getting it worked out as I type. Then, I'll get those pics posted....Your article is copied and will be on its way to you in a day or so.

Andy

[pockets]

Thanks, Andy. Looking forward to seeing both. I make no bones about being a computer illiterate. I generally just abuse it until it subjects itself to my whims.....

Regards,
Greg B.