# DRILLING HOLES IN THE CENTER?



## John J (Dec 29, 2007)

Ok 
In another thread we talked about adding aftermarket bearins to some rolling stock.

We all know there is some kind of insolation material in the steel wheels.

Say for some reason one replaced or filled in the area in the center of a steel wheel.

How would you go about drilling a new hole in the center of the wheel?

How would you determin the center and how would you center it in a Drill press?

Would it be easier to get a small lathe and use it.



PS 69 days till Marty's


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## Totalwrecker (Feb 26, 2009)

Use a tapered shaft chucked into the drill. Lower and let it center the hole. Lock in your answer... er piece and replace taper with drill bit. 

John


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## Totalwrecker (Feb 26, 2009)

If you want to replace the insulation, keep the wheel in place, use a slighly over size bit, twice the thickness of your insert (top and bottom). I have heard of acetate being used in smaller scales, but those stresses don't compare... the idea was to set the wheel/axle and acetate with epoxy, using the drill press the keep the axle true to the wheel while the epoxy set.... 

I suspct those with knowlege will join in soon. 

John


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## Totalwrecker (Feb 26, 2009)

Was rereadind orig.... 

Oh you mean a wheel without a hole? 

Dividers are like a compass used way back in youngin's school, except for a point and pencil we want 2 points. Measure diameter and use slightly more than half for the dist. between points. Pick 3 spots on the out side of the wheel and lightly scribe three arcs around the center, the center of the resulting triangle is center, the closer to 1/2 diameter , the smaller the centering tri. 

Mechanically; a lathe, you'll need the larger chuck they have to chuck the wheel. 

John


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## Greg Elmassian (Jan 3, 2008)

Lathe 

Greg


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## SteveC (Jan 2, 2008)

For finding the center you could use one of these.


MicroMark








*Center Square – 2.5” Capacity*



*Center Square – 5” Capacity*


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## Les (Feb 11, 2008)

Not real sure what you mean by filling in the center of the hole in the wheel.

If you're meaning what you say, the simplest thing to do is leave enough of the existing hole in the wheel to accommodate a drill bit. Presto. Automatically centered.

That's why I wonder if I understand.

Getting a lathe to do _anything _ if you don't already own/know how to use one, is going to take a bit of learning and practice.

Just make sure your drill in your drill press is square to the table in x & y directions.

Drill bit won't fit, too small, it'll wobble offcenter? Go to the next closest size OVER the hole diameter. Carefully grind the flute diameter down to a slip fit the entire length you'll need to get through the wheel. Note: this is not easy to do, so investigate MM dims for drill bits that'll do.


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## John J (Dec 29, 2007)

On G scale steel wheels there is a Nylon busing of some sorts to eletricaly isolate the wheel from the axel. Thus preventing shorts accross the track. 
Since i don't run track power I am thinking of removing the isolator and fill in the hole wtih JB weld and re drill the center hole to fit the bearing. 
I only intend on doing this on my USA articulated container cars. This means I have to turn down the shaft to fit a 3 MM inside bearing race and thendrill a 6 MM hole in the center of the wheel that I just filled. My thought was to find a three jaw lathe chuck and put it on the bed of my drill press. Then chuck up a wheel in the three jaws. Using a tapered reemer mounted in the chuck of the drill press I would aliegn the Lath chudk to the drill press chuck. Then I would clamp down the lathe chuck in place. I woulld then fill in the wheel center. Chuck it back in the three haws and drill a new 6 MM hole 

That's my plan so far.


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## Greg Elmassian (Jan 3, 2008)

JJ, why fill in the center? find a bearing that allows you to increase the size of the existing hole in the usat wheels. Find one that also takes minimal machining of the axle. There has to be a bearing with an outer race larger than the existing hole. 

How large is the hole in the USAT wheel without the insulator? 

Whose bearings are you looking at (web site)? 

Regards, Greg


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## John J (Dec 29, 2007)

I thought of finding a bearing to fit the hole. But then I have to build up the Axel to match the iner race of the bearing.


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## Greg Elmassian (Jan 3, 2008)

So, if I read between the lines, a bearing that has the right inner race diameter is smaller than the hole in the wheel with the insulator removed? wow.... 

I really think you can find bearings in a size that you won't have to build up the hole. 

What is the axle diameter and what is the diameter of the hole in the wheel? 

http://www.bocabearings.com/ 

Regards, Greg


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## Les (Feb 11, 2008)

I am altogether confused. (Not a new feeling, for me.)









Is the hole through the wheel the same diameter all the way through, or is it 'stepped', i.e. a larger diameter for the outside race of the bearing, then a smaller diameter where the axle goes on through to the outside face of the wheel? I can't comment further until I know that. Can you post a pic?

The idea of the chuck on the drill press ain't too shabby at all. I'd give it a try. Accuracy will depend on the repeatability of the 'table' chuck to tighten to the same center repeatedly. Also, how much 'shake' do you have in the quill with it fully extended? Extended just far enough to do your job?

What you could do with your 'chuck-on-drill-press' idea is to take one wheel, after you're all set up, and put a small hole all the way through of a diameter you have some already-made machined round stock. Then drill the wheel, mount it on your piece of rod, and rotate it slowly against either an indicator or even some fixed object like the the end of a scribe taped to your vise. See if it's good enough to suit you. That should tell you a lot about the accuracy of the center. A dial indicator would give you numbers.

One thing you're assuming is, the wheel flanges themselves are round and not 'egged'. A mike or dial indicator should answer that question.

But yeah, I think your idea has a lot going for it.

I dunno if you've been following the lathe thread on the Tools Forum, but HF has a little basic lathe for $250, if you're thinking about buying one. Give 'em a visit and look it over. You can't cut threads on it because there's no half-nuts & gearing to do so, but for the sizes G gauge guys are working with, it's just about as good to cut threads with a button die, anyway. I _think _someone even sells a die holder for the tailstock. (Though you can make your own.)


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## Greg Elmassian (Jan 3, 2008)

Les, he's just thinking about putting ball bearings on existing wheelsets, the USAT ones to be specific. I have lots of USAT cars, and the hole in the wheel is the same diameter all the way through. There is a black plastic insulator between the wheel and the axle. 

As I understand the last response, he was having thoughts that he could not find the right size bearings. I think we need to start with the diameter of the axle, the inside diameter of the hole in the wheel without the insulator, and the thickness of the wheels. Those are the dimensions we select the bearings with if I am not mistaken. 

Then, a bearing is chosen that takes the least effort to fit. It would seem to me that opening up the wheel's id would be easier than turning down the axle, since you have to turn down the axle from the very tip to where the bearing will reside. 

Regards, Greg


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## Les (Feb 11, 2008)

Thanks Greg.

I have no wheels with bearings and don't foresee ever using any on my little layout. I can see where the outside runners using heavy stuff would need them, however.


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## Greg Elmassian (Jan 3, 2008)

Funny thing, is that a number of respected people have tested ball bearing wheelsets, (one or more wheels rotate independently of the axle) and ball bearing journals (both wheels fixed to the axle, but axles in ball bearings). 

Not everyone has found an improvment. While it is very clear that rolling a car on level straight track takes less energy, many people have found what I have found, very little improvement on grades or curves. 

The lack of improvement on grades is easy to explain, you are still "lifting" your cars up in the air, even with no rolling friction, you are still doing work to accomplish this. 

But the lack of improvement on curves is not so obvious, and I can only offer theories, like the curves are so sharp you are rubbing flanges, or that the sloppy fit between wheel gauge and track gauge lets the trucks "skew" and create more friction. 

The USAT container cars are not really that heavy. 

Regards, Greg


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## John J (Dec 29, 2007)

Well if you read my other thread in tools. I bought a lathe from HFT. Playing with it I stuck a wheel in the three fingers jaw. I was surprised to fine that if I chucked it using the flanges. The wheel wobbled. So I chucked it using the part of the wheel that rests on the rails. That was much better It ran true. 
Then I decided to try the axel. No matter how I put it in the chuck it wobbled something allfull. 

I need to experiment more I will get back to you


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## Greg Elmassian (Jan 3, 2008)

You need to hold the other end too. 

This stuff is not made to high tolerances! 

Regards, Greg


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## Les (Feb 11, 2008)

John,

The first thing you need to do is chuck up something known to be straight. A drill blank is best, but if you don't have one, roll something across a piece of plate glass or the like to make sure it's round. Make it at least a 1/4" dia to give you something for the jaws to grab. Use your indicator and see how much runout it has. On second thought, it might be best to buy a drill blank if you don't have one. You need something that is known to be straight an w/o deviations in the diameter.

When you tighten the chuck jaws, do it in sequence, gradually drawing the jaws tight.

I would expect just what you found from the wheel, out-of-round around the flanges (which doesn't matter much), and true when gripped by the tread. I suspect that's a problem with more wheels than you'd think, especially when it comes to derailing through switches.

Before you do much else, get some means to mark each jaw of that chuck, '1, '2', 3, and mark the chuck shell where each one goes. Also, take the chuck apart and clean it, inspect for burrs and whatnot.

I wrote this in another post: use a mike or good dial calipers and check the OD of the flange a few different places, and also the tread. Be interesting to see what you come up with.


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## Les (Feb 11, 2008)

Posted By Greg Elmassian on 26 Jul 2009 06:36 PM 
You need to hold the other end too. 

This stuff is not made to high tolerances! 

Regards, Greg 







Actually, you don't need to hold the other end, if the surface being gripped is true.


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## Greg Elmassian (Jan 3, 2008)

It's not true, JJ proved that... that's why I indicated "THIS" stuff is not made to high tolerances... specifically wheelsets on freight and passenger cars. 

Also, I would question chucking something up on a thing axle or the tapered part of a wheel tread and trying to do something to the axle at the other end... would think you could have a dangerous situation here... 

Regards, Greg


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## Les (Feb 11, 2008)

Posted By Greg Elmassian on 27 Jul 2009 03:09 PM 
It's not true, JJ proved that... 
/// I don't know that his chuck is true, it may be, but a new lathe of the kind he has is suspect. That's why I asked if he's checked his chuck, and if he'd made measurements across the diameter of the flange from various points.

that's why I indicated "THIS" stuff is not made to high tolerances... specifically wheelsets on freight and passenger cars. 

Also, I would question chucking something up on a thing axle or the tapered part of a wheel tread and trying to do something to the axle at the other end... would think you could have a dangerous situation here...


/// JJ said he did it. Thus I have to assume, with the type of flange he has, it is possible. There are too many details left unstated to really know, which is why I asked the questions I did. At some point he'll discover the advantages of a fixture to hold the wheel by the axle hole, or by some other means, if it's a case of drilling out the center. A 'known' is needed to true off of, be it the CL of the hole, or the flange, or the taper. In his case it looks like truing everything from the axle hole would be easiest.


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## John J (Dec 29, 2007)

I have dial indecators that measure in Microns. For traming gears on a printing press to correct for sluring. ( That is for when I really want to count rivets.) 
Today is SAT the 1st of Aug I have some things to do today but later on I might have time to fiddle with the latthe and take some measurements. 
I will get back to you guys later. You are creating a very interesting discustion.


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