Turning Wheels on a Mini Lathe.

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Stan Pope
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Turning Wheels on a Mini Lathe.

Post by Stan Pope »

Some folks have asked how I produce very low runout wheels on a typical (or maybe worse than typical) mini lathe. I promised somewhen to post some details. I got some "round tuits" in the post today, so here's something worth a few thousand words: Each video is less than 2 minutes.

Overview

Closeup View From Left

Closeup View From Center

Closeup View From Right

To understand now precision is maintained, recall my bore ream guide. Then look at the mandrel to identify the part locating features.

Even though I've improved the chuck so that it will typically rechuck a shaft to 0.001" runout, that is IMHO totally inadequate, so step 1 in a wheel run is to prepare a fresh mandrel. As you can see, there is little work necessary to accomplish this part of the job. The most difficult feature of the mandrel is the gently tapered center pin which is dressed down a bit at a time until it just engages the outer end of the reamed wheel bore when the spoke face contacts the face of the mandrel. Once the pin is sized, smooth the mandrel face and pin with emery paper.

The job of the pin is only to locate the wheel bore, not to hold the bore in place ... that is the job of the clamp on the right side. The clamp presses the spoke face against the face of the mandrel. This clamp shown was purposely made long and thin, although many like to use a nice short clamp that is easier to center.

Note the directions and orientations of the lathe features ... allows to approach the wheel from the outer side. (A good suggestion from Teeeman!)

The steps shown are not everything that happens, but the rest is easy if you can do this part well.
Stan
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sporty
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Re: Turning Wheels on a Mini Lathe.

Post by sporty »

Nice video.

Stan shared this with me last year and I use a very close version of this.


I have produced wheels with .00015 run out, using this process.

Thanks for sharing and posting video clips.

Can you do a close up of your bit ? The cut on yours looks very different from mine.

I would enjoy a better look to make one like that and see how it compares.


Sporty
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

sporty wrote:Nice video.

Stan shared this with me last year and I use a very close version of this.


I have produced wheels with .00015 run out, using this process.

Thanks for sharing and posting video clips.

Can you do a close up of your bit ? The cut on yours looks very different from mine.

I would enjoy a better look to make one like that and see how it compares.


Sporty
The cutting edge is on the underside of the bit since I am running in full reverse. (I didn't want to grind a new, mirror image bit to attack the wheel from the outer edge.)

Runout of 0.00015 is PDG! Congrats!

For now, I'll let folks build on what I've shown.

Meanwhile, don't pay any attention to any other cutters in the tool post. They weren't supposed to be visible.

BTW, even though the mandrel only engages the outer edge of the bore some may fear bore distortion that survives bore polishing. A simple avoidance tactic is to notch the axle slightly right at the axle head so that the distortion rides on air. The notch need only be wide enough to compensate for the small hub-body clearance that most use.
Stan
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Re: Turning Wheels on a Mini Lathe.

Post by whodathunkit »

Very nice video on the Mini Lathe Stan.

I like you're home made Mandrel, it would work well with the coned hubs also. ;)
Are you useing a derbyworx hub tool in the chuck..
Or one that you have turned out?

This beats turing them by hand on the hand lathe,
Or sanding them with a drill or drill press.

Now Stan, you know most rules don't allow Lathed Wheels.
:scratching: You Outlaw you!
Whoda.
What type of automobile can be spelled the same forwards & backwards?
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Stan Pope
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

whodathunkit wrote:Very nice video on the Mini Lathe Stan.

I like you're home made Mandrel, it would work well with the coned hubs also. ;)
Are you useing a derbyworx hub tool in the chuck..
Or one that you have turned out?

This beats turing them by hand on the hand lathe,
Or sanding them with a drill or drill press.

Now Stan, you know most rules don't allow Lathed Wheels.
:scratching: You Outlaw you!
Whoda.
Clarification: The "mandrel" is chucked in the lathe 3-jaw chuck on the left of the wheel. The "clamp" is on the right of the wheel between the wheel and the live center.

The prohibition of "lathed wheels" customarily refers to "interesting" features on the tread, such as a central ridge or wide central depression, and sometimes to interior material removal. If I were to replace the ground HSS cutter with a block with sandpaper inserted into the tool post, then it would entirely satisfy the "light sanding" permission and accomplish the low runout goal! Even chucking a DWx mandrel in a drill press and running it against a sandpaper block is technically a "lathe" operation.

Fortunately, our rules describe what the finished wheel may look like rather than how it got that way. :)

Since the homemade mandrel touches only the spoke face and the outer edge of the bore and the clamp touches only the flat area just behind the spoke face, the shape of the inner hub is immaterial!

The reason for the form of the mandrel is that rechucking accuracy is only about 0.001" of runout. Therefore, for each run of wheels, the mandrel blank is chucked, the face and pin are machined (a short operations since the pin is so short), and polished. The chuck is not loosened until the run of wheels is complete. If I have visitors, each gets to prepare his own mandrel! Material cost is about 1/10" of mandrel stock! Not a problem, since the mandrel stock shown in the vids is about 8" long! :) And there's another few feet of 5/8" stock leaning against the wall.

The long skinny clamp is fussy to get centered on the wheel ... the hole that goes around the hub is a bit oversized. A short clamp ismore easily centered. However, for this run, I'm making samples of illegal wheels to train the inspection crew. This includes some interior machining and, for that, I need the clearance that the long skinny clamp provides. :)
Stan
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Re: Turning Wheels on a Mini Lathe.

Post by whodathunkit »

Stan Pope wrote:
Now Stan, you know most rules don't allow Lathed Wheels.
:scratching: You Outlaw you!
Whoda.
I'm making samples of illegal wheels to train the inspection crew.[/quote]

Stan I have a Sample for that inspection crew! ;)
Image
I used a junk wheel and my scroll saw to do up this one.
What type of automobile can be spelled the same forwards & backwards?
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

Grandson is a 1st year Webelos this year. So he got to prepare his own mandrel! :) Dad looking over his shoulder and Grandpa looking over Dad's shoulder.

The prep was understandably slow, but he finished with a mandrel that did not move the dial indicator and the wheels will be a "snug, but not too snug" fit on the mandrel. And the surfaces are smooth as a baby's cheek! When he cuts the wheels, they should have TIR comparable to Sporty's 0.00015"! :)

For his first time through, with instruction (lots of instruction) and measuring help (lotsa that too) it took 1 hr 45 minutes... about an hour and a half longer that it takes me ... but learning new stuff is fun! And, unless he forgets it all, next year should go even faster!
Stan
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Re: Turning Wheels on a Mini Lathe.

Post by whodathunkit »

Now if i only had a Mini Lathe.
I could have fun learning new suff.. like this!

Stan, You All Have A Very Merry Christmas.

Whoda.
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Stan Pope
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

whodathunkit wrote:Now if i only had a Mini Lathe.
I could have fun learning new suff.. like this!

Stan, You All Have A Very Merry Christmas.

Whoda.
Et tu, Whoda!
Stan
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Re: Turning Wheels on a Mini Lathe.

Post by Teeeman »

Nice job Stan!

We never got better than .0005".



On a tour just last week of a manufacturing facility, the gent leading the tour said all the tooling for the really tight jobs... they get setup, and leave alone.

I knew why thanks to machining wheels :)

I left a mandrel chucked once for over a year ;)

I was the only "rocket scientist" on the tour who knew what this guy was talking about... I can credit Stan and PWD for teaching me what it takes to make the parts we "enginerds" so easily design in a CAD system...

... by encouraging me to try it, and then leading me almost literally (save for a few hundred miles of distance) by the hand to learn.

:)
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Re: Turning Wheels on a Mini Lathe.

Post by ScoJo »

Stan, have you provided instructions for making a mandrel like this somewhere? Last year we used a pin gauge, but this year we're looking to do better.
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

ScoJo wrote:Stan, have you provided instructions for making a mandrel like this somewhere? Last year we used a pin gauge, but this year we're looking to do better.
No, I don't want a cookbook written. But I've told you everything you need to know to replicate it. Just apply what you have learned about using a lathe.

I'll list the critical concepts here again:

1. part locating reference:
a. spoke face of wheel (orients the wheel perpendicular to the bore axis),
b. outer edge of bore (locates the center of the outer edge of the bore).

2. clamping surface:
a. spoke face of wheel.

3. bore:
a. trued to part locating reference (see "bore ream guide").

"Part locating reference" defines those aspects of the wheel which are used to control the location and orientation of part during alteration.

"Clamping surface" identifies aspects fo the wheel to which holding force is applied.
Stan
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Re: Turning Wheels on a Mini Lathe.

Post by ScoJo »

Can you share any tips for fixing a damaged 60 degree live center? I have one that I bought several years back that was a cheapie spring loaded one for a micro lathe. The actual center is just a piece of tool steel machined to a 60 degree (I'm guessing) point. I don't recall what happened to it, but most likely I had it in something that wasn't 60 degrees and the tip of the live center got chewed. Any advice as to how I can clean it up and get the angle right?
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Re: Turning Wheels on a Mini Lathe.

Post by ScoJo »

I'm guessing I can just chuck this into the headstock and clean it up with a cutting bit, but I guess I'm looking for advice on how to get the angle exact.
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Re: Turning Wheels on a Mini Lathe.

Post by Stan Pope »

ScoJo wrote:Can you share any tips for fixing a damaged 60 degree live center? I have one that I bought several years back that was a cheapie spring loaded one for a micro lathe. The actual center is just a piece of tool steel machined to a 60 degree (I'm guessing) point. I don't recall what happened to it, but most likely I had it in something that wasn't 60 degrees and the tip of the live center got chewed. Any advice as to how I can clean it up and get the angle right?
Can you chuck it, or disassemble to the point that you can chuck the point? If so, then turning the point should be possible. Sounds like it is (or is intended to be) harder than most steel you would work. That may limit your cutting tool selection ... HSS may not do the job. Might have to go directly to honing!

Can you change the angle of your cross-slide so that you can run the cutter along the angled face of the point? That would probably make a cleaner looking result.

In any case, you probably have to give it a good application of emery paper to clean up the surface when you are done cutting. I like to use a leather strap as backing for the emery paper ... reduces stress on the paper AND protects my fingers from getting too close to the rough-cut surface.

To me, the exact shape of the live center point is less important than that it is "pointy and well centered." That may make chucking the point more challenging. But, I'm sure that it can be done somehow.
Stan
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