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Hulett Ore Unloader in 1:32th

Started by Bernhard, February 08, 2023, 08:20:58 AM

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Bernhard

Thank you all for your interest.

Russ, the rest of the day I will spend with a few bikini beauties, drink beer and think a bit about how to proceed.

Hauk, I have worked in mechanical engineering for a long time and therefore know pretty well how such a machine should be built. Unfortunately, most hobby machines do not even come close to meeting this requirement, or they are far too expensive. I have therefore bought a self-built machine. It's not perfect in terms of craftsmanship, but it meets my mechanical requirements.

Bernhard

Bernd

Quote from: Bernhard on February 15, 2023, 08:57:26 AMThanks for your hint, Bernd. In fact, I have been able to find the drawings by Mike Rabbit for some time. Apparently there has also been a CD with photos. Do you know where I can still get them?

Bernhard

Hi Bernhard,

I have no idea where you would be able to find the CD. I did not even know there was a CD available. Sorry.

I will be following this project closely. I'm fascinated by your machine work. I have two CNC machines, a Sherline and a ROBO router/engraver. I only work in HO (1:87) scale so these machines suffice for me.

Bernd
New York, Vermont & Northern Rwy. - Route of the Black Diamonds

Hauk

Quote from: Bernhard on February 19, 2023, 12:12:24 PMHauk, I have worked in mechanical engineering for a long time and therefore know pretty well how such a machine should be built. Unfortunately, most hobby machines do not even come close to meeting this requirement, or they are far too expensive. I have therefore bought a self-built machine. It's not perfect in terms of craftsmanship, but it meets my mechanical requirements.


But you are also using a manual Wabeco mill, right?
Regards, Hauk
--
"Yet for better or for worse we do love things that bear the marks of grime, soot, and weather, and we love the colors and the sheen that call to mind the past that made them"  -Junichiro Tanizaki

Remembrance Of Trains Past

Bernhard

Bernd, show us more of your work!

Hauk, yes, I have been working with the Wabeco for some time and I am very satisfied with it. However, there are many parts in the current project that you can hardly make on a manual machine. That's why I decided to buy a CNC machine.

Bernhard

Lawton Maner

Can those with CNC machines please chime in on the +/- of theirs.  The field is moving so fast that some of the older ones are outdated.

Bernhard

That's not so easy to answer, Lawton. It always depends on what you want to do with the machine and what you are willing to invest.
But I can try to show you what makes a good CNC milling machine from my point of view.

Stability
The more unstable the machine, the more the tool vibrates. This shortens the tool life and the quality of the surface becomes poor.
In our area you can often find offers for self-built machines made of wood.  This does not work at all!

Stable guides
Preferably pre-stressed profiled guide ways. Everything else is not recommended, e.g. round guides that are not supported over the entire length, plain bearings or guides on rollers.

Drive of the axles
Recommendation: ball screw with preloaded nut. This has no backlash. A trapezoidal screw, on the other hand, always has some backlash.
Of course, the spindle must be correctly mounted (radial-axial bearing on the locating bearing side, radial bearing on the non-locating bearing side).
The worst thing I have seen in this regard: the spindle is mounted in two plastic plain bearings and fixed directly to the motor with a bushing. This is the perfect self-destruction mechanism for the motor. The machining forces act directly on the bearings of the motor, which are in no way designed for such loads.

Motor mounting
If possible, motors should be mounted directly on the spindle with a coupling. Belt drives worsen the positioning accuracy. Very bad are for example Y-axis drives with 2 spindles, one motor and one long drive belt.

Milling spindle
Preferably with water cooling for good heat dissipation. With air cooling you have to keep an eye on the temperature, because heat expansion of spindle and tool lead to errors in Z-direction.

Modular control
Separate power stages for all axes simplify troubleshooting and repair.

And finally, of course, all axes must be precisely aligned, then it will work.

Bernhard

Bernhard

The rear casing of the angular gear is made from a piece of pipe.

Hulett 0037.JPG

The recess for the bevel gear bearing is milled out.

Hulett 0038.JPG

The cover is made on the CNC milling machine.

Hulett 0039.JPG

Then the parts are soldered together.

Hulett 0040.JPG   

Bernhard

The bearing for the bevel gear is mounted and four more parts are ready.

Hulett 0041.JPG

Bernhard

The front casing is actually made of sheet metal. But it is relatively difficult to bend it to fit exactly, so I make it out of solid material.
First, a brass block is roughly hollowed out.

Hulett 0042.JPG

Then the inner contour is milled on the CNC machine. To prevent the part from being deformed in the vice, I leave 0.8 mm of wall thickness. This is very oversized, but you won't see it on the finished part.

Hulett 0043.JPG

For the re-milling of the outer contour I first have to build a small clamping device.

Hulett 0044.JPG
Hulett 0045.JPG   

Bernhard

The inner wall is milled out of 0.3 mm sheet metal.

Hulett 0046.JPG

Finally, the brackets are soldered on with the resistance soldering device.

Hulett 0047.JPG

The finished parts:

Hulett 0048.JPG   

Bernhard

Now I have to get into series production: I have to turn 36 steel wheels. Repetitive tasks have never been my thing, but I have to get through them.
First one side is faced, then the running groove is cut.

Hulett 0049.JPG

Since I can't cut such parts on my lathe, I cut them off the bar with the circular saw.

Hulett 0050.JPG

After 12 hours of work, 36 pre-machined wheels are ready for the next operations.

Hulett 0051.JPG

But how can the wheels be clamped for further processing? This is not possible with the normal three-jaw chuck.
I therefore have to make special additional jaws first.

Hulett 0052.jpg   

Bernhard

I turn three rings that can be put on the jaws of the three-jaw chuck without any clearance.
They are pre-machined from behind on the milling machine.

Hulett 0053.JPG

The rings are put on the chuck, clamped against a disc and secured with stud bolts.
Now the face can be turned over first.

Hulett 0054.JPG

Then the clamping diameter is turned out.

Hulett 0055.JPG

With this I can clamp the wheels on the running surfaces, then face the second surface and make the axle hole. Clamping on the running surface ensures that the axle bore runs exactly round.

Hulett 0056.JPG   

Bernhard

Now the circumferential groove is milled on both sides with a torus cutter. The cutter has a diameter of 5 mm and an edge radius of 1 mm.

Hulett 0057.JPG

Since I want to conduct electricity to the model via the rails, all wheels still have to be provided with an insulating sleeve made of plastic.

Hulett 0058.JPG

Normally I don't count my working hours, because it's all just a hobby. But here I made an exception: for the production of 36 wheels I spent about 42 hours.

Bernhard 

finescalerr

Well, that was quick, simple, and easy. What's next? -- Russ

Barney

AH Gasp  -Just took the tablets and a dose of Oxygen Was going to come out from under my Rock - But second thoughts I stay here
Barney
Never Let someone who has done nothing tell you how to do anything
Stuart McPherson