Another "How to make" question

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Mr Ron
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Another "How to make" question

Post by Mr Ron »

I hope I'm not being a nuisance asking all these how to questions. If so just ignore me.

Here is a sketch of a locomotive wheel for an electric B1 switcher as used by the Pennsylvania and Long Island railroads. My model will be in 1/16 scale, be capable of operating on a track, but mostly for display. A previous locomotive I built, used wheels that were cast from epoxy resin of a Shore durometer 90D (very hard), 4810 psi tensile and 12500 psi compressive. I plan to use the same process for the 6 new wheels. My question is how would you go about making the pattern for the wheel. Previously, I made a pattern from a piece of aluminum plate. I tried using a RT to machine the spokes, but that didn't go too well; ended up with many hours of filing and grinding with a Dremel tool.
B1 wheel.jpg
B1 wheel.jpg (12.07 KiB) Viewed 5763 times
Mr.Ron from South Mississippi
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Steggy
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Re: Another "How to make" question

Post by Steggy »

Mr Ron wrote: Wed May 23, 2018 11:30 am I hope I'm not being a nuisance asking all these how to questions. If so just ignore me.

Here is a sketch of a locomotive wheel for an electric B1 switcher as used by the Pennsylvania and Long Island railroads. My model will be in 1/16 scale, be capable of operating on a track, but mostly for display. A previous locomotive I built, used wheels that were cast from epoxy resin of a Shore durometer 90D (very hard), 4810 psi tensile and 12500 psi compressive. I plan to use the same process for the 6 new wheels. My question is how would you go about making the pattern for the wheel. Previously, I made a pattern from a piece of aluminum plate. I tried using a RT to machine the spokes, but that didn't go too well; ended up with many hours of filing and grinding with a Dremel tool.

B1 wheel.jpg
Your image is much too small to be read.
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NP317
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Re: Another "How to make" question

Post by NP317 »

3D print the pattern.
There are many available resources to have this done.
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Mr Ron
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Re: Another "How to make" question

Post by Mr Ron »

BigDumbDinosaur wrote: Wed May 23, 2018 3:59 pm
Mr Ron wrote: Wed May 23, 2018 11:30 am I hope I'm not being a nuisance asking all these how to questions. If so just ignore me.

Here is a sketch of a locomotive wheel for an electric B1 switcher as used by the Pennsylvania and Long Island railroads. My model will be in 1/16 scale, be capable of operating on a track, but mostly for display. A previous locomotive I built, used wheels that were cast from epoxy resin of a Shore durometer 90D (very hard), 4810 psi tensile and 12500 psi compressive. I plan to use the same process for the 6 new wheels. My question is how would you go about making the pattern for the wheel. Previously, I made a pattern from a piece of aluminum plate. I tried using a RT to machine the spokes, but that didn't go too well; ended up with many hours of filing and grinding with a Dremel tool.

B1 wheel.jpg
Your image is much too small to be read.
I hope this is more legible.
B1 wheel.jpg
B1 wheel.jpg (27.69 KiB) Viewed 5711 times
Mr.Ron from South Mississippi
Glenn Brooks
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Re: Another "How to make" question

Post by Glenn Brooks »

Mr. Ron,

+1 on the idea to draw the wheel up in CAD of some sort and print it, using Shapeways, or other vendor. Then you could use the printed wheel to have a foundry make cast iron wheels, if you wished. They would only be a couple of inches diameter, so not all that expensive for 8-16 wheels. Indeed, the 1/2” , 3/4” or even 1” scale folk, if there are any still around, might have a supplier, or hobbyist who could supply the needed castings.

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Re: Another "How to make" question

Post by Harold_V »

BigDumbDinosaur wrote: Wed May 23, 2018 3:59 pm Your image is much too small to be read.
Yep! Pretty much useless.
When posting pictures, don't make them thumbnails. The software does that automatically. If it's important that they are legible, post them an appropriate size. The software shows a thumbnail, but it can be clicked so readers can see the image in the size posted.

H
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Mr Ron
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Re: Another "How to make" question

Post by Mr Ron »

Glenn Brooks wrote: Wed May 23, 2018 11:38 pm Mr. Ron,

+1 on the idea to draw the wheel up in CAD of some sort and print it, using Shapeways, or other vendor. Then you could use the printed wheel to have a foundry make cast iron wheels, if you wished. They would only be a couple of inches diameter, so not all that expensive for 8-16 wheels. Indeed, the 1/2” , 3/4” or even 1” scale folk, if there are any still around, might have a supplier, or hobbyist who could supply the needed castings.
Glenn
If I were to make the wheels from cast iron, I would have to machine 6 wheels. I indicated that I would make them from an epoxy resin meaning I make a pattern and cast 6 wheels from the pattern with no machining required; only the pattern would be machined. My question was; how do I make the pattern?
Mr.Ron from South Mississippi
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Re: Another "How to make" question

Post by RSG »

Mr Ron,

Is this what you are after?

Chuck some 4.5" dia. aluminum roundstock
Turn the face contour, bore center hole and dia.
Part off
Machine soft jaws to finish the back side.
While it's still in the chuck pull the chuck off the lathe and clamp it to a rotary table in the mill, dial it in.
Plunge all the connecting holes with the desired dia end mill at the varying degrees around the wheel at the correct distance radiating from the center point.
Connect (cut) all the holes in the radius
Rotate the rotab and offset the "X" axis on the mill table to connect all the lines.
Done!

Cast it in Amazing Molding Putty http://canada.michaels.com/on/demandwar ... d=10410575 then pour each wheel.

You might need to tun the face of each one were you cast the part from.

Hope this is what you were looking for.
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Mr Ron
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Re: Another "How to make" question

Post by Mr Ron »

RSG wrote: Fri May 25, 2018 1:00 pm Mr Ron,

Is this what you are after?

Chuck some 4.5" dia. aluminum roundstock
Turn the face contour, bore center hole and dia.
Part off
Machine soft jaws to finish the back side.
While it's still in the chuck pull the chuck off the lathe and clamp it to a rotary table in the mill, dial it in.
Plunge all the connecting holes with the desired dia end mill at the varying degrees around the wheel at the correct distance radiating from the center point.
Connect (cut) all the holes in the radius
Rotate the rotab and offset the "X" axis on the mill table to connect all the lines.
Done!

Cast it in Amazing Molding Putty http://canada.michaels.com/on/demandwar ... d=10410575 then pour each wheel.

You might need to tun the face of each one were you cast the part from.

Hope this is what you were looking for.
The problem with using a RT is the angles are 7.4° and 14.8°. I can't accurately dial in those angles with my RT. I can only set it at 1° increments. To use a RT, I would have to "eyeball" the cutter path. I did make some wheels for another loco and used epoxy resin in a rubber mold. Those came out perfect with no further machining required; a little flash but that was all. If I wanted, I could machine a band and press fit it unto the resin wheel. That epoxy resin is very strong.

One option I have been thinking about is to make the pattern from machinable wax. From that, I can make a rubber mold and then cast the wheels from the mold.
Mr.Ron from South Mississippi
whateg0
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Re: Another "How to make" question

Post by whateg0 »

You could rough it on the rotab and then do like the guy who makes the clickspring videos does, and file each spoke by hand.

Dave
Mr Ron
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Re: Another "How to make" question

Post by Mr Ron »

whateg0 wrote: Fri May 25, 2018 3:48 pm You could rough it on the rotab and then do like the guy who makes the clickspring videos does, and file each spoke by hand.

Dave
Looks like that will have to be my solution. Thanks all.
Mr.Ron from South Mississippi
whateg0
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Re: Another "How to make" question

Post by whateg0 »

4-1/16" is probably just outside the work envelope for my little Sherline CNC or I could cut it. Might see if anybody else could do it. It would be a fairly quick little job.

Dave
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