Stephenson's Rocket

[gbritnell]

Hi Brian,
So after all that sweating, worrying and wrangling what was the problem with the lathe?
curious minds want to know!
gbritnell

[Brian Rupnow]

This is what was wrong with my lathe One picture is of the gear cover that sets on the end of my lathe to protect my fingers from the gears. Notice the bent bracket at the lower right corner of it. That bent bracket pushes on a switch which disables the electrics on the lathe if the guard is removed. I haven't had that cover off the lathe in more than a year. Somehow---Perhaps metal fatigue? the bracket bent far enough that it no longer pushed on the button, and consequently the lathe stopped right in the middle of a cut. The switch it presses on is right below the gears and is virtually impossible to see unless you stand on your head to look for it. When I left the lathe in Concord at Busy Bee, I told them that my rpm indicator only worked intermittently and please either fix it or replace it, as well as please fix whatever is wrong that I have no power to the lathe. They replaced the rpm indicator, scratched their heads a bit and then found that bending the bracket by hand fixed things so it pushed the button and restored power to the lathe. I either didn't know, or else forgot that switch was even there.They charged two hours labor and the price of the new readout. My bill came to $129. So, they treated me quite honestly I think. They could have told me it needed a new motor and charged me another couple of hundred dollars but they didn't.

[gbritnell]

Hi Brian,
I'm glad to hear it was so simple and a relatively low cost fix.
Now, make chips!
gbritnell

[Brian Rupnow]

Now it's time to get into some complex stuff. To assemble all of the wheel parts and keep them all correctly positioned in relationship to each other, we have to use a "jig".--Also called a "fixture". In each wheel there will be 13 parts. An inner hub to align the spokes, a centering hub which fits inside the inner hub to adapt it to the axle, 10 spokes, and an outer rim. My plan is to use J.B. Weld to attach the spokes to the inner hub, and to tig weld the spokes to the outer rim. I started out the day by buying a 5" square piece of 3/4" thick aluminum plate which was scribed corner to corner to locate the center, and then a 5/16" center drill was used to put a center "divot" into the plate. The plate was then mounted in my lathe 4 jaw chuck, centered, and a boss was turned that is an exact fit into the inside diameter of the outer wheel rim. Then a 3/4" hole was drilled and reamed thru the center, and a countersunk pocket was put in the center to locate on the outer diameter of the inner hub. The two pictures I have loaded show the fixture after turning operations were completed, and with the inner hub, outer rim, and one spoke set in place. The depth of the turnings was calculated to give .062" of "air" below the spoke, so that it only is supported by the outer rim and the inner hub. There will be more posts as the wheel is developed, but this is my starting point.

[Brian Rupnow]

Here we have the first wheel assembled in the jig.--all the spokes were covered with J.B. weld at the inner ends, then slid into the slots in the inner hub. They were all tapped down into the correct position in the outer rim, and then the outside of the centering hub was coated with J.B. Weld and then it was inserted thru the center. A very healthy 3/8" bolt and nut squeezes everything together, and will be allowed to set up for 24 hours. I will then tig weld the outer ends of the spokes to the outer rim. The welds will be on the side of the wheel which faces in towards the center of the Rocket, so will not be visible when all is assembled

[rudydubya]

Nice work, Brian.  Quietly following along.

Regards,
Rudy

[crueby]

Great looking wheel, nice way to make it.

[Brian Rupnow]

So, what do you do while you wait 24 hours for the J.B.Weld to set up on the wheel in the jig?--Well of course, you make the outer rims for the non driven wheels. Unlike their bigger brothers which were machined from a piece of very heavy wall tubing, these smaller wheels were made from a solid piece of 3" diameter steel. My largest metal drill is 1" diameter. The holes in these smaller rims are 1.943" diameter. Thats a lot of boring passes at 0.015" depth of cut. Tomorrow morning I will make the hubs for the smaller wheels.

[steamboatmodel]

fault light?,, I find many of these machines use cheap plug and spade connectors,, when my mill was faulting I replaced the power cord to machine connectors with better ones,, never a fault again,, I used to work for biotech company that provided machines that had to run,, service people would respond 24/7 to get the unit back up and running,, the phone in check list started with #1 have you checked all the electrical connectors and fuses,, # 2 go back and really check all the connectors and fuses, #3 did you use a meter?  one of techs drove 3 hours one way in the wee hours to change a fuse that was claimed to have been checked,, (the machines were provided with a very well stocked spare parts box) good luck..

Did computer and network trouble shooting for a while 30years back. Had one client who had a branch office in Buffalo NY and tice drove from Toronto Ont. to there branch to find the unit unplugged the first time and a circuit barker blown the second. The last time I was down there they had laid the cable between units on top of a heat rad in the winter. My wife went down one time and spent 13 hours and discovered someone was typing a O letter instead of a 0 zero number.
Gerald.

[Brian Rupnow]

This morning I completed the hubs for the two smaller non-driven wheels, and machined a fixture to hold everything in position for tig welding. I used up every inch of 1/8" square keystock I had to make spokes for the small wheel that is in the jig. If all goes well with the tig welding, I think these are going to be very nice wheels for the Rocket.

[Brian Rupnow]

So, here we are with one big wheel and one little wheel welded. The wheels haven't been removed from their jigs yet. They look nasty/ugly, but remember, all of the brown smoky stuff is going to disappear. The side with the welds on it is going to face inwards, so very little of these welds are going to be visible. I will post another shot of the same wheels later today after I get them cleaned up. I used my new tig welder for this job, because it is the only welder I have that can deposit a small controlled puddle of weld where I want it.

[stevehuckss396]

So is the plan to mount them on a spindle and take some very light cuts to true up the wheels.

[Brian Rupnow]

Steve--Actually I planned on posting about that exact thing. No matter how much care is taken with the jigs and set-up, there will end up being visible "wobble" when the wheel is rotated on the center hole in the hub. This can be addressed by taking "truing cuts" from the outer edges and sides of the wheel as the wheel rotates if the wheel is supported on an "axle" which fits into the hole in the center of the hub.
 I was just in the process of doing that, when I had a thought. I would strongly recommend that anyone who sets out to build fabricated wheels like this, put a bore thru the hub center 1/16" less than what it will end up being. This lets you build a fixture which accommodates the smaller center hole. Then when the wheel is removed from the jig, set it up in the lathe so that the chuck is gripping the outer diameter of the wheel, and that it is rotating "true" with no visible wobble or run-out. Then re-bore the center hole in the hub to the correct size. That is much easier than trying to re-machine the outer diameter and sides of the wheel to make it run true.

[stevehuckss396]

Makes sense to me

[crueby]

Great tip!