MARBLE LIFTING AUTOMATION

[Brian Rupnow]

Since I have been unable to find a satisfactory "ready made" gear to suit me, my next step may be to create the orange colored 108 tooth gear. The gear is a 24DP spur gear which I can make with the cutters I have. It is 4.5" pitch diameter, and with the rotary table and divider plates I have, it will require me to use 15 holes on an 18 tooth divider plate.--Yes, there is less than 3.33 degrees between the teeth and my rotary table is a 90:1 ratio.--That's going to make for a LOT of cranking. I like the look of the gear which I have modelled.--Rather than a solid plate hub, which is the easiest way to go, I think I will make the center section a built up weldment from steel and shrink the brass gear to the outside of it. Not because it will work any better, but because it will look better and presents a bit of a challenge.

[Brian Rupnow]

It looks like there may be as much work in this gear as there was in the rest of the machine----

[Brian Rupnow]

I may not do any machining tonight. I meant to go down to my steel supplier today and pick up some cold rolled to start the hub for my built up gear, but after working 9 hours on my current design contract, I don't have much energy left and the steel supplier is closed now anyways. That's okay. I just downloaded Stephen King's latest novel onto my e-reader. Maybe tonight I'll just set in my big chair and let old Steve horrify me!!

[Brian Rupnow]

So---Here is the beginning to my 108 tooth gear. I only need a couple of inches of the 1 1/4" cold rolled but I bought a foot, because it will always get used. The 660 bronze which will become the actual gear was a "short" that was laying in the "shorts rack" and the steel pipe which will become the outer rim that the bronze gear attaches to is a piece of 4130 that just happened to be the right size.

[Brian Rupnow]

This project is going to involve some rather "intense" machining (for me anyways). The diameters involved are right on the ragged edge of what my lathe chuck can open to and hold. This is the first step, boring and facing the 4130 steel "rim". I am using the "reverse jaws" in the chuck. When I locked the work up in the 3 jaw chuck, I used a 1/8" parallel between the back side of the work and each chuck jaw, so that I could run the boring bar in far enough for a complete "clean up" of the bore without my boring tool hitting the chuck jaws. The parallels were, of course, removed before I fired up the lathe. Now I have a "witness face" which is perfectly square to the bore.

[Brian Rupnow]

Same-o  Same-o, only this time with the 660 bronze. The o.d of that bronze as it sets is 4.820". I have a note written on the wall over the lathe that says "Largest diameter I can hold with the reverse jaws is 5.25", so I am approaching the envelope. That's all the turning that I have to do until after the steel hub, rim, and spokes are welded together. Next thing I have to do is set up the rotary table to drill holes in the rim and hub every 60 degrees.

[Brian Rupnow]

And this is where I will be going the next time I get a spurt of energy!!!

[Tinkerer58]

Welcome back Brian, good to see common sense has prevailed.

[Brian Rupnow]

Thank You Tinkerer.---Brian

[swilliams]

Good to see normal transmission resuming Brian. Looks like solid progress and I'm curious to see how the whole thing comes together.

Steve

[Brian Rupnow]

Tonight was rotary table night. I put a divider plate on so I could turn EXACTLY 60 degrees between each hole. First I drilled the 1 1/4" cold rolled that will become the hub for the gear. The 6 holes in it will be tapped. Then without moving my set-up I was able to mount the outer rim and drill 6 holes with a 3/16" diameter drill and then counterbore with a 3/8" endmill.  The plan is to thread the end of my six 3/16" diameter "spokes" on one end and put them thru the 3/16" holes in the outer rim, screw them into the hub, then cut them off flush with the rim outer diameter, assemble everything in a jig, and then mig weld the end of the spokes. That is what the 3/8" counterbore is for, to fill up with mig weld. Will it work?--I have no idea. After everything is welded in a jig, I will mount the 1 1/4" hub (which is left extra long at about 3") back into the lathe and turn the outer diameter of the rim to a proper fit to go into the inside the bronze that will have the gear teeth cut into it. I have drilled the holes 5/16" in from the face of the hub and the outer rim so I will be able to "clean up" the faces in my lathe.

[Brian Rupnow]

This is very interesting!!! I may go into business making ships wheels. And as far as the comment that was made by someone who said "That hub will be self centering."--Nah, not even close. I am going to have to set the hub up in the lathe chuck and using my dial indicator, chase the outer rim around by tapping it until its close to being concentric, before I make up a jig for welding.

[wagnmkr]

Brian, In my wood turning days I made several ships wheels for folks, and that is exactly how I did them.

For your jig, all you need is a piece of plywood or mdf in you lathe, make a tight fit groove for the outer ring and one for the hub. Make it only half the rim and hub depth for no spoke interference and then thread in your spokes and secure them however you want. I make my miniature wagon wheels this way too.

Cheers,

Tom

[Brian Rupnow]

Whenever somebody hears "Build a Jig" they automatically think of something complex. It isn't always that way. My jig for welding the gear was made from a piece of 1/2" aluminum plate. A 1/2" hole was drilled on center, a 1 3/8" counterbore .150" deep. and the outer edge turned away to leave a "spigot" that was the exact size of the inner ring diameter x 0.150 deep. I took a piece of 1/2" cold rolled steel about 2" long, drilled and tapped a 1/4"-20 hole in the end of it, then inserted it in the 1/2" bore in the end of my "hub" and cross pinned it there with a 1/8" spring pin. I set it up so that about 5/16" of the 1/2" rod extended past the face of my hub. That allowed me to set the entire built up pulley in the jig, run a 1/4" bolt thru a washer and thru the jig plate from the back side, and tighten the hub in place against the face of the 1 3/8" counterbore. The  1 3/8" counterbore was clearance on the hub o.d. because the actual locating was done by the 1/2" cold rolled. Then an assortment of welding clamps and c-clamps were used to clamp the outer rim tight against the jig.

[Brian Rupnow]

And this is how the welding went---In the second picture down, you can see the 1/8" spring pin which was holding the 1/2" diameter cold rolled in the hole in my hub.