Taper attachment

Was looking at my Craftsman 12x36 lathe this morning and found that I have access on the backside to the end of the cross slide screw. I am going to try to make a mandrel that screws onto the cross slide screw that I can then attach different size wheels to. In stead of using wire I am going to use small diameter line used on boats. These lines are stronger than steel with less stretch and are designed to go around sheaves in blocks. I am going to make the wheels wider and try to create a threaded surface so the lines don't tend to cross over each other. The line will wrap around the wheel two times. With all the other projects and stuff I have going on it is going to be several weeks or longer before I can get this done. I'll take pictures and do a complete report when I get it finished.
 
I follow you, you are referring to multi-strand stainless steel cable sometimes called "aircraft cable"? That's what I would use too, around 1/16"
 
I thought about the small 1x7 or 1x19 SS cables but think that the synthetic lines like dynema and other brands would work better. They are more flexible, have less stretch and are designed to run in small blocks. The small SS cables are flexible and can turn corners but aren't really designed to make complete circles. Especially small circles. Sorry for the boating terms. I have been actively sailing for almost 50 years up and down the coasts of California and Mexico.
1x19 and 1x7 refers to the number of strands in the cable. 1x7 is more flexible than 1x19 but has more stretch. Neither like going around a complete circle, especially small circles which will deform the wire.
 
With my spacer project completed I will now concentrate on this. The acme screw on my cross slide appears to be 1/2" x 10 tpi left hand thread. I don't have a acme thread gage and the space on the cross slide is too narrow get an actual measurement on the diameter of the screw. My lathe is a craftsman 12x36 . Can anybody confirm to me that this is a 1/2" x 10 tpi LH?

Here is my plan. I will put a coupler nut on the end of the cross slide screw and screw around a 6" piece of acme threaded rod into the coupler nut. I might have to turn down the coupler nut to fit in the cross slide. The end of the cross slide is open and there are two existing threaded holes on the end of the cross slide. Holes look to be 1/4 x 20 tpi. I will make a plate to cover the end with a hole for the threaded rod to extend through, secured by bolts into the existing holes. I will take another coupler nut and turn it to be a flange nut. This flange nut will act as a bearing to keep everything in alignment and provide a flat surface for the wheel to sit against. I will use a nut to lock the wheel against the flange nut.

In looking at the backside of the lathe there is an existing bolt roughly level with the lathe bed that can be used to anchor one end of the line. The far end of the lathe bed does not have any existing bolts that I can use. I will have to make a stand off to anchor this end of the line. I will do a rough sketch of what I am thinking and take some pictures of the cross slide and the back side of the lathe.

If the cross side screw is 1/2 x 10 tpi McMaster Carr has the nuts and threaded acme rod that I need to make this.

Any and all comments and suggestions are welcome.
 
cross slide.jpg
This is a rough sketch of the end of my cross slide. It is not to any particular scale.

cross slide with taper.jpg

Here I have added the taper attachment. The only thing you can't see in this sketch is the flange nut/bearing. It is hidden behind the wheel. Again not to any particular scale. Just representative of what I am thinking would work.
 
"Spider Gear", is that like a splined end on a shaft, but somehow different?
 
Why do you want the extension, to which the wheel is secured, to be threaded? Why not just a shaft connected to the leadscrew with a coupler?
 
You have to use different diameter wheels for different tapers. Although by adding purchase on the line going around the wheel you would change the taper. For example if you had a wheel that gave a taper of 1/8" per foot with no purchase by adding a 2 to 1 purchase the the taper would increase to 1/4" per foot. 3 to 1 would be 3/8" per foot and 4 to 1 would be 1/2" per foot. Without the mechanical advantage of the purchase the wheel keeps getting smaller and smaller as the taper per foot increases. At some point in time you have to add purchase to the system. Also having the wheels as large as possible decreases any error in the amount of taper due to an error in the diameter of the wheel. When I get to making the wheels I will do the math to determine what wheel size and purchase to use for a given taper. I'll leave that for another day.

The shaft has to be threaded at the wheel end in order to secure the wheel to the shaft and to be able to use different size wheels. You could just thread the end of the shaft where the wheel goes and attach the shaft to the the lead screw with a non-threaded coupler with set screws. The set screws would damage the threads on the end of the lead screw over time and I don't want that to happen.

Your suggestion would be simpler to make. Thinking about it I would still use a threaded coupler to thread onto the lead screw and slip the shaft into the other half of the coupler. The shaft could be secured to the coupler with a set screw. This would eliminate the threaded flange nut which also acts as a bearing. The smooth shaft wouldn't need a bearing and I could thread the end of the shaft to any convenient thread size.

I like your suggestion. Thanks
 
Why not attach your various wheels with a key and set screw instead of a threaded nut? Or a dimple and a setscrew (e.g. shallow hole and dog point setscrew)?
 
magicniner said:
"Spider Gear", is that like a splined end on a shaft, but somehow different?
Click to expand...

The (bevel) gears on the end of the halfshafts, that deliver power from the differential's (bevel) planet gears to them - with the reduction in the diff' and the radius of the wheel/tyre, there's a lot of torque between them and the halfshafts under Firm Acceleration.
I think the sudden change in section where the flange and halfshaft meet is where they snap? so reducing the section of the halfshaft (the taper) lets it act as a torsion spring and relieves some of the stress at the stress-raiser?

Not on Spridgets, but I've seen halfshafts with 3/4 of a turn of twist on them before they've broken - one was from a schoolfriend's Morris Minor with a supercharged 1275 Spridget engine...

Dave H. (the other one)
 
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