I drink coffee some mornings with a contractor friend who mainly does big public works projects and has gravel and sand pits and crushers. Half a year ago I asked him if I could buy half a truckload of masonry sand and half a load of crushed stone for a concrete project I was mixing up. I was surprised to see him deliver the two loads personally, and then refuse payment. He said maybe I could help him some day in return since I had metal working machines.
Well that day finally came and he asked if I could turn down the middle of two pins that were part of a bucket loader assembly. The pins were new and standard fit 65mm dia for the bucket, but the quick change gripper on his machine was intended for grabbing 60mm pins. Pins were about 18" long. He wanted a middle section of each pin turned down to 60mm for a distance of about 11". I said I thought I could do it.
This presented a few problems for me. First, my "new" homemade 9" dia. lathe in my tiny shop has only a 12" length capacity. I do have an old Craftsman 12" x 36" lathe in my old larger storage shed, but it hasn't been used in a decade. It also doesn't have a steady rest. The new bucket pins did not have centers drilled into the ends and were way too long and heavy to be held in the Craftsman's 4 jaw chuck without support. Also no way of sliding a pin into the spindle bore (1" in diameter) in order to drill a center.
However I did have the steady rest I that built for my "new" lathe as detailed in the last pages here:
https://www.madmodder.net/index.php?topic=13498.msg162485#msg162485 And my "new" lathe and the Craftsman share the same dimension and type bed and ways, so the steady would fit on the Craftsman. But the new lathe is a 9" dia and the Craftsman is a 12". So my first step was making a riser block for the steady rest. Not a big deal, I found an old scrap piece of 1" plate about 6" wide and sawed off a 1-1/2" thickness to provide the necessary height. Two holes were drilled in it to allow the mounting bolts for the steady's cast ring to pass through to the base. And that was done.
But now there was the problem of how to set up the steady rest accurately for turning down these bucket pins. It would have actually been easier If I'd been working from oversized raw stock to make the pins completely. Center-pop both ends and mount between centers, then turn all of the diameters at once. But working with existing pins, I had to preserve the end diameters and mount them exactly concentric and parallel with the lathe centerline.
Well YouTube to the rescue, right? Lessee..... two or three videos....nope.... rejected after a few minutes of intro. Just people working with oversized raw stock then approximate center punching. Others were sliding small diameter stock into spindles to center drill. Wasting time with these intros.... Okay what about Blondihacks? Nope, also not applicable here. Joe Pie? Well, okay, at least he's mounting existing thick stock accurately. To do this he built a special tool, then he used gage blocks to set it, then did a few calculations to account for offsets, etc. Then he set his special tool in a collet in the spindle bore and swept it to set two of the steady rest fingers. Once they were set he slid the steady out to its final position. Doing some testing with a DTI, he got his steady set within a 5 thou taper.
Well, sorry but no time to make a tool (my friend needed this for a job right now!) no full set of gage blocks, no collets for the Craftsman, etc. etc. Sure I like Joe Pie's tool and methods -- some day maybe I'll make one. But the principle of setting the steady near the chuck to a known dimension, then sliding out was something I could use. So I kept that in mind.
Building a Dave Gingery lathe 24 years ago as my introduction to machining taught me that expensive precision measurement equipment is nice, but you can do many close tolerance tasks using your lathe where no (or little) actual measurement is used.
Using that kind of thinking (what would Dave Gingery do?) I decided all I really needed was to turn another piece of stock to the OD of the pins (65mm) in the chuck, then set the steady from that, and slide it out to its final position. Great! Only I couldn't find any short round aluminum or steel or even plastic or pipe stock in my scrap pile of about the size I needed. Also I'm cheap, and hate to just chew up aluminum or steel stock into swarf if I don't have to.
Well, in the real olde days, machining especially at hobbyist level, often employed wood for many purposes that we seem to feel we need need metal for. I have plenty of dry rock maple limbs in the woodpile and for this temporary use, why not?, and so I just grabbed a piece cut off a chunk, and turned it in the chuck to 65mm.
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Then I slid the steady over the turned piece, and set the two lower fingers.
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This sets the steady support to the right diameter, height, and position for the pins automatically. The upper finger simply rides on the pin to keep things in place, and is set after sliding the steady out on the ways.
Here's the final setup, doing its job of turning the reduced diameter in center to 60mm:
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How did it turn out? Well the total taper amounted to .07mm over ~11" using a chunk of firewood for setup. Well within what my friend said was acceptable to fit the work-worn gripper on his machine. And better on this 75 year old Craftsman lathe than the Jo Pie setup had yielded him as well. Can't complain!
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