Hi C I would personally think about making it from two pieces and soldering it together. Use a piece of 16th diameter for the stem and drill the 1/4 inch to take the stem which was finished to size.

David

I think a box tool would be better as it supports the rod right at the cut all the way along, with minimal flex. After cutting OD, part off the needle and chuck it in a 4 jaw to centre it perfectly. Then put the cone on the end with the cross slide set at the needed angle. Leave just enough of the rod projecting from the chuck to do the length of the cone.

Jeff,

Can you please enlighten me what a box tool is? Getting parallel cuts on thin bar is something that crops up from time to time in what I do, and I don't yet have a fully satisfactory method for doing this

Regards, Chas

Interesting video.

Thank you, bear..

Box tool I had in mind was a homemade type used for various production jobs in toolroom and in screw machine room in the old days. Consisted of a rectangular mild steel or tool steel bar held on the compound rest or carriage, with a central hole a close fit on the rod stock to be cut. On the back (right) side a HSS tool would be mounted and adjusted to cut the exact size needed. The adjustment was often done with a screw behind the short HSS tool. A cap plate was usually fitted over the HSS tool to firmly hold it clamped in place. The bar was relieved at the right side to allow oil flow in and chips and oil out. If a lot of chips were being removed the tool would be planned to operate upside down to let the chips and oil fall out by gravity.

The youtube video posted above has roller or vee versions of this tool. Much nicer build than the rough ones we used to make, and roller one in particular would operate with much lower friction than the basic ones with a hole that we used to make. The ones in the video operate on exactly the same principle though – of holding the work close to the tool , closely controlled, regardless of length of cut.

Sharp HSS tool side cutting tool plenty of rake, light feed. Dead on centre height. Cut in one pass from maybe 10 – 12mm bar. this should self support itself depending on the length you require.

Effectively you are leaving a 1/16 thick long pip!

Oh and allow for a few tests to get it right.

Why silver steel ? it is available in lots of sizes and ground to size, will or should be straight and is very strong. Not expensive to buy.

Charles – could do an article I guess, I do have more than adequate drawing capability, but at the end of a day doing machine design on CAD (my day job) the last thing I want to do is draw some more! The other thing to consider is that the box tool is usually made to fit a particular lathe in the height and clearances so they can not easily be designed as a universal fit. (At risk of boring you with legal matters I don't really want my effort / drawings to become intellectual property of My Time Media or whoever for minimal if any cash.)

You could use bushings in the tool for various sizes of shaft IF a) they are well secured against falling out b) there is enough adjustment length designed in for the HSS tool to cope with the diameter range of the bushings.

Again these tools were typically made for a particular production job making hundreds of thousands of parts, so each was purpose built. They were only an afternoon's work for a toolmaker so designing in variability / wide adjustment range was not a focus. We'd make them, adjust them to run the job well, and after that they made parts until sharpening time for the HSS tool, or the setup was torn down to do a setup for a different part. On some of the tools used often, we would make a gauge plug with a tail the rod size and an end at diameter to correctly set tool position. Using this plug, setup after sharpening took seconds – just move the tool up to the setup diameter and clamp it, start the job again. These plug gauges were stored on the tool in a drilled hole with a homemade brass set screw in a drilled and tapped hole at 90 degrees to the storage hole to secure them. Brass screw prevented marring the OD.

Don't suppose it helps but would the original carb needle have been ground to shape rather than turned on a lathe?

Industry often use other methods than those available in a small workshop. Be interesting to know what percentage of cutting is done by each of the available techniques. Ordered by volume of metal removed, my guess:

1. Grinding – probably by a large margin.
2. Punching (mostly cold, especially sheet metal)
3. Milling and Drilling
4. Sawing
5. Turning & Boring
6. Laser, Water Jet, Plasma and gas axe

The order would have changed over time, in 1918 perhaps:

1. Turning and Boring
2. Drilling & Punching (mostly hot.)
3. Cold Chiselling & Planing
4. Milling
5. Sawing
6. Grinding
7. Gas Cutting

Dave