Test bars are very straight, very round bars used to setup machinery and work fixtures in the shop. They can also be handy for inspecting run-out in chucks and collets. You can buy them commercially, but like most metrology equipment they can be very pricey and therefore hard to justify for the limited use seen in the home shop. In this article a moderately priced bar is made that should satisfy most home shop needs.
The last project required a keyway to be broached in a shop made gear. I already have a nice Hassay-Savage keyway broach kit, but as is so often the case, the kit didn't have a guide bushing for the particular sized hole used in this gear. Rather than wait a week to get the correctly sized bushing via mail order, this article will show how to make one in the shop out of scrap so the job can be completed in a timely manner.
If you are working on old gas light fixtures or strangely enough, microphone stands, you might have the need to single-point cut a 27 TPI thread with your South Bend Lathe. While this particular thread setting isn't directly available through the QCGB, with the addition of a 42 tooth gear into the gear train cutting this thread is possible. Back in the day there was enough interest in this that South Bend sold the optional gear.
The gear creation project continues with indicating the blank to run true, setting the cutter height, cutter depth and finally cutting the blank with an involute gear cutter. After the blank is deburred, the gear is inspected with the two wire method and a recommended web page with gear information is shown. After that, the gear keyway is cut with a broach and another way of making gears is shown.
Several future projects in the work queue will need some shop made gears. Almost all the necessary tooling for gear making is already in the shop and I would like to make a gear now to help streamline the process for making future gears. Since I already have a set of the proper involute gear cutters for the lathe's change gears, I'll start with making a gear that will allow single-point threading on the lathe a thread TPI that is not available as a selection with the lathe's QCGB.
After the VFD installation, sometimes when using the lathe I wished for a tach to keep track of the spindle RPM's while adjusting the variable speed control. While not completely necessary, it is sometimes convenient to have an accurate gauge of spindle speed than just a guess by the sound of the lathe and location of the drive belts. Luckily, digital tachs using a hall effect sensor are accurate, cheap and relatively easy to install as shown in this article.
In the hobby shop it's a quite common need to gently tap objects into various forms of alignment. A soft blow hammer works great for this, but sometimes it's difficult to get enough room for a good swing or the item to be moved is quite small. This shot filled dead-blow knocker, with non-marring Delrin and brass ends, is very handy in such cases and is a fun weekend project that is machined entirely on the lathe.
Time to wrap-up the VFD installation for the South Bend 10K lathe by installing the motor into the lathe cabinet and making a custom mounting bracket to mount the VFD and avoid any unnecessary holes. The VFD was installed in a slightly unusual position so it is discussed why I didn't go with a more typical controller spot and why this was the best position for my usage. Also an emergency stop switch was installed that will completely kill power to the lathe.
Immediately after it was purchased the SB10K lathe had been using a 115V single phase motor which is not usable with a VFD so a different motor (3 phase) was required. This article goes over what specifications were desired in a replacement motor and what motor was eventually installed. For the VFD, various features and models are discussed and then I elaborate on why I went with the VFD that was eventually installed in the lathe.
A variable speed drive is a nice option for any piece of metal shop equipment. For the lathe, it's especially handy to be able to adjust the spindle speed during a cutting operation, like increasing the RPM's during a facing operation so the cutting speed at the tool is constant as the cut diameter gets smaller. In the next few articles I will describe how I installed a variable frequency drive into my old South Bend 10K lathe.