Plans, projects and how-to's for home machinists

Snub’s ball turning tool

I think this is a brilliant idea.  “Snub” made a ball turning tool and used a 4-jaw chuck as the base.  He says it works perfectly and leaves an almost perfect finish.  I don’t doubt him because of the weight and rigidity of the chuck and the large bearing he used as a pivot.  His design also looks like it is quick and easy to make.  Notice that he didn’t make a holder for the carbide insert.  Instead took an existing holder and drilled it so he could bolt it to a piece of steel.

Unfortunately, you can’t use Snub’s idea if you have a small lathe.  It would definitely be too tall for a 7x mini-lathe, and I don’t think it will work on my 8×12 even if I use a shorter 3-jaw chuck and somehow directly mount it on the ways.

Free Plans: Ball Turning Tool Post for the 7x Mini-lathe

I want to tell you about Ralph Patterson’s free plans for a ball turning tool post that will fit a 7-by-whatever mini-lathe, and show you how he used it to fix a broken shower head.  I’ve also included a YouTube video that shows a similar tool post being used to make a ball end for a tool handle.  Near the end of the article you’ll find a link to download the plans for this tool, along with a link to where you can get Ralph’s other plans.  And if you read carefully you’ll also find a link that leads to plans for a ball turning tool that will fit a 9×20 lathe.

This ball turning tool post is part of set of more than 25 free plans Ralph made for some very useful mini-lathe accessories and modifications.  He also designed a boring bar holder, a quick change tool post, a leadscrew hand wheel, two versions of a tailstock lock, a carriage clamp based on Vicki Ford’s design, a die holder, a modification for slowing down the leadscrew feed rate, a file guide, a spindle indexer, a spindle crank, a height gage that uses a digital caliper, an adjustable tool rest for a bench grinder, and much more.  In addition to drawing nice plans, Ralph also did something I think is very smart.  He included photographs with most of them so that those like me, who don’t have a lot of experience reading prints, can easily see how the parts fit together and what the finished project will look like.  He also includes a parts and material list with his more complicated designs, which is something I wish more people did.

The original swivel neck was made from plastic and it broke

Ralph is an excellent CAD drafter, skilled machinist and a gifted designer who knows a lot about mini-lathes.  I’m very surprised that his designs and plans aren’t more widely known.  (I intend to do something about that if he doesn’t mind).

His ball turner is adapted from one that Steve Bedair made for his 9×20 lathe.  If you go to Steve’s web site you will not only find free plans for his design, but also photos showing how it is made and used, along with pictures of some of the things he has made with it.  Besides things like ball ends for handles, this kind of tool post can also make beads on a straight rod, and with a little modification it can also do coves.  They’ve also been used to make the lenses for optical center punches.

Ralph’s ball turner attaches to the top of the cross-slide with a couple of bolts and it doesn’t look like it will be hard to make.  The most critical dimension is the height of the cutting bit and Steve Bedair has a nice picture that will show you how he measured it.  The base has a recess that can probably be bored on a lathe if you have a 4-inch, 4-jaw chuck, otherwise you’ll need a mill and a boring head.

Ralph gives you a choice of four different tool bit holders that you can make.  Three of them use carbide inserts and they’ll require you to mill a number of angles, some rather precisely.  A forth version uses an HSS cutter made from a 3/16-inch drill bit.  Both it and the HSS cutter look like they should be fairly simple to make.

If you would like to get in touch with Ralph or thank him for the plans then the best way to do that is to join the excellent 7×12 minilathe discussion group.   [Editor’s note, 6/18/2020: After Verizon bought Yahoo in 2016, they made changes to Yahoo Groups that limited their usefulness and caused many to cease operating.]

Addendum 05/25/2011

There’s a small error in the plans.  The materials list says to use aluminum for the body and base, but the plans say to use steel.  I asked Ralph about it and he said to use aluminum, or whatever you would like.

He also had this to say:

“If I were to make the tool again, there are a couple of improvements to consider.  In order to move the cutter toward the center of rotation as the ball is formed from the straight round stock, it is necessary to loosen the 3 clamping screws, re-position the slide, and tighten again.  For doing that operation easily, the clamping screws should be on the right side of the body.  To make room for the clamp screw holes, the operating handle should be moved a little further down the side of the body.

Secondly, moving the tool holder manually and guessing at how much movement has been made, it would be nice to incorporate a screw into body that can be used as an external feed screw to regulate that movement.  The screw could have a shoulder that engages a slot in the side of the sliding part, so that the tool could be moved both into and away from the work.  Maybe making the slider longer at the base would enable a feed screw/slider to travel through the entire desired range of distance.  Some thought is required.

Thirdly, the cutting tool sometimes needs moving to the left of the axis of the swivel screw of the tool.  This would enable the cutter to move much closer to the axis of rotation of the workpiece when working on the chuck side of the ball.  Maybe the tool holding slide could be made a half-inch lower in height to enable a cap piece that is adjustable from side-to-side to be mounted atop the post.  A variety of cap shapes might be useful.

I am dangerous when thinking about these possibilities, instead of trying them out first.

HTH, Ralph”


Download Ralph Patterson’s Ball Turning Tool Post from (PDF)

Ralph said the carbide insert he normally uses couldn’t reach in far enough to cut the ball at the theaded end. So he temporarily rigged up a larger cutter.


The finished repair

Free Plans: Quick-Release Lathe Mounted Dial Indicator Holder

QRHLD1SwarfRat Enterprises has a set of free plans for a quick-release dial indicator holder that mounts on the front of a mini-lathe.   The holder is made from a 5-inch long piece of .875-inch square aluminum stock.  It also uses a quick-release lever from a bicycle seat or wheel that can be purchased inexpensively or salvaged off an old bike.  It looks like it should be fairly easy to make, although it will require a mill.

I am thinking about making one but not to use with a dial indicator.  With a little modification it might make a great carriage stop, much better than the one I’m using now.  For those rare times when I need to measure the movement of the carriage I use a dial indicator with a large magnet mounted on its back.  It’s easier to make and I can also use it on my mill, which makes it a really useful tool.

SwarfRat also makes instructional videos that will show you how to use a mini-mill or mini-lathe, how to repair them, and how to use some tooling like a rotary table.

You can buy them at their web site.  SwarfRat also rents them for about $9 a week.  That seems like a pretty smart move because there’s another company becoming well known for the how-to videos they specialize in renting.  That company probably buys just one or two copies and keeps renting them out.  My guess is that all those rentals destroy the sales of the companies that invested time and money to produce the videos and removes the incentive to make more videos we might be interested in.

But for some strange reason SwarfRat does not rent all of their titles, only a few of them.  And I’m disappointed because they don’t rent their video about the rotary table, which is the one I would really like to see because I just bought one.  They also don’t provide any sample videos and I can’t find any reviews of their products.  So I’m not going to be taking a chance and spending $44 to buy a copy.

Use Friction Turning to Make Thin Disks and Flywheels on the Lathe

Friction Turning on a Mini-Lathe

Click for more pictures

This article describes how I made two round disks on my lathe out of sheet metal that was too thin to be held in a lathe chuck.  I also could not use a mandrel because one of the disks was not going to have a hole drilled through its center.  The two disks were made from .073-inch thick aluminum sheet metal and are about 5-inches in diameter.  They are the top and bottom cylinder plates for the Stirling engine I am building.

First, I want to give credit where it is due.   I learned this from “Bogstandard” who described it on the Home Model Engine Machinist Forum and illustrated it with lots of nice pictures.  He calls this method friction turning and uses it to make flywheels out of flat plates for models, which can be sometimes be easier and cheaper to obtain than a chunk of large diameter round stock.

With this method the work piece is held against the jaws of the lathe chuck by a live center in the tailstock.  This allows you to turn down the diameter of the entire length of the work piece.  The jaws are opened so their outside edges are a little less than the finished diameter of the work piece.  Bogstandard recommends that you put an appropriate size piece of round stock in the chuck, presumably so it helps support the middle of your workpiece.  I did not do that for this project and it still worked fine.

Continue reading Use Friction Turning to Make Thin Disks and Flywheels on the Lathe

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