Rich Carlstedt’s E-Z Rest

Welcome to my E – Z Rest, a tool you may find useful in turning long thin parts on your lathe. I developed this tool almost 20 years ago when I needed to turn a long thin part in my Boxford lathe which was almost impossible using regular tooling. The solution created as a simple fabrication is clean and useful and therefore I gave it the name E-Z Rest (picture1)   This picture(picture2) shows a challenge to turning in an ordinary lathe operation. The material is steel and is 10” x 0.25” x 0.125” steel flat bar that had to be turned eccentrically to a 0.109 “diameter. After roughing the stock in a saw, the challenge led to building the E – Z Rest in order to machine the round diameter for the part seen in this photo (picture3) and which demanded to be entirely made in one piece of steel.

One of the neat things about lathes is the ability to turn odd pieces of material into round rods. This easily performed task becomes more difficult as the length of the material increases and then even more difficult for thin cross-sections which tend to either whip in the lathe or deflect from tool pressure with the resulting loss of diameter control. To help minimize these effects lathe makers generally offer follow-rests or steady-rests as accessories to the lathe. While these two rests are generally very effective in performing the task of stabilizing long heavy work, their size can represent cumbersome obstacles for smaller jobs in some cases and their cost may be out of range for some home shops. Now you may already have a steady rest or a follow rest to handle similar work but using those styles of support can inhibit free movement of your carriage. The need exists for a light duty work stabilizer which allows full use of the carriage and is quick in set up and adjustment and cost little !  The solution is the E – Z Rest for such work (picture4) and is made from two blocks and utilizes the lathe’s tailstock barrel and a few boring bars. carriage and the E-Z rest allows the carriage to go from headstock to tailstock 100 % limited only to the length of your “now” multi-use boring bar.  Instead of having a tool bit in the boring bar, a brass rod is substituted to support the work piece during machining. This I call a support crotch because it has a V shaped crotch on the working end and is a bit different from a normal “jaw” or “finger” found in commercial rests. To do this, a hole must be drilled in the non-used end of the boring bar at 90 degrees for the support crotch insert and a set screw added to the end of the bar for clamping the support crotch. The boring bar then becomes the “support shaft” for the E-Z Rest unit

To start, look at the lathe as a clock face viewed from the rear of the tailstock looking forward towards the chuck. You will find that in normal lathe work the tool bit approaches the workpiece at the 9 o’clock position. As cutting forces are applied from the tool bit, the resulting force vector tries to deflect the work to the 1:30 position (and this is reflected many times when you analyze wear in headstock bearings) but the tensile strength and size of the work piece resists the movement unless the work piece  is very small in diameter. For such small diameters, the solution to prevent deflection is to provide maximum support at the 1: 30 position to resist cutting forces(picture5). This is done by mounting the support shaft (boring bar) at the 1: 30 position and using the support crotch to directly engage the work for maximum stability. The lathe tailstock barrel ( quill) presents a superb mounting place for the support shaft as it is stable and in total alignment with the spindle’s centerline- A Perfect resource !

Now to attach the support shaft to the tailstock barrel at the 1:30 position you only need the E – Z Rest clamp block. The design of the clamp block should allow the support shaft to be easily adjusted to any location needed for work support.  Depending on the work, I have used it in other radial locations. To set location adjustment and clamping it is nice to have a threaded handle that is easily accessible, I know a bolt will work, but it requires a wrench and that leads to complications ( ie. three hand adjustments ) . The basic concept of this rest is to utilize existing boring bars that you may have on hand, which in my case I had both ¾” and 1-1/8” diameter boring bars for normal lathe boring operations that required two different versions of the rest, a small one and a larger one, The two Sizes are shown in (picture 6) The small one uses ¾” boring bars and the larger is 1-1/8” diameter. I will detail the smaller one and readers can modify their needs appropriately depending on the task at hand and material available. I will also show the larger one size change for reference

This is the Aluminum plate I started with. (picture7) but there is a wide range to choose from (even solid) based on the individual needs. The only material needed is a block or two of aluminum and a threaded knob (handwheel) for clamping and you have yourself a support system for long work.

To layout your rest requires 3 dimensions:  

1.Tailstock barrel diameter

2.Boring bar diameter (your inventory!)

3. Dimension for clearance needed at the tailstock clamps (picture 8)

My drawing dimensions here (Picture 9) are for a Boxford Lathe but the reader should confirm this with their lathe and reflect that in modifying the center locations of the two support holes in the clamp block

To start the work you have several options, and the easiest is to use aluminum plate or bar to fit your design. The clamp may be made in solid form and sawn in half later,  as I did on the smaller clamp block or it may be made by making two pieces from material described earlier. The picture (Picture 10) shows the larger clamp block made from two pieces. I cut the two blocks out of 1-inch-thick plate to a size of 2” x 4.3”.  Please note, in actual fabrication, clamp block size will be based on your individual design  (!).  To determine the size of your block you need to look at your tailstock clamps (2). As you can see in these pictures(picture 5 and 11) I provided about ½ inch extra for the boring bar to clear the barrel clamp lever. This is needed if you have a long bar but intend to use it near the tailstock center and also near the chuck. This clearance allows you to retract the bar over the body of the tailstock without hitting the barrel clamp or the tailstock clamp. . Note: You may need to add a washer under the tailstock barrel clamp handle as shown in the picture -if your rotated handle position interferes with the bar.

This was not done with my small clamp block as I have an assortment of ¾” boring bars in many lengths and only used a 1 ½ inch center distance between the bores and by fully extending the barrel first before locking the barrel gives me added adjustment length for the clamping block. To determine centerline distance, put a dead center in the tailstock and hold a boring bar in the clearance position while measuring the centerline distance. Take that distance and add the larger diameter bore to it and then add 1/2 inch which determines the needed size for the block.

Clamp block length = (Center Distance + Largest Bore Diameter  + 1/2”)

I milled the ends and sides so that the two blocks matched exactly. Take the blocks and place some heavy paper (refer to drawing) between them for all the following operations. Having paper to separate the blocks means that after the finished boring with the paper removed, there will be adequate clamping on the boring bar and the tailstock barrel. The first task is to drill and tap a through hole in the center of the two blocks so that they may be clamped together (picture12) using a bolt during fabrication. Later when complete you want to mount a handwheel for easy machining use.

My suggested size of 3/8 – 16 was due to have several spare handwheels on hand, but select what is most convenient to you like 10mm or even a finer thread. There is no magic here and you will find many handwheels available that will fit this requirement and to your thread size. Wixroyd or Berger-Tools  or similar UK suppliers have some to consider if your stores are empty. The ones I used are called Threaded-Stud Knobs in the USA.  After running a tap drill through the blocks, proceed to drill a clearance hole in one block and do your tapping in the other block. You can now clamp the blocks together with a bolt and proceed to start drill starting holes (picture13) for the main bores using the calculated center distance.  Clamp the block in the mill and use a large end mill if possible, to pre-bore the holes so your boring head has minimal removal of material(picture14). I like to pre-bore to within an 1/8” if possible if I have such an end mill on hand. (Picture 15) Then proceed to bore your holes and check size using a very unique method of bore measurement.

This easy method does not require ID Mikes, Bore Gauges or Telescopic Gauges and is one that I have taught for many years to my machinists at work. The process is to use a good adjustable parallel gauge(picture16)!  Adjustable parallels are a neat way of measuring bores because they not only can give you accurate size but if you can wiggle the parallels, they will tell you if your bore is Coke bottle shaped or if the bore is tapered. You want good adjustable parallels that have smooth even corners and no burrs or dents. Insert the gauge in the bore and expand it, then measure “cross corner” with your micrometer as shown and at the same time it’s a good idea to measure your boring bar(picture17) so that you can quickly and accurately compare the size. Using the same measuring instrument means less chance of error!   When you have reached size, we are done with the boring operation and need to disassemble the blocks, or if you made it from a solid block version, then it is time to use the bandsaw and cut the block in half. The saw cut reproduces the same effect as a paper insert on two pieces.  One of the problems that occurred when I first made the clamp block was that my bore was so closely matched to the bar that I could not slide the bar easily when setting up my work.

Technically, the last 7 degrees of the half arc (180 deg) is a locking taper and the bar sticks to the block. To prevent this, you need to remove material on the bore with an end mill as seen in the picture (Picture18) and on the drawing. Just a light pass on the major diameter about .125” deep and .005” on the diameter relieves the sides so the clamp does not grip the bar when the clamp is loosened for adjustment. You may wish to do this on the tailstock barrel bore as well, but I suggest you try it first in case your bore is slightly oversize in which case the endmill pass is not needed.  To make the “crotch” in the brass  support crotch. (picture19), just mount your brass rod in the mill at a 45-degree angle and bring a endmill down and touch the two edges as shown in the sketch and using the diameter of the brass rod, you multiply it by .707 to determine how far to lower your cutter. This is the amount to feed the endmill down to produce a 90-degree centered crotch in your support piece. (ie. for a .375 rod x.707=.265”). I suggest you move the Y axis and do the cutting in steps as brass has a tendency to grab cutters .

Some applications  to show the E-Z Rest’s advantages besides free zone work

On some work I place a dowel of desired size in the Lathe chuck and then set the support crotch so I now have the size I want, then when I move to reset near the tailstock, I know I am exactly where I want the support to be.  (picture 20) In the picture , I am using the stock for setting . Note that the Clamp Block and support are Vertical then clamped, which makes it more of a temporary hands free access mode.

Now by withdrawing the bar and setting it near the center-drill, (picture 21 and 22), you get great support for starting long work pieces  and then by extending it , you can make a cut on the right side of the support (picture 23). Cutting on the left side- as we saw in the beginning (picture 24) is no slouch either.

Lastly for really small diameters like 1-2mm and high speed I have at times added a common shaft collar ( picture 25) with a small bent brass rod attached as shown  and slipped this on the crotch support , and then after the work piece was installed, slide the collar down and rotate it and then locked the collar set screw and you will have 3 contacts with the work and it will be totally captured from movement away from the crotch.   Hope you enjoy this unique tool, the E-Z Rest for those extra long projects !

Rich Carlstedt

Photo 1	Photo 2	Photo 3	Photo 4
Photo 5	Photo 6	Photo 7	Photo 8
Dwg 9 3/4″ version	Dwg 10 1-1/8″ version	Dwg 11 – view from tailstock	Photo 12
Photo 13	Photo 14	Photo 15	Photo 16
Photo17	Photo 18	Sketch 19 Crotch Support	Photo 20
Photo 21	Slide 22	Slide 23	Slide 24
Sketch 25 Shaft Collar