Beam Engine Progress or Go With What You Got

I have gotten out of the habit of regular posting as my current machining focus is a bit off the beam from what this blog started out as. I have finally admitted to myself that it will be a while before significant model railway activity takes place and also have reminded myself why I chose the blog name I did. So, I shall report on what I am doing in hopes that it will be of some interest albeit perhaps not to exactly the same audience.

To recap, I have been developing my machining skills by working on a model beam engine based on plans by Elmer Verburg. This engine is commonly referred to as #24 (Elmer created many plans and made them freely available, may he rest in peace). I have done the base, flywheel bearing, flywheel, eccentric hub, and column. Here is a dry fit of those pieces.

The part in progress is the beam. This is attempt the second as the first effort is now part of the scrap pile with the end of a #55 drill firmly embedded in it. Trying to drill that size of hole with the lathe going at 1100-ish RPM was not a success. The mill going at 4300 and a less ambition depth did the trick.

There are three 1/16th inch reamed holes in that piece. Photographing shiny aluminum close up is still something I need to work on.

Next step will be to flip the part over and mill it down to final thickness and take off the edges at an angle to produce an elongated lozenge shape. I have a plan but it may not work out. On the other hand, the only crucial dimensions on this part are the holes and the thickness of the hub. All else could be done with a saw and a file.

Model Building of a Different Sort

It has been quite some time (March!) since I posted. I have not been idle but work on Comstock Road has been minimal although I have enjoyed a few impromptu operating sessions which have gone surprisingly smoothly given the general lack of activity.

I recently reached a point in my machining journey where I felt it was time to make something that wasn’t a tool for making things. I hit upon a site containing many plans for model stationary steam engines created by the late Elmer Verburg. These plans can be built from standard metal shapes without the need for castings which makes them ideal for beginners who may need multiple attempts to make a part(ahem).

I have begun the process of creating a horizontal beam engine aka Elmer’s Engine #24. I have three parts made with the second and third requiring two attempts each due to measuring errors caused by duffing fractions to decimal conversions. I need a wall chart.

Anyway, here is the project to date with the base and flywheel bearing assembled. Eccentric hub not show as it is currently clamped in a vise awaiting drilling and tapping for a set screw.

All of those holes will eventually get something in them. It is an interesting contrast to the usual railroad model build in that each part is a project in itself requiring planning, setup and machining. It has also been a good skill bilding exercise as I have had to execute a variety of new operations.

Next part will be the flywheel, I think. This will be all kinds of new challenges as I deploy my shiny new rotary table for the first time. Adding a fourth axis to my mill means more thinking and care are required. I have laid in lots of extra stock for the likely multiple attempts. 🙂

Metrology Monday: Calipers

What Are Calipers For?

The title seems a little silly for this one since most everybody has at least seen calipers if not used them. They are used for a reasonably precise method (I have already covered at least one unreasonably precise method) of measuring the distance between two surfaces in a quick and convenient way. Presuming you can find them, of course. Note that no vernier scale caliper is pictured above even though I own one…

The most used measurement is the outside one. I will often use calipers for marking out a part as well as measuring an existing object to find out what size it is. Handy if you have unlabeled metal stock lying about. In the picture, we can see that the shank of my 3/8″ end mill is about .001″ under sized according to my inexpensive caliper. If I needed more precision, I would get out a micrometer.

Using the other set of blades, one can measure inside distances between flat surfaces. It turns out my 21mm wrench is actually a 21.11mm wrench.

Calipers can also be used to measure depth in two different ways. The first is what I have used for years, the other end of the caliper.

The second is one I only learned about recently and while it is somewhat specialized, it allows a more reliable reading of a step using the end faces of blade end. I held it above the piece for what I fondly hope is clarity.

Alternatives

The alternatives to calipers are fairly well known and are all a tradeoff between precision and convenience. There are probably people out there doing fine work with just a rule or just micrometers but they are giving something up.

Options

Calipers come in Vernier, dial and digital models. Vernier versions are the most robust and proof against fluids (cutting coolant) but slower to read. Many have both Imperial and metric scales on them. Dials are quick and easy to read but only come in one set of units. Digitals can convert between Imperial and metric, can be zeroed at any point and can give implausibly precise readings. And they need batteries which is why my pictured one is not getting used for any of the action shots.

Calipers come in a vast range of quality from very cheap plastic models (1.99!) to very uncheap ones you would be careful not to breath on. They also come in lengths from 6″ to 24″, at least at my local tool supplier which lists 83 different models ranging in price from $50CDN to over $500. Mine are much more in the $50 range (probably less) but do a good enough job anyway. I use them to get close and then check final dimensions with a micrometer if it matters.

Metrology Monday: Precision Machinist’s Level

What Is A Precision Level For?

This is one of those tools that you don’t need until you do. As evidenced previously, I have managed to turn out some parts that are less perfect that one would hoped. While the list of possible sources of error is long, a fundamental part of setting up machine tools is levelling them. Even a solid casting like a lathe bed or a milling machine base can acquire detectable twist in it when you bolt it down. To take out the twist, you put shims under the low corners or some other adjustment until the measured surface is level. To detect twist, you use a precision level.

I have avoided going through what is almost certainly a fiddly process with either of my machine tools but I decided the time has some so I acquired the Starrett level depicted. The certificate in the box asserts that each division on the tube represents .005″ difference in elevation over 0ne foot. This ought to do it.

Initial readings on the mill Y-axis ways (which are the ones that are part of the base casting suggested that my previous attempts with carpenter’s level were less than perfect. At least I didn’t buy this thing for nothing.

Fortunately, the stand has leveling feet so off I went with a wrench and a lot of bobbing up and down and cranking. It turns out that one of those .005″ marks represents about a half turn on a foot. Presuming that the other foot is on the floor… I need to develop a method that avoids trying to level an inadvertent tripod.

After a lot of faffing about, I got to about one mark of level and at least the back and front agreeing on which way that out of level goes. I called it done for now because I was chasing that mark around the corners. I need to do some more reading up but I suspect that this is where the shims come in. The top of the milling vise show just about the same reading so nothing inherently funny is going on.

Alternatives

There are methods of detecting twist in a lathe that don’t involve a level. Twist in a lathe bed manifests as a taper in what should be a parallel turned surface. You can turn two ends of a round bar and measure the result with a micrometer. You then shim whichever tailstock corner is low. Repeat until both ends come out matched.

You can also buy a pre-turned bar, mount it between centers and use a dial test indicator to compare ends. At least I think that’s how it works.

Presumably, you can carry out the same sort of process with a mill but given the way the mill table takes up most of the space, it would be a pain to say the least. You can’t trust the spindle or column at this stage so I think you would have to remove the table and sweep the ways with an indicator mounted on the ways. Suddenly, a fancy level doesn’t seem such a bad idea!

Options

This is one of those purchases that will get seldom used which is why I avoided it as long as I did. My “budget” model Starrett level was about $180CDN. You pay for greater length so my 6″ model is the shortest I could get away with. The 18″ one is about $1200.

There are digital machinist levels that cost more than the analog ones. I don’t know if they work as well. They claim similar resolution and I even found one online that has an app that relays the readings. That would be handy if you wanted to avoid jumping up and down to check as you adjusted things. It would be a huge time saver if you were levelling a CNC machining center, for instance.

Metrology Monday: Toolmakers Vise

What’s A Toolmakers Vise For?

At first glance, a vise is not a measuring tool so why am I talking about this thing? Well, a toolmakers vise is a vise (duh) that is precision ground on just about all of its surfaces, certainly all six square sides, the jaws and ways are square and parallel to a high degree. The depicted vise is also a “screwless” design that uses an hex draw bolt instead of the usual screw to secure the moving jaw in both an inward and downward direction. This avoids introducing error due to jaw lift.

Suppose you have a part that you want to check for parallelism of some awkward surfaces. As an example, I have just made some t-nuts for securing things to my milling table. I was wondering how I did with my setup. An actual metrology application or, as a certain Youtuber says, “the surface plate: where dreams go to die”. As you can see, checking the vertical surfaces of the inverted T is not just a matter of plunking it on the surface plate. The darned thing won’t stand up on that face.

And so the vise comes into play. I know that it is very square and so if I clamp the t-nut in the vise, the clamped surfaces should also be parallel to the corresponding vise surfaces. If I check both ends, it will tell me how off it is. To take the reading, I leave the indicator and stand stationary and slide the vise and part around under the indicator tip.

And the answer is, in machinist terms, quite a bit, about .0015 if I am generous. The same error is present on the other nut I made so at least I have repeatably created the error. This is why one makes t-nuts for practice. The required precision is not great and you can mess things up and still have a usable result. If it was important, I would have to investigate the source of the error (milling vise alignment, mill head nod, etc…)

As is probably obvious, you can also use a toolmakers vise for workholding. I have seen various videos of this sort of vise being used to hold a part being milled.

Alternatives

Toolmaker’s vises come in different designs and many sizes. Mine is only about 2.5″ long overall. They can get expensive really fast.

As an alternative, you could clamp the part against a 1-2-3 block and rest it on the plate. Or use a v-block or some other way to prop it up vertically. In this case, you would likely need to move the indicator stand around which is finicky in that you can tilt things and mess up your alignment.

Options

As always, you can spend a lot of money on a toolmakers vise if you want to. There are some beautiful makes and models out there that are breathtakingly expensive and certainly more than most hobbyist need. The cheapest 25mm/1″ version I found online goes for about $60CDN. Mine is a somewhat higher quality model but still accessible at least in this small size.

Sieve Experiments

My soil sieve arrived unexpectedly early so I took advantage of the sunny weather to experiment outside and see what I could come up with. I started with some of the contents of a leftover bag of limestone screenings with thoughts of producing my own ballast. (When it’s not cinders, ballast in southern Ontario is usually limestone.)

The sieve came with three different meshes: 1mm, 3mm, and 5 mm. 1mm is about 2 O scale inches so about right for ballast. Or that was the theory, anyway. What I failed to account for was all the smaller bits and outright dust that also passes through that mesh. What I got was good “dirt” material but not ballast.

I then hunted around the house for something with a finer mesh. I was partially successful in that I found a bit of plastic screening but it looks to be about the same as the 1mm. I tried sandwhiching it between two of the screens and did get some “ballast”. I think it looks darn good but the amount produces is such a low ratio to the total material processed that I could not reasonably produce enough to do even a small layout such as Comstock Road.

Not to be discourages, I decided to use the “dirt” as a first texture layer on the foreground test scene. It is undeniably an improvement over brown paint.

Next I need to round up a suitable brush for stippling on glue and shoot some grass on this thing.

Backwards Bandsaw Teeth

Today I decided to swap out the default blade that came with my metal cutting bandsaw in favour of a bi-metal blade which is a recommended upgrade. Much to my dismay, when I went to install it the direction of the teeth was backwards. How could the vendor do this to me when I bought both at the same time? ARRGH!

A bit of online research later, I found a saw vendor’s note about how you can just flex the things and turn them “inside out” and thus change the direction of the teeth… I am very glad I did the look up before I called the store to announce my ignorance.

Foreground Staging: Useful Scenery Practice

I have been sporadically putting in the foam scenery base of Comstock Road but with no sense of urgency. I think that part of that lack of drive is due to a bit of uncertainty about the next steps. I know what they are, more or less, but have not done some of them in a long time (mixed Sculptamold in various consistencies and configurations) or ever (applied static grass). What I need is a practice project with low investment, material or emotional.

Coincidentally, I have been using my scheduled reading time to catch up on my pile of partially read model magazines and came across the perfect project concept. In the November 2020 issue of Railroad Model Craftsman, George Dutka presents the idea of foreground staging. This is a small, simple, scenicked diorama used to provide foreground in layout photography and hide the front fascia. It also provides a way to temporarily deploy structures that don’t otherwise have a home. (If you are familiar with George’s work, you will know that he probably has an extra structure or two about the place. 🙂 )

Given the narrow depth and close to the edge track locations of Comstock Road, some foreground staging is something I can definitely use. The entire scene in front of the traverser will only be about 6″ deep. The diorama is inherently expendable and quick. So I am off! I have gotten as far as the “paint the Sculptamold” phase but am stalled a bit on some materials.

I am assembling appropriate ground textures from local sources, a process much slowed by the current Toronto area lockdown but not impossible. Hopefully, once I get ahold of some suitable sieves I can get this done. With curbside pickup and online shopping only, I can’t stroll the housewares aisles looking at the size of the meshes in the strainers so I have resorted to the online retailing behemoth for a set of soil sieves. Now we wait. And collect and dry used tea bags. By the time I get this done, I should have shaken out all the bugs in a basic scenery system.

As a thoroughly unimpressive illustration of the concept, here is what the aforementioned foreground track looks like with and without my work-in-progress foreground bit held in front of it.

Including of a structure to frame an edge will require a steadier setup than board held in left hand and phone in right. George recommends accumulating a suitable stack of boxes.

Metrology Monday: Telescoping Gauges

What Are They For?

Telescoping gauges are for measuring the diameter of holes, the width of slots, and any other gap that is impossible to get calipers into. The standard model is T-shaped with the bar of the T composed of two sprung arms with round ends. The other end of the handle has some sort of locking mechanism. You stick the appropriate sized gauge into the hole, lock the arms, pull it out and then measure the result with a micrometer or calipers.

I say appropriate size because each gauge has limited range of measurement and thus telescoping gauges come in sets or at least collections. Mine is a motley assortment bought from a used tool store.

For small holes, there is a different style of gauge that is a split cylinder with a center plug that adjusts the split. I only have one of those.

Alternatives

There are digital and dial direct reading bore gauges which are the more precise but more expensive choice.

Options

The basic import sets go for about $40CDN and cover a range like 5/16″-6″. You can spend more for better ones just like other measuring instruments but for the money a dial bore gauge set would be a better buy, I think. I don’t have one of those because I have not had cause to use my telescoping gauges enough to start wanting better.

Metrology Monday: Sine Bar

What is a Sine Bar For?

I consider this sine bar to be the most exotic measurement tool I have. I bought it mostly for fun. A sine bar consists of two cylinders of the same diameter fixed with their centers a known distance apart. The top of the connecting bar is parallel to the line between the two centers. All this done with as much precision as you are willing to pay for.

What the bar is used for is to “construct” precise angles between the bar surface and the surface the bar is resting on, typically a surface plate. Given the desired angle, one does the appropriate calculations (hence the sine name) to get vertical displacement for one end and builds that height out of gauge blocks.

Here as an arbitrary example, is a setup to get an angle of 32 degrees, 16 minutes and 27 seconds. Reference to an online calculator produced a displacement of 2.670″.

I called this tool exotic because it is difficult to conceive of a circumstance where I would actually need to measure to set up an angle this precise. I can use it as part of a machining setup or to check something like my engineer’s protractor for accuracy. I expect that an experienced machinist has more uses for one so who knows.

Alternatives

Budget sine bars cost less than $50CDN new so it wouldn’t break the bank if you decide you needed one. There are lots of protractor variants that are probably more practical for most jobs.

Options

The “sine tool” family includes plates and vises. The plate is just a wide bar. The vise is a vise but includes some sort of angle locking mechanism and the two cylinders to allow precise angle setting. Like a lot of precision tools, spend as much money as you want for increasing precision well in excess of the average hobbyist’s needs.