Fits and Starts

I have managed to get crank attached to the crankshaft. A simple operation of you do it correctly or, in my case, not so much.

The drawings call for a press fit. This is where the shaft is about .001″ larger than the hole. You usually obtain it by using an “under” reamer, in this case a .124″ reamer to go with a .125″ shaft (O-1 drill rod). I had no such reamer and my choices were order a complete over/under set which seemed expensive or buy a single reamer for double the per/unit price of the set and a trip across town. So, of course, I opted for the third choice, use the nearest drill I had.

That turned out to be a #31 drill at .120″. Surely 5 thousandths is close enough for me to press a shaft in. Technically, I proved this to be true. Now if you specify that the shaft in question should not acquire a bend in it during the process then, no, I did not. It would not line up the holes in the flywheel bearing which is kind of the point.

I knocked the erstwhile shaft out with a punch and hammer and ordered the o/u reamer set like I should have done. I lucked out in that I did not have to remake the crank so I figured I should quit while I was ahead.

Here is the properly press fitted crankshaft in place.

Next I need to drill and tap for a set screw on the flywheel hub and then I think I will do the bits to connect the crank to the beam so I can see some bits moving together.

Cranking It Up

I may be getting the hang of this milling thing. Today I got most of the way through making the crank for the beam engine. This was two setups and more tool changes than it probably should have been but I am pleased with the result. I just need to mill off the back of the part to separate it from the block of stock I used as a handle.

It looks like it should even if it may not exactly match the drawings. I realized that the only things that really matter are that the two holes are parallel, the correct size and the correct distance apart. Everything else is mostly shaping things to resemble the cast part a full size engine would have. As long at things are symmetrical, nobody will notice if the end radii are a bit too large or small.

I also improved my finding of the center of the rotary table by using a new gadget, a coaxial centering dial indicator. This device gets chucked in the mill spindle and you center on the hole while the mill is spinning (at low RPM). This is actually fun as opposed to the usual dial indicator spinning holder that makes you keep having to move around to see the readings.

The other improvement which is much less photogenic was the acquisition of some drill blanks. I used a 3/32″ dill blank chucked in the mill to center up the part on the table center for the second setup so I could round the small end. I previously just used a reversed drill bit and I don’t think it produced as accurate results. The drill blank is both more rigid and has not flutes to mess with the alignment.

Cylinder Head

I finished up the cylinder head this afternoon. I had long abandoned my plan to drill the remaining holes on the cylinder since they are all varieties of clearance anyway. Instead, I used a 1/16″ drill blank to center the piston rod hole previous drilling on the lathe under the mill spindle and worked from there. As long as I got the relative placement of the holes correct, all would be well. Or almost, anyway.

I used my milling pallet in the vise and clamped the head face down on a small square of hardboard. The hardboard is flat enough and allowed me to drill through holes without messing up the shiny surface of the pallet.

I had a bit of a bad moment when I went to test fit the head on the cylinder block and the screws would not fit in the alleged clearance holes. Only then did I remember that I needed bigger holes for the M2.5 screws I was using. Back under the mill and a bit of hole size increasing and it was done. Here is the head fastened to the top of the cylinder block.

Since I had some more time and had a head of steam up (hah), I took care of a couple of small tasks I had been putting off. I shortened the machine screw that holds the flywheel bearing to the main body so it no longer projects into the flywheel’s running space. I also cut and cleaned up a suitable length of 1/16″ drill rod for a shaft for the beam. After a bit of assembly, here is the current state of the engine. Flywheel shaft is still pending so the flywheel is just propped in place.

It Has Been Remade

While waiting for paint to dry, I got started on a second instance of the beam engine cylinder only this time with less broken taps embedded. I consider this a triumph of will over fear of failure. I also suspect that the diligent work on the lathe drawer project concealed a bit of anxiety about the second attempt. With the drawers done, my anxiety was left place to hide so off I went before some other project arose!

This time around, I exercised extra care about the depth of the M2.5 blind holes in the cylinder end. I purchased a set of M2.5 taps (taper, plug and bottoming) and used the two extremes to get my thread depth without any optimism about hole depth. All was completed without incident although I think I could use a somewhat smaller tap wrench for this work. The one I have will hold the tap but I fear its weight threatens a break all by itself. I will have to do some research.

I resorted to marking the required depth on the taps with a marker. This seemed simpler than counting revolutions of the tap. 🙂

The cylinder is complete with the exception of plugging the two small holes in the side of the cylinder. These were the result of drilling through the valve into the cylinder bore. Those internal holes are wanted, the outside ones are not.

Next up is drilling the matching holes in the cylinder cover.

It Had to Happen Eventually

I was tapping the second of the two holes for the screws that hold the beam engine’s cylinder head onto the cylinder and carefully feeling for the bottom of the hole and…

That shiny silver bit in the bottom left small hole is what’s left of my M2.5 tap. It had to happen on the last thing, of course. I was turning the tap wrench with just two fingers on the barrel and apparently I can’t tell when it hits the bottom.

As a personal triumph of character development, I uttered only a single profanity, cleaned things up and went off to see what my options were. Unfortunately, tap extractors exist but not for taps this small. I had no luck sticking some straight pins down the flutes and twisting with pliers as an impromptu extractor. I do have some nicely spiral pins now, though. Further research brought me to the chemical approach. I am now attempting to corrode out the tap with an alum(potassium aluminum phosphate) saturated solution. And taking a day off to look at other projects/pieces of the beam engine.

Offset Turning

As discussed in the last post, I need the beam engine cylinder head partially complete as part of my plan for drilling the various matching holes in the cylinder. This is a fairly straightforward turning of a 1/4″ projection on one end of a 5/8″ round bar. The fun part is that the projection is offset from the center of the bar by 3/32″. I thought it would be fun to show how I get the part set up in the lathe to achieve that.

Firstly, I blue and mark up the end of the length of 3/4″ brass bar. (It was actually .748″) Knowing the diameter of the bar, I measure the height of the bar sitting in a vee block on the surface plate. Subtracting half the diameter from that gives me the height of center.

I use the scriber on the end of the height gauge probe to scratch a line on the bar. I then rotate the bar and scratch a line twice more. If I haven’t messed up anything, all three lines should cross in the same place and that is the bar center. I then scratch a line 3/32 below center as perpendicular to one of the center lines as I can manage and center punch that point.

Now comes the magic part. I put the bar in the four jaw chuck and I set up my wiggler in the tail stock with the point in the center punched mark. I then adjust the chuck jaws until the pointer stops moving when I manually rotate the chuck. (Some people can just put an indicator on the bar and move the bar via chuck adjustment. I one try at that was an unqualified failure. This method works for me.)

Lastly, I set a dial indicator against the pointer and and refine things until it shows no movement.

Visually, success is demonstrated when I power up the lathe. The center mark should not be moving even as the actual bar gallops around. This is the ML7 going flat out at about 1100 RPM. It really is in focus! 🙂

Lastly, here is the finished product. Brass is like aluminum in that is comes out nice and shiny and looks really good.

I just need to drill the appropriate hole through the projection, and then I can re-chuck the bar in the 3-jaw chuck, turn it down to 5/8″ and part it off.

Milling Pallet

Much of my shop time in the last year(!) has been consumed with making tools for my tools. A later addition that turned out to be way more useful than I expected is my milling pallet.

A milling pallet is a flat piece of metal with a bunch of threaded holes in it. Matching bolts, clamps, and whatever are used to fix pieces of stock in place for machining. Mine is a 6x6x1″ square of aluminum with a grid of holes spaced 1″ apart. This is a common shop project so there was lots of ideas to glean from the internet but here are the features I settled on:

  • Through holes are tapped M6 except that the top 1/4″ is reamed .25″ to take dowel pins. The pins can be used as something to bump against in a repeatable setup.
  • A shallow step is milled into the bottom to allow clamping the pallet into my milling vise. The edges of the pallet are square with that step which means I can use the edges to align things, even before clamping the vise.
  • Extra counterbored holes allow me to bolt the pallet to the top of my rotary table. The rotary table only has four radial t-slots so this greatly improves my clamping options.
  • I made two sizes of .25x.50″ toe clamps that combine with an assortment of M6 hardware to do most of my clamping.

Here is the flywheel for my beam engine project in progress clamped on the pallet on the rotary table.

Swarf Curtain

I am willing to bet that nobody had “fish patterned swarf curtain” on their 2022 bingo cards. I turns out that I had all the materials on had to solve on of the issues identified during my recent operation session. The cute fish pattern is more festive than I would choose if I was paying but free is better. It turns out that there was a corresponding set of curtain hanging rings also in the stores along with a suitable length of wooden dowel.

A quick and simple project but I think the inhabitants of Comstock Road will appreciate an abatement in the periodic rain of hot metal fragments.

Goals for a New Year

Lookit here, third post in as many days. Christmas sugar rush still in effect. I have a few things I would like to get done and putting it out there in a post is one way of adding a nudge towards action. I am blessed with the required resources of time and money but struggle with inertia, motivation, getting started, whatever you want to call it. I am also still alive so there is still hope for improvement. 🙂

At the risk of upsetting anyone who has seen too many corporate management fads go by, I am defining goals that fit my version of SMART(specific, measurable, achievable, realistic, and time bound). The specific is the important one to me, improve shop organization is vague, create a set of drawers for the lathe stand is specific. Everything can be done with infinite time so some target deadline helps me but I am not going to be too stressed about it. I am going to aim to get it all done by the end of May.

Without further ado, here are the ones I want to start with:

  • Machining – Complete Beam Engine: already ongoing
  • Shop Organization – Lathe Tool Rack: started on some widgets, need the thing to hang them on.
  • Shop Organization- Organize Measuring Tool Drawer: Kaizen foam in hand, need to work out a layout
  • Modelling – complete On30 railbus kit: this one is a bit ambitious but I think the machine shop gives me a way to fix my blocking issue
  • Comstock Road – Traverser Automation – I have already applied the paddles to this long dormant project, still working on rebuilding my development environment. With this done, I can complete the backdrop and mock all the structures.
  • Comstock Road – Rough Scenery – foam is half done. I want to finish that and get everything covered in basic ground cover.
  • Blog Regularly – I will aim for once a week at minimum. It may be me talking about why I haven’t done anything since last week…

That is all I am going to put on the list but of course there are many other projects lying about. Hopefully, this

What All the Fashionable Vises are Wearing

I made my milling vise some chaps! Inspired by YouTuber Yuchol Kim’s Vise Chaps 2020 (and the aggravation of trying to clean chips out of the vise innards), my holiday shop improvement is a protector for the open top of the vise.

This is just a piece of leather secured to the back of the moving vise jaw using the available outside jaw mounting points and a piece of aluminum.

I milled a 1/8x1x4″ length of big box building store mystery aluminum into a retaining bar. There is a .040″ indent milled across the entire back except the top 1/8th to give the leather somewhere to hide behind and hopefully soak up less cutting fluid.

The leather is a piece of craft store tooling leather which means it is unfinished, easy to cut and will probably soak up things well. For instance, that stain in the bottom left corner is machinist blood from when the alleged machinist forgot that end mills are sharp and failed to remove the current one from the mill when done.

One of the less noted advantages of a name brand vise is that the specs for the hole layout is well documented so I just had to put in two clearance holes for 3/8-16 bolts in the aluminum bar. And make a second trip to the big box for a third bolt after one of the first two went missing during final assembly. My shop is much tidier as a result of the ensuing hunt but I still only have two bolts. The struggle continues.