machining – Twisted and Delusional

Let’s make our own CMM….

Yup, this big arm is nice. I’ve got the power section working again, now I need to see how the rest of the electronics are working.

But…… this arm is too big for doing smaller pieces on my bench top. So I want to use the lessons learned so far to make my own. I have the Langmuir MR-1 cnc to make my aluminum parts, and I can buy carbon fiber tubes. Most of the hard work will be making sure there isn’t any slop in the joints.

This is the MR-1 cnc in the shop…

Gantry style 3 axis with tool measurement and touch probe. I’m really happy with this machine.

I started laying out the structures for the joints. I’m using encoders and carbon tubes available from Amazon. Who knows, someones else may want to build one and specialty suppliers are no fun.

Rhino 3D, the only CAD program I like to use. I have experience in Solid Works, Sketchup, Fusion 360. Rhino is the only one you buy and use, no subscriptions. Used Rhino4 for years up till a few months ago. Upgraded to Rhino8 commercial for less than a year of Fusion.

As you can see, picked up some nice looking carbon tube and started cutting pieces. Watch for future updates, when its running I will make a parts list. Maybe make a couple arms to sell if there are people wanting them.

I’m back again……. I think….

Ok, it’s been a while since my last post again. I may make a separate post with all the details, all the changes, jobs, experiences, ect. But it isn’t this post. This post is about an arm…..

This is a CMM arm, or a coordinate measurement machine. This arm is incomplete and broke, but that has never stopped me from making useful tools from unloved parts piles. The purpose of this arm is that you fix the base firmly in space (like to a table where it won’t move), and you use the other end to probe an objects shape.

This is the end the probe goes in, I’m gonna have to build one. This arm is so old you can’t get parts for it unless you luck out on Ebay or some other online antique shop. Once you have the probe up against the object you want to measure, press the button. This will cause the software (don’t have that either, lol) to measure the angle of al the joints in the arm and create a data point in 3D space using the fixed base as the reference point. Move the probe to another spot on the object to be measure and press the button. Doing this repeatedly creates a Point Cloud that is a digital outline of the object that can be used in modern CAD software. It’s a very useful tool to digitize large parts like the missing pieces of my various projects. If there is a left side part on my project, but I am missing the right side, I can digitize the side I have, and then mirror it in software and have one of my machines make the missing part.

So why but a broken arm missing pieces with no software? Because these arms new go for tens of thousands of dollars. Used arms go for multiple thousands of dollars. This arm was a couple hundred dollars, with a bunch of metal bits I don’t have to machine from raw stock, and expensive encoders that measure the angles in the joints for accurate point data. Bonus is the arm has carbon fiber tubes that make the machine accurate in almost any temperature or humidity level. So……

I pulled it apart to see how bad it is.

Not gonna lie, it’s a mixed bag. On the bright side it’s a known major manufacturer, using good hardware, so that’s a win. On the down side, it’s going to need some major work. I applied power to the unit and checked voltages. It should use 12VDC in, which is knocked down to 10VDC using a LM33T, followed by a 78M05 to give me 5VDC. The 10VDC and 5VDC test pads are showing the full 12VDC. The whole arm is getting unregulated voltage that may have wiped out sensitive components elsewhere in the arm electronics.

First things first, have to get my voltage under control. So I will be replacing the LM338, the 78M05, and any other item I find out of spec in the power regulation section. Once I have done that, I will continue posting the progress on this. I may also make a smaller arm from scratch using the ideas I see in this arm for inspiration. It will have much simpler electronics though……

Random stuff…

I have a little bit of time so I thought I would post some random things.

First off, most of you know that I have been growing my coffee plants for around 5 years. I have only had blossoms on them twice and earlier this year was the one of them. I was really happy to see blossoms, since its a good indicator that I’ve finally gotten close to making them happy. I was watering them a couple days ago and almost didn’t notice these…

Those are coffee beans! The very first time in years of growing I have had coffee beans! They are hard to notice because they really blend in with plant. As proof, see how many beans you can count in the next photo..

Hint: there are 5 beans in that photo, but I bet you counted 3. I’ll post more pics if they get to the ripe phase and turn red. Overall, I’m just happy to see any beans, ripe or not.

Switching gears…… Some of you know I enjoy making small engines and I have met many wonderful people going to miniature engine meets and forums. One of the great men I got to meet was Bruce Satra. He revived a model engine from the 1940’s called the Morton M5. The Morton model engine is actually based on the LeBlond engines in the previous post. Here is a pic of the Morton Bruce built in the ’80’s.

I started a Satra M5 from castings that Bruce sold several years back, but I didn’t buy a complete kit, just a few to get me started. When I ran into a couple machining questions I emailed Bruce and he was always super helpful. Unfortunately Bruce passed away several years ago and many of us were left without parts. A friend of Bruce, whom I will not name but is an easy Goggle search to find, was supposed to keep the Satra Morton M5 going in memory of Bruce. Alas, he has completely dropped the ball, even going so far as not keeping VernalEngineering.com (Bruce’s M5 webpage) running. Here is a pic of the fantastic castings Bruce used to sell…

So, left without a source of parts after several attempts over several years to contact Mike (oops, wasn’t going to name drop) I am left with my usual answer. I will make my own castings based on Bruce’s notes and conversations we had. (As if some of you out there couldn’t guess I was going to say that)

I’ve started the process and here is a little info on progress. I started by modeling the parts in CAD software and then printing out the parts to verify dimensional accuracy…

Those quick and rough prints checked out, so now I am making my wax molds. I’m a couple revisions in on the rod and piston molds, and have found a wax suitable to injecting into the small lines and cavities. Now I am just refining the molds to help with the last small imperfections in the wax parts. I’ll post more pics and info when I have some final wax parts before attempting the first metal castings.

Adding another machine to the shop…..

I do a lot of work on antiques and custom projects, so a lot of times I need to either produce or reproduce parts made of plastic. My go to technique has always been casting resins, but many times they don’t have the ‘feel’ of plastic parts even if they look the part. Sometimes there just is nothing like an injected plastic part.

I started work on a David Gingery style home made plastic injector a couple years ago, but I was never happy with the way the ram was designed. I purchased a nice electronic PID temp controller for the project, and temp control was never an issue, but there were enough other issues with it that I never put it into use.

Last week I saw this pop up on ebay…..

Hmmmm, a $2500-3000 injection unit that had been torn open and no one knew if it was working. The seller was asking a price that would put it on my doorstep for around $200. After looking at the pics, I figured that the ram and chamber were were professional made, the lever linkages would have proper geometry, there was a neat little filler for the plastic feed, and as a bonus there was a mold hold down clamp. Those were all things missing in my home made unit. If the only thing wrong with it is the temp control, then this would be a good purchase so I bought it.

It showed up on my doorstep a couple days ago and I didn’t waste any time tearing it down to see what I had received for my money.

I stripped the heat guards off of it to see what was left under the covers. Turns out that nothing in the heater and injection parts had been touched, things are looking positive!

Here is all the temp wiring as I received it. Everything looks good, I couldn’t see anything obvious wrong with it. I did notice that it is an older type mechanical temp control which are prone to temperature fluctuations, I decided to replace it with my digital PID controller. The data plate on the back said it’s a 220V unit, I will rebuild it as 110v since I will be rewiring everything anyway.

During the tear down to get to the heating cartridges I noticed a few things that the professional unit had that the home brew didn’t, like this bevel on the ram to make feeding pellets easier.

Another lucky bit were the heating cartridges used in the machine. They wired two 110v heaters in series to make a 220v unit. I could just rewire them parallel to make the 110v unit if they were still working. I decided to test them since I had them out of the machine. I put them on a large steel plate as a heat sink, wired them to my digital controller, and tested the system I wanted to install on the bench.

Everything worked. The heaters got hot, and the controller turned them on and off. The next thing to do was modify the heating chamber to install the temp sensor that feed information back to the temp controller.

In the upper center of the picture is the heating chamber and heat cartridges, in the middle is the temp sensor I need to install. I chose to drill out and tap the small hole towards the bottom of the heating chamber where the original heat probe was located.

Hole drilled and tapped. Temp sensor installed. Time to reassemble.

Reassembled with the new parts in it. I hadn’t put the heat shroud back on yet since I wanted to do a test of everything. The test went well, I brought it up to 131’C which is a good temp to begin melting polypropylene plastic for injection.

Since the digital sensor will let me regulate all the way down to room temperature I can melt several different materials for injection molding, so another use for this machine will be injection of casting wax into molds. This will let me make precise investment molds for metal casting.

Aircraft Radio Lenses…

Another project in the long string of micro-manufacturing and prototype work I love to do. I needed to make replicas of certain parts of aircraft for a simulator project I was working on. This particular cockpit was using King Bendix KX155 nav/coms. A friend of mine who works on aviation radios happened to have a KX155 that he was repairing and allowed me to borrow a very badly damaged lens to base my reproductions on.

The upper right lens is the original that I borrowed, it literally was in pieces. The lower left lens is one of my reproductions. Here is a couple pics of the the reproduction lens next to the radio that donated the loaner lens.

As you can see, the remaining lens in the real radio is starting to de-laminate like the loaner lens.

Gold mirrors….. magic?

I have been following Russ Sadler’s series on Youtube for a while now, learning everything I can about my clone laser cutter. I honestly, watched about 3 hours of vids before I even uncrated it to make sure I didn’t mess anything up. In a recent video Russ showed some charts on wavelength reflectivity while trying to achieve maximum output from his laser tube. It seems not all mirrors reflect equally, and the material the mirror is made from makes a large difference in how much power makes it to the cutting board. The stock mirrors aren’t too shabby, but gold and silver mirrors rank higher with silver being the benchmark everything else is measure against. I thought to myself, since I plate silver and gold objects I need to get hold of Russ and see what we can come up with. After a couple emails (Russ is a super nice guy by the way), he sent some copper mirrors for me to plate and send back to him. We talked it over and since silver is susceptible to tarnishing we would try just gold plated mirrors.

Here is one of the copper discs with it’s electrode wire wrapped around it (click any pic to see a larger version if your browser allows it). I chose to go with a circumference contact to try and minimize any distortion on the mirror. Locating the electrode contact point in one area may have lead to a heavier deposit of gold due to a higher ‘charge’ or flow of electrons in a defined area. Stainless wire was used as the electrode since it is specified to be used as the anode in the gold solution.

Here is the disc in a prep bath, the cleaner makes sure the surface is ready to plate. It removes oils, tarnish, and makes the surface more receptive to plating. I limited the amount of time in the solution though to prevent any surface pitting. One again, I needed to be conscious of the surface as a mirror and not to distort it.

The disc is in the gold solution, doesn’t look very gold-like does it? You can see the Stainless anode to the back, plenty of surface area to carry the electroplating charge. Russ sent six disks, or two sets of 3 mirrors. I ran the first batch at 2.5 minutes plating time which is enough to coat the surface but isn’t a thick layer. I ran the second batch at 5 minutes and is the typical plating job I would do for jewelry or decorative objects.

Gold mirror on the left, copper on the right and both highly reflective of visible light. Once again, I tried to put as little gold on the first set to minimize and distortion that might happen, and ran the second set at standard thickness to see if there was any noticeable difference once installed in the machine. Now it’s time to pack them up and send them off to Russ for evaluation. I did not polish the mirrors or apply any treatment to the surfaces. It’s my belief that the anti-tarnish coating in the polish Russ used for the copper mirrors had adverse effects on the reflectivity of those mirrors. The light would have had to pass through that coating twice, once to reach the mirror and once leaving the mirror surface. Any diffraction in the coating would then have a double effect on the light path.

I excitedly await the results. If Russ posts a video on it I will put a link on the blog.

Continuing work part 3

It was another productive weekend in the garage/shop. I’ve been needing to get the valve work finished on the Fairbanks-Morse motor so I decided to tackle that. I wasn’t comfortable with the bronze valve guide expansion rate in the cast iron when heating while running. We used Bronze valve guides in the cast iron heads when I worked for Harley, but replacement heads are easier to find for old Harleys than they are for this engine. So, I made a new set of guides in cast iron, to go in the cast iron head, and everything should expand approximately the same and nothing should crack. I won’t go into the making of the guides as the machining is the same as the bronze guides. After the guide is cut then the head needs to go on the mill table and be prepared for machining the previous guide hole to accept the new guide.

The head is locked to the table and I have chucked a piece of material in the spindle that is the same size as the old valve guide bore. This is my home-brew way of aligning the work piece to the mill machine, and it works good enough for this kind of work. I keep adjusting the mill table until the chucked material moves freely in whatever I am trying to align.

Once it’s a free slip vertically in the hole, I consider it aligned and its on to the next step. Make sure you use a straight piece of material in the spindle, otherwise your hole will still be off. Next I removed the locating piece and chucked up a 21/32″ HSS drill bit and started roughing the bore in.

I always take it easy when starting a hole in soft material like cast iron with a large bit like this. It’s too easy for one of the drill bit flutes to bite and ‘grab’ the work, pulling the drill bit off center and throwing off the bore. It goes against proper machine work, but I kick the spindle speed up really high and then lightly ‘peck’ at the hole a few times to get the bore started and just below the surface. Then I slow the bit down to proper cutting speed and cut at normal feeds/speed. In the above pic the bore looks centered and it’s cutting good.

Done with the drilling portion and there is a nice even amount of material still left around the hole. Hit it pretty dead on center and I’m happy. Now I need to ream it to final size. Since the reamers I have are of different types, chucking and hand reamers, I sometimes have to get creative about how to ream a hole. I would prefer to have all chucking reamers so I can just drop the drill bit out, chuck up the reamer and keep everything concentric, but my budget isn’t going to allow that. Lol

So here is how I keep my hand reamers in line and concentric. I have a brass center I turned up and mount it in a collet, which sets in the pilot hole in the back of the reamer. I use small amounts of manual down feed to keep the center ‘locked’ into the pilot and then turn the reamer with a wrench till it feels free in it’s rotation. Apply a little more down feed and repeat. It’s slow but it works.

You also get a visual indicator when the reamer is through the material. That concludes the work needed on the head until it’s time to insert the new guide. The next step is to take measurements from the hole that you just made in the head, and a measurement from the outside diameter of the guide that will go in the freshly made hole. The reamer finishes a hole to 0.6875″ and the outside of my guide was at 0.710″. I turned down the outside of the guide for a proper interference fit of 0.0015″ larger than the hole. I then put a chamfer on one outside edge of the guide, put a tiny bit of high pressure lube ont it and checked the fit.

Well, that looks about right. Feels about right. Astute readers will see a line cut toward the top of the guide. I part most of the way through the guide at total length plus about 1/8″, it comes in handy during the install of the guide. Time to smack it a few times with the hammer and see how it seats.

Almost fully inserted to depth, you can see how much is left thanks to the groove that is cut. Now the lube isn’t on the portion that is driving into the head and there is more resistance to the guide going in the hole. If I got everything right, just about the time it gets to the right depth…..

Perfect. The valve seated to depth and the last tap with the hammer caused the groove to fracture, leaving about 1/8″ standing proud over the hole. Now the head goes back over to the mill table.

A nice pic of the guide and you can see the parting line where the top snapped off. I like to finish this off in the mill with a cutter to bring the guide flush with the old castings, making everything look nice and neat.

That takes care of the outside of the guide, the inside is already done, and we are finished with using machines to do the work. From here on out, it’s all by hand and feel just like I was taught.

A quick run of the reamer through the guide to make sure any burrs or debris is clear of the hole and I can slide the new valves into the head. The valves look and feel good, I get a satisfying whump when they drop into place, the sound that says they will take just a little lapping to seal up good and tight. The sound you dont want to hear is a tinny ring when you drop the valve in the hole. That ringing means some part of the valve isn’t seated against the head. Final pics before lapping the valves.

Building a super mosin….

I’ve been lazy about posting for a bit due to holidays, trying to get a piece of property, work, ect. Posting should pick up again, unless I get that property then I’ll be moving stuff.

I have been busy out in the garage, working on various projects. Lately it’s been a mashup of small things from the hit-miss motor restoration to model engines and firearms. I took a series of pictures on the latest Mosin Nagant 91/30 overhaul and figured I’d share them with everyone. The 91/30 is a WWII era Russian rifle, the one in the pictures was made in 1936 and bought surplus from a box store. Firing one of these in it’s as-purchased configuration is painful, it kicks solidly and the buttstock has a metal plate on the end. Somewhat uncomfortable on the shoulder after a few rounds. Also, it doesn’t have any place to put an optic on it as it came from the factory unless you want to use a WWII era PU scope, which I dont. Optics have come a long way since the 1930’s, and even a ‘cheap’ optic made recently is easier to see through and use.

On to the pictures and descriptions…..

There’s the basics of the rifle with the bolt removed and taken out of all the woodwork. Not a lot of parts there, basically the trigger, trigger spring, chamber and barrel. I will be doing a trigger job, installing an optic rail, changing the bolt handle, refitting an M1944 muzzle break to fit the 91/30 and installing it, putting it in a more comfortable stock, and putting a bipod on it. To give you an idea how radical the change is here is a before and after of a previous super mosin I built.

As you can see, it’s a tiny bit o’ difference.

Time to get the trigger out for a little modification. The trigger is held in by the trigger spring, which is held to the gun by that big screw in the middle of the pic, and a pin that acts as the trigger pivot. Thats it, remove the screw and the pin and everything comes out. What those parts look like….

The trigger spring is on the left, trigger on the right, pin and screw in the middle. The trigger spring passes through the trigger out the other side. That weird block on the spring is the sear, when the trigger depresses the spring enough it releases part of the bolt and the firing pin sets off the cartridge. The problem with this is that there is usually a gap between the trigger and the spring, allowing the trigger to just kinda flop around before making spring contact. I don’t know about you, but that annoys the shit out of me. Floppy triggers suck and need to be fixed. Fortunately, a little time and a set screw can go a long way to remedy this situation. First we need to get the trigger in the mill (or a drill press) to drill a hole.

Trigger is in the vise, wrapped in a surplus business card from my last employer. No need to mar 70 years of patina if I don’t have to. 😉 Next comes a center drill to make sure I place the dimple in the right spot and get a good penetration on the surface for my drill bit. Center drills arent expensive, they are very rigid, and they beat the heck out of trying to start a hole with a drill bit wandering all over trying to get a start. Buy them, use them. On to drilling the actual hole.

In case anyone is wondering, I’m going to install a 4-40 set screw. Go bigger if you want, I don’t think it will hurt anything, I just have always used 4-40. I typically use a HSS numbered bit for drilling tapped holes. Tapping charts are available everywhere to download so I won’t get into numbers. Once the hole is drilled, time to tap it.

Whoo hooo, the joys of free hand tapping. Slow is best, break off a tap in that hole and you’ll be shooting with a sloppy trigger, guaranteed. Once again, retired business card to preserve the patina. I use a tapping compound to keep the threads going smoothly, picture of that later in the series I think. I also use mineral spirits and an old toothbrush to clean the tap about every two full turns , it gets the grease and any trapped debris out of the cutting threads and helps prevent chip binding. Learn from what I say, don’t add to your scrap pile by repeating mistakes I’m trying to help you avoid.

Once the hole is tapped, put a set screw in it and reinstall the trigger. Access to the set screw is through the receiver from the top with the bolt removed. Even without the bolt you can adjust the set screw and get a feel for the adjustment possible on the trigger. I usually take the slop out of the trigger, install the bolt, feel the trigger break, and then remove the bolt and make adjustments as needed. Once I find my happy place, a drop of green (bearing retainer) loctite keeps it from changing.

By the way, here’s a pic of my loyal shop companion. Usually hangs out right by my side through all of my workshop time keeping me safe from roving bands of shopping-cart-pushing zombies.

I bet you thought it would be a dog……. lmao! Next post, optics rail.

Continuing work part 2

I did quite a bit this weekend and didn’t think to get any pics of it. Just for the fun of seeing how it would turn out I stared the fermentation of 15lbs of red flame raisins in my main fermenter. It’s just the raisins, a couple pounds of sugar for starter, and the yeast. I’ll post more on it when I get the first taste and see if it was worth it. I also worked on the cast iron treadle base from the table project. I tried to braze one of the cracks but couldn’t get enough heat for the rod to stick and silver solder didn’t like the cast iron. I may have to get a specialty braze for it. The mead is still giving the occasional bubble in the water lock, so the ferment isn’t done yet. I am looking forward to pulling that batch and getting the first taste once it’s done, I’ll be posting that moment for everyone. And I spent Saturday morning partly on my Kenwood TS430S radio talking to people on 40m Ham bands and partly playing my bagpipes.

Yes, you read that right. Bagpipes.

I began the machining of a new valve guide for my 1929 Fairbanks-Morse hit-miss engine in part one HERE. It’s a couple weeks later and I felt like spending some more time on it, so here is the next bit in it’s making.

The inner bore where the valve itself rides is done, now I need to turn the outside down to be an interference fit with the reamed hole in the cylinder head. An interference fit means that the part to go in the hole will be just slightly larger than the hole itself so that the parts ‘wedge’ themselves together. They have to be a tight enough fit that when they get hot from running the engine, and expand at different rates, that they stay ‘wedged’. This also means that I have to turn the whole length of the guide to size, and I cant grab on to it with the chuck in the usual manner, instead I’ll have to hold the work piece from the inside while I machine the outside.

In the picture above you see the valve guide in the middle with and expanding lap on the left and a ‘live’ tailstock center on the right. The expanding lap goes into the guide bore and the center does the same from the other side. The pointy part of the center is mounted in bearings that allow it to rotate with the part it is contact with, thats why it’s called a ‘live’ center, it moves. All together in the lathe it looks like this.

Now that it is all in place it’s just a simple matter of turning the outside diameter down to size. Any machinists out there who look at the next picture, yes, I know that I’m cutting using the back side of the insert and it isn’t proper. I did it on purpose because there is just enough ‘spring’ in the insert holder that running the cut backwards gives a smoother finish. And since I need a fine finish for the press in fit, it works for me.

And the guide all finished inside and out, ready to be sized to length and pressed into the cylinder head.

Continuing work….

Last night before I fell asleep the thought crossed my mind to bring the materials and tools for a valve guide I need to make to work with me. This morning I miraculously remembered to bring the tools and materials, and today at lunch I began the construction of the second valve guide for my dad’s Fairbanks-Morse hit and miss engine. I had already made a set of guides from cast iron to go in the cast iron head. Those guides didn’t work out, so I decided to try bronze this time since I have successfully used bronze guides in cast iron Harley heads when I worked for a dealership. And since I need stuff to blog about, you can suffer through it with me….. lol.

That’s a 1″ diameter chunk of solid bronze rod all ready for me to abuse it and coerce it into some kind of usable object. to begin i need to put it in the lathe and turn one of the ends flat. The process of turning on of the ends flat is called ‘facing’, probably because we are dressing up the ‘face’ of the material. When done it looks like this

The next thing to do is to make a dimple in the exact center of the area I cleaned up so that when I go to drill through the material the drill bit stays centered. It may seem weird to think that a drill bit almost 1/2″ in diameter would flex and drill off center, but they do. It’s a strange thing to see in person, but I have and it will mess up whatever you are working on really quick. So, out comes the center drill (funny they would name the tool that) and I get it set in the tailstock chuck. Center drills look a little odd, not like a regular drill bit.

The shape gives the tool extra strength so it won’t flex or move, perfect for doing it’s intended job.

Now I can run a drill down the center of the bronze and get the bore for my valve opened up. Pop the center drill out of the tailstock chuck, get a 27/64″ drill bit in there instead and start drilling!

Wait….. WTF?!?! Really? Dammit! Remember what I said about drills wandering earlier? That is just what happened. The drill bit is a little bent, not enough you can see it but enough that it is cutting off center and leaving a little cone of material right in the middle where there should be a hole. Now I have to center drill the mistake out and try with another 27/64″ drill bit.

The ‘cone’ in the middle is removed, borrowed a bit from one of my co-workers, let’s try drilling that bore again.

Oh yeah, now we are getting somewhere. It took another 15 minutes to get this hole all the way through the rod. You can’t rush this kinda thing or you break tools, machinery, and parts in a very impressive way. Usually the results of carelessness or ignorance is a shower of drill bit shrapnel, broken or badly damaged drill chuck, and a mangled part with some of the drill bit still stuck in it. All that accompanied by a sound like a large firecracker going off. Overall, not a pleasant experience and I’ve had my share.

The hole is rough, and it’s still slightly undersized by design. The next step it to use a reamer to make the hole a precise size and make it smooth through the entire bore. I have a chucking reamer for this purpose and it goes in the tailstock chuck where the drill bit was. By doing all of these steps without taking the material out of the machine I have the best chance of keeping all the separate tools traveling down the same path to make the hole, and keeping the hole kinda precise.

Dang, lunch break is over. This will have to be continued in another post…..

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