Author Topic: The Return of No. 83, a Hot Air Engine  (Read 45976 times)

Offline nickle

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Re: The Return of No. 83, a Hot Air Engine
« Reply #75 on: March 24, 2025, 11:18:46 PM »
I also have a home brew cnc. Mine is an x2 driven by Linux cnc and an old pc with a parallel card installed. I looked in to replacing the pc over the past 12 months and found that there are pcie parallel cards available for desktop pcs. I’ve lost touch with the Mach products and am too stingy to buy a new licence so I tried a recent build of Linux cnc and found it much improved over what it was over a decade ago. There are some alternative interfaces that I find easier to use than the default and the whole thing seems to accept my 18 year old pc and it’s parallel card.

I need to get going on refurbishing my foundry too. Just gotta keep bringing up the kids and earning the cash for a while longer.

Keep posting your work. It’s great

Offline awemawson

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Re: The Return of No. 83, a Hot Air Engine
« Reply #76 on: March 25, 2025, 04:00:46 AM »
I agree that the loss of the like button was a great shame. It was a quick way of showing support and appreciation to contributors.

Not sure if it was changing forum software constraints or a choice by the team ?
Andrew Mawson
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Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #77 on: March 25, 2025, 10:36:29 AM »
Nickle, funny how digital tech ages, vs manual machines. Short lifespans without major attention. Which is the reason they are used by me so little -- the very problem for me is I don't use them except very occasionally -- and that's when they tend to evidence aging problems, so the broken machine then becomes another project in itself. Right now it's the need to change over to something free without need of a parallel port, so it looks like GRBL is the way to get some use out of them for me. I have a box of Arduino Unos, so nothing fancy or more expensive or modern is going to happen here.

Dwayne, Andrew, Tom, funny, I never used the "Like" feature when it was here because it required allowing online tracking scripts to run in my browser that I normally block. As a result I did not either see the likes (my own or anybody else's) or have available a "Like" button. Also, the best most lively time here was the time before likes. I think they ushered in the decline, it wasn't their removal that caused it.

But from a larger perspective, When I participate as a forum member, I don't want personal votes (which is what a Like is) I want conversations. To me, Likes are just one more way of automating communication. It doesn't take effort, and it doesn't do anything except kind of indicate popularity. You can look at hits on a topic to judge that, anyway.

I see a forum like a pub. A place where people talk. If they're not talking and just pushing buttons, there's no point to the forum. A forum's great strength compared to a video, is that it is an active form of communication, instead of passive. You can discuss things at length. You can ask questions. You can co-create projects. And it's focused on an area of interest, and presents things in a very readable way. Like articles in a collaborative magazine.

This combination is very different to anything else, and I'd hate to see this forum in particular disappear. It has a very egalitarian feel compared to others I've participated in. It has never been filled with "experts and dunces" or, "the right way and the wrong way." Rather there was always a deep respect for individuality and experimentation -- and that also is rare these days. This thread itself would not exist if I felt otherwise. This is the place for me.

Oh, one other thing about "Likes," you have to be a member, and signed in to push the button. There were 500 anonymous visitors the other day when I looked, and 3 members signed in -- one of which was me. I don't think likes are going to make a dent in that. I think good conversations and good will is.

People want to be around other people with shared interests.

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline Country Bubba

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Re: The Return of No. 83, a Hot Air Engine
« Reply #78 on: March 29, 2025, 09:22:43 AM »
I am one of the "lurkers" that you are talking about.  I subscribed to the group many years ago and usually don't post to a thread that I am interested in unless I feel I have something to contribute or to ask a question on a subject is of interest to me and need some clarification especially if it involves some project that I may be working on. 
But being in my 80s, the number and type of projects is diminishing for various reasons. 
BUT I do enjoy seeing how other people doing things and trying to learn in case I might ever need that type of info.

One great example is your other thread on the cnc controller! 

Always enjoy your posts over the years!

 Country Bubba
Art
Country Bubba

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #79 on: March 30, 2025, 12:16:37 PM »
Thanks Country Bubba! Great to hear from people even if you don't have a question or feel you want to add something. It's just nice to hear from people.  :beer:

I have been down a rabbit hole of CNC and old computers so deep this last week, I was wondering if I would ever find my way out! :bang: :bang: :bang: :lol:

What a waste of time. Absolutely for sure I could have made by hand a hundred samples of what I want to make one of via CNC during this time. But I get stubbornly stuck on solving a problem, and I can't stop un til I eventually decide it isn't solvable, or I beat it.

I'm sorry I haven't continued with No. 83 in the meantime, but like I said, I was stuck on this nearly pointless set of CNC problems.

Ultimately, the problem turned out to be two bad driver laptop computers -- one with a bad keyboard and (after replacement) a bad system board, the other with a bad single memory location in low (soldered) memory on the system board, some messed up hard drives, and old programs. The problems which confounded those were the need for parallel ports by the driver boards, and Microsoft XP for one of the hot wire foam cutting programs. Finally, none of my existing foam cutting driver programs will cut the shape I want, since they are primarily geared toward cutting wings.

Okay, I've given up, trashed the two bad laptops, and written off the foam cutting programs. I'll either write my own, or (probably) just write G-code directly to do what I want to do -- which is basically simple shapes. I also might just make up a simple(er) and smaller hot wire foam cutter than the one I have since I am NOT planning to cut wings in the future.

Anyway, explanation above of why I am momentarily away. Back at this engine shortly again.....

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline Country Bubba

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Re: The Return of No. 83, a Hot Air Engine
« Reply #80 on: April 05, 2025, 09:06:42 AM »
Know what you mean about the lpt problem for cnc.  I have two cncs that are run by TurboCnc. I like the program and have even developed some custom features for it.  But unfortunately, I am down to my last two computers that will run dos and have lpt and the compiler (for Pascal) won't run on this win10 piece of crap! 

Some people call it progress, but I call it planned obsolescence and a few other censored words!  :jaw:

 There is a lot to be said when you build something from the ground up and know HOW it works so most of the time you can fix it.

Have a great day

Art
Country Bubba

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #81 on: April 05, 2025, 11:11:32 AM »
Hi Country Bubba. :beer:

Yes, I used TurboCNC for a long time, too. Shows you how simple CNC needs to be DOS and a few megabytes of code will do it.

I did finally get my foam cutter working with an old Thinkpad T43 with a parallel port. It runs Jedicut, for foam cutting under windows XP.

That laptop will probably run TurboCNC, too, for my gantry mill. I was mainly using LinuxCNC when the Thinkpad 600Es died. The T43 technically shouldn't run LinuxCNC because of a latency issue, but there is a possible workaround for that I may try.

Presently trying to convert the mill to arduino/grbl as detailed elsewhere on the forum. Hope to be finally off of this irritating CNC stuff and back onto No 83 again shortly.
Manual control, organic intelligence, forever!  :lol:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #82 on: April 08, 2025, 07:11:39 PM »
Okay engineers, back on engines! Not a big part, but progress none-the--less. A new connecting rod, this time with a ball bearing pressed into the big end.

If you could call it big. It's a 3mm bearing. I will have to re-pin the flywheel, since the former bearing was 1/8". I don't have any 3mm rod, so I'll have to turn down some 1/8". Well maybe grind it down with the lathe's milling attachment.

 
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #83 on: April 09, 2025, 08:10:14 PM »
I actually didn't want to re-pin the flywheel, because I'd like to be able to revert the engine to its original running condition. Also it's good to be able to go back when comparing tests while experimenting. So I took the opportunity to make a new aluminum flywheel. Something I'd already planned as an experiment.

 



The old flywheel was steel, and possibly heavier than needed. I did like the way it looked, though, so rather then making a smaller flywheel, I switched materials to aluminum. That should reduce the weight by two thirds, yet still look the part. I hope this new wheel will have enough inertia.

Guess we'll find out!  :ddb:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #84 on: April 10, 2025, 03:53:02 PM »
And as a result of changing from 1/8" to 3mm on the flywheel, the old crankshaft link for the displacer no longer clamped properly to the flywheel crankpin. So I had to make another.

And that one also turned out to be a problem because the displacer just "ticked" the end of its cylinder. If I tried to adjust, it would tick at either the hot end, or the cold end. But never missing both. So that means the throw (and pin spacing) is just a tiny bit to large. I'll have to make another.  :wack:

Heading out to the shop again right now. I want to have the engine running this evening.  :loco:

Two down, one more to go:

 
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #85 on: April 10, 2025, 07:22:03 PM »
Done! Third time's the charm. Everything fits and no stroke interference. I gave it a brief run-up tonight and it hit 1296 RPM at 100 watts using the electric heater. For this I was running with the thicker flange displacer cylinder.

The engine is much quieter and smoother. It starts running with the new lighter flywheel after 4 minutes of warmup (the electric heater at 100 watts is somewhat slower than Sterno was, I believe) and starts at about 700 rpm, gradually increasing as the furnace heats up.

There seem to be stages of steady rpm, then increases to higher levels, where again it stays relatively consistent for a time before increasing. Maybe its some set of resonance levels. There's a fair amount of vibration (for a small engine) and I notice that if I place my hand on it to steady, I can sometimes get an increase in RPM.

I think balancing the crankshaft might help top speed, but not sure how to do that with an inline twin with a 90 degree phase difference.

Anyway, here it is with new flywheel, new power piston conrod (ball bearing big end), and new crank arm:

 
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline nickle

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Re: The Return of No. 83, a Hot Air Engine
« Reply #86 on: April 10, 2025, 08:42:08 PM »
I'm still here and still enjoying the show. What if you considered it to be two single cylinder engines that need individual balancing that just happen to be on the same shaft? I imagine that the displacer has different mass and stroke to the power piston, so normal twin cylinder engine dynamics are well and truly out the window.

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #87 on: April 10, 2025, 10:04:21 PM »
Hey nickle! :beer:

I'm reading up on balancing now. Lots of theories -- mostly similar for singles -- a certain percentage of the reciprocating weights plus the rotating weights added to a flywheel. What they don't say is how big is the flywheel and how far out the weights -- in other words, no mention of the arm.

I have a 600 pound Listeroid diesel single with two 24" flywheels powering a generator for emergency outages. Believe me, that is vibration! Yet I balanced it to the point where I don't think it is going to tear down the shed it is housed in any more. It seems quite tame actually. No math involved.

To balance, I set it on railroad ties atop a 2" rubber horse stall mat, then filled in around the ties up to level with gravel. That's like a spring and shock absorber in a car sort of. That's not balancing, but it allowed me to begin after steadying it that way so it wasn't walking around. How I balanced it was just holding a piece of chalk close to one of the flywheels near the top so that it just contacted the chalk during a major excursion. This marked the flywheel at the point of major unbalanced thrust in that direction.

Then while the engine was stopped, I picked a point 180 degrees opposite on the flywheel and added modeling clay there. I started the engine again and checked with chalk again. Less movement, but still some. It was marked in the same place, so I added more clay opposite. Eventually the excursion was nearly gone, and I called it done. I checked the other flywheel the same way. I epoxy glued on equivalent weights to the clay for a more permanent solution.

 
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #88 on: April 10, 2025, 10:24:09 PM »
Andy Ross once worked out that a countershaft running opposite the crank direction could have counterweights that exactly balanced oddball hot air engines -- and that makes perfect sense to me. But my question is, how much power are you losing in driving the countershaft vs the gain it may provide through vibration reduction?
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

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Re: The Return of No. 83, a Hot Air Engine
« Reply #89 on: April 11, 2025, 02:41:27 AM »
Now that accelerometers are available in chips could you not set up some in three mutually perpendicular axis, and with a crank shaft position sensor plot their output in real time revealing how much and where the unwanted motion is?
Andrew Mawson
East Sussex

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #90 on: April 11, 2025, 09:57:38 AM »
Hi Andrew, that would be ideal.  :coffee:

If there was a one day project already posted by someone else, cheap, I'd build it!

If you're in the mood to take on an electronics challenge......?

(Probably no time, I'm guessing, due to landscape, livestock, and guest, infrastructure support  :whip: )
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #91 on: April 11, 2025, 10:24:16 AM »
Could be a single accelerometer and a triggered cheap LED panel as a strobe instead of a computer control interface and position sensor.

Thus portable between engines.

Apply in the direction of the axis of interest.

Anybody out there up for that as a project to post here on Madmodder? Come on, you know you can do it! Think of the glory!  :lol:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

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Re: The Return of No. 83, a Hot Air Engine
« Reply #92 on: April 11, 2025, 10:26:20 AM »
You need some young whiz kid who lives and dreams Arduino not an old codger like mine with an atrophied brain!
Andrew Mawson
East Sussex

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #93 on: April 11, 2025, 10:28:30 AM »
Mine is atrophying, too, plus I'm getting lazy these days. Message to youngsters for rescue sent in a bottle.... :lol:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #94 on: April 11, 2025, 11:11:39 AM »
New test this morning, 100 watts, 1280 RPM tops after long ramp up, again starting at 650-700 RPM. Same displacer cylinder as before. So that pretty much confirms the consistency of this setup.

Performance appears to be 300 RPM better than it had been before the changes to flywheel, con rod and crank link, when tested at 100 watts.

I'm going to let it cool down and change displacer cylinders to the one with the thinner steel flange and copper end, and test again.  :coffee:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #95 on: April 11, 2025, 12:22:18 PM »
Test with the thinner flanged, copper ended cylinder (100 watts input) : Started earlier at ~800 RPM. Maxed out earlier at 1367 RPM with an average at the end around 1350 RPM.

Unfortunately, due to double variables (flange difference, end material difference), there is no way of telling specifically why this cylinder is better. Just that it is better, by close to 100 RPM, than the other. Tch tch, mixing variables.  :wack:

Oh, also, it did the same thing -- ramped up at "rpm levels" and responded to a steadying hand pressure by increasing revs.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #96 on: April 11, 2025, 06:46:20 PM »
I made a firebox door this afternoon, to replace the one that was lost.

 
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline RussellT

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Re: The Return of No. 83, a Hot Air Engine
« Reply #97 on: April 12, 2025, 05:01:05 AM »
steadying hand pressure by increasing revs.

Have you tried clamping it down to the bench?

Russell
Common sense is unfortunately not as common as its name suggests.

Offline raynerd

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Re: The Return of No. 83, a Hot Air Engine
« Reply #98 on: April 13, 2025, 04:17:09 AM »
Well it's kind of disappointing to see the very small amount of interest most visitors to the site pay to people posting here. Other than a welcome few comments from old friends, it's as if we were alone.

Yet I'm seeing 2000 views a day on the progress of this little engine. and in the forum statistics on the front page right now, 500 visitors, and only three members signed in.

This is a rather sad state of affairs, and a forum like this will not continue unless others join, sign in, comment and, one hopes, even add interesting projects of their own. Certainly, now, I'm asking myself just who is it I want to communicate projects to? If it's just lurkers, bots, spiders and AI content reapers, then no thanks, I'd rather just work on my own.

Nope I'd rather talk with real people. Are there any out there in that group of 2000 views, or those 500 visitors today? Say something. Say hello. Say anything! Let us all who post here know that we have a reason to do so. Organic Intelligence.  :mmr:

It is a really sad fact. It seems everywhere is quiet. I thought people may have moved to facebook groups but there is sod all on those as well. I remember back in 2009-2011, you could post a picture at 9am in the morning and you`d have a hand full of replies and comments by midday. I don`t know what has happened. I think it is quite self for filling as well- the less people contribute, the less it makes me contribute. I`m not very skilled and learnt everything from this forum and its users when I was really getting into engineering. I use to comment on the comments based on something interesting someone had said, as much as replying to the poster. Discussions spiralled. It is why I started making my little videos but it is all because I enjoy doing it, feedback is minimum.

Hopefully it`ll come back around and people will start posting more.

Your engine is looking great and I`ve enjoyed the pictures  :D :mmr:

Offline vtsteam

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Re: The Return of No. 83, a Hot Air Engine
« Reply #99 on: April 13, 2025, 11:55:26 AM »
Thanks Chris! :beer: great to see your icon and hear your voice again! Always loved your projects. I'm presently hopeful we can re-kindle interest here.

I also learned a great deal of what I now can do participating here over the years. When I started on madmodder I got a lot of help from the late Rob Wilson, and tons of  encouragement from the late Dsquire. The loss of some of us due to attrition might be a factor, too, sadly.

I think during the last five years or so, YouTube has substituted for fora, and I have a few videos there myself. But it's a very different experience there -- basically passive and disconnected other than brief comments and likes. A forum is a very different animal. It is communication, and a group atmosphere. Shared progress through projects. Frankly, it's more fun -- at least to me.

Anyway, on the positive side of things, I'm seeing more new member requests, and a fair number of views here, so let's keep talking and going!  :nrocks:  :headbang: :coffee:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg