Author Topic: Robinson Hot Air Engine. (Read 126928 times)

DavidA · « **Reply #125 on:** December 19, 2010, 01:08:33 PM »

While most of my 'stuff' is in the big shed that is only heated up when needed, my 'machine shop' is heated constantly in this weather by a small electric greenhouse heater. Keeps the place at around 12C. When the outside air temp gets back above freezing I will switch it back to four hours on-six hours off via the timer to save on fuel.
Really need to incorporate a room-stat in the circuitry to add a bit more control.

Dave.

shoey51 · « **Reply #126 on:** December 22, 2010, 01:40:34 PM »

I have the oposite problem I need to get Aircon installed to cool the workshop down

Stilldrillin · « **Reply #127 on:** January 19, 2011, 03:59:52 PM »

Well, it's been quite a while......

What with weather, health, family, friends.......
Even the new lass in the inspection dept has caused problems! She's been off for a fortnight.
Spent a few nights in hospital, for chopping and stitching together. She's back to her young self now, though......

Just, had to grab a few minutes, whenever I could.

Mounted faceplate on the rotary table. Centre adaptor bush, and the displacer bush screwed to the wrong side of the casting......

This held the assembly central to the displacer housing bore.......

Milled through the 3mm steel cover plate......

Swapped cutters and opened out the bore, and machined the lower, and upper joint faces.
Gave the cover plate an extra 5 thou' per side, for easier assembly, when painted......

Finish turned the replacement section of the displacer cylinder. (That's not a false start, by the flange, it's the 5 thou' for paint)......

Fits quite snugly.......

Shows how the brass repair tube snugs up to the cylinder. Also, the plugged water hole......

Next job was the chimney........

Opened out carefully......

Eventually, to 18mm......

Then a bush, to adapt to a 15mm copper elbow.......

Looks ok, I think......

Next up, is the in/ out coolant pipes.

That's it. For now!

David D

sbwhart · « **Reply #128 on:** January 19, 2011, 04:17:53 PM »

Cracking bit of machining Dave, looking real good

Hope your little inspector has made a full recovery and is doing well.

Stew

Dean W · « **Reply #129 on:** January 19, 2011, 07:47:56 PM »

You made a good show of that, David. Even I can understand it! ; )
Looks very good, and the chimney is a smart addition.

Brass_Machine · « **Reply #130 on:** January 19, 2011, 11:48:03 PM »

David,

Just found this thread. Missed it when it started. 1st, I love reading about how you restore engines. You do a great job. 2nd, what an interesting engine, I am with MadJack on this... I think I have to build one now!

Keep it up.

Hope the little one is doing better. What a cute one.

Eric

shoey51 · « **Reply #131 on:** January 20, 2011, 02:09:23 AM »

this is coming along nicely David I cant wait till the next instalment

Stilldrillin · « **Reply #132 on:** January 20, 2011, 04:29:37 AM »

Thanks for all your kind comments Chaps!

Re the new inspector..... She was born with a cleft palate.

The Surgeon should be a member here, for his wonderful Moderfication......

However he worked such magic. In a very confined area. Using only available materials, I shall never know!

The man's a genius! They all are.......

David D

Bogstandard · « **Reply #133 on:** January 20, 2011, 04:42:13 AM »

That engine has been given a new lease of life Dave, when it is all finished and running, you should be proud of yourself.

If you are going to give that base a coat of heat resist paint, maybe you could rebuild that broken foot with some epoxy based putty, shaped and filed to match the original. By the time the paint is on there, you would never know it had been broken. It would only need a few thin pins putting into the casting for it to grip onto, just to give it a bit of support and strength.

John

NickG · « **Reply #134 on:** January 20, 2011, 05:09:07 AM »

Nice 1 David, getting there and it's looking 1000 times better.

Nick

andyf · « **Reply #135 on:** January 20, 2011, 06:17:42 AM »

Quote from: bogstandard on January 20, 2011, 04:42:13 AM

..... maybe you could rebuild that broken foot with some epoxy based putty, shaped and filed to match the original. By the time the paint is on there, you would never know it had been broken. It would only need a few thin pins putting into the casting for it to grip onto, just to give it a bit of support and strength.
John

Or even stand the base on a flat surface, put a light film of oil (release agent) on one of the good feet, build a little coffer dam round it with Plasticine or something, fill with plaster of Paris, and thus make a mould. Put some thin pins into the poorly foot, pop the mould on and fill that with poxy resin. That might reproduce the "as cast" surface finish.

Andy

Stilldrillin · « **Reply #136 on:** January 20, 2011, 01:14:48 PM »

John, Nick, Andy.
Thanks for your comments!

Frankly the foot is some distance down the list, as yet..... I'm surprised you're recommending poxery resin. Will it stand the heat?

I was contemplating Jack's suggestion of a piece of cast iron and silver solder...... Though, I'm not confident at high temp soldering, as yet.

My main concern, is to get this project finished to running condition, ASAP. As a pal wants my mill and r/t etc.
He is offering very sensible cash for the assembly...... Allowing me to upgrade a little.

One more step along the way, this afternoon.......

Opened out to 7mm......

Rather out of focus, 5/16" slot drill, 3/8" deep.......

Leaving a small step in the bottom, to support the depth of the 7/8" long tubes......

Looks ok, I think.......

That's it until next week.
Busy weekend, including a 1st birthday party!

David D

NickG · « **Reply #137 on:** January 20, 2011, 03:15:15 PM »

Looks great David, not ok!

Dean W · « **Reply #138 on:** January 21, 2011, 08:17:43 PM »

Yes, looking very good David!
With all the work you've done, this has been near the same as building the engine from the raw castings.

Dean

madjackghengis · « **Reply #139 on:** January 22, 2011, 10:29:02 AM »

Hello David, you've been moving along quite nicely since the inspector got out of the shop, and back at home, did you ask the surgeon if he was going to post a build log on the madmodder site? Perhaps an invitation would have brought out the artist in him

glad to hear your little darling is going to be fine, bit of a start when you spoke of being in surgery and all, glad to know it was something easily fixed and not a major deal. I think you've done a very nice job in thinking through your alterations, and you are going to end up with an engine that can be hooked up to something to do work, from the looks of it. I would readily follow Bog's idea if I wasn't so sure a piece of scrap iron and the silver would do the job. As he says, if it's going to get paint, you can always make it look right, but I'd still do the silver and iron or steel or for that matter, you could simply puddle up some brazing with a clay dam, with the whole sitting on a brick, and then file it to shape, and it wouldn't show with paint on it, and high temp paint will definitely stay on for quite some time, it stays on the heads of an iron head Harley sportster for about a year before it finally goes away, and they run hot, right on top. I don't know if it's available or common there, but I get wrinkle finish high temp paint here, it's rated at seven or eight hundred degrees, and the wrinkle finish makes cast look great, and hides any cracks brazed up or the like. I use it on all the Harley cylinders I bore and hone and fit for pistons because nothing else looks as good on engine cylinders of iron, and air cooled. It dissipates heat well too.
I think you've got a real piece of work there and very nicely cleaning up to run. I'm really looking forward to seeing it finished, and watching the video.

cheers mad jack

Stilldrillin · « **Reply #140 on:** January 22, 2011, 12:29:15 PM »

Nick.
Thank you!

Dean.
Yes, you're right! But, I love sorting out orphan engines' problems......

The first Derbyshire Mineworker I ever met, told me. When there's a problem...... "Allus blame t'other shift".

The buck stops here, on a first build!

Jack.
I've bought some dark green smoothrite, for the engine. Think I will do the skirt in black barbecue paint. That should stand the heat, and hide any lumps & bumps......

Right, then......

This air transfer tube has caused me a lot of thinking time....... Still not happy!

Can we have a committee meeting?

This is what was originally fitted. Water could leak between tube and casting. (Never minding the termite holes!).

Around 3" long. 5/16" o/d. 5.5mm bore. 36tpi threaded through the displacer cylinder wall. 5mm transfer hole. Screwdriver slot in outer end......

The available area/ space, now looks something like this.
With the 7mm bore ending within 5thou' of the cylinder wall, I thought sealant on the thread would squirge into the little gap, as the tube is threaded home......

This is my idea for the tube.
I have an M7 x 1 tap & die. But the 5.5mm bore might leave things a bit thin.........

Anyone got any good/ better ideas?

David D

Bluechip · « **Reply #141 on:** January 22, 2011, 12:55:26 PM »

Hi Dave

No good or better idea, except I have M7 x 0.75 mm pitch taps & dies ... might give a microtad or so more wall thickness. Although I don't suppose it's a lot of difference from 1 mm pitch .. welcome to a loan if you require

BC

Stilldrillin · « **Reply #142 on:** January 22, 2011, 01:02:22 PM »

Quote from: Bluechip on January 22, 2011, 12:55:26 PM

Hi Dave

No good or better idea, except I have M7 x 0.75 mm pitch taps & dies ... might give a microtad or so more wall thickness. Although I don't suppose it's a lot of difference from 1 mm pitch .. welcome to a loan if you require

BC

Ohhh..... Dave!

Didn't I always tell everyone, what a great guy you are?

My t&d are out of a set from Chesterfield market. Untried/ untrusted. Yours sounds perfect.

Yes, PLEASE!

David D

Bluechip · « **Reply #143 on:** January 22, 2011, 01:29:30 PM »

Quote from: Stilldrillin on January 22, 2011, 01:02:22 PM

Quote from: Bluechip on January 22, 2011, 12:55:26 PM
Hi Dave

No good or better idea, except I have M7 x 0.75 mm pitch taps & dies ... might give a microtad or so more wall thickness. Although I don't suppose it's a lot of difference from 1 mm pitch .. welcome to a loan if you require

BC

Ohhh..... Dave!

Didn't I always tell everyone, what a great guy you are?

My t&d are out of a set from Chesterfield market. Untried/ untrusted. Yours sounds perfect.

Yes, PLEASE!

David D

Steady on there Dave ...

Cannot deal with anything vaguely resembling recognition or adulation.

Don't forget, I spent my life as a Field Techy on IT gear. Dog-hangings and b0ll0ck1ngs by the truck-load, yes. Can cope with them. No procedures in place for owt else ...

.. never been required .....

Mine are new too. Apex UK. So don't know if these work either .. ??

So, .. When and how ?? PM your phone # if you want a natter. As it's for nowt at weekends ..

Dave BC

Stilldrillin · « **Reply #144 on:** January 25, 2011, 03:59:04 PM »

Well.....
With the amount of cast iron dust I'm producing, I should have called this posting. "Getting down n dirty with Mrs Robinson".

The saga continues.
Fitted the skirt and displacer tube together..... Just a little mismatched!

The crescent, is the end of the displacer tube.......

No wonder I couldn't get the hot cap properly centralised!

Bored the mouth of the skirt concentric to the displacer bore......

That's the new, glued in place, repair section I'm gripping on.....

Great stuff, that high temp slidelock Dean! Thank you!.

Drilled and started tapping, the 6off, 6BA threads holding the deck casting to the repair section. The (new) plug tap feels very stiff to turn.....

Job stopped. Quality tap ordered, before anything goes snap....... I hate that sickening/sinking feeling!

David D

Bogstandard · « **Reply #145 on:** January 25, 2011, 04:31:19 PM »

Looking real good now Dave, you'll soon be there.

You are doing the right thing by waiting for a new tap, too many get broken off down holes by people thinking they will last forever. If you have drilled the right sized hole, then it should cut fairly easily, any sign of it going tight after the fwds/bkwds motion, throw it and get a new one.

John

NickG · « **Reply #146 on:** January 26, 2011, 06:18:54 AM »

Good point John. I did the same with my BA taps and dies until the 8ba literally wouldn't cut anything! So got some soba ones for christmas from Chronos I think it was. Having said that, the 10ba tap didn't want to know on the 1/6" stainless I had though.

Nick

Stilldrillin · « **Reply #147 on:** January 27, 2011, 12:54:50 PM »

Just finished plug tapping the 6off 6BA threads, in the displacer cylinder.

The new, German made, HSS tap, "purred" as it did it's job......

Seems there's no substitute for quality!

David D

NickG · « **Reply #148 on:** January 28, 2011, 04:33:15 AM »

David, I can testify that having had 2 BMWs and a Mini Cooper S, in my experience German made stuff does tend to purr!

Someone at work always used to say buy cheap buy twice and that motto has turned out to be correct on a few occasions - but I still don't learn my lesson!

Nick

madjackghengis · « **Reply #149 on:** January 28, 2011, 10:51:47 AM »

Hi David, I started buying my tools when I was about six, and figured out very soon, cheap tools cost more than good ones, always spend you money on the tools you will use often, with the greatest care for quality, and only ever buy a cheap tool if it is a one off job, and it's not likely the tool will break on its first job. I have taps and dies I bought from men who retired from the tool and die trade forty and more years ago, which are still sharp and cut well, and I have a few taps which I bought new which I never got a first hole done with, and have saved only because the shank may be used to grind into a cutter some day. I will say German tools tend to be good, but every country has tool and die makers who make and need the finest tools, so they can be had domestically, it's just a matter of knowing what quality looks like. I try to always buy new taps in sets of three, taper, plug and bottoming, because I will always need all three if I don't, and because cheap taps don't come in anything but taper, so the sets are so far, always good quality. Spend extra money if buying cutting tools for stainless, but you will get you money's worth, even if you spend the extra to use on aluminum or cast iron, getting a lifetime of use from them.
On the other note, your engine is looking very good, and like it is getting very close to being a finished runner, and almost ready for video. I'm really looking forward to seeing it run right now.

mad jack

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Author Topic: Robinson Hot Air Engine. (Read 126928 times)