Robinson Revisited.......

[Stilldrillin]

Geoff.
Those boards were made with us in mind, I think! 


Had another test run today. Just over 1/2 hour.

The burner is better, with the choke ring. But, there's still a lot of heat, where it's not wanted. Some lovely colours on the copper chimney! 

Have started to make another rose. Probably, with 1.5mm holes, over a 3/4" diameter area.

Also, ordered a couple of No 3 jets. (One for the Huxtable).......

David D

[Stilldrillin]

Here's a little conundrum....... 

The new crankshaft bearings I'd made had too much clearance, on the new 6mm silver steel shaft. 
So, I bought some 10mm o/d needle roller bearings. Mounted the pedestal on a mandrel, and recessed each end of the casting bore, to suit.

The needle rollers had a bigger wobbability factor than my original bushes!!   

Can't work that out. Am I missing something?   


Managed to locate four ball races. 6 x 10 x 3mm.




And these fitted perfectly, in pairs, either end of the pedestal........




Job's a good un. But, I can't work out why the rollers seem to be oversize, on the 6mm shaft.......   

David D

[ths]

For some reason there's a voice saying that needle rollers (some, anyway) are a push/press fit into their housing. This fit then reduces the ID to the specified size. Mebbe, mebbe not, but it works as a reason for your conundrum.

Cheers, Hugh.

[Stilldrillin]

A press fit  sounds reasonable Hugh! 

The clearance seems somewhere around 5 thou, to me...... So, they would certainly need some PRESS....... 

David D

[Stilldrillin]

I said it was too getting hot, under her skirt. Didn't I? 

Even with the choke ring, the present burner is too enthusiastic.......   




Some mica insulation, under the feet........




Fitted a No3 jet, and made a smaller rose.......




Good. But still too much........




So, I reduced the burner area even more........




And, I reckon it could still work well, even smaller........




Start up from cold, is now "instant". 10secs is all she needs to begin to run.

Here's a little vid, taken during during a 1hr test run. Mounted on a plastic turntable. Should give a smile.......

<a href="https://www.youtube.com/watch?v=cvnjBj8WQr8" target="_blank">http://www.youtube.com/watch?v=cvnjBj8WQr8</a>


That was when I realised the flywheel balance weight was out of sync. After fitting the new bearings! 

Just got to find why she clonks, when hot....... But not when cold. 

David D

[fcheslop]

 

[Stilldrillin]

As an addendum to the burner development.......


Gas power is usually used, to get as much heat as possible, under a boiler. 
The problem is. I need a gentle, controllable, flame.

It finally dawned on me, what's needed, is lower gas velocity. Provided by larger holes!

As an experiment, I removed the rose insert. But it then insisted on burning, down inside the body.

Made a rose, with 3.5mm holes. (And 2mm central hole, which was already in the piece of bar).

The old, and new roses.......




No. 3 jet, giving a full flame. Which doesn't blow itself out when full on.......




But will turn down, sufficient for the engine to stop, with the burner still lit.......




Heading the right way, now. I think!

David D

[NickG]

Ah, that looks a lot more sensible. 

[Ian S C]

Forgot to mention earlier, 23rd Nov., was local A&P show, and the vintage machinery group, and me with one or two of my hot air engines display our bits and pieces. One of the lads bought along a full size Robinson hot Air engine that he bought in Austrailia, it arrived in Christchurch the day before. Once the fire was lit under it, and we waited about 20 minutes, it ran, and kept going all day, lovely engine. At some stage I may have a photo.   Ian S C

[IanR]

It wasn't a 4.5" bore tiddler then? Would be nice to see a photo.

[Stilldrillin]

At some stage I may have a photo.   Ian S C

I would like to see that, Ian! 

David D

[Ian S C]

The Robinson motor is one built by Gardeners in UK about 1890/94, it seems to be rated 1/3 HP, I forgot to measure the bore, it's somewhere about 8", or 10".  Ian S C  ps my little engine on the table(ex ironing board), top right corner.

[Stilldrillin]

WOW!! 

Thanks for showing, Ian. 

That's the largest Robinson I've ever seen..... 

David D

[fcheslop]

Another Wow, thanks for the pic Ian
wont get that one on the coffee table David 
cheers

[EASy]

Here's a Robinson No. 6. This is the largest size made - 5/8HP with a bore and stroke of 10".