Author Topic: Twin Oscillators  (Read 6350 times)

Online Jo

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Re: Twin Oscillators
« Reply #45 on: May 14, 2019, 04:56:23 PM »
Coming along well Jo, When you go to show it off to your supplier could you enquire how his No1 is going or not?

I was planning on doing that tomorrow when I visit him  ;) He had been using the excuse that for months he had been waiting for a replacement Eccentric strap casting to turn up.. When I mentioned he could give them a  :stickpoke: at the Harrowgate show it had suddenly turned up the day before  :noidea:

Jo
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Online Jo

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Re: Twin Oscillators
« Reply #46 on: May 15, 2019, 06:21:53 PM »
The latest on Eric's Stuart No 1 was: " I'll be getting back on those shortly".   I don't think any parts had moved since last time I visited  :disappointed:


He is now regretting letting me have the Blackgates castings, he is almost as difficult as Surus to recover your engine from when you take one round to show it to him  :ShakeHead:

Jo
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Online Jo

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Re: Twin Oscillators
« Reply #47 on: May 17, 2019, 02:57:37 PM »
The cylinder ends come out of a nasty bit of bronze. Each piece was nearly enough to make a spare cover if needed. As is traditional I like to use as little material as possible so I chose to make the lower covers back to back and then part them off. Did I mention nasty bronze  :facepalm: it was none too happy at being parted off with a cheap as chips Chinese parting off carbide tip.

The other covers were turned to fit into the cylinders from the provided bronze  then parted off at 4mm total thickness and held on the 0.8mm long flange to machine the top of the covers. The three holes were put into the covers using my dividing head at the correct distance only to find that the slots in the cylinder are not supplied deep enough  >:( so they had to be hand filed out.

One cylinder done the second one to go. The spare piece of bronze has been added to the come-in-handy drawer  :)

Jo
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Offline b.lindsey

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Re: Twin Oscillators
« Reply #48 on: May 17, 2019, 03:02:07 PM »
Those still came out nice Jo! One can never have too much bronze in the come in handy bin...nasty or otherwisei  ;)

Bill

Offline AOG

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Re: Twin Oscillators
« Reply #49 on: May 17, 2019, 03:15:21 PM »
I feel your pain Jo. I had to do the same thing on mine.

Tony

Offline Jasonb

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Re: Twin Oscillators
« Reply #50 on: May 17, 2019, 03:40:29 PM »
Is it the photo or is your insert not parallel to the holder, looks to be pointing to the right. Parting a large dia while holding by a small spigot will always be "interesting"

Also a MGGN will be better than a MGMN on non ferrous

Online Jo

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Re: Twin Oscillators
« Reply #51 on: May 23, 2019, 04:57:38 PM »
The material provided for the crankshaft was tough as old boots  :ShakeHead: I don't know why people seem to think you need some sort of exotic hard bit of steel for a crankshaft when on our little aero engines (that run much faster and do potentially much more work) it is normal to use standard EN1A up until crankshafts of about 6mm diameter. I tried using it  :facepalm2: it was horrible :Doh: especially as the crank was only 4mm diameter so it would not fit in my crankshaft turning jig so I attempted to use a collet chuck in the jig and was still not happy turning the pin :disappointed:

In the end I threw that attempt away and make the crankshaft up out of some bits of silver steel and loctited it together.

On the other end of the crankshaft goes the flywheel it is supposed to be brass one the drawings but I didn't like the look of that so it has been replaced with a Cast Iron one which has the advantage that the grub screw is the same colour as the crank  :)

Edit: Just re-read the parts list  :facepalm: It shows that the crank pin is supposed to be a separate item. I should have realised as the drawing shows two part numbers for the crank  :Doh:


Its Thursday so it should be casting fondling evening, I wonder which set I will be allowed    :wine1:

Jo
« Last Edit: May 26, 2019, 12:49:21 PM by Jo »
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Offline b.lindsey

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Re: Twin Oscillators
« Reply #52 on: May 24, 2019, 01:00:26 AM »
Looks good Jo. Hope Surus will give you free run of the casting collection.

Bill

Offline Jasonb

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Re: Twin Oscillators
« Reply #53 on: May 24, 2019, 07:15:30 AM »
it was horrible :Doh: especially as the crank was only 4mm diameter so it would not fit in my crankshaft turning jig so I attempted to use a collet chuck in the jig and was still not happy turning the pin :disappointed:

This looks to be a very similar problem to the earlier cylinder covers where a relatively large diameter is being machined while held by a small one. In this case a small BS-0 ctr drill in the end of the crankpin would have added additional support. In these situations a lot of fine cuts and patients with a sharp tool either **GT or HSS will be better than deeper cuts with a **MT insert, other alternatives are to mill away most of the material around the pin first.

The setup with jig and the length of the collet holder does not help with the increase in overhang, maybe an ER block in the 4-jaw would have been shorter and more rigid. Better still a block with a 4mm hole in it held in the 4 jaw.

Online Jo

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Re: Twin Oscillators
« Reply #54 on: May 24, 2019, 09:44:26 AM »
Thank you Jason it was the turning off of the centre support that I was concerned with - It would have needed a travelling steady.

I don't have any ER blocks. If I did then mounting it in a four jaw would still have had the same overhang and would have needed a travelling steady to remove the centre mark.


I am happy with how the crankshaft turned out and am now looking at how to drill the base, assuming that playing in the garden is not too tempting this morning :embarassed: and of course there are my village commitments  :facepalm: this afternoon. I am sure I had more time when I went to work  :noidea:

Jo
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Online Jo

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Re: Twin Oscillators
« Reply #55 on: May 24, 2019, 11:54:54 AM »
I have started on the base: First up was to find a happy medium position for the three holes - I have a pointed tool I use to do this (it is also strong enough to be dropped down and used as a scribe if required  ;) ). I chose to reduce the distance out to the two cylinder pivots by 0.3mm to make the cylinders sit in the middle of the port faces.

First drilling the centre of the crank with a nice sharp PCB drill then a slow brass drill bit before reaming the required 4mm. The two cylinder pivot holes are drilled the same but I played it safe and used the machinist's level to keep checking the casting had not moved. All holes were de-burred before going further.

Turning it over the location of the holes looks good  :)

Jo
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Offline Admiral_dk

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Re: Twin Oscillators
« Reply #56 on: May 24, 2019, 08:19:21 PM »
They came through perfectly in place Jo  :praise2: - mission accomplished  :cheers: .... ups I forgot that you prefer  :wine1:

Online Jo

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Re: Twin Oscillators
« Reply #57 on: May 25, 2019, 04:34:21 PM »
Thanks Per  :cheers:

The stand was turned over and using a piece of 4mm in the collet vice to hold the stand in line it was clamped in the machine vice. Having first faced the ports it was then a case of offsetting to each cylinder pivot and co-ordinate drilling the four port holes.

Then the steam passages could be drilled, thankfully I had a long reach 2mm drill for the difficult hole. All the holes were checked they went through using a torch  ;)

The stand just needs the threads tapped and the plug fitted so time to celebrate  :wine1: 

Jo

P.S. I do like some beers as well as wine but preferably not on the same evening  :hellno:
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Offline Admiral_dk

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Re: Twin Oscillators
« Reply #58 on: May 25, 2019, 08:27:14 PM »
Looks like it's almost ready to have the "loose bits" applied to this center part  :ThumbsUp:

Quote
P.S. I do like some beers as well as wine but preferably not on the same evening  :hellno:

Agreed - very bad idea. I do actually hardly drink any beer anymore .... I usually tell people that I consumed far more alcohol as strong beer and hard liquor in my youth than most people consume in a lifetime (very true) => I do NOT drink alcohol any more ...!.... but I do enjoy some from time to time - preferably as a good Scotch (or Irish) whiskey, cognac, rum or white wine (Red is NOT an option - allergic), in the right company  :cheers:

Online Jo

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Re: Twin Oscillators
« Reply #59 on: May 26, 2019, 12:40:57 PM »
The two sets of four plugs are shown parallel but I chose to turn to 4mm long and leave the top rough cut so that there was something to get hold of if needed. I also countersunk the tops of the holes on the stand to give the solder a little more to grip on.

Each plug was then coated with flux and poked in their holes - one fell out while I was soldering the other side  :facepalm: luckily the workshop Gnome has not been seen since Surus arrived so it was easily found and refluxed before soldering into its hole. Once cool each of the plugs were filed flush.

Finally the threads were cut into the stand and I knocked out the two steam/exhaust adapters while I thought about them. Time to decide on the next bit  :thinking:

Jo
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