Author Topic: Triple Orphans  (Read 214825 times)

Offline Ian S C

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Re: Triple Orphans
« Reply #975 on: February 01, 2017, 12:45:25 PM »
I,m watching.
Ian S C

Offline Bluechip

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Re: Triple Orphans
« Reply #976 on: February 01, 2017, 01:55:02 PM »
Yeah, we are watchin' ...  :ThumbsUp:

In fact, some of us are verging on the agoggin'.  :popcorn:  &   :DrinkPint:  to hand.

Dave

Offline Jo

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Re: Triple Orphans
« Reply #977 on: February 05, 2017, 03:43:24 PM »
 >:( Don't trust Stuarts sizes on their parts list: The bolts on the eccentric arms are clearly shown as being 3/8" long. So I made them that long  >:( >:(  as you can see that is not right  :ShakeHead: and there is not even enough space for a standard 7BA nut between the expansion link and the two side arms  :disappointed:

Measuring things the space between the two arms is only 9.6mm and the ends of the rods are 6.3mm wide. Which means I have 1.65mm gap on either side of the ends of the arm.  That means I have to make all 27 bolts again  :( and cut down some nuts.

Nuts are never easy to get hold of. I find screwing them on to a spare screw provides an easy way to handle them. First leaving the nuts sticking 0.5mm out of the collet to face and file the taper. Then turning them round to cut down to 1.5mm thick.

Two reversing gear sets down, 7 more on these engines. I might check a few more of my orphaned casting sets to see if Stuart tried the same trick on their reversing sets  ::)

 :thinking: The eccentric bolts may need undersized nuts to make them look right. Will these engines ever end  :-\

Jo
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Offline Jasonb

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Re: Triple Orphans
« Reply #978 on: February 05, 2017, 04:13:24 PM »
I suspect the parts list shows the standard bolt that has to be modified to suit as they don't do 5/16" long ones

Do you really have to make them all again? Why not a simple split bush so you can hold them by the shank to reduce the length of thread, then hold by shank to skim down the head thickness.

I find an easier way to adjust my nuts is to have a bit of bar with suitable thread on the end, hold this in the collet, screw on a nut so it stops against the collet and then face off. This way the collets front face acts as your back stop so you can just face off a whole batch at one setting. Quick and simple. Your way is fiddly to get them in the collet then you need to touch off the existing face, zero dro and then take your cut. No wonder these engines are taking you so long :mischief:
« Last Edit: February 05, 2017, 04:18:10 PM by Jasonb »

Offline Jasonb

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Re: Triple Orphans
« Reply #979 on: February 05, 2017, 05:02:19 PM »
Jo are you sure about that 9.6mm dimension

The bosses on the arms are 1/4" long less the 1/16" thickness of the arms leaves 3/16". Expansion link is 1/8" thick and sits between the two .

3/16 + 1/8 + 3/16 should give you 1/2" (12.7mm)between arms not 3/8" (9.6mm)

I which case stock 3/8 long bolts would have fitted with standard thickness heads and nuts.

Offline Jo

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Re: Triple Orphans
« Reply #980 on: February 05, 2017, 05:37:41 PM »
Yes I measured it, and it looks like your drawings are different from my ones, as you can just about make out from the photo it shows the two bosses at 4mm and 4.76mm thick. If they were thicker then the bolts that go through the two ends would also need to be longer and the list shows them at 16mm long.

I will stick to holding my nuts in a collet to cut off .7mm rather than risk machining it whilst being held by 3 threads on a thread that is itself only 0.2mm tall. A decent chuck could also hold the nut for facing but not an ER collet  :disappointed:

Jo
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Offline Jasonb

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Re: Triple Orphans
« Reply #981 on: February 05, 2017, 05:58:25 PM »
Thats interesting considering where my drawings came from.

You should not rip your nuts off doing it my way. Those locknuts on that conrod I sent you a pic of are M2.5 and screwed onto a M2.5 thread for machining cut onto 3/32" rod so probably less than 0.2mm engagement

Online steamer

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Re: Triple Orphans
« Reply #982 on: February 05, 2017, 06:01:01 PM »
A filing rest is an easy way to make nuts from bar stock...it really is pretty fast if you're set up right....

Dave

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Damned ijjit!

Offline Jo

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Re: Triple Orphans
« Reply #983 on: February 05, 2017, 06:11:21 PM »
Thanks Dave  ;)

I have several lengths of 7BA Hex, that could be used to make some but it was a bit of a waste as the parting off material is greater than the nut thickness. What I am using up is some old 7BA nuts that have surface rust on their faces.

Jo
Enjoyment is more important than achievement.

Offline Roger B

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Re: Triple Orphans
« Reply #984 on: February 05, 2017, 06:16:16 PM »
I'm still watching along in the background, but can't offer much other than  :wine1:  :wine1:  :wine1:
Best regards

Roger

Offline scc

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Re: Triple Orphans
« Reply #985 on: February 05, 2017, 08:57:50 PM »
Me too, :popcorn:

Regards,             Terry

Offline stvy

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Re: Triple Orphans
« Reply #986 on: February 06, 2017, 10:43:11 AM »
Jo,

I can't quite see it clearly or not but Are you using hexagon 5c collets to hold those ba nuts? If so where did you source them. The only source I've found is hardinge for 0ba thru 8 ba and that's too expensive for me at this time. Your collet looks to not be a hardinge. I would also like to source down to smaller sizes if possible.

Thanks,
Steve


Online steamer

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Re: Triple Orphans
« Reply #987 on: February 06, 2017, 11:29:50 AM »
stvy

They're out there....

http://www.dunhamtool.com/5c_collet.html

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Jo

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Re: Triple Orphans
« Reply #988 on: February 06, 2017, 11:46:53 AM »
Hi Steve,

I am using a 3/16" collet there, which is very tight on 3/16 hex but has just enough play in it to be able to hold the 7BA hex . I was lucky enough to get some other standard BA sized Hex collets ;D

I think Arc do hex collets in the UK. By mixing metric hex with imperilous ones you can get close to most sizes you need.

Jo
Enjoyment is more important than achievement.

Offline rhankey

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Re: Triple Orphans
« Reply #989 on: February 06, 2017, 01:55:39 PM »
Stuart definitely did revise some of the dimensions with the crosslinks/reversing links.  Older plans did result in clearance issues for bolt heads and nuts.  Newer plans solve those problems, but they forgot to revise the length of the 6 crosslink bolts they provide, which are now too short.  So, I had to make 6 longer bolts.  This was the only area I found Stuart had any errors in their Triple drawings.

 

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