Author Topic: Arnold's take on the MEM Corliss  (Read 134621 times)

Offline arnoldb

  • Administrator
  • Full Member
  • *****
  • Posts: 1338
  • Windhoek, Namibia
Re: Arnold's take on the MEM Corliss
« Reply #180 on: April 22, 2013, 10:39:30 PM »
Thanks all who checked in  :praise2:

Vince, Simon is correct it should be fish belly - don't know where my thoughts were when I called it fish-tail  :-[

Bill, it's not finished, so there was no family shot.  Hopefully I get some time this coming weekend to finish it, another part, and start to mount things... That's a family picture I'm really looking forward to  :)

 :Director: Now, listen to Jo everyone - her description is a much better method of turning fish bellies.  IIRC, Jason also did a very good write-up on turning them, as did Stew a couple of days ago.

Like Jo mentioned, fish bellies are actually made up of more than one angle which then gets blended together to form a curve.
If you look closely at my fish belly you'll notice it's slightly asymmetrical - that's because I was lazy and didn't even bother with setting angles on the top slide to cut by.  It was just eyeballed with some coordinated in-feed on the cross slide while feeding along the length - you can see the "steps" in the third-to-last photo - before having at it with the file - also just to eyeball mk1.  This won't pass muster in a model engineering engineering competition, and on an engine with more than one similar fish bellied rods it would stand out like a sore thumb.

For those that don't want to mess with setting the top slide and want a good result, there are some other ways of getting fish belly - and  for that matter, other turned curves - done. 
  • Marv's "PROFILE" program can be used to calculate the needed values to approximate the curve needed. 
  • Draw up the curve in CAD, print to size, and stick on a bit of cardboard / thin plate /stiff plastic sheet to cut out to form a template to use to check the workpiece against.
  • If you're good at sketching, fold a bit of paper in half, and just sketch half of the curve needed and cut it out.  When unfolded, the paper can be treated the same as for CAD above - stick it to something or trace it to make a nice symmetrical template to check the workpiece against.
  • Got CNC?  QED.  Not quite for me, as I prefer hands-on manual machining as my work days are already spent at computer consoles.  There's nothing wrong IMO with using CNC to build engines, and one-off CNC'd engines can be stunning as well as representative of the operator's effort.  But more than one CNC copy, and the originality is lost.
Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline vcutajar

  • Full Member
  • ****
  • Posts: 2482
  • Marsascala, MALTA
Re: Arnold's take on the MEM Corliss
« Reply #181 on: April 22, 2013, 10:44:04 PM »
Thanks for the info Arnold.  Hopefully I will remember it when I come to do it.

Vince

Offline arnoldb

  • Administrator
  • Full Member
  • *****
  • Posts: 1338
  • Windhoek, Namibia
Re: Arnold's take on the MEM Corliss
« Reply #182 on: May 04, 2013, 06:41:24 PM »
Pleasure Vince  :)

Things have been very topsy-turvy in my world the last two weeks, and shop time suffered badly.  It's not all doom and gloom though; my sister visited from South Africa for a couple of days, and besides pleasant company she brought along a box of riches.

A set of 0 to 10 BA taps and dies that belonged to my grandfather, who sadly now has reached the age where he cannot continue doing much in his own shop.  My dad could have grabbed the set, but he passed it on to me - so thanks Grandpa and Dad  :NotWorthy: .
By all accounts the set is more than sixty years old - and still complete; a great tribute to how well my grandpa looked after his tools.  It looks to be carbon steel, but very well made and high-quality, and all stamped LAL - Made in England.  At some point Grandpa added a couple of extra holes for some metric die nuts as well:


On to a bit of shop time for a change.  The connecting rod still needed quite a bit of work to finish off.  First was to square out the rounded section left on the inside of the fork end (if you have a look at the last photo I posted before this, you'll see it).  I left this on purpose earlier on; I had no easy way to mount the workpiece vertically to mill out the excess, and would have had to resort to filing for that.  But with the crank end now much smaller than when I started, it was easy to just stick the four-jaw chuck on the rotary table and chuck it up to mill out.  When I made the RT I left it's spindle hollow to cater for scenarios such as this:


All done:


Off to the big vise for a spot of filing to get rid of tool marks - I thought it would be a heck of a job to do this, as this stainless is a bit on the tough side, but it filed very nicely:


A quick check on what's built of the engine so far, and it was obvious that the tapered sections from the plans are definitely needed on the forked end of the connecting rod, so I meticulously set up the workpiece to eyeball Mk1 in the milling vise - a thin drill through the hole in the fork end to allow as much clamping on it as possible, and a bit of plate to support the other end at the approximate angle needed. Depth of cut was set to _just_ start removing metal at the center line of the hole through the fork:

Please don't adjust your spectacles; I don't know where the focus was on that photo  :-[

A bit more filing and rounding over, and the connecting rod was done:


A quick turning session on the lathe, and some 8mm hex brass ended up in the crosshead pin and screw.  Being my normal lazy self, I left the parting pips on for the next operation:


I must get my grubby hands on some ER25 collet blocks...  I abused my home-brew lathe collet chuck by lightly clamping it up in the mill vise.  Then I eyeballed a 1mm slitting saw against the parting pip to set center height to cut the screw slot:


Done:

While typing this up tonight, I suddenly remembered something, and I owe Stew (sbwhart) an apology: - Sorry mate; I forgot I promised some photos of using the height gauge to set up jobs like this.  I'll try and do a mock-up for you in my next shop session.

I changed the 6mm collet for a 3mm one, and cut the slot on the "screw" section of the pin as well.  I've found that grabbing on to threaded sections with collets does not damage the threads for light machining operations.
The bits screwed together:


A family photo - here one can clearly see why the tapered sections on the fork end is needed.  If those were not done, the fork would get interference in the cross-head guide bore:


Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

fcheslop

  • Guest
Re: Arnold's take on the MEM Corliss
« Reply #183 on: May 04, 2013, 06:46:44 PM »
Hi Arnold, that the same set of taps and dies I have didn't realise they were that old :ThumbsUp:
Iv just been quietly following along you're nice build its on my list :Lol: as are a lot of things
cheers

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12626
  • Hampshire, england.
Re: Arnold's take on the MEM Corliss
« Reply #184 on: May 04, 2013, 06:58:52 PM »
I like your crosshead pin design Arnold  :ThumbsUp:

In fact the whole connecting rod is looking good  8)

Jo
Usus est optimum magister

Offline tel

  • Administrator
  • Full Member
  • *****
  • Posts: 1657
  • Bathurst District, NSW, Oz.
Re: Arnold's take on the MEM Corliss
« Reply #185 on: May 04, 2013, 08:51:35 PM »
Quote
In fact the whole connecting rod is looking good  8)

Agreed! The whole job, in fact - you are making very good progress.  :ThumbsUp: Only wish I could find the time to get back to my build!
The older I get, the better I was.
Lacerta es reptiles quisnam mos non exsisto accuso nusquam

Offline vcutajar

  • Full Member
  • ****
  • Posts: 2482
  • Marsascala, MALTA
Re: Arnold's take on the MEM Corliss
« Reply #186 on: May 04, 2013, 10:26:45 PM »
Arnold

Love your (and also Jerry's) family photos of the parts coming together.  For someome like me with an inexperienced eye, it puts things from the drawing in perspective.

Vince
« Last Edit: May 05, 2013, 05:18:52 AM by vcutajar »

Offline Maryak

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1818
  • Aldinga Beach South Australia
Re: Arnold's take on the MEM Corliss
« Reply #187 on: May 05, 2013, 02:05:45 AM »
Arnold,

As always fantastic job on the Corliss.  :praise2:

Heirloom tools are very precious and I'm envious because mine were stolen when thieves broke into the Maritime Museums workshops some 7 years ago. Sure I bought replacements but it's just not the same. So please keep them in a safe place.

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline Don1966

  • Full Member
  • *****
  • Posts: 5996
  • Morgan City, LA (Along the Gulf Coast)
Re: Arnold's take on the MEM Corliss
« Reply #188 on: May 05, 2013, 02:42:45 AM »
I like your crosshead pin design Arnold  :ThumbsUp:

In fact the whole connecting rod is looking good  8)

Jo
I agree great job and lessons are being learned following along. Thanks Arnold.

Don

Offline Pete49

  • Full Member
  • ****
  • Posts: 651
  • top of the gulf SA, Gateway to the Flinders Ranges
Re: Arnold's take on the MEM Corliss
« Reply #189 on: May 05, 2013, 05:03:29 AM »
Great job Arnold and keeps me interested  ;D
Pete
I used to have a friend.....but the rope broke and he ran away :(

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 10316
  • Central Massachusetts, USA
Re: Arnold's take on the MEM Corliss
« Reply #190 on: May 05, 2013, 10:22:59 AM »
Looks great from this side of the pond Arnold!....Glad your not sleeping at your keyboard and are instead in the shop! :ThumbsUp:

I have a set of dies from my Dad....I think of him everytime I use them

Goodonya mate!

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

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13647
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Arnold's take on the MEM Corliss
« Reply #191 on: May 05, 2013, 11:15:58 AM »
Lovely work all around Arnold. The connecting rod alone is a work of art!!

Bill

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6375
  • West Chester, PA, USA
Re: Arnold's take on the MEM Corliss
« Reply #192 on: May 05, 2013, 12:46:39 PM »
Beautiful connecting rod Arnold.
I wish I were as 'lazy' as you.  ;D
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline arnoldb

  • Administrator
  • Full Member
  • *****
  • Posts: 1338
  • Windhoek, Namibia
Re: Arnold's take on the MEM Corliss
« Reply #193 on: May 11, 2013, 10:40:31 AM »
Thanks to all who responded  :praise2: :praise2:

With regards to the very positive feedback on the connecting rod: Thank you all.  This part is one of those rare occasions where I stepped back and was pretty much satisfied with how it came out.  And it was a huge learning experience for me; I'd never machined stainless steel to this extent.  Actually I'm quite surprised at how well it went, and some of the lessons learned might just help improve my finishes on mild steel as well.

Vince, I'm as inexperienced as you are.  In fact, we're all learning from each other, and that is what MEM is about.  Have a look at my post today, and give yourself a huge pat on the back; I think you did a much better job on the crankshaft than I did  :NotWorthy:

Carl, it can take a bit of effort to be lazy  :lolb:

I have a four-day long weekend - we had a public holiday yesterday and I took leave for today.  Yesterday was spent doing all kinds of needed odd-jobs around the house; banal things like changing water tap (faucet for the US people) washers on leaking taps, giving the kitchen oven a really good scrub-down and so on.  A big part of today was spent running around town to do one of the things I hate most - shopping; and mostly trying to find sensible, presentable, subdued and comfortable attire; I'm not a natty dresser and it's really hard to find the type of boring clothing I like  :Lol: .  The highlight of my shopping was a visit to the metal store, though they didn't have everything I wanted.

I managed a couple of hours in the shop this afternoon though.  I'm trying to steer away from mild steel for parts of the engine that will not be painted.  The crank web is one of those, and I could not get suitable stainless, so I decided to make it from bronze.  A bit from the offcut bin volunteered, and after locating the edges I brushed some permanent marker ink on it and spot-drilled in the needed locations - very lightly at the crankshaft end:


The lightly spotted hole was used as a pivot to mark out the periphery of the web for later operations:


I love my camera to bits - it works very well, but it does have one vice...  The batteries last for hundreds of photos on end, but between the time it shows a low battery warning and completely shuts down, it can take just two or three photos...  Today was such a day.  Off to the charger with the batteries, and some minor work happened.

The crankshaft end of the web was drilled and reamed 8mm - the "slightly scaled down" 24mm to the inch I'm working on called for 9mm for the shaft, but that's a hard-to-find size of shafting locally, so I had a choice of 8mm or 10mm, and back when I built the bearing blocks I'd already decided on 8mm (~= 5/16" for the non-metric people).  I'll also be fixing the web to the shaft with bearing retainer, and pin it, so I just plonked the reamer right through, rather than making a press-fit like Vince did.

I also drilled the crank pin hole 3.3mm and tapped it M4. With the camera batteries charged up a bit, I took this photo after using a scribing pin in the mill chuck to mark out some more on the workpiece - the DRO is nice for that as well:


On to a bit of shaping...  Once again I cheated / was lazy.  Setting up the workpiece to mill off some excess, I just used a long 4mm cap screw and a drill bit to set things up.  The cap screw was long enough that it's "cap" section didn't touch the vise. Most metric screws are smaller than nominal size if measured over the threads.  This M4 cap screw measured 3.8mm across threads.  To keep things sort of parallel I used a 5.9mm drill  as a spacer in the "big" hole and milled out   the rest:


A bit of facet milling worked OK to shape the roundy-bits:


Some filing followed and I ended up with the web and  shaft:


Family photo - I didn't have time to make the crankpin.  The shaft and web are loctited together to set up so I can drill and pin it:


Kind regards, Arnold
 ::) Posted the morning after, as my Internet was down last night.
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12626
  • Hampshire, england.
Re: Arnold's take on the MEM Corliss
« Reply #194 on: May 11, 2013, 10:49:06 AM »
A big part of today was spent running around town to do one of the things I hate most - shopping; and mostly trying to find sensible, presentable, subdued and comfortable attire; I'm not a natty dresser and it's really hard to find the type of boring clothing I like  :Lol:

A man after my own heart  :ThumbsUp: I can never understand why women are supposed to like shopping :facepalm:  and as for buying clothes  :hellno:

She is coming together nicely   :)

Jo
Usus est optimum magister