Author Topic: Chris' Build of a Lombard Hauler Engine  (Read 301980 times)

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1005 on: March 23, 2017, 02:17:57 PM »
More info on the valve rod movement. I drew up the geometry involved in the CAD package, and found the following details (sorry Zee, math follows, and no pictures!  :ROFL: )

With a 12.5" long rocker arm on the original, pivoted in the center, and a 1.28" total travel on the valve rod, the pivot arm introduces a 0.03285" vertical deflection at either end. Not much, considering that the valve rod projects out from the valve gland about a foot and a half.

For the model sized version, there is a 0.9468" rocker arm, pivoted in the center, and a 0.106" total travel on the valve rod. That introduces a 0.00298" vertical deflection at either end of the travel, over about an inch and a half. Again not, much.

So, given that the valve gland as I will make it will have an o-ring seal, just a slight over-sizing of the holes through the gland will allow that tiny bit of angular deflection, and the adjusting nut in the valve slider (I am planning a typical model type valve-nut-in-the-center style valve slider, not the balanced slider like the original) can move that much with no problem, I think I can do without the extra link at the rocker arm, like the original.

If the travel was longer, more like the piston has, this would never work, but the valve motion is so small that I think it will be okay. Can always retrofit an extra link if it is a problem.

Does that sound right to you guys?

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1006 on: March 23, 2017, 06:31:38 PM »
After the investigation into the valve rod movement this morning, did get some time in the shop to get the bearing blocks roughed out. I started with some 1/2" x 1" stainless bar, cut off enough for both bottom blocks and split another piece for the stock for the caps. After marking out the rough shape,

I went back and cut off the bulk of the excess material with the reciprocating saw:

To give you an idea of where these are going, here are the blocks sitting on the engine bed rails.


And for those who don't think (some types of) bar stock has internal stress from the manufacturing process, even these short sections showed a detectable amount of bowing on the flat surfaces that were on the outside of the bar. After shaping the inside edges, a light pass will be made to straighten those outside edges again.
« Last Edit: June 05, 2018, 05:34:50 PM by crueby »

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1007 on: March 24, 2017, 01:16:51 AM »
Continuing on with the bearing blocks for the crankshaft, milled down the sawn edges cap blanks, taking the last cut on the formerly-flat outside edge to straighten it again after it bowed slightly when splitting down the wider bar.

Then moved on to taking the lower blocks down by taking the back end to shape:


then turning the blocks around and taking the front end down to size (left both ends slightly thick to allow for a flattening pass later)

To mill the angled faces, used a 45 degree face on the ruler to set the parts in the vise,

and then milled the short side in,

and finished with the long side

Here are the parts so far, ready to fit the caps and bore the shaft hole:

And a shot of one up on the frame in the approximate spot it will sit:

Plenty done for one day, time for a cookie and some TV to fall asleep in front of...
« Last Edit: June 05, 2018, 05:34:55 PM by crueby »

Offline 10KPete

  • Full Member
  • ****
  • Posts: 1577
  • Nordland, WA, USA
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1008 on: March 24, 2017, 01:46:54 AM »
Wow, you do more in a day than I seem to do in a week or two! Beautiful....

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1155
  • The "Naki" New Zealand
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1009 on: March 24, 2017, 04:10:42 AM »
Hi Chris,

 :popcornsmall:

Still here still having a fun ride.

On the valve front sounds like you've got it sorted, one suggestion make the valve "nut" from rod not the usual square material.......with rod it will fit nice & rotate just that little bit to help with the rod angle changes.

Cheers Kerrin
Get excited and make something!

Offline MJM460

  • Full Member
  • ****
  • Posts: 957
  • Melbourne, Australia
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1010 on: March 24, 2017, 06:11:02 AM »
Hi Chris,

Your valve rod solution looks OK to me.  Especially with steamers valve nut idea.  I don't have experience using o- rings this way, but my reading suggests that many do.  I assume you will use a high temp viton so it stands the steam temperature.

Your great work is continuing in those bearing blocks.  I admire the way there never seems any impediments, you just get going.  You must work on some of those solutions in your sleep!

MJM460
The more I learn, the more I find that I still have to learn!

Offline paul gough

  • Full Member
  • ****
  • Posts: 405
  • Tropical Queensland, Australia
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1011 on: March 24, 2017, 07:01:35 AM »
Hi Chris, Regarding your vertical displacement in the rocker arm, it is small at 3 thousandths. I would expect you will find it might actually be a bit different due to machining and fitting tolerance variations once you get it assembled. The usual arrangement would be to locate the centreline of the valve spindle halfway in relation to the vertical displacement in the arc the rocker, this allows 1 1/2 thou each way rather than 3 in one direction. This sort of tolerance might be hard to achieve, so I might suggest doing the best you can with machining then packing the rocker arm support, the cylinder bracket support or even a slightly different thickness gasket under the valve chamber walls depending which is the easiest or most satisfactory from your point of view. This might entail assembly-test-measure-disassembly-packing-reassembly-recheck, but it was how things were done with older steam locos because there was always a bit of variation that had to be accommodated. The accuracy achieved was just as good as CNC, but it was got after machining with filing, scraping and sometimes packing, this is the 'individuality' of steam locomotives. From my days as a machine tool maintenance fitter, very small but necessary adjustments when no very thin metallic packing is available can be had using good quality paper, made from rag is best but not absolutely essential. It is a bit intuitive as you need to 'guess' the crush. Believe it or not I have seen roll your own cigarette papers used to get perfect alignments.

One thing with the valve gear on the Lombard. I would be most interested to know if the eccentrics are set to give negative lead in full gear, this was reasonably common with locomotives using Stephensons valve gear. Its lead increases as one 'notches up' which is useful at speed but better starting can be achieved with negative lead. In the model this may be irrelevant but it might have been a design consideration with the full size one, if you could find out and enquire by how much I would be very grateful. Regards, Paul Gough.

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1012 on: March 24, 2017, 12:29:50 PM »
Hi Chris,

 :popcornsmall:

Still here still having a fun ride.

On the valve front sounds like you've got it sorted, one suggestion make the valve "nut" from rod not the usual square material.......with rod it will fit nice & rotate just that little bit to help with the rod angle changes.

Cheers Kerrin
I had not thought of that, neat idea, drill and tap through the side of the rod, right? Clever!

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1013 on: March 24, 2017, 12:33:16 PM »
Hi Chris,

Your valve rod solution looks OK to me.  Especially with steamers valve nut idea.  I don't have experience using o- rings this way, but my reading suggests that many do.  I assume you will use a high temp viton so it stands the steam temperature.

Your great work is continuing in those bearing blocks.  I admire the way there never seems any impediments, you just get going.  You must work on some of those solutions in your sleep!

MJM460
Yes, been using the viton rings since the Shay build, Kozo used them on all the shafts, works out great, gives some tolerance in the seals.


And I do get my best ideas late at night, learned long ago to write them down or they are gone in the morning!

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1014 on: March 24, 2017, 12:38:40 PM »
Hi Chris, Regarding your vertical displacement in the rocker arm, it is small at 3 thousandths. I would expect you will find it might actually be a bit different due to machining and fitting tolerance variations once you get it assembled. The usual arrangement would be to locate the centreline of the valve spindle halfway in relation to the vertical displacement in the arc the rocker, this allows 1 1/2 thou each way rather than 3 in one direction. This sort of tolerance might be hard to achieve, so I might suggest doing the best you can with machining then packing the rocker arm support, the cylinder bracket support or even a slightly different thickness gasket under the valve chamber walls depending which is the easiest or most satisfactory from your point of view. This might entail assembly-test-measure-disassembly-packing-reassembly-recheck, but it was how things were done with older steam locos because there was always a bit of variation that had to be accommodated. The accuracy achieved was just as good as CNC, but it was got after machining with filing, scraping and sometimes packing, this is the 'individuality' of steam locomotives. From my days as a machine tool maintenance fitter, very small but necessary adjustments when no very thin metallic packing is available can be had using good quality paper, made from rag is best but not absolutely essential. It is a bit intuitive as you need to 'guess' the crush. Believe it or not I have seen roll your own cigarette papers used to get perfect alignments.

One thing with the valve gear on the Lombard. I would be most interested to know if the eccentrics are set to give negative lead in full gear, this was reasonably common with locomotives using Stephensons valve gear. Its lead increases as one 'notches up' which is useful at speed but better starting can be achieved with negative lead. In the model this may be irrelevant but it might have been a design consideration with the full size one, if you could find out and enquire by how much I would be very grateful. Regards, Paul Gough.
Good tips! I don't know about the lead, will see what I can find out. For the height adjustment, I have a selection of thin shim stock, and I have used paper and also foil too in the past. Whatever makes it fit!

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1015 on: March 24, 2017, 04:59:20 PM »
More work on the crankshaft bearing blocks, centered up the caps on the mill with an edge finder,

spot drilled

and drilled the clearance holes for the bolts:

then drilled a matching pattern of holes in the bottom blocks

and finished with the mounting holes in the bases

Here are the parts tapped and bolted up

and showing where they go on the engine beds

Next up will be to drill/bore the holes for the bearings, and make the bearings themselves.
« Last Edit: June 05, 2018, 05:35:14 PM by crueby »

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3776
  • Springfield, Tennessee. USA
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1016 on: March 24, 2017, 06:48:15 PM »
Really nice. If you stare at them long enough at this time on a Friday afternoon (beer thirty 8) they almost start to have "faces"  :lolb:. NS, Try it  :stir:

Eric

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1017 on: March 24, 2017, 07:21:29 PM »
Really nice. If you stare at them long enough at this time on a Friday afternoon (beer thirty 8) they almost start to have "faces"  :lolb: . NS, Try it  :stir:

Eric
Now thats disturbing... Cause they DO!  :stickpoke:


Glad I finished boring the bearing holes before seeing this, or I would have been waiting for the scream as the bit went in its ear!

Offline Don1966

  • Full Member
  • *****
  • Posts: 6059
  • Morgan City, LA (Along the Gulf Coast)
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1018 on: March 24, 2017, 08:53:07 PM »
Damn nice Dog, you just keep setting the scale bud and those bearing block are looking to cool. Those elfs are sure busy little fellows huh? :lolb:
Still following some great craftsmanship Dog!


Don  :popcorn:

Online crueby

  • Full Member
  • *****
  • Posts: 9635
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1019 on: March 24, 2017, 08:57:16 PM »
Damn nice Dog, you just keep setting the scale bud and those bearing block are looking to cool. Those elfs are sure busy little fellows huh? :lolb:
Still following some great craftsmanship Dog!


Don  :popcorn:
They sure are busy, I could sit and watch them make parts all day!   :Lol: