Author Topic: Stuart 7A Build  (Read 948 times)

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Stuart 7A Build
« on: May 13, 2018, 08:57:34 AM »
Hi guys,

my first attempt at building a model steam engine; or any engine at all for that matter.
Package arrived all the way from UK to Melb, Aust in 5 days. TNT express certainly know the meaning of express!  :ThumbsUp:


I must admit to being a little disappointed after the original excitement had worn off. The plans were so faint I could hardly read many of the dimensions. The castings were pretty rough (certainly inferior to an old Stuart I had purchased second hand a few months ago.)   They will require a lot of hand finishing.



Also they seem slightly undersize;  to the point that there certainly is no room for errors. Measure 5 times, cut once will definitely b the order of the day here.
is time to make a start.  :cartwheel:

First up was to get the base sitting flat on the mill table. I did this by shimming one corner with an appropriate  feeler gauge. Then running a cutter over the appropriate surfaces to correct height.
Then I flipped it up side down and skimmed the base flat.

« Last Edit: May 13, 2018, 09:04:47 AM by warrenmaker »

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #1 on: May 13, 2018, 09:00:09 AM »
Then the bearing caps were machined and fitted. Sounds easy when u say it fast. But the bearing caps alone took me 4 hours....  :facepalm:

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #2 on: May 13, 2018, 09:02:10 AM »
I am waiting on the correct size drill for my reamer so I can drill and ream the bearings; so onto machining the standard.

Offline Chipswitheverything

  • Full Member
  • ****
  • Posts: 235
Re: Stuart 7A Build
« Reply #3 on: May 13, 2018, 10:20:30 AM »
Thanks for posting pictures of your build, looks like a very good start on what will be an attractive engine.  The trunk column held with the slotted clamps on the f'plate is a nice example of classic "Stuart Turner" vertical engine machining set up!    But I note what you have said about the rough castings and lack of "meat" on them, that's not good.   
  Dave

Offline jeff l

  • Full Member
  • ****
  • Posts: 162
Re: Stuart 7A Build
« Reply #4 on: May 13, 2018, 03:19:06 PM »
A good start to a fine engine .

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #5 on: May 16, 2018, 03:35:28 AM »
Hi guys, can any one help with a dimension please... it simply is not shown on the plan for the Stuart 7A. I can't figure out the overall length of the cylinder head.It should b shown on drawing #1 on the plans but not on mine.   :headscratch:

Any help would b appreciated ,
thanks in advance.   :help:

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #6 on: May 16, 2018, 03:56:30 AM »
ALL GOOD,, found it,,,  ;D

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #7 on: May 16, 2018, 04:25:12 AM »
Got a bit more done today,

bored the cylinder and faced off the valve ports

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 10998
  • Hampshire, england.
Re: Stuart 7A Build
« Reply #8 on: May 16, 2018, 06:25:53 AM »
ALL GOOD,, found it,,,  ;D

Stuarts are good at hiding dimensions on their drawings ::)

Jo
Usus est optimum magister

Offline Mcgyver

  • Full Member
  • ****
  • Posts: 91
  • Toronto
Re: Stuart 7A Build
« Reply #9 on: May 16, 2018, 02:33:29 PM »
yes, looking good.  Regarding the comment on rough castings perhaps undersized,  I'm curious where you bought the castings from.  I keep hearing tales of unscrupulous vendors use OEM castings as patterns....did they come from Stuart or could that be the issue?

Online Gas_mantle

  • Full Member
  • ****
  • Posts: 929
  • North Yorks - UK.
Re: Stuart 7A Build
« Reply #10 on: May 16, 2018, 02:45:01 PM »
Looking good Warren  :ThumbsUp:  I'm following along with interest as I'm attempting something similar.

I was surprised to see in your castings the box bed and soleplate are a single casting, I bought a casting kit for a 10v on ebay recently and mine is in 2 parts although it looks to be a recent kit.

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #11 on: May 17, 2018, 11:56:49 PM »
Turned the cylinder end caps today and all went smoothly so onto the valve chest.

Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #12 on: May 17, 2018, 11:59:15 PM »
Ever had one of those days when you you just shouldn't have gone into the work shop.

First I broke a $30 solid carbide end mill, and then this.....   :embarassed: :'(




Offline warrenmaker

  • Full Member
  • ****
  • Posts: 24
Re: Stuart 7A Build
« Reply #13 on: May 18, 2018, 12:01:42 AM »
Looking good Warren  :ThumbsUp:  I'm following along with interest as I'm attempting something similar.

I was surprised to see in your castings the box bed and soleplate are a single casting, I bought a casting kit for a 10v on ebay recently and mine is in 2 parts although it looks to be a recent kit.

Yes the castings came direct from Stuart. I also have a #4 part set of casting I picked up at a flea market. They are dated from 1977. They are FAR Superior to the #7 I have purchased for this build .

You can probably see in the pic above the casting for the valve chest has a lot of porosity up around where it broke.

Also you will notice when I drilled the through hole for the valve rod up into the dome it wandered off center slightly. Any tips on how to stop this happening. I may go and buy a new drill bit. MB that will help.
« Last Edit: May 18, 2018, 12:09:05 AM by warrenmaker »

Offline Jasonb

  • Full Member
  • *****
  • Posts: 5324
  • Surrey, UK
Re: Stuart 7A Build
« Reply #14 on: May 18, 2018, 07:20:54 AM »
Buy a tube of JBWeld from Ramon :Lol:

Best fix will be to mill the top edge flat and open the hole out to say 3/16" then make a dummy end bush with a 5/32" spigot that fits down the hole and drilled for the end of teh valve rod. These bushes are gland shaped and retained by two small screws so you can assemble and get it into a position where the rod moves freely hence the larger hole than spigot and then spot the hole positions for the screws. make the bush blind as it is not worth adding glands on such a small size part.

To avoid the problem next time make sure the inner face has been cleaned up so the drill starts on a flat surface and the use of a long series center drill will help a lot.