Author Topic: Stuart Major Beam Engine  (Read 32645 times)

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #165 on: September 12, 2019, 10:12:01 PM »
More fiddly bits - part No 74 'Parallel Rod' two required.
The method is very similar to that used for making the two radius rods in post 155 et seq. However the small diameter of the rod - 5/32" at two points and 0.126" for the 5BA threaded end was a challenge working out how to hold the job and requiring great care and patience. I am at the halfway stage with the second rod.

The parallel rod started out as a 5/8" diameter steel bar. Two flats were milled on opposite sides of the end of the bar.

Parallel Rod by Andy, on Flickr

The marked out bar was held in a quick change boring bar holder, carefully set up at a right angle to the axis of the lathe and adjusted to the correct centre height. The hole was drilled and reamed  to 3/8".

Parallel Rod by Andy, on Flickr

A brass keeper was fitted to the eye to prevent distortion when supported by a live centre, rough turned then finished with a ball turning tool.

Parallel Rod by Andy, on Flickr
Parallel Rod by Andy, on Flickr

The brass keeper stayed in the eye whilst the rod was machined to a 'fish bellied' shape..

Parallel Rod by Andy, on Flickr

The 'eye' end of the rod had a stub used for support with a centre. The stub was sawn off and the eye filed smooth. The other end was turned down to 0.126" diameter to be threaded 5BA.

Parallel Rod by Andy, on Flickr

One finished parallel rod, one more to be made.

Parallel Rod by Andy, on Flickr

Fitted to the cross head.

Parallel Rod by Andy, on Flickr

Parallel Rod by Andy, on Flickr
Oops the bronze piston rod bush popped out.

Andy
« Last Edit: September 12, 2019, 10:23:09 PM by Chipmaster »

Offline Chipswitheverything

  • Full Member
  • ****
  • Posts: 307
Re: Stuart Major Beam Engine
« Reply #166 on: September 13, 2019, 02:40:35 PM »
Hi Andy, nice progress on the two "other" parallel motion rods. As all the parts of the parallel motion build up, the assemblage starts to look interesting.  On the parts that you have just shown, as on my engine, the steel bore runs on the steel bearing surface of the crosshead.  Not that great a design, I drilled an oil hole in the top of the oval boss so it could be lubricated a bit better. Don't suppose any of these models run enough for the matter to cause a problem...     Dave

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #167 on: September 14, 2019, 09:00:50 PM »
Thanks Dave, I finished the second Parallel Rod this afternoon. The design is indeed odd running steel on steel when a plain bronze bush could be fitted in the eye of the rod. As you said most Stuart Majors wouldn't be run for long periods and I reckon the bearing is lightly loaded and not much movement.
Andy

S Major 0645 by Andy, on Flickr

Both Parallel Motion Rods fitted to the cross head,
S Major 0644 by Andy, on Flickr

S Major 0643 by Andy, on Flickr

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #168 on: September 18, 2019, 10:08:59 PM »
Started work on the Parallel Motion Straps, part number 70 - four required.

Copied from the plans.
Part 70 Parallel Motion Strap (copied from plans): Four required. by Andy, on Flickr

Picture of a Stuart Major under construction exhibited on the Stuart stand at the Bristol Model Engineering Show 2014. The four straps can be seen in this picture.

Parallel motion straps by Andy, on Flickr

Job partially marked out.

Parallel Motion Strap by Andy, on Flickr

I considered making them  bending steel strip but as I couldn't obtain the exact imperial size required I used 3/4 x 1/4 mild steel and milled that to shape.

A 7/16" hole was drilled then the slot was milled using a 3/16" diameter slot drill which was a slow process. i left a gap or bridging in the end to strengthen the legs during subsequent procedures.

Parallel Motion Strap by Andy, on Flickr

I decided to speed up the process by drilling two 7/16" holes  then I would use a 3/8" slot drill to mill out the metal between the holes.

Parallel Motion Strap by Andy, on Flickr

The embryonic strap was marked out to have  3/32" wide slots in where gibs and cotters (wedges) will be used to retain bearings.

Parallel Motion Strap by Andy, on Flickr

Milling the slot slowly backwards and forwards deepening the cut by 0.010" each pass.

Parallel Motion Strap by Andy, on Flickr

Of course the slot drill left a radiused end to the slot.

Parallel Motion Strap by Andy, on Flickr

The ends of the slots were squared by using a needle file.

Parallel Motion strap by Andy, on Flickr

Another strap under construction.

Parallel Motion Straps by Andy, on Flickr

To be continued.....

Andy

I hope I live long enough to finish this!





« Last Edit: September 19, 2019, 02:36:08 PM by Chipmaster »

Offline Chipswitheverything

  • Full Member
  • ****
  • Posts: 307
Re: Stuart Major Beam Engine
« Reply #169 on: September 19, 2019, 01:29:01 PM »
Andy, the problem is not so much living long enough ,  (I'm sure that you will ) , but actually retaining the will to live as this lot proceeds!
  Anyway I see that you have tackled the slots by the "proper" method and not by the eye deceiving naughty method that I used!  Though it did give very crisp slots...    The external shape as per the drawing is worth the trouble, with the offset centre at the top of the "U" and the thinning of the sides, looks nice..    Dave

Online Alyn Foundry

  • Full Member
  • ****
  • Posts: 867
  • North Wales, Great Britain.
Re: Stuart Major Beam Engine
« Reply #170 on: September 19, 2019, 01:46:14 PM »
Hi Andy.

Well.... I was going to suggest a " square push broach " but crikey, have you seen the price? I have one only at a 1/4" square, inherited at some point in time.

The other option is " slotting " but my slotting head is so heavy I can't lift it anymore. That particular tool made me a fortune when I was making parts for the preservation movement 3 decades ago.

Cheers Graham.

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12779
  • Hampshire, england.
Re: Stuart Major Beam Engine
« Reply #171 on: September 19, 2019, 04:01:02 PM »
I use a tee slot cutter on either side then finish with a ground down needle file  :-X

Jo
Enjoyment is more important than achievement.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #172 on: September 19, 2019, 09:46:35 PM »
Oh well Dave you have lived to tell the tale. I didn't feel the urge to employ your 'eye deceiving naughty method' because I have a few 3/32 slot drills in stock and some new Vallorbe needle files that are excellent. I didn't realise you had also used your cunning naughty method on your straps. I used it for the connecting rod - Reply No 80.

Hi Jo, I haven't seen tee slot cutters small enough for these slots, well done with your Chuk by the way.

Hi Graham, I would be afraid of breaking an expensive broach on this job. However, is such a broach available that would form these 3/32" x 11/32" slots?

I made progress with two more straps today and still haven't broken a 3/32 slot drill..............

S Major 0661 (2) by Andy, on Flickr

I'll do the needle filing job squaring the ends of the slots on Sunday when rain is forecast. There are still a few more operations required to complete these straps.

Andy

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6742
  • Surrey, UK
Re: Stuart Major Beam Engine
« Reply #173 on: September 20, 2019, 06:51:19 AM »
Woodruff cutters would do the 3/32 but like you I have not seen tee slot that small.

Don't make too much progress you will be wanting more drawings!

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12779
  • Hampshire, england.
Re: Stuart Major Beam Engine
« Reply #174 on: September 20, 2019, 07:45:31 AM »
Hi Jo, I haven't seen tee slot cutters small enough for these slots, well done with your Chuk by the way.

I picked up some 1.6mm wide but for the recent engines I made my own from Silver Steel and hardened them and they worked well  :)

Thanks for CHUK 2, we never saw/heard more on those CHUK 1 castings  :(

Jo
Enjoyment is more important than achievement.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #175 on: September 20, 2019, 09:49:13 AM »
Good morning Jason, I havenít any experience with Woodruff cutters. After reading your post I found various 3/32Ē Woodruff cutters for sale so perhaps Iíll try one next time.

How are the rest of the Allman plans? I havenít had enough time to get on with my Allman and the other sets of castings stored in my workshop.

The stationary engine club that Iíve been a member of for 32 years is having a memberís only rally this weekend. I sold off my collection of stationary engines so Iím going to take as many model i/c engines as possible tomorrow. Iíve been cleaning and polishing them since yesterday. It will be good to take the Retlas, Economy, Gardner O Type and RLE engines out and show them running.

Itís the Winterbourne House, University of Birmingham annual toy / model steam gathering next Saturday 28/9. Iíll be spending even more time cleaning and polishing steam and hot air engines to exhibit there.

https://www.winterbourne.org.uk/whats-on/toy-steam-and-traditional-hobbies-day/

Morning Jo, yes I can imagine that Woodruff or your tee slot cutters would be well suited to cutting these slots in these straps that are only 5/32Ē thick.

Andy
« Last Edit: September 20, 2019, 11:19:58 AM by Chipmaster »

Offline Johnmcc69

  • Full Member
  • ****
  • Posts: 520
  • Erie Pa., USA
Re: Stuart Major Beam Engine
« Reply #176 on: September 20, 2019, 06:43:07 PM »
Nice job on those straps Andy!
 Hoping to see pic's of your engine display next weekend.....

 John

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #177 on: September 20, 2019, 08:09:01 PM »
Hi John, thanks for the encouragement. I have a way to go with those straps. I think iíll have to work on the finish if theyíre to be acceptable.
Iíll take pictures of the Winterbourne event for MEM.

Andy

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 617
Re: Stuart Major Beam Engine
« Reply #178 on: October 25, 2019, 08:47:08 PM »
Plodding on with the parallel motion straps.

I cut the four straps off the parent bar then milled each edge to form a step as per the plan.

S Major 0661 by Andy, on Flickr

S Major 0662 by Andy, on Flickr

Then machined and hardened two 11/16" od bushes with a 7/16" bore to act as filing buttons, a 7/16" bolt put the bushes in just the right place for grinding and filing the round ends.

S Major 0663 by Andy, on Flickr
S Major 0664 by Andy, on Flickr

After sawing away the keeper between the ends of the strap they needed tidying up.

S Major 0665 by Andy, on Flickr

Here are the four straps but they still need much more work to make them presentable.

S Major 0667 by Andy, on Flickr

Andy

Offline steam guy willy

  • Full Member
  • ****
  • Posts: 2248
Re: Stuart Major Beam Engine
« Reply #179 on: October 25, 2019, 10:03:36 PM »
Hi , interesting work on the straps.. and working from accurate drawings is a good way to go ...on my engine as it is a 1/18th scale model I scale the drawing down . But then have to adjust the dimensions to be able to use standard drills and milling cutters etc. What I do actually is just use the hole centres and go from there !!..the Bressingham engine uses the same type of rods as yours but they use brass inserts with adjusting screws/bolts to take up the wear..here is a photo of them..There is also an extra part that locks the cotter in place to stop it moving...real belt and braces  on the original. it is small details like these that make all these prototypes so interesting ,and challenging to make !! I have just looked at the drawings of the motion rods and have noticed that the holes are spherical ( a 1/16th offset of the radii )rather than round and so perhaps a split bush could have been used with the small bolts to adjust for wear..??

Willy
« Last Edit: October 25, 2019, 10:15:00 PM by steam guy willy »