Rob Roy coupling rods

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Rob Roy coupling rods

This topic has 14 replies, 8 voices, and was last updated 16 July 2022 at 19:36 by Rex Hanman.

Viewing 15 posts - 1 through 15 (of 15 total)

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15 July 2022 at 17:43 #605976
Dalboy
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@dalboy
Getting back to where I was with the coupling rods on the Rob Roy and ready for final machining one of the jobs is to make some bushes for them (Except the centre ones as I have made those) Now for the question I notice on the plans that the rear rods have bushes in them but the front do not show any, all it shows is a recess for the washer to hold it on with a 4BA screw.

Has anyone built the Rob Roy and did you add a bush in the front rod or leave it as steel on steel.
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15 July 2022 at 17:43 #2141
Dalboy
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@dalboy
15 July 2022 at 17:50 #605979
Saxalby
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@saxalby
Hi, My Rob Roy has bushes on all the rods.

Regards
15 July 2022 at 19:21 #605991
Dalboy
Participant
@dalboy
Posted by Saxalby on 15/07/2022 17:50:50:

Hi, My Rob Roy has bushes on all the rods.

Regards

Thank you I just thought it strange not to have them on all but the front two
15 July 2022 at 21:27 #606008
Rex Hanman
Participant
@rexhanman57403
I would have to check but I'm pretty sure that I bushed it! Crazy not to!

Out of interest I will have a look, but I'm away tomorrow. On Sunday it is entered into our club efficiency competition, I will try to look then.
16 July 2022 at 08:26 #606019
Nick Clarke 3
Participant
@nickclarke3
This is taken from the original magazine. The bushes are clearly on the drawing although it only says there are two of them, not three and the text does not add more except the drill sizes to get a running fit without reaming – which sounds a bit scary to me!
16 July 2022 at 09:07 #606022
MichaelR
Participant
@michaelr
Derek, This build log may be of interest Link lots of pictures of Rob Roy build it does show bushes in the coupling rods.

MichaelR
16 July 2022 at 09:07 #606023
Dalboy
Participant
@dalboy
Thank you Rex and Nick.

Nick it was the one on the left I was talking about as you can see the centre and rear(On the right) one clearly shows bushes.

I think I will drill and fit one on the front as well after comments here and on another forum, the reason in the book for drilling the front and rear for a slightly over size hole is to allow for uneven running on the track. The centre one however is reamed to the pin

Thank you MichaelR for the link I have looked through it but it does not really show if he added bushes to the front only shows the retaining washer which he made from brass or similar material

Edited By Derek Lane on 16/07/2022 09:22:59
16 July 2022 at 11:04 #606031
Robin King
Participant
@robinking15611
I've just had a quick read of the construction book – page 28 in the paperback edition – last 2 paras cover it.

After checking/adjusting the initial drilled hole positions on leading and trailing holes in the rods Martin describes drilling out to letter N, reaming 5/16" and fitting bushes 'as drawings'. The drawing doesn't clearly show a bush on the leading end but the text does read as though they are intended to be bushed. The idea of running steel on steel makes me shudder!
16 July 2022 at 12:02 #606037
Dalboy
Participant
@dalboy
Posted by Robin King on 16/07/2022 11:04:30:

I've just had a quick read of the construction book – page 28 in the paperback edition – last 2 paras cover it.

After checking/adjusting the initial drilled hole positions on leading and trailing holes in the rods Martin describes drilling out to letter N, reaming 5/16" and fitting bushes 'as drawings'. The drawing doesn't clearly show a bush on the leading end but the text does read as though they are intended to be bushed. The idea of running steel on steel makes me shudder!

And that is the problem either the book is incorrect or the plans yet they were done by the same person. And as the book stated

"and fitting bushes 'as drawings" and as the drawing don't show a bush in that hole in either the book or plans.

As it is I have decided to put them in regardless after reading all of the comments here and on another forum

Edited By Derek Lane on 16/07/2022 12:08:19
16 July 2022 at 12:04 #606038
Perko7
Participant
@perko7
Looking closely at the drawing, it seems the front hole is bushed, but the bush is housed in a 1/16" deep counterbore in the face of the rod, presumably so it clears the slide bars on the cylinder? In this case the bush would need to be 1/16" shorter than the other two as well.

You are right though that the text on the drawing implies only 2 bushes per rod.
16 July 2022 at 12:13 #606041
Dalboy
Participant
@dalboy
Posted by Perko7 on 16/07/2022 12:04:00:

Looking closely at the drawing, it seems the front hole is bushed, but the bush is housed in a 1/16" deep counterbore in the face of the rod, presumably so it clears the slide bars on the cylinder? In this case the bush would need to be 1/16" shorter than the other two as well.

You are right though that the text on the drawing implies only 2 bushes per rod.

If you examine the drawings the front one does not show the dotted line for a bush like the centre and rear one. Yes it is counterbored for a washer and countersunk screw so as to allow clearence for the connecting rod
16 July 2022 at 13:57 #606049
Dave Halford
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@davehalford22513
It's not like people don't forget stuff when pushed for deadlines whilst using a stencil typewriter.
16 July 2022 at 18:11 #606079
Nick Clarke 3
Participant
@nickclarke3
Posted by Dave Halford on 16/07/2022 13:57:58:

It's not like people don't forget stuff when pushed for deadlines whilst using a stencil typewriter.

Remember that at this time drawings were redrawn by the house draftsperson (at one stage the future Mrs Evans) introducing another opportunity for things to be missed.
16 July 2022 at 19:36 #606089
Rex Hanman
Participant
@rexhanman57403
It rather depends how you read the text on the drawing. To me it means 2 coupling rods, one off left hand and one off right hand, both with bronze bushes. I don't read it as meaning only 2 bushes. It would be less confusing if the term "2 OFF" didn't appear twice. Put the bushes in, we all know it makes sense!
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