Help ! Kit 8 brake screw

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Help ! Kit 8 brake screw

Post  Rickster on Wed 29 Dec 2010, 10:13 am

Hi all,

I have hit upon a problem with my build when trying ed to fit yet the brake assembly to the tender.

On attempting to fit the brake screw to the brake lever, I can see a noticeable bend when viewed from the back of the tender. I noticed this as the application of the brake wheel was causing binding and upon investigation, the brake screw is actually bending away from the tender and gets progressively worse as the brake is wound on. (the bend gets sharper as the brake screw nut moves up the thread)

It applears to me there could be one of two issues - either the right hand side brake shaft that exits the tender is too long or the Brake bracket holding the brake screw to the tender is not thick enough. Either one will create a bend if not in alignment.

I noticed where the brake screw nut sits in the brake lever, it is being physically pulled off centre towards the tender, trying to compensate for the bend in the screw.

Question is - without the back axle I can't work out whether to take 3mm off the brake shaft. If I did this It concerns me the brake block wouldn't align with the brake rim on the right hand side wheel. Leaving me with the option to fit some kind of a spacer plate to increase the gap by 3mm.

Any help would be most welcome....


Thanks

Rick

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Re: Help ! Kit 8 brake screw

Post  Tim Watson on Wed 29 Dec 2010, 3:55 pm

Haven't got this far with my one yet, but is the offside brake bearing flange inside the tender? If not, it would give you the wrong offset. Didn't look a problem on the control model at Sandown Park when I played with it.

Tim

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Re: Help ! Kit 8 brake screw

Post  greystones on Thu 30 Dec 2010, 3:19 am

Hi Nick

Just assembled mine and found it to be perfect.

Only thing I had to do was file a bit off the oposite side carrier where the washers go to make the shaft free.

Apart from that it is as free as a bird.

I was amazed that the two bushes lined up perfectly for the shaft

Any one know what the countresunk hole is for which the top casting half covers. It would seem that it will all have to come off again if a screw goes in it.


Mike


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Hep!

Post  Rickster on Thu 30 Dec 2010, 5:31 am

Hi Tim,

yes the flange is definately on the inside of the tender on that side, so I can't see why it is out of alignment.

Rick


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kit 8 brake screw

Post  Tony King on Thu 30 Dec 2010, 7:14 am

I also have a problem with the brake screw rod being out of line. I also notice the brake shaft that passes through the tender appears short by a similar amount to the off set, indicating that the off side tender bearing thingy has not been machined to correct length, thus the brake lever is too far away from the side of the tender.
The bearing thingy is deffinately on the inside of the tender!! So I think we have a manufactureing problem here!
Regards,
Tony

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Kit 8- Graystones?

Post  Tony King on Thu 30 Dec 2010, 10:25 am

Hi Mike,
If you could find the time, would you please measure the distance from the face of the offside bearing flange to the tender side.
Mine is sitting at 33mm. Be interesting to see if yours is different!!
Many thanks, for all your interesting posts on this forum.
Tony

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Re: Help ! Kit 8 brake screw

Post  craig@STW on Thu 30 Dec 2010, 11:39 am

it would seem that some kits are going together and some are not so this does point to a manufacturing/tolerance issue with one of the parts.

unfortunately we cant check the remaining stock until we go back next week.

until then, any measurements that people can take will be helpful

craig

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Re: Help ! Kit 8 brake screw

Post  greystones on Thu 30 Dec 2010, 11:51 am

Hi Tony
I can confirm that the measurement of the offside bearing carrier of 33mm is the same on my engine.

One point to watch is the key on the near side for the brake shoe arm. It is too long. I had to cut about 3mm off to allow it to be recesed into the brake shoe arm. The washers will then butt up to the shaft and not the key. I think I am right in saying that if not it will push the offside of the shaft outward ..... ie the problem you have.

Let me know if this is the case with your problem

Mike

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Help! Brake screw

Post  Tony King on Fri 31 Dec 2010, 12:32 am

Hi Mike,
Thanks for your reply, interesting, it now looks like the fault moves to the brake arm.
The brake lever is right up against the offside bearing flange, but there is still a miss-alignment of around 6mm. i.e. the screw rod is being "bent " outwards away from the tender.
I wonder if the brake arm casting could be gently bent without breaking it?
Any others out there with this problem?
Any further suggestions?
Tony

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Re: Help ! Kit 8 brake screw

Post  greystones on Fri 31 Dec 2010, 1:14 am

Tony
Sounds as if the hole in the top mounting bracket ie the square one is not drilled parallel to the mounting face and the brake rod is running at an angle.

Mike

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Help brake rod screw

Post  Tony King on Fri 31 Dec 2010, 2:29 am

Hi Mike,
I think you have hit it on the head there, I have just placed a couple of washers under the lower fixings of the top bracket & all now works!!
Have then checked the hole in the top casting & it ain't parellel to the machined base, however I have a sneeking suspicsion it ain't meant to be!!
Could I ask another favour of you please? Would you measure the distance from tender side, to the centre of the screw shaft at the end of the brake lever where it goes through the brass nut. Mine is again 33mm ( give or take!!)
If yours is the same, then top square plate is the "culprit" with missaligned hole!!
Many thanks,
Tony

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Re: Help ! Kit 8 brake screw

Post  greystones on Fri 31 Dec 2010, 2:51 am

Hi Tony

We have a difference as the distance from the tender to the centre of the brass nut is 28.6mm. Not being funny but is the top square casting on the right way up !!! . Just to add the handbrake rod runs parallel to the tender body on mine at 28.6mm top and bottom of the rod. Have a look and see what the distance is from the flat face of the top mounting to the centre line of the hole, again mine is 28.6mm Hope this helps

Mike


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Brake Screw Problem

Post  Rickster on Fri 31 Dec 2010, 3:09 am

Thanks Greystones and Tony,

I've just been out to the workshop and turned the brake bracket on the side of the tender upside down i.e. 180 degrees and though it can't be fixed this way, it all aligns perfectly. Seems that some brake brackets have been machined the wrong way round.

cheers

Rick

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Help kit 8 screw

Post  Tony King on Fri 31 Dec 2010, 3:21 am

Hi Mike,
Thanks for quick responce.
Yep, the top square casting checks out same as yours, but the brake lever don't!! So, it's the "culprit!!
I wonder if this is a maliable iron casting? If it is, might be able to "encourage it" back to correct position!!??
I'd better speak to STW before I bung it on a 10 ton press!!
Many thanks again!!
(Definately had top square casting up the right way, might have big problems if I made too many errors like that!! )
Regards
Tony

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kit 8 brake screw

Post  Tony King on Fri 31 Dec 2010, 3:39 am

It has ocurred to me, that it might be easier to simply enlarge the hole through the top square casting!!
This would allow mechanism to fit together & may actually improve things because the brake lever end actually discribes a radius, which does put a bending strain on the screw rod at the extremities of its travel!!
If the hole was drilled to within, say, 3mm of the top of the casting, the rod would not "bind" & consentrcity of the shaft in the hole would not be lost!!
What do you guys think?
Tony

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Brake screw conundrum

Post  Rickster on Fri 31 Dec 2010, 3:45 am

Hi Tony,
I had the same thought as you, but think I will leave it to STW to provide a solution here. I still think there will be a certain amount of ''setting'' required for the brake bracket to get the optimum free play between brakes on and brakes off which will be difficult to determine until the the wheels are on and we can try it all out for real. I think I'll leave the brake bracket fairly loose until then, depending on STW's solution of course.

cheers

Rick

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Re: Help ! Kit 8 brake screw

Post  craig@STW on Fri 31 Dec 2010, 6:47 am

i will look into this first thing on Tuesday and see whats what, from what you guys have said it would seem some of the castings have come out less than perfect. i know we have hit some very hard spots in some other castings that have wiped out tooling completely so this could be a possible reason the holes have "wandered".

im not going to make any further suggestions until then at the risk of making myself look stupid Embarassed some of us are machine operators, not steam enthusiasts/designers Rolling Eyes Wink Laughing

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kit 8 brake screw- solved!

Post  Tony King on Mon 03 Jan 2011, 8:42 am

Hi All,
Today, I decided to simply open up the hole in the square top braket, from the bottom, with a 13mm (1/2") drill!! The size is not crittical, however, it must be stressed that if you take this course of action you must leave the last 6mm (1/4") at the top, untouched, to keep the screw shaft running true & not flapping about all over the place. I have now assembled all the bits & brake operation is now as free & positive as you like.............. Problem solved!!
The rest of kit 8 fitted together like a dream, with the usual superb results that one has come to expect from STW.
Thanks, particularly to Mike for measuring things, couldn't have done it without your help!!
Happy New Year everyone,
Regards
Tony

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Re: Help ! Kit 8 brake screw

Post  craig@STW on Tue 04 Jan 2011, 1:57 am

yes, the problem does seem to be with the brake bracket. i have checked all the stock and some of the holes do seem to have "wondered". they start in the right place but wonder off. some of these castings do seem to have some very hard spots.

we do have some good ones in stock and will be sorting out the problem ones by milling the hole out and fitting bushes in them.

if you are having problems then send your bracket (BS40830) back to us for replacement

Craig

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Re: Help ! Kit 8 brake screw

Post  craig@STW on Fri 07 Jan 2011, 5:35 am

just to let you all know, Steve has decided to modify the brackets using the method that was suggested by Tony...

Tony King wrote:
... simply open up the hole in the square top bracket, from the bottom, with a 13mm (1/2") drill!! The size is not critical, however, it must be stressed that if you take this course of action you must leave the last 6mm (1/4") at the top, untouched, to keep the screw shaft running true & not flapping about all over the place. I have now assembled all the bits & brake operation is now as free & positive as you like.............. Problem solved!!

he has gone with this method because, as tony said..


This would allow mechanism to fit together & may actually improve things because the brake lever end actually describes a radius, which does put a bending strain on the screw rod at the extremities of its travel!!

we have actually drilled ours out to 16mm. and as above left 6mm untouched. if you choose to do this yourself remember to go in from the bottom of the casting (as it sits on the tender).

if anyone is having trouble (or even if your not but just want to add the mod) return your bracket and we will send you a modified one. we have plenty in stock so you wont have to wait

Craig

PS: thanks Tony Cool

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Re: Help ! Kit 8 brake screw

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