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3 1/2 inch small boilered TICH

Construction of TICH according to the words and music by LBSC

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stephen.13/11/2014 17:28:50
19 forum posts
12 photos

000_0092.jpg

stephen.13/11/2014 17:29:11
19 forum posts
12 photos

000_0093.jpg

Ryan Norton14/11/2014 06:55:47
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190 forum posts
774 photos

HI Stephen

I see what you are saying! I have the following drawings, which may be of help but I think it would be prudent to hear from some post Tich builders to see what they have done.

I would be inclined to use the dimensions from my drawings for my build as they are in the book and all as one unit.

 

return crank.jpgcombination leaver.jpg

 

These drawings are from the original 1950's Model engineer articles. I can confirm that they are also the same drawings that appear in the version of the book from the 1970's which I have.

Stephen, I think you can download the original Tich articles from John tom- www.john-tom.com

 

 

Edited By Ryan Norton on 14/11/2014 06:57:47

Edited By Ryan Norton on 14/11/2014 07:03:47

julian atkins14/11/2014 11:57:10
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1212 forum posts
353 photos

hi ryan,

i think you would be well advised to consider carefully the drawing uploaded by stephen. at some point the original dimensions have been re-drawn presumably to deal with excessive return crank throw and excessive lead. such errors are not uncommon in the designs of LBSC, martin evans, and don young. the revised drawings will give a slightly smaller lead, and the shorter return crank throw will avoid the valves overrunning when the die block in the expansion link is at top and bottom of the slot, and avoid the dieblock having to be in a partly 'notched-up' position to give the correct valve events.

i should add i havent built a TICH, but i have come across this problem on a number of well known 5"g designs.

it is very little extra work to make up a spare set of combination levers and return cranks to the revised drawings with dummy eccentric rods when trying out the gear and setting it - just dont pin the original return cranks if you fit them first but make a clamp arrangement, and dont finish the eccentric rods.

cheers,

julian

Edited By julian atkins on 14/11/2014 11:59:00

Edited By julian atkins on 14/11/2014 11:59:46

Weary14/11/2014 13:56:05
289 forum posts

I made my small-boiler Tich to the drawing dimensions as shown in Stephen's post and it runs fine.

BUT..... as I have not made fittings to the book dimensions I cannot give you a comparison. However I would echo Julian's comments above as it is well known that LBSC (knowingly) rounded many of his valve gear dimensions with a view to simplification for those constructors of the period who were using basic measuring tools and equipment.

Regards,

Phil

MK14/11/2014 16:53:08
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24 forum posts
20 photos

Great job Ryan :D Your'e getting there!

Do you have any drawings of the larger boiler version? I think there may be a few missing from ME 1950 and also did you use drawings when you made the brake axle?

Just worked on Tich today. Made the smokebox and smokebox door.

Good luck on your build ahead!

Cheers

MK14/11/2014 16:59:17
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24 forum posts
20 photos

The combination lever holes is just about 0.5mm further apart.

David Haynes14/11/2014 17:32:48
168 forum posts
26 photos

Hi all,

Do you know about the 3rd Tich boiler? A Belpaire which has a 9% larger grate than the large boiler, but not as simple a build as the other two.

Dave

MK14/11/2014 19:49:49
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24 forum posts
20 photos
Posted by David Haynes on 14/11/2014 17:32:48:

Hi all,

Do you know about the 3rd Tich boiler? A Belpaire which has a 9% larger grate than the large boiler, but not as simple a build as the other two.

Dave

It was in the Model Engineer 20 February 1958. There seem to be quite a lot of variations of TICH's boiler, but the small and large boiler being the easiest. I have only just seen one TICH boiler of the Belpaire type.

MK14/11/2014 19:51:54
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24 forum posts
20 photos

I think we should start a TICH discussing thread somewhere.

 

Edited By MK on 14/11/2014 19:52:34

stephen.14/11/2014 20:31:29
19 forum posts
12 photos

Hi Ryan

thank you for the link, looks to be a useful site, i think i am inclined to agree with Julian and copy as per the most recent drawings as they must have been changed for a reason.

Julian, thank you for your helpful advice, the combination lever has actually been lengthened by 8 thou rather than shortened could you please explain the reason for this? how would it effect the valve events? interesting that the smaller centers have been shortened by a thou or is this insignificant? unfortunatly i have already made it a while back but only bought the large drawings recently. only myself to blame!

many thanks

Stephen

julian atkins14/11/2014 20:49:34
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1212 forum posts
353 photos

hi stephen,

to simplify things somewhat the combination lever provides the lap and lead part of walschaerts valve gear, and so lengthening the distance between the bottom and middle holes or their proportions compared to the middle and top hole reduces the lead. the 8 thou difference is frankly immaterial and could easily be negated by the odd slight tolerance error on the valve lap or valve setting.

however the return crank throw alteration is more significant, but wont in any way affect performance, just wear on the valve gear. with the longer return crank to provide the correct cut off in full gear the die block wont be anywhere near the end of the expansion link slot and probably just halfway down from centre. altering the return crank length also alters the eccentric rod length.

cheers,

julian

David Haynes15/11/2014 00:13:07
168 forum posts
26 photos

Hi Stephen,

If you are able to look at the Christmas edition of EIM, besides reading about some lucky people who built a portable 5" track on a frozen lake and steamed on it,, Don Ashton has given a bit of a refresher on valve gear.

Also, Curly's Belpaire Tich is pictured in the 'Simple...' Tich construction book with outside Stephenson's valve gear.

Best wishes,

Dave

stephen.15/11/2014 09:09:40
19 forum posts
12 photos

Thank you Julian, that is most helpful, i have saved many of your posts in the past as they are always worth listening to.

Thank you Dave, i do not have access to E.I.M but will try to get hold of a copy, its all useful information!

Sorry Ryan, back to your build diary...

Many thanks

Stephen

Ryan Norton17/11/2014 07:35:36
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190 forum posts
774 photos

HI Guys

Thanks for all the great discussions. It is extremely useful!

I shall heed your words Julian and rather use the newer drawings for the return crank. Thank you for this advice.

Ryan Norton17/11/2014 07:41:41
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190 forum posts
774 photos

Here are some more photos of the machining of the valves:

v28.jpg

v27.jpg

v26.jpg

v25.jpg

Ryan Norton18/11/2014 13:41:21
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190 forum posts
774 photos

I am slowly milling my way through the valves. Last night I drilled the 3/16 holes in the sides of the two embryo slide valves and was well chuffed to find that all was well once done.

Always a good feelinglaugh

v29.jpg

v30.jpg

v31.jpg

v32.jpg

v33.jpg

v34.jpg

v35.jpg

v36.jpg

v37.jpg

julian atkins18/11/2014 18:24:57
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1212 forum posts
353 photos

hi ryan,

you are making a very good job of those valves!

going back to the revised return crank drawings, i forgot to add another advantage in that swing of the expansion link will be less and so with the shorter return crank the gear will be easier to change from forward to reverse.

cheers,

julian

Ryan Norton19/11/2014 05:18:55
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190 forum posts
774 photos

HI Julian

Thanks.

Thank you for the advice!

It is much appreciated!

Ryan Norton19/11/2014 05:55:21
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190 forum posts
774 photos

Julian

What are your thoughts on return cranks of the following nature?

small.jpg

Instead of squeezing them on, having a locking bolt?

Are there any disadvantages to this type of setup apart from the crank moving if it is not tightened properly?

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