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Brian's 1" Minnie Traction Engine

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henryb01/05/2020 09:22:57
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Posted by JasonB on 01/05/2020 07:37:01:

Henry, it will be OK to do as you say making them from steel or brass and then fitting a bronze bush or you could make a steel plate with oversize hole matching the spigot size that locates in the hornplate and silver solder a bronze "teardrop" shape to it with an integral spigot that locates in the plates hole . Then treat it as a casting to bore bearing and drill other holes

minnie bearing.jpg

Thank you very much for the reply.

Yes that is another idea. i think i will just sleeve it though.

Ron Laden01/05/2020 12:40:37
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1916 forum posts
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Henry, have you considered one piece cast iron bearings, thats what I am going with for all the bearings in my electric version. C/I is reasonably cheap, machines very well and as I understand it a good bearing material which I would have thought fine for a slow moving vehicle such as a traction engine.

A picture below of a test bearing I machined for the main axle.

Sorry to intrude into your thread Brian, your Minnie looks excellent by the way very nice indeed.

dsc06677.jpg

henryb01/05/2020 13:06:19
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Hello Ron. Thanks for the reply.

I was thinking about cast iron but i ordered some steel square this morning.

Your cast iron one looks good though.

I hope mine comes out as nice as brians.

Brian Abbott24/05/2020 23:17:25
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448 forum posts
82 photos

Hello all.

I am after some material to make the brake band,

Drawing calls for 5/16" wide x 0.015" thick, some sort of spring steel.

Does anyone know a supplier for this material?

derek blake25/05/2020 07:27:00
556 forum posts
140 photos

You could try eBay and buy an old clock spring? That’s what I did for the Allchin.

JasonB25/05/2020 07:32:01
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I got mine from Reeves, they do it annealed, probably have to come up to 24g as they don't seem to have the width in 28g now.

Brian Abbott25/05/2020 20:59:56
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448 forum posts
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Thanks Both,

I just dropped Reeves an email.

peter hobbs 229/05/2020 10:46:26
3 forum posts

hi

has anyone experienced firing problems with Minnie

fire keeps going out ,also on subject of the brake band I used 15 thou steel shim it seem to work well

cheers

pete

Brian Abbott31/05/2020 23:01:55
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448 forum posts
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Hello.

What do you think i should use for the brake blocks, some seem to turn from a solid block, the book suggests ply wood, can you remember what you did Jason?

Hi Peter, not got that far but a friend of mine has one which he fires without problems.

Thanks.

peter hobbs 201/06/2020 12:39:46
3 forum posts

hi

I have been experimenting over the weekend and found the smaller the coal the better but I will keep trying I managed to get steam up to find pump wasn't working against boiler pressure so I got another problem to solve all good fun as they say. when I did my brake blocks I used 3 mm thick ply wood and steamed a suitable length until it was supple enough to pull it round the brake drum clamp it until it was dry and that did the job

I steamed it in our vegetable steamer

cheers

pete

JasonB01/06/2020 13:32:21
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Brian, I laminated mine but will need to look to see if I used thin (1.5mm) aero ply or individual layers.

Peter, some users find lump wood charcoal works well, start with some that has soaked in paraffin then as that burns replace with dry. Any small engine like this needs almost constant attention to the fire unless running on gas or meths.

peter hobbs 201/06/2020 13:40:08
3 forum posts

i will have to try lump wood charcoal and see how I get on

I have thought about gas firing its much cleaner but its where to put gas tank

thanks

pete

Brian Abbott18/06/2020 12:42:18
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448 forum posts
82 photos

Hello All

I am having a problem with a bouncing link assembly when in reverse.

Thought a video might explain it better than i can, just hope it works.

Any help would really be appreciated.

Thanks

Link Arm

Edited By Brian Abbott on 18/06/2020 13:04:42

Dan Jones18/06/2020 13:19:31
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78 forum posts
316 photos

Brian,

It looks like you’re holding it up too high or there isn’t enough clearance between the bottom of the radius link and the die block. You might find that when you hook it up to the reversing lever it’ll hold itself in place and allow you to set your notches/time it all properly.

It all looks good apart for that, good work!

Cheers,

Dan

Brian Abbott18/06/2020 14:08:44
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448 forum posts
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Thanks Dan.

You've just hit the nail on the head, don’t know why i didn’t see it myself.

As explained in the book, leave a little room for the slide block to move.

Just need need to check the valve travel.

Update!

Much better but still happening, problem is i don’t think i have enough through to open the valve correctly.

Never kind, keep looking

 

 

Edited By Brian Abbott on 18/06/2020 14:20:41

Paul Kemp18/06/2020 23:11:23
477 forum posts
18 photos

Brian,

Are you sure your eccentric rods are exactly the same length? Easy way to check is stand the strap half and rod on a surface plate with the rods vertical and try passing a pin (drill shank even of the right size) through both clevis's. If they are different lengths it can play havoc with valve events in general. I don't have any experience of Minnie and looking at the video it's hard to judge but the crank centre line seems markedly higher than the valve spindle centre line? Might be worth rechecking everything is to drawing such as distance from crank to centre of weigh shaft, throw of the weighshaft arm etc. It's not unusual with Stephenson's gear to have some kick through the reach rod to the reverser but yours does sound a little excessive. Jason B is probably best qualified to comment having built one.

Paul.

Brian Abbott18/06/2020 23:25:54
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448 forum posts
82 photos

Thanks Paul.

I have re-read the book tonight, and he does clearly say that this arrangement suffers from "link slip" and to leave a little free space in the link slot beyond the die block ( his words ).

As suggested by Dan I have tried clamping the reach rod with a couple of mm clearance in the link slot and it does seem ok (ish) so I think I need to finish all the reverse lever assembly and set everything up properly.

I am fairly sure everything is made correctly, I know when I made the eccentric rods I did take care, but costs nothing to check these things.

Thanks for the advice.

Paul Kemp18/06/2020 23:40:58
477 forum posts
18 photos

Brian,

No worries, these snags can sometimes be a b*****r to find. In general TE valve gear is usually a fairly inefficient compromise, the road engine boys never really seemed to catch up with their rail brethren when it came to valve gear! Wallis and Fowler probably came closest.

Paul.

JasonB19/06/2020 06:59:24
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Your finger on the far side holding the arm is moving which is allowing the lifting links to move up and down, once reverser is in it's notch that can't happen, Try clamping it solid while you turn the engine over.

Also not quite low enough to get full forward and too high in reverse.

Edited By JasonB on 19/06/2020 07:01:11

Edited By JasonB on 19/06/2020 07:04:19

Brian Abbott19/06/2020 16:36:11
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448 forum posts
82 photos

Thanks all for your help and advice.

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