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Post by peterdebeus on Jul 7, 2013 21:49:44 GMT
Hi John, Im sure my compressor wont do the job for longer than just a few seconds, its a small 25L ell cheapo compressor! But is was just a small test to see what happens, and there was so much air comming out of the chimney that i dindt do any more to try it. I think the friction isnt realy the problem, it runs quite light now, i can push it forward with one finger and the wheels turn quite smooth.... also i am not sure if the valve timing was already set or not, but first im going to make sure the pistons and valves are ok, and after that i will have a look at the setting. When you open the regulator it realy sounds like there is nothing between the regulator and the chimney, its just blows like its an open pipe! (same sound when you open the blower) can you please explain me more about what is wrong with the motionwork? Thanks for all the advise  |
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pondok
Part of the e-furniture
My 5" gauge SAR class 15F
Posts: 359
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Post by pondok on Jul 8, 2013 7:19:04 GMT
Hi Peter, as John says, suitable solid push-fit PTFE rings in your existing bobbins, exactly as in John's photo, will almost certainly solve the blow-past and totally transform your loco. If your bobbins are in one piece, you can just as easily slit the PTFE rings with a thin craft knife and push them over the bobbin into the groove. cheers, andy
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Post by peterdebeus on Jul 8, 2013 10:19:55 GMT
Andy, Thanks a lot for your answer. The bobbins are fitted with plates on the outside that lock the rings so they are easy to replace. I will check the roundness of the cylinders and hone (not sure if thats the right word) the cylinders, so the surface is smooth and exactly round. I am a car machanic so pistons and cylinders are the way to go for me Then i will see if somebody can make some PFTE rings for me (i dont have a lathe myself). Would love to replace also the steel piston ring to PFTE, think this saves a lot of friction? And when its wears out (i think it wont go that fast) its easy to replace and the cylinders will last for ever... Btw you have a lovely engine! thumbs up! Peter |
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Post by ettingtonliam on Jul 8, 2013 15:36:27 GMT
Umm, when the tight spot disappeared, it wasn't because something jamming the valve gear gave way, and now the valves are set in a position giving a straight passage to exhaust? Its just that the pistons and valves would have to be really bad to blow straight through as you describe, with no attempt at the engine running.
Just a thought.
Richard
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uuu
Elder Statesman
your message here...
Posts: 2,861
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Post by uuu on Jul 8, 2013 15:59:24 GMT
Would love to replace also the steel piston ring to PFTE, think this saves a lot of friction? And when its wears out (i think it wont go that fast) its easy to replace and the cylinders will last for ever... Peter The piston ring in the picture looks like a realy nice cast iron one. I wouldn't rush to replace it. |
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Post by peterdebeus on Jul 8, 2013 16:14:05 GMT
Hi Richard!
I have realy no idea if the valve timing was actualy set or it was just put together and nothing done.
It Was only a small test to see if something happend when opening the regulator, it runs free so the risk that anything would damage.
And i thought its quite strange that the air comes out like that because they have to seal the most of it.
i will try to mesure the diameter of the valve and the cylinder to see how much space there is in there
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Post by peterdebeus on Jul 9, 2013 17:37:19 GMT
it looks like somebody made a mistake with mesuring and making the valve rings.
the inside diameter of the cylinder 24.01 mm
The outside diameter of the valve rings (uncompressed) 24.08
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Post by peterdebeus on Jul 21, 2013 7:45:38 GMT
can somebody tell me how tight the PFTE seals need to be inside the cylinder so they dont get stuck when they get warm? Thanks |
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Post by Deleted on Jul 21, 2013 8:12:57 GMT
Hi Peter
I made mine so that the assembled valve can be pushed easily backwards and forwards with minimal friction. I also left a little gap between the inside of the PTFE ring and the metal bobbin, so that when the PTFE can't expand outwards any further it can deform inwards. I think this helps to give a tight seal when running without excessive friction.
Kind regards
John
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Post by Deleted on Jul 21, 2013 9:46:15 GMT
Hi Pete
Same as jj here when I did mine... still not been steam tested but worked in boiling water so should be ok.. will know one way or another very soon....I did do a little research first and hopefully allowed enough of a gap for when in steam, iirc PTFE expands about 16x more than steel if that's of any help.
regards
Pete
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Post by peterdebeus on Jul 22, 2013 13:39:58 GMT
Thanks for your help, i will make solid PFTE rings and will do some testing to see how much they expand. Last week i was at a club day, and somebody told me he makes PFTE springs combined with a o-Ring. He made some steam water pumps and few locomotives and told me that its works perfect! Think it might be interesting to see, for me its to difficult to make i guess. Attachments:
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Post by peterdebeus on Jul 22, 2013 14:11:19 GMT
ahhhh im getting sick of those check valves leaking all the time, (was trying to test my injectors with new pipework).
can somebody tell me how to solve this? i already ordered new stainless balls, tapped them with a center, and put
new bals in again. but it keeps leaking.... are the modelworks valves just bad quality and should i replace them
for some proper items, or is there a way to solve this problem?
Sometimes i see nitrile bals? are they any better?
Peter
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leliev
Seasoned Member
Posts: 114
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Post by leliev on Jul 23, 2013 6:15:44 GMT
What happens when you cool the checkvalves with water?
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Post by peterdebeus on Jul 23, 2013 6:55:24 GMT
I have tested them with steam pressure, and with the compressor (cold) makes no difference....
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leliev
Seasoned Member
Posts: 114
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Post by leliev on Jul 23, 2013 11:10:56 GMT
I suppose the balls don't seat properly than. Maybe another punch with a hammer on a new ss ball to re-seat it and afterwards againa new ball.
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Post by peterdebeus on Jul 23, 2013 12:26:35 GMT
i think so, but this was already done few times, they do seal quite ok, but they keep dripping a bit... going to try nitrile bals |
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Post by Deleted on Jul 23, 2013 12:39:29 GMT
Hi Peter
considering the problems you've been having and the cost of these items i think I would replace for new... perhaps the seats of the current clacks are too badly damaged.. cut your losses and go for good new clacks Pete..
Pete
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Post by peterdebeus on Jul 23, 2013 14:51:30 GMT
Pete, where would be the best place to buy some quality items if i want them?
Are they ok from maidstone engineering?
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Post by Deleted on Jul 23, 2013 15:26:49 GMT
I have bought clacks from both Maidstone and steam fittings.co.. both seem to work well but to be honest they have had little use to date, perhaps someone will know which are the best available. Perhaps the best would be those made personally but for the cost and ease the clacks from the two companies mentioned above should be fine imho..
Pete
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Post by peterdebeus on Jul 24, 2013 11:19:57 GMT
Ok thanks Pete! i have ordered nitrile balls now, see if this is off any help, and just interested to see if they are any good.
think if the seating isnt 100% perfect, the nitrile will seal it off completely, but we will see!
If not i will order new items!
Also ordered a mesurement tool to mesure the exact inside diamter of the valve liners.
Also realy usable for mesuring cylinders of my '73 Kreidler 50cc racing motorcycle
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