Kerr Stuart Skylark build

[Greg Elmassian]

Rik, are all the parts on a resin printer? it appears so...

PhilP: was your "kit" printed on a filament printer or a resin printer, normally a world of difference in finish...

Greg

 

[ge_rik]

Nope, just a normal filament printer. I'm using PETG rather than PLA for this build though

Rik

 

[ge_rik]

Fitted the outside frames and given her a test run to make sure the frames don't bind. Need to ass a few more details and then give her a paint job - bit she seems to run and to my mind look OK

Rik

 

[ge_rik]

OK. Although she ran OK, I wasn't entirely happy with the way she looked. The body was riding too high on the motor block and there was a distinct rake to the boiler - which was rising up at the front.

So, a fair bit of hacking about with the razor saw to both the body and the motor block and the body is now 7.5mm lower than before. Also, 2mm hacked off the smokebox mounting and the boiler looks more or less horizontal.

Still a fair bit to do - but I'm happier with the way she now looks.



Rik

PS - I had a comment on Youtube from one of the guys who is building a full size replica of the original loco saying he'd love to see my model for real when it's finished ...... no pressure then!

 

[Hal Farsed]

Brilliant piece of work!

 

[Greg Elmassian]

In my opinion, you got an exceptional finish for a filament printer. Looking good! ( I do see that you did some sanding and/or filling)

Greg

 

[musket the dog]

Looks fantastic Rik! I can't wait to see it in it's final form I'm very impressed/jealous by how quickly you've taken to coaxing such great results out of your printer.

 

[dunnyrail]

OK. Although she ran OK, I wasn't entirely happy with the way she looked. The body was riding too high on the motor block and there was a distinct rake to the boiler - which was rising up at the front.

So, a fair bit of hacking about with the razor saw to both the body and the motor block and the body is now 7.5mm lower than before. Also, 2mm hacked off the smokebox mounting and the boiler looks more or less horizontal.

Still a fair bit to do - but I'm happier with the way she now looks.

View attachment 291195View attachment 291196View attachment 291197

Rik

PS - I had a comment on Youtube from one of the guys who is building a full size replica of the original loco saying he'd love to see my model for real when it's finished ...... no pressure then!

Nice job as ever, lowering the body as you have makes things look much better in the pony truck area.

 

[ge_rik]

Thanks chaps.

In my opinion, you got an exceptional finish for a filament printer. Looking good! ( I do see that you did some sanding and/or filling)

Greg

I use a setting in Cura (my slicer program) called 'Ironing' which gives a very smooth final layer. I find PETG needs more work than PLA to get a ridge-free final layer though - hence the filling and sanding (you may spot a few diagonal ridges on some of the surfaces)

Looks fantastic Rik! I can't wait to see it in it's final form I'm very impressed/jealous by how quickly you've taken to coaxing such great results out of your printer.

It's taken a while, but slowly getting there (see above).

Nice job as ever, lowering the body as you have makes things look much better in the pony truck area.

Quite so. It just didn't look right - especially with that large gap under the cab. It took a bit of head-scratching but in the end I figured how I could lower the body. The problem was that the driving wheels are really too large and so if you look really closely you can see the flanges do appear unprototypically above the top of the running plate. The outside frames help to disguise this. Thinking about it, I could use a small wheelbase USAt motor bogie (with extended axles) if I could track down a seller. However, the bonus of the Lyn block is I get the motion as well - though I still have to decide if my version will have valve gear - either Walschaerts (as per the actual locos) or Joy (as per the proposed locos).

Rik

 

[ge_rik]

Now more or less finished, I decided to see how she performed with some stock. Not entirely happy with the sound - I'm using the Lyn's built-in chuff cam. I might need to do a bit more experimenting with the settings. But she seems to run OK.

Rik

 

[Greg Elmassian]

I did not hear any anomalies from the chuff cam (missing or double beats), I might have heard one early in the video, but that is a maybe.

So what is the issue with the chuff cam? Does the dwell affect the chuff sound?

Greg

 

[ge_rik]

I did not hear any anomalies from the chuff cam (missing or double beats), I might have heard one early in the video, but that is a maybe.

So what is the issue with the chuff cam? Does the dwell affect the chuff sound?

Greg

Hi Greg
Not sure what you mean by "dwell"

I can't fault the synch when it's running, but the issue for me is the start-up and deceleration. If you compare the cruising to a stop and the pulling away on this video with the Kerr Stuart video I'm sure you will see what I mean. The chuff cam gives a far more abrupt start and finish than the subtleties of the Black Hawthorn's electronic regulated version.

Rik

 

[JimmyB]

Hi Greg
Not sure what you mean by "dwell"

I can't fault the synch when it's running, but the issue for me is the start-up and deceleration. If you compare the cruising to a stop and the pulling away on this video with the Kerr Stuart video I'm sure you will see what I mean. The chuff cam gives a far more abrupt start and finish than the subtleties of the Black Hawthorn's electronic regulated version.

Rik

Dwell is part of the cam motion, but here is a link that can explain it better than I can

Dwell mechanism - Wikipedia

en.wikipedia.org

 

[ge_rik]

So, I take it the "dwell" is the amount of time a cam follower is stationary? So the dwell could be the time the contacts are making contact but it could also be the time in between when they aren't.

I'm not really sure how the soundcard handles the cam input, but I think the cam just triggers the chuff sound and the length of the sound is handled by the card rather than the cam.

Anyhow, as mentioned above, the problem for me is when the loco starts up and coasts to a halt which is a bit abrupt to my mind. I've not had a chance to play around with all the settings yet, so I might be able to improve the coasting to a stop - but I'm not sure I can do anything about the start-up as the card can only sense when the cam contacts are making contact - by which time the loco is already in motion.

Rik

 

[JimmyB]

I'm not really sure how the soundcard handles the cam input, but I think the cam just triggers the chuff sound and the length of the sound is handled by the card rather than the cam.

I have MLS using a Bachmann cam for the chuff on my 10-wheeler, and it sounds okay to me, as does yours (though my hearing isn't the best ) and I agree the cam triggers the chuff, and once triggered the sound is handle by the card.

Anyhow, as mentioned above, the problem for me is when the loco starts up and coasts to a halt which is a bit abrupt to my mind. I've not had a chance to play around with all the settings yet, so I might be able to improve the coasting to a stop - but I'm not sure I can do anything about the start-up as the card can only sense when the cam contacts are making contact - by which time the loco is already in motion.

Wouldn't the inertia handle that, which I believe can be managed by the Rx 65, or in my case it is managed via my Tx22X Tx.

 

[PhilP]

Rik,
You might be able to improve the starting, a little, by tweaking the starting voltage setting?

It will also depend on which loco 'voice' you have chosen.

I don't think it is one of the latest cards in that loco?

PhilP

 

[ge_rik]

Rik,
You might be able to improve the starting, a little, by tweaking the starting voltage setting?

It will also depend on which loco 'voice' you have chosen.

I don't think it is one of the latest cards in that loco?

PhilP

Hi Phil
It's the most recent card - bought last week.

As it's using the cam for the chuffs, it doesn't sense the motor voltage so nothing there to tweak. The chuffs start the moment the first input pulse is detected from the cam so the loco could move forward a quarter turn of the driving wheels before the first chuff comes. Alternatively, if the loco has stopped just before the next contact is made on the chuff cam, it could start immediately. I could always trigger the safety valve to blow before moving off - this will mask any lag between movng off and the first chuff.

I've not yet figured how adjusting the sensitivity affects the coasting setting when using the cam. On the default setting (2), it was giving me the coasting sound continuously so I had to up the sensitivity to 4, which gives a good chuff but it now doesn't seem to sense deceleration. I might try changing the sensitivity to 3 to see if that works.

I might drop Peter a PM to ask about the sensitivity settings when using a cam. All new territory for me.

Rik

 

[JimmyB]

Hi Phil
It's the most recent card - bought last week.

As it's using the cam for the chuffs, it doesn't sense the motor voltage so nothing there to tweak. The chuffs start the moment the first input pulse is detected from the cam so the loco could move forward a quarter turn of the driving wheels before the first chuff comes. Alternatively, if the loco has stopped just before the next contact is made on the chuff cam, it could start immediately. I could always trigger the safety valve to blow before moving off - this will mask any lag between movng off and the first chuff.

I've not yet figured how adjusting the sensitivity affects the coasting setting when using the cam. On the default setting (2), it was giving me the coasting sound continuously so I had to up the sensitivity to 4, which gives a good chuff but it now doesn't seem to sense deceleration. I might try changing the sensitivity to 3 to see if that works.

I might drop Peter a PM to ask about the sensitivity settings when using a cam. All new territory for me.

Rik

So my 10-wheeler has also go the new MLS, and on the default (set to USA) setting the chuff is very quiet on coasting, i.e. down a gradient, or throttle backed of, I can only assume the motor voltage does affect the chuff, even with chuff sensor active.

 

[Greg Elmassian]

Yes, I see what you referred to in post #32, and my answer is it is supposed to be that way.

When coasting, locos can be almost silent, and what you hear is the MLS card trying to reproduce the prototype.

dwell is normally defined as the "on" or "connected" time... may Peter will pop up and let us know more. Motor voltage is most likely irrelevant here, unless Peter has found a way to measure BEMF and act on it.

Greg

 

[PhilP]

How elseWould it detect either load, or coasting, without using BEMF?

I suppose it could sense the current being drawn

PhilP