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NZG LTM 11200 Custom Boom Cylinders & More Options · View
CmdrByron
Posted: Friday, September 16, 2016 8:30:27 AM
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Joined: 9/13/2016
Posts: 14
Awesome work! Trying to garner the courage/motivation to attempt something similar - hard pressed to spend almost $200 (currency conversion + import taxes + shipping) for those awesome YCC cylinders, never mind the similar cost for the 5 Ton counterweights. Jib Cylinders are actually doing an awesome job, holding every angle with a modest load (~4 lbs) with a 12m NA and a 12m NM lattice segments installed beyond the eccentric portion (shorter T7YVENZF configuration).

My own unit may or may not have had a slight issue where the boom dropped 30ish degrees when it was partially raised to support reeving of the 350 ton hookblock. Operator will neither confirm nor deny any such occurrence, simply citing that the unit "remains fully operational, with no evidence to suggest such an occurrence" Anxious Not talking
Davie82
Posted: Saturday, September 17, 2016 4:07:42 PM
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Joined: 5/11/2009
Posts: 570
CmdrByron - thanks!

I don't think I would trust a cylinder design that relies on friction to hold that kind of load - for me it has to be either pins or a threaded bolt!

Here's my progress on the 5 ton plates. Having acquired some new polyurethane resin I got busy yesterday doing casts at a rate of one every hour or so (working between times) and I'm really happy with these casts... so much so that all my other ones are going in the bin.

I have ordered some RAL 1007 spray paint which should have arrived today (Amazon Prime) and once they're painted I will need to figure out how to get the warning triangles on them... I'll probably paint them the old fashioned way with masking tape and a brush!

I have cast eight in total and have enough resin left for another two, after which time I'll probably call it quits. Total material cost for all this is about £12 including the paint, so that works out quite a bit cheaper than the YCC ones.

Paul R
Posted: Saturday, September 17, 2016 6:08:05 PM

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Joined: 1/11/2007
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Location: Lincolnshire
Davie82 wrote:


I have cast eight in total and have enough resin left for another two, after which time I'll probably call it quits. Total material cost for all this is about £12 including the paint, so that works out quite a bit cheaper than the YCC ones.


So I've around 20 LTM 11200's. Maybe 4-5 have the YCC kits already so maybe the others need the Davie82 kits now!!

But in all seriousness, a great job well done. I love what you've done.

Paul R
Don L
Posted: Saturday, September 17, 2016 6:33:15 PM
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Joined: 8/11/2016
Posts: 200
Location: Orlando, FL
Davie82 wrote:
Marty K - thanks!

I'm ticking off things on my to-do list one by one as I find the time to do so, and something I really want for this model is the 5 ton weights so I can display it with full ballast. The only drawback is that the YCC ones are LUDICROUSLY expensive (almost £20 each including shipping), so I thought I'd have a go at making my own.

I can say without any hesitation that this has been THE most difficult scratch building project I have ever undertaken, and it has been extremely frustrating at times, but I'm happy with the result. I certainly wouldn't sell these, but they'll do fine on my own crane.

I made a master weight from sheet styrene and used it to make a mould, and this evening I've been pouring black fast cast resin into the mould and having mixed results because my resin is way past its shelf life, especially the isocyanate which has become so viscous it's almost impossible to pour or mix. From seven casts I have four good pieces, but I've got more resin coming in the post tomorrow or Friday and I should have a 100% success rate with the new resin. I only need four plates but I might make eight just to have them handy.

More to follow soon - thanks for looking!




Holy crap! I would sure like to learn how to make a mold like that. Is it made from plaster? I have never used resin before so I am totally clueless when it comes to molding model pieces.

Oh, be extremely careful working with isocyanates. That is really dangerous stuff if you inhale the vapors.

Truly amazing work Davie82.
Don L
Posted: Saturday, September 17, 2016 6:37:08 PM
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Joined: 8/11/2016
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Location: Orlando, FL
Davie82 wrote:
CmdrByron - thanks!

I don't think I would trust a cylinder design that relies on friction to hold that kind of load - for me it has to be either pins or a threaded bolt!


I heard that Davie82. I got a brand new Link Belt ATC3275, opened the box and took it out, and the cylinder (supposed to be stiff and uses friction) won't even hold the boom up (much less a load). One of these days, I will try to figure out what to do about it.

Take care.
Davie82
Posted: Tuesday, September 20, 2016 2:16:15 PM
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Thank you guys - it's much appreciated. Paul I would love to "mass produce" these but it'll have to wait until I have more time to perfect the process and iron out the problems. As it is, I'm running into problems with painting because something in the resin is attacking the paint and causing it to rupture very slightly in places. And these are nowhere near YCC quality, which can't be stressed enough - this is very much a part of the hobby for me, and very much trial and error! Teeth But I am extremely pleased with how these turned out myself, especially after finishing them up.

Here are a couple of pics showing the finished plates and a closeup of the surface anomaly caused by the resin reacting with the paint. The only thing I haven't done is varnish the warning triangles to give them a protective layer.




Don, the mould is made from RTV silicone and is the simplest form of mould possible: one piece. The counterweight parts are completely flat on one plane, e.g. no protrusions (relief detail is OK), so they can be cast in a one piece mold from the bottom up. I just fixed the custom made plate to the bottom of a small box I made from styrene, and filled it with silicone. That's all it takes for a mould like this; after that, it's a simple case of pour resin and demould, rinse and repeat! The silicone is cheap and takes about 6 hours to cure, but the drawback is it will degrade with each cast because the resin cures by exothermic reaction. Eventually the mould will become brittle because of repeated exposure to heat. My plan for future projects is to get some of the more expensive silicone (addition or "platinum" cure) which will last considerably longer.

I hadn't done any casting until about a year ago, and I learned pretty much everything by watching youtube videos. Jason (hummer13) was very helpful and has a lot of experience in that area, as do other model builders on this and other forums. Experience is the best teacher, and you learn by doing... truer words were never spoken!
hummer13
Posted: Wednesday, September 21, 2016 1:45:40 AM

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Did you pressure cast these ? They look great either way. 1 trick you might try is spray your mold with primer it will dry on your silicone then pour your resin. The outside of your piece will be primed. I have done this a few times.
Don L cast can be very stressful when starting. Also not cheap the silicone i use is $178 a gallon. The real success in casting is making the perfect mold. Really gets tough when you get into 2 pc molds.

Great job on everything Davie
Jason

Nikl Scale Models
nikl scale models shapeways store
Davie82
Posted: Wednesday, September 21, 2016 9:13:20 AM
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Posts: 570
Thanks Jason! No pressure casting yet - the resin I bought seems to be of very high quality and it doesn't take in much air when mixing, so hardly any bubbles at all in the final parts. But I'm using extremely small amounts for each cast, about 12g in total.

And yeah that silicone is expensive... mine cost me about £50 for 5L, just over a gallon, which is equivalent to around $75.
Diego_994
Posted: Monday, September 26, 2016 8:48:49 AM

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Location: Huesca , Spain
Hi Davie, same problem with the paint has happened to me sometimes. Make sure resin is completely clean of silicone rests from the mold. I usually sand the pieces and clean them with alcohol. Even so, not always 100% successful.
I mean, if there's something wrong with the paint, I think is because of silicone rests or resin oil on surface resulting from a bad mixture from the process. ( said by the same method trial /errorTeeth )



Davie82
Posted: Tuesday, September 27, 2016 10:09:46 AM
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Joined: 5/11/2009
Posts: 570
Thanks Diego - that's helpful to know. I think you're right that it's all down to mixing, and it's really hard to mix the resin properly when you have so little time. I have about 30 seconds to mix my resin and then another 30 seconds to pour it before it starts to set.
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