MOK Standard 4 2-6-0 in S7
- Thread starter SteveB
- Start date
SteveB
Western Thunderer
Hi Richard
Yes, replacement etches are intended to be the same as supplied, just a bit wider. I'm going to try Shapeways for the castings just to see what they're like. I'll post some photos when I get them but it could be several weeks if not months before I get round to it. Thinking about it though, I might just do one casting just so I know if the process is feasible.
Regards
Steve
richard carr
Western Thunderer
Steve
Let us know how the tab and slot works.
I'm trying it on some wagon W irons Dave Sharpe clearly has it down to a fine art but I fear it's trickier than it appears making all the allowances for the undercut.
Mine are back from ppd I just need to get back to work to pick the etch up.
Richard
Let us know how the tab and slot works.
I'm trying it on some wagon W irons Dave Sharpe clearly has it down to a fine art but I fear it's trickier than it appears making all the allowances for the undercut.
Mine are back from ppd I just need to get back to work to pick the etch up.
Richard
SteveB
Western Thunderer
Hi Richard
The Hollywood, How to.... does cover slot and tab. It might be worth a look.
www.hollywoodfoundry.com/HowToPapers.shtm
You're quite right about Dave having it down to a fine art. I can't remember having a single issue with his. Good luck with your etch.
Regards
Steve
The Hollywood, How to.... does cover slot and tab. It might be worth a look.
www.hollywoodfoundry.com/HowToPapers.shtm
You're quite right about Dave having it down to a fine art. I can't remember having a single issue with his. Good luck with your etch.
Regards
Steve
Rambler
Active Member
I've had a number of etches done by PPD in 0.4mm nickel silver and it appears that the etch undercut (the amount the etching goes sideways) is about 0.05mm. I reckon that you can mostly ignore this, unless you've got narrow strips of metal - if you want a strip 0.7mm wide but it comes out at 0.6mm wide then it might look a bit weedy.
Regards, Eric
Regards, Eric
Ian@StEnochs
Western Thunderer
I have been making some cylinder and motion bracket patterns for a loco which I will be building more than one of, at least one in S7 and some in Fine standard O. The patterns I made to suit S7 frames and wheels as it is easier to add a bit of packing to suit narrower than scale frames than cut off excess for scale width. It would be good if kit designers made provision for S7 at the design stage. I applaud Dave Sharp for what he has done for us so far especially his excellent standard tank.
On my build list is one of the standard 3f moguls which I remember fondly from my yoof! The abiding detail which I have to incorporate is the minuscule clearance behind the wheels and frames. I recall that I could hardly get my fingers into the space which with the high footplate is so noticeable. Warrens photo of 76026 is superb until I see the gap especially at the wheels next the firebox! I will watch this build with great interest.
Steve I am interested in some of your castings as the standard 4 mogul also features in my list!
Ian.
On my build list is one of the standard 3f moguls which I remember fondly from my yoof! The abiding detail which I have to incorporate is the minuscule clearance behind the wheels and frames. I recall that I could hardly get my fingers into the space which with the high footplate is so noticeable. Warrens photo of 76026 is superb until I see the gap especially at the wheels next the firebox! I will watch this build with great interest.
Steve I am interested in some of your castings as the standard 4 mogul also features in my list!
Ian.
SimonT
Western Thunderer
Steve,
the method of using 3D prints for lost wax casting is now well established and was detailed in a couple of articles in the GOG Gazette last year. There are two sets of inside valve gear in the Laurie Griffin range that where produced using these methods and the completed kits only required a final polish to assemble. Shapeways will only be a route to disappointment as their surface finish is not good enough and I have doubts about their dimensional reliability. In 3D printing quality costs as it does in any other walk in life. Try PD Models for your printing. Apply standard shrinkage allowance to your digital model as a final step before exporting as a .stl. (Scale a copy by 1.03%).
The caster will use the prints to make a RTV mould and he will then produce the waxes in the mould. When the mould wears out he makes a new one. Proof is on here in the pages on Nick Dunhill's T3 locos. Look at Page 31 for the finished valve gear on Nick Dunhill's Workbench thread. I would post a link but couldn't make it work and lost the will to live trying to find out!
Simon
the method of using 3D prints for lost wax casting is now well established and was detailed in a couple of articles in the GOG Gazette last year. There are two sets of inside valve gear in the Laurie Griffin range that where produced using these methods and the completed kits only required a final polish to assemble. Shapeways will only be a route to disappointment as their surface finish is not good enough and I have doubts about their dimensional reliability. In 3D printing quality costs as it does in any other walk in life. Try PD Models for your printing. Apply standard shrinkage allowance to your digital model as a final step before exporting as a .stl. (Scale a copy by 1.03%).
The caster will use the prints to make a RTV mould and he will then produce the waxes in the mould. When the mould wears out he makes a new one. Proof is on here in the pages on Nick Dunhill's T3 locos. Look at Page 31 for the finished valve gear on Nick Dunhill's Workbench thread. I would post a link but couldn't make it work and lost the will to live trying to find out!
Simon
daifly
Western Thunderer
Simon
Just click on the #postnumber at the end of the post and the link appears! Copy it and paste here:
Nick Dunhill's 7mm workbench.
Dave
Just click on the #postnumber at the end of the post and the link appears! Copy it and paste here:
Nick Dunhill's 7mm workbench.
Dave
SimonT
Western Thunderer
daifly
Western Thunderer
Simples!
SteveB
Western Thunderer
I appreciate your comments. Its actually the RTV stage that I’m trying to avoid, purely on grounds of cost. Quite important really when dealing with such low volume requirements. I suspect that Simon could well be right about dimensional reliability, Shapeways tolerance is +/- 0.125mm. This may be high just to give them commercial wiggle room. Their X,Y,Z resolution however is miniscule. They tell me they use 16 micron for 3D printed waxes. I think the only reliable way to be sure is to try them. I’ll let you know how I get on.
Regards
Steve
Regards
Steve
SteveB
Western Thunderer
As I mention in an earlier post, I’ve already done a replacement etch for the tender chassis so I can convert it to CSB.
The top chassis is the original supplied by MOK and the lower one is my altered one.
There’s some published figures on the CLAG website for 6’6” wheelbase tenders, which I’ve used, although I did move the fulcrums out a bit (0.5mm) for the centre axle hoping that it would soften it sufficiently to help the tender stability.
I’ve made my own axle boxes from Acetal, which is quite a nice plastic to machine. You can see that theres no handrail stanchion on the top. The curved surface just bears on the CSB. The axlebox is quite tall, so I can position the CSB above the brakes and out of sight.
They're not very good photos I'm afraid. I haven't put the wires in yet for the split axles, as I find they get in the way quite a bit, especially when the whole assembly needs to come apart quite frequently.
Regards
Steve
The top chassis is the original supplied by MOK and the lower one is my altered one.
There’s some published figures on the CLAG website for 6’6” wheelbase tenders, which I’ve used, although I did move the fulcrums out a bit (0.5mm) for the centre axle hoping that it would soften it sufficiently to help the tender stability.
I’ve made my own axle boxes from Acetal, which is quite a nice plastic to machine. You can see that theres no handrail stanchion on the top. The curved surface just bears on the CSB. The axlebox is quite tall, so I can position the CSB above the brakes and out of sight.
They're not very good photos I'm afraid. I haven't put the wires in yet for the split axles, as I find they get in the way quite a bit, especially when the whole assembly needs to come apart quite frequently.
Regards
Steve
Attachments
SteveB
Western Thunderer
Whilst I’m waiting for loco etches, I thought I might as well get on with the rest of the tender. If the tender is anything to go by, then this will be a very enjoyable build. I thought the Std 4 Tank was good, but this is better. Having only built MOK kits so far, I think I’m going to ‘come back down to earth with a bump’ when I try another manufacturer! In my collection of kits to build, I do have one of Dave’s 9F’s and a Finney7 WC, so it’ll be a while yet.
The instructions in the kit are a bit daunting but quite straight forward. The whitemetal sides were soldered on (as recommended in the instructions) with 145deg solder with the iron set at around 300 deg. The whitemetal is such a large heat sink, it worked fine, although I must admit, I was quite nervous about it to start with.
I was fortunate to see Scanlons thread on his build of the 2-6-0, so I was aware that I shouldn’t fit the water pick up and that there were missing rivets on the back.
Incidentally, can anyone advise me about what they did with the Water Scoop Handle? I assume, they wouldn’t have fitted it, but what would they have done? I’ve looked at Scanlons photos. It’s difficult to make out, but it looks like the handle boss was there, just not the handle itself, can anyone help please?
Its actually a shame about not having to fit the Water Scoop. The castings supplied are really nice.
The holes in the coal space will be for my tender speaker. I came across an interesting article regarding speakers and sound. I’ve mentioned it before in a previous post.
www.youtube.com/watch?v=j4kgLeDltxg
Well worth a look. I carried out some trials myself as I didn’t really believe that a speaker would actually be better when it’s not mounted in an enclosure, but it’s all true.
Regards
Steve
The instructions in the kit are a bit daunting but quite straight forward. The whitemetal sides were soldered on (as recommended in the instructions) with 145deg solder with the iron set at around 300 deg. The whitemetal is such a large heat sink, it worked fine, although I must admit, I was quite nervous about it to start with.
I was fortunate to see Scanlons thread on his build of the 2-6-0, so I was aware that I shouldn’t fit the water pick up and that there were missing rivets on the back.
Incidentally, can anyone advise me about what they did with the Water Scoop Handle? I assume, they wouldn’t have fitted it, but what would they have done? I’ve looked at Scanlons photos. It’s difficult to make out, but it looks like the handle boss was there, just not the handle itself, can anyone help please?
Its actually a shame about not having to fit the Water Scoop. The castings supplied are really nice.
The holes in the coal space will be for my tender speaker. I came across an interesting article regarding speakers and sound. I’ve mentioned it before in a previous post.
www.youtube.com/watch?v=j4kgLeDltxg
Well worth a look. I carried out some trials myself as I didn’t really believe that a speaker would actually be better when it’s not mounted in an enclosure, but it’s all true.
Regards
Steve
adrian
Flying Squad
why didn't I think of that! Bleeding obvious solution now you mention it. I'm part way through making some telescopic axles and have just ordered some insulated axles from Slaters at £8.35 + p&p for 6. Making my own would be much more flexible - smaller axles, ball races etc. I will google it but where do you get the acetal from?
SteveB
Western Thunderer
Hi Adrian
I think I got it from Plastics Direct www.directplastics.co.uk. I bought 22mm dia and I think the postage was more expensive than the plastic. They do sheet as well rod, its just easier for me to use rod.
Regards
Steve
I think I got it from Plastics Direct www.directplastics.co.uk. I bought 22mm dia and I think the postage was more expensive than the plastic. They do sheet as well rod, its just easier for me to use rod.
Regards
Steve
Brian McKenzie
Western Thunderer
Shapeways do a reasonable job of printing their waxes - but insist on 'tumbling' any brass castings subsequently made from them. This rounds off sharp edges and can damage detail. Waxes seem to be built with longest part length standing uppermost. If orientation of layering is important, suggest arranging the part using some subterfuge, or by combining parts so they will layer up in the direction you prefer (bounding box size will be a limitation to this). Suggest adding material to any faces of parts where subsequent filing or machining can be easily achieved, and is straightforward, to 'sharpen' up the casting without harming adjacent detail.
If obtaining waxes from Shapeways, use another supplier for doing the lost wax casting. This also gives you the chance to 'breathe' on the waxes (if you are game - they are very soft) to smooth out imperfections before casting. No allowance for shrinkage seems necessary (after I've been adding some).
Some low cost DLP 3d printers are now outputting superior finishes to the vastly more expensive printer from 3D Systems that Shapeways uses. However, the 'wax' used by these cheaper machines is some sort of hybrid and is often troublesome for the caster.
-Brian McKenzie
If obtaining waxes from Shapeways, use another supplier for doing the lost wax casting. This also gives you the chance to 'breathe' on the waxes (if you are game - they are very soft) to smooth out imperfections before casting. No allowance for shrinkage seems necessary (after I've been adding some).
Some low cost DLP 3d printers are now outputting superior finishes to the vastly more expensive printer from 3D Systems that Shapeways uses. However, the 'wax' used by these cheaper machines is some sort of hybrid and is often troublesome for the caster.
-Brian McKenzie
SteveB
Western Thunderer
Thank you Brian. Thats very useful to know. When I made my enquiry with Shapeways, they said to be not to make any shrinkage allowance. I thought that was strange and put it down to their slack tolerances.
I've been contemplating getting a Form2 printer. I've seen what they can do and its very impressive for a relatively cheap printer. Whats put me off was finding anyone that would cast for me from these 'waxes'. I've seen YouTube videos about doing your own lost wax casting using domestic microwaves to melt the brass or bronze. I'm tempted but I don't think I'm ready for that yet.
Regards
Steve
I've been contemplating getting a Form2 printer. I've seen what they can do and its very impressive for a relatively cheap printer. Whats put me off was finding anyone that would cast for me from these 'waxes'. I've seen YouTube videos about doing your own lost wax casting using domestic microwaves to melt the brass or bronze. I'm tempted but I don't think I'm ready for that yet.
Regards
Steve
adrian
Flying Squad
Thanks for that link - £3.68 for 500mm will make a lot of insulated axle boxes, they also stock tufnol rod so I will be ordering a few bits and pieces from them.
SimonT
Western Thunderer
Adrian, Steve,
I bought into the Formlabs at the beginning with a Form1. It was very good at the small, printing perfect GWR point rodding stools that Shapeways couldn't print. However, due to some problems with the laser and the peel mechanism, it was not as good at the large. Essentially the performance was what to expect from the first go. The Form2 is excellent but rather too pricey for me at the moment with the lousy exchange rate. Formlabs have finally got more professional with a range of resins that have proper engineering properties. They did a 'lost wax' resin fairly early on to answer the cries from all the jewlers and I presume that it worked well as their complaints stopped on the Forum. And yes, some of the competing DLPs are starting to provide good competition to the lasers.
I still make the point that the purchase and running costs of something like a Form2 buy a huge amount of printing at somewhere with a high quality machine who are more interested in quality than quantity. Obviously I don't include Shapeways in that!
The pattern will still need shrinkage allowance. It is there for the shrinkage of the metal in the mould and that physics hasn't changed with the advent of 3D printers.
Simon
I bought into the Formlabs at the beginning with a Form1. It was very good at the small, printing perfect GWR point rodding stools that Shapeways couldn't print. However, due to some problems with the laser and the peel mechanism, it was not as good at the large. Essentially the performance was what to expect from the first go. The Form2 is excellent but rather too pricey for me at the moment with the lousy exchange rate. Formlabs have finally got more professional with a range of resins that have proper engineering properties. They did a 'lost wax' resin fairly early on to answer the cries from all the jewlers and I presume that it worked well as their complaints stopped on the Forum. And yes, some of the competing DLPs are starting to provide good competition to the lasers.
I still make the point that the purchase and running costs of something like a Form2 buy a huge amount of printing at somewhere with a high quality machine who are more interested in quality than quantity. Obviously I don't include Shapeways in that!
The pattern will still need shrinkage allowance. It is there for the shrinkage of the metal in the mould and that physics hasn't changed with the advent of 3D printers.
Simon