On My Virtual Workbench...
- Thread starter S-Club-7
- Start date
S-Club-7
Western Thunderer
A mere dozen or so posts ago there was a vague promise about crank axles. My long-lost Stratford drawing of July 1882 of the batch of J15's built by Sharp Stewart revealed some details not evident in my one photograph nor in the Gardner drawings. It appears that the shape of the crank webs changed at some stage. I'm sure that Buckjumper will tell us upon which wet Wednesday that happened (I'll just call them the GER and LNER variants until then) but that means there are now two crank axles to be drawn and not just one. Add into the mix the 11 inch crank throw of the J tanks and the 12 inch throw of the J15's and the draughtsman's workload is doubled again...
First off the blocks is a 12 inch throw GER variant:
Shortly followed by the LNER variation:
The eccentrics still need some bolt detail and there may be some more adjustments required to enable the 3D-printing in stainless steel to be achieved but it's all squeezed into 22mm wide with a slightly undersized axle hole right through which will need reaming to 3/16 inch.
The real thing at Sheringham on 14th March 2003 for comparison - I know, the colour is wrong!
First off the blocks is a 12 inch throw GER variant:
Shortly followed by the LNER variation:
The eccentrics still need some bolt detail and there may be some more adjustments required to enable the 3D-printing in stainless steel to be achieved but it's all squeezed into 22mm wide with a slightly undersized axle hole right through which will need reaming to 3/16 inch.
The real thing at Sheringham on 14th March 2003 for comparison - I know, the colour is wrong!
Osgood
Western Thunderer
If anyone else is at the same stage of learning as me and does not have a clue about printing in materials other than plastics, here is the information from Shapeways site on how objects are printed in stainless steel:
Fascinating stuff!!
How it's 3D printed
To build steel models, special 3D printers deposit small drops of glue onto layers of stainless steel powder, one layer at a time, until the print is complete. We carefully remove these models from the printer. At this stage of the process, the objects are very fragile, similar to wet sand. The models then go through an infusion process that replaces the glue with bronze, creating a full metal product. Models are then processed to achieve your desired finish, sprayed with a sealant, and shipped to you.
To build steel models, special 3D printers deposit small drops of glue onto layers of stainless steel powder, one layer at a time, until the print is complete. We carefully remove these models from the printer. At this stage of the process, the objects are very fragile, similar to wet sand. The models then go through an infusion process that replaces the glue with bronze, creating a full metal product. Models are then processed to achieve your desired finish, sprayed with a sealant, and shipped to you.
Fascinating stuff!!
Eastsidepilot
Western Thunderer
.........and here's the E4 version, Dave 
Col.
Col.
S-Club-7
Western Thunderer
This image shows the work still to be done according to Shapeways:
The regions which are non-green are too thin to 3D-print in stainless steel: a slightly smaller hole for the axle (may need drilling before reaming); thicker spokes and rims for the eccentrics. The latter will need adjusting with care so that it doesn't look too heavy.
So that's 3 different crank shapes (thanks Col!); each in 11" and 12" throws. Anybody else have any more variants that they'd like done?
So that's 3 different crank shapes (thanks Col!); each in 11" and 12" throws. Anybody else have any more variants that they'd like done?
Steph Dale
Western Thunderer
Looks good, but for the thin areas might I suggest building up on the outside, rather than inside? It'd be much easier to have at em with a decent sized file rather than trying to drill and ream - you could provide witness marks to file back to.
I've also got a couple of questions if I may; can these parts be soldered or would you have to use Loctite to assemble?
Can you give an idea of how much the parts would cost? I imagine that the process isn't all that affordable.
Could you not include the axle in the drawing? I've got HO locos with inside motion that were provided with lost wax cast crank axles and work very well.
Sorry about all that, sometimes the most random things get the neurons firing on the right order.
Cheers,
Steph
I've also got a couple of questions if I may; can these parts be soldered or would you have to use Loctite to assemble?
Can you give an idea of how much the parts would cost? I imagine that the process isn't all that affordable.
Could you not include the axle in the drawing? I've got HO locos with inside motion that were provided with lost wax cast crank axles and work very well.
Sorry about all that, sometimes the most random things get the neurons firing on the right order.
Cheers,
Steph
S-Club-7
Western Thunderer
The Shapeways 3D-printing process for stainless steel is quite crude with relatively poor tolerances and detail; hence witness marks may not be consistently visible. The chances are that some post-printing work would be required in addition to their polishing processes.
I've never tried soldering the material (the bronze infusion may help in this respect) but a pin in a drilled hole secured with Loctite should work.
I did consider including an axle but the poor tolerances meant that this would need machining to size -- issues to resolve include mechanical strength; split axles; square ends for Slaters wheels; length of axles (S7 or O Fine).
The pair of crank axles shown in post 145 above are currently costed by Shapeways at:
£25.30 in stainless steel
£35.37 in lost wax cast brass or bronze
£7.95 in acrylic detail plastic
£10.67 in frosted detail plastic
Note: it must be remembered that because of the way that Shapeways items are costed then one crank axle will NOT be half of these prices; they are included here just to give some idea to those interested. Indeed, thickening to enable it to actually be 3D-printed in steel will cost more due to the increase in the amount of material used. Compared to the cost of purchasing a set of Laurie Griffin castings I think that these prices are not too unaffordable.£35.37 in lost wax cast brass or bronze
£7.95 in acrylic detail plastic
£10.67 in frosted detail plastic
I have just ordered a set in frosted plastic to check dimensions etc which should be available for viewing at the S7 East Anglian Group meeting at Sudbury on the 31st for those of you who are really interested.
Many thanks for your comments; all will get considered and discussed. Nothing is yet written in stone but it could be 3D-printed in sandstone at a later date...
S-Club-7
Western Thunderer
Good idea, but probably not yet, at least not in 7mm scale or smaller.
The minimum thickness required for printing the stainless steel is larger than some parts of the chairs (and the web of the rail). And part way through the production process the parts must be transferred from one machine to another whilst they have the consistency and strength of wet sand. The Shapeways material page for steel explains all.
S-Club-7
Western Thunderer
Just sorting out the final suggestion from last month's S7 meeting.
No prizes for guessing what it is.
If the loco brake assemblies (see above) are successful them I may try creating complete working wagon brakegear requiring no assembly by the purchaser. Anybody interested?
If the loco brake assemblies (see above) are successful them I may try creating complete working wagon brakegear requiring no assembly by the purchaser. Anybody interested?
Osgood
Western Thunderer
Oh yes. It would certainly enhance many an existing kit-built wagon!
Heather Kay
Western Thunderer
Wagon, coach and loco brake shoes - and suitable rigging where possible - would go down well with me.
S-Club-7
Western Thunderer
The first test prints of the crank axles and brake hangers arrived during the week. I finally read the camera manual (only had for about 15 years!) and squeezed a little more depth of field from it.
Firstly the GER 12" throw crank axles:
Printed in the Shapeways FUD acrylic material to check dimensions and appearance. Apart from the outer rim of the eccentrics I'm almost tempted to use them as they are: I do feel that we modellers have an aversion to not using metal for locomotives, especially the moving parts. Second opinions welcomed at the S7 area group meeting in Sudbury tomorrow!
Thoughts are now turning to 3d-printing the entire valve gear ready-assembled and working... I am leaving a paper-trail behind me so that I can get back to the real world
Next the GER loco brake blocks, hangers, mounting brackets and (non-prototypical) spacers:
When I opened the packet (at work, surrounded by intrigued colleagues!) one of the hangers broke away from the bracket when I tried to wiggle it. I think that there needs to be a bit more than the Shapeways minimum recommended clearance between the parts, and the pivot could do with being a larger diameter as well. Both of which may reduce parts of the hanger to below the minimum allowed thickness 
Some of the others on the sprue do actually pivot so I don't think that there's much in it; the blocks pivot on the hangers which was the main purpose of the exercise.
The photography has highlighted the layering which is not noticeable on the original 3d-prints when viewed at 1:1.
Firstly the GER 12" throw crank axles:
Thoughts are now turning to 3d-printing the entire valve gear ready-assembled and working... I am leaving a paper-trail behind me so that I can get back to the real world
Next the GER loco brake blocks, hangers, mounting brackets and (non-prototypical) spacers:
Some of the others on the sprue do actually pivot so I don't think that there's much in it; the blocks pivot on the hangers which was the main purpose of the exercise. The photography has highlighted the layering which is not noticeable on the original 3d-prints when viewed at 1:1.
OzzyO
Western Thunderer
If they could print in wax it could be a good way of getting the masters done for castings!
OzzyO.
PS. see how I'm thinking take out the making of the normal master for making the wax for the casting and also take out one of the problems with making the mould for the wax and that should end up with less joint lines on the part.
adrian
Flying Squad
Len Cattley
Western Thunderer
And not only Shapeways do this.
Dan Randall
Western Thunderer
Hmmm, looks like GWR buffer stop to me. That's as far as I've got with my drawing, which I started about 2 years ago! I still haven't done the chairs for it....
Regards
Dan
Regards
Dan
Compton castle
Western Thunderer
Il be down for a few !!