oldravendale
Western Thunderer
Thanks for that description of the process, Mick. As a State Registered Technophobe even I understood the logic!
Brian
Brian
7mm Mickoo's Commercial Workbench
- Thread starter mickoo
- Start date
OzzyO
Western Thunderer
Hello Mick,
instead of the nuts in the smoke box. Why not use the brass inserts that you fit into holes in the smoke box by heat (a modified soldering iron tip will work), you can get them off the bay of E I know that you can get M3 ones, you may also be able to get them in M2.
or you could try this one.
Hope that the link works.
ATB
OzzyO.
instead of the nuts in the smoke box. Why not use the brass inserts that you fit into holes in the smoke box by heat (a modified soldering iron tip will work), you can get them off the bay of E I know that you can get M3 ones, you may also be able to get them in M2.
M2.5 to M6 METRIC THREADED INSERT SOLID BRASS FOR PLASTIC, PRESS-IN, 3D PRINTERS | eBay
M6 internal thread x 12.30mm Length, Hole Size 7.70 to 8.20mm (10 Inserts). Lead spigot is used to locate insert square in hole before pressing insert into moulding. Thermoplastic material, making them popular with all major plastic moulders.
www.ebay.co.uk
or you could try this one.
Hope that the link works.
ATB
OzzyO.
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Big Train James
Western Thunderer
Hi Ozzy,
Unfortunately the UV cured resins we are typically using are not the right types of plastic for the process you linked to. The inserts work great for thermoplastics like ABS or styrene, which can be melted and reformed. Thermoset plastics cannot be remolded, they burn rather than melt. It's the same reason that the various "ABS like" resin for 3d printing are not suitable for burning out for investment casting. They burn rather than melt, leaving ash that will contaminate the castings.
The threaded inserts do work fine with parts printed in ABS (and possibly others) with a filament 3d printer.
Threaded inserts can still be used with resin printed parts, but the process of "setting" them will be different. I would look at creating a keyed cavity of some sort that the insert fits into, and then add uncured resin (or epoxy) around the insert to fill the cavity. Once the added material cures, the insert should be locked in place.
There are also "screw-to-expand" inserts that do exactly what it sounds like. They lock in by forcing the insert to expand, deforming the surrounding plastic to form the keys that retain the insert.
I found this article from Formlabs that describes the various insert types and applications for filament versus resin 3d printed parts.
Jim
Unfortunately the UV cured resins we are typically using are not the right types of plastic for the process you linked to. The inserts work great for thermoplastics like ABS or styrene, which can be melted and reformed. Thermoset plastics cannot be remolded, they burn rather than melt. It's the same reason that the various "ABS like" resin for 3d printing are not suitable for burning out for investment casting. They burn rather than melt, leaving ash that will contaminate the castings.
The threaded inserts do work fine with parts printed in ABS (and possibly others) with a filament 3d printer.
Threaded inserts can still be used with resin printed parts, but the process of "setting" them will be different. I would look at creating a keyed cavity of some sort that the insert fits into, and then add uncured resin (or epoxy) around the insert to fill the cavity. Once the added material cures, the insert should be locked in place.
There are also "screw-to-expand" inserts that do exactly what it sounds like. They lock in by forcing the insert to expand, deforming the surrounding plastic to form the keys that retain the insert.
I found this article from Formlabs that describes the various insert types and applications for filament versus resin 3d printed parts.
Jim
mickoo
Western Thunderer
End of week update, early today as packing up for CTL Seal show tomorrow.
More progress on the LNWR 2-4-2T, but, as often happens, new information arrives after the horse has bolted
Basically new smokebox and cylinder modules in the machine now ready for fitting Sunday.
But this one does have the final resolution and expected surface finish and it does all fit, so we're just talking tweaks to details.
The grey plug goes inside the boiler and smokebox, it'll be bonded to the boiler as well as the front metal disc (which is recessed to take the plug) and allow the nut to be fixed inside to hold both together, then the boiler will be inserted into the smokebox and bonded with adhesive, once it's on it'll be on for good.
I revised the smokebox to have an open rear as printing the door with it's thin lip and fragile hinges was problematical, now the whole front end is one printed piece and much stronger/neater.
The chimney is internally sleeved with thin bore brass for strength and there is an internal plug on the underside of the smokebox to accept it and make a good robust joint. I did toy with printing the chimney on the smokebox but it adds about three hours to the print due to orientation. Plus, the optimum angle for the smokebox is not the optimum angle for the chimney, so it makes sens to split them.
The upper autogear cylinder is just loosely fixed, it'll slide off the rod as well as the lower cylinder, then the small platform can be added under the lower cylinder. The rod will be secured to the platform and add strength to the whole assembly, normally I'd not leave the thin arm as 3D but it's close to the engine and in a low snag risk area.
More progress on the LNWR 2-4-2T, but, as often happens, new information arrives after the horse has bolted
Basically new smokebox and cylinder modules in the machine now ready for fitting Sunday.But this one does have the final resolution and expected surface finish and it does all fit, so we're just talking tweaks to details.
The grey plug goes inside the boiler and smokebox, it'll be bonded to the boiler as well as the front metal disc (which is recessed to take the plug) and allow the nut to be fixed inside to hold both together, then the boiler will be inserted into the smokebox and bonded with adhesive, once it's on it'll be on for good.
I revised the smokebox to have an open rear as printing the door with it's thin lip and fragile hinges was problematical, now the whole front end is one printed piece and much stronger/neater.
The chimney is internally sleeved with thin bore brass for strength and there is an internal plug on the underside of the smokebox to accept it and make a good robust joint. I did toy with printing the chimney on the smokebox but it adds about three hours to the print due to orientation. Plus, the optimum angle for the smokebox is not the optimum angle for the chimney, so it makes sens to split them.
The upper autogear cylinder is just loosely fixed, it'll slide off the rod as well as the lower cylinder, then the small platform can be added under the lower cylinder. The rod will be secured to the platform and add strength to the whole assembly, normally I'd not leave the thin arm as 3D but it's close to the engine and in a low snag risk area.
Lancastrian
Western Thunderer
Did the underside of the cylinder block not have a cover plate ?
Dave Holt
Western Thunderer
The smokebox, with cylinders included, looks very neat indeed - as we've come to expect from you. I'm intrigued to know if this model is to have a representation of, or even working, inside motion? If so, there will be an interesting interface between the cylinders (part of the body) and the valvegear/motion bracket/slide-bar support(part of the chassis).
Dave.
Dave.
mickoo
Western Thunderer
Maybe but I don’t have a Time Machine to check and besides, mine dropped off
mickoo
Western Thunderer
Cylinder block is attached to the frames with a joint to the front face (attached to the smoke box and footplate) behind the first rib and drain cock stubs.
Has to be this way for the inside valve gear to work, that’s going to be fun as there’s nothing to exactly fit, so lot of cutting and trial fitting ahead.
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LarryG
Western Thunderer
Back in the 1980's, I befriended a railwayman who in his younger days had fired the various LNWR small tank locos stationed along the North Wales coast. He told me that everything about them was wrong, from the narrow cab doorway to having to step over that balancing pipe, which made the cab floor even narrower.
He was messing around on a Coal Tank one day holding a rag near a vacuum pipe or something. Suddenly is sucked the rag out of his hand and down into the brake system! No wonder they had poor brakes haha...
He was messing around on a Coal Tank one day holding a rag near a vacuum pipe or something. Suddenly is sucked the rag out of his hand and down into the brake system! No wonder they had poor brakes haha...
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mickoo
Western Thunderer
Back to the JLTRT Crab for a few days, certainly a kit from a bygone era, some horrible over sized slots to fill in the side frames and tweaks here and there to get a good square fit.
But, if you take care a nice rolling chassis isn't so hard to achieve. The devil of course, is in the detail and sadly like the last JLTRT kit I had, several castings are annoyingly missing.
Some I can replace with 3D (brake cylinders, cylinder block valve recess etc) others I can scratch build (to many to list) or buy 3rd party castings; the end result is still the same, more time lost, longer delays on future project timelines, more expense for the client.
But, if you take care a nice rolling chassis isn't so hard to achieve. The devil of course, is in the detail and sadly like the last JLTRT kit I had, several castings are annoyingly missing.
Some I can replace with 3D (brake cylinders, cylinder block valve recess etc) others I can scratch build (to many to list) or buy 3rd party castings; the end result is still the same, more time lost, longer delays on future project timelines, more expense for the client.
mickoo
Western Thunderer
I think this one originally came from Chowbent?
mickoo
Western Thunderer
More JLTRT Crab. Running projects on the docks we had big wall planners with set target dates, we never hit them, seems like model trains follow the same pattern 
Today's target was full valve gear, footplate and cab assembly, in fairness I do have all the footplate cleaned up ready for fabrication, but the valve gear....oh dear.
Nevertheless there has been some decent progress so far this week, even if it's two steps forward and one back on occasion; we do have a nice free rolling chassis and what valve gear that is fitted, all wriggles like it should.
Today's target was full valve gear, footplate and cab assembly, in fairness I do have all the footplate cleaned up ready for fabrication, but the valve gear....oh dear.
Nevertheless there has been some decent progress so far this week, even if it's two steps forward and one back on occasion; we do have a nice free rolling chassis and what valve gear that is fitted, all wriggles like it should.
Yorkshire Dave
Western Thunderer
More JLTRT Crab. Running projects on the docks we had big wall planners with set target dates, we never hit them, seems like model trains follow the same pattern
Naturally, targets are there to be missed.....
mickoo
Western Thunderer
They're not bad except they're laminated etches from 0.7 mm; nice and beefy but massive cusps....which on an over etched sheet leaves very little of a flange around the edge.
I do need to go back and fill the slots in the frames, I tried low melt but the slots are so big that the low melt just poured through the hole onto the desk below
Milliput I think is the answer.
mickoo
Western Thunderer
They make a lovely 'whooshing' sound as they rip pastNaturally, targets are there to be missed.....
Lancastrian
Western Thunderer
That would have been "nil points" when I was competition shooting.They make a lovely 'whooshing' sound as they rip past
Scale7JB
Western Thunderer
I used to solder a bit of wire in to the hole to help fill and give it a bit of meat to file back.They're not bad except they're laminated etches from 0.7 mm; nice and beefy but massive cusps....which on an over etched sheet leaves very little of a flange around the edge.
I do need to go back and fill the slots in the frames, I tried low melt but the slots are so big that the low melt just poured through the hole onto the desk below
JB.