Wooden ore cars

[Hauk]

Hauk,

are you going to rearrange the items to save space / material?

Volker

O  yes. This is just an early layout for checking that all parts are drawn. When I made the final layout for the etchings for the Westinghouse engines I spent a lot of time fitting all the parts into one A3 sheet of brass. Or more precisely 1 sheet of 0,5mm brass and one sheet of 0,3mm brass for two complete engines.

[Hauk]

Long time, no progress, but today hardware for 9 cars arrived in the form of brass castings from David Sciacca of Valley Brass & Bronze.
The master was printed by Prescision Wax in England on a Solidscape Printer.

I think the parts look fine, especially the casting must have been quite demanding with the thin cross-section of 0,45mm X 1,4mm.
I was in contact with several casters that just said it could not be done, but David stepped up the plate.  I can really recommend his casting service.

Precison Wax put in a remarkable effort to print the master. Several 3D printers said it could not be done, but PW  came through with flying colors! I have only one regret, and that is not going for full resolution of the wax print, It would have been even better at 0,127mm layers instead of 0,254. I really don't know why I missed this... Damned macro images, I was perfectly happy until I started to examine the images!

Well, too late for regrets... I will use the parts, I think they will work well in the context of the complete car.

If you look closely, you can see that some of the nuts have holes instead of rods. These dimples are starter holes for drilling. Brass pins will be soldered into these holes. The plan is that these pins will help secure the hardware to the wooden sides.

Half of the cars will also have working door, the others will have the doors fixed permanently.

[Juke Joint]

They look great considering the size! And they hinge! Are those printed in wax or did Valley Brass make a wax pattern from the print?

Philip

[Ray Dunakin]

I agree with Phillip, considering the size they are really nice. Once installed and painted they'll be just fine.

[Hauk]

Thanks for the encouragement!

I agree that they probably will look fine on the finished model, but knowing that they probably could have been even better is a nagging me a tad...

Regarding the print, they are indeed printed in wax. This is a bit unconventional, as wax prints are usually used for making a plaster mould directly. The wax is covered in plaster, and the wax part is burned out in an oven. This is the loosing of the wax  in "lost wax" casting! Doing it this way you would have to make a wax print for every single part, which would have been way too expensive.

David made a RTV rubber mould from the wax master. In this mould he made new wax parts that was assembled into a casting "three".

A lot of people have said that you can not do it like this. But the wax prints from Precision Wax had far better surface detail than prints made in other materials, so I am certain that it was a very wise decision on Davids part to use the wax master.

[Chuck Doan]

I'm glad you guys are pushing the envelope.

[Hauk]

I'm glad you guys are pushing the envelope.

Well, my contribution is only making unreasonable demands! And taking some calculated risks. PW warned me firmly against having a delicate wax like this shipped across the atlantic... A least one wax print was destroyed during post-processing, but PW printed a new one at no extra cost.

Both PW and David pushed their skills and tools to the limit. It is a pleasure to work with people that takes so much pride in their craft.

[finescalerr]

They are almost perfect. If you need to improve the finish, would a light sandblasting help? (If you paint them I doubt it would matter. Sandblasting might help only if you chemically blacken them.) -- Russ

[Hydrostat]

Hi, Hauk,

Regarding the print, they are indeed printed in wax. This is a bit unconventional, as wax prints are usually used for making a plaster mould directly. The wax is covered in plaster, and the wax part is burned out in an oven. This is the loosing of the wax  in "lost wax" casting! Doing it this way you would have to make a wax print for every single part, which would have been way too expensive.

I'm not sure about the last point. You're right, that the printed wax part usually is being burned out, but the thereby resulting casting is then going to be your brass master form, which you can rework if necessary - without shipment problems of delicate parts. Afterwards a mould is made out of this reworked master form which then is used to make the wax parts in an arbitrary amount. No need to repeatedly print any part. Of course there's a risk to loose your printed part due to a casting mistake (which can be the company's risk, too). So if you don't like the surface, you may rework one of them and ask the casting company to use this for a new mould for the wax parts. But there might be a problem with shrinkage: Your parts already came from a mould, where the shrinking happens, so you would have new shrinkage if a new mould is made from these parts (there's no shrinkage when casting the printed part directly via lost wax).

I agree that they probably will look fine on the finished model, but knowing that they probably could have been even better is a nagging me a tad...

I can understand your disappointment. It's really annoying if it could have been better so easily.

Volker

[Hauk]

I'm not sure about the last point. You're right, that the printed wax part usually is being burned out, but the thereby resulting casting is then going to be your brass master form, which you can rework if necessary - without shipment problems of delicate parts. Afterwards a mould is made out of this reworked master form which then is used to make the wax parts in an arbitrary amount. No need to repeatedly print any part. Of course there's a risk to loose your printed part due to a casting mistake (which can be the company's risk, too). So if you don't like the surface, you may rework one of them and ask the casting company to use this for a new mould for the wax parts. But there might be a problem with shrinkage: Your parts already came from a mould, where the shrinking happens, so you would have new shrinkage if a new mould is made from these parts (there's no shrinkage when casting the printed part directly via lost wax).

I agree that they probably will look fine on the finished model, but knowing that they probably could have been even better is a nagging me a tad...

I can understand your disappointment. It's really annoying if it could have been better so easily.

Volker

I agree that I should have made a metal master from my wax. As you said, I could then have made final adjustments to it as well as getting a chance to examine a real metal part.

Pictures of the prints can be deceiving. And in addition my only complaint about PW is that they are not able to take decent macro pictures of parts. I find it sort of amusing that they have printers worth several thousand dollars, but obviously not a compact camera worth a couple hundred dollars. I use a Canon G12 and a desktop lamp for my macro images.

And yes, it is a bit annoying that PW confirms that they in fact *could* have printed the part with better Z-axis resolution!

All that asides, the parts will work fine, and I have starter the post-processing work on them. This is no small task!

The process is something like this:

1. Cut all the parts from the sprues.
2. Remove any flash (almost none, fortunately!)
3. File all parts to the proper length.
4. Straighten the parts using an arbor press. ( Do not worry, I use stripwood as protection on the detail side!)
5. Drill holes for pins and hinges
6. Clean up all parts with fiberglass eraser.
7. Wash parts with laquer thinner
8. Blacken the parts in a 1:200 solution of Birchwood Casey brass blackening.
9. File/sand the back of the parts smooth. I remove about 0,1mm of the thickness. This sounds like a horrible job, but using the wooden protection pieces as "handles" this in fact quite simple. During the pressing the wood becomes negative "moulds" of the part.
10. Solder bits of 0,3mm brass wire into all pinholes and assemble hinged parts.
11. File wire doen to proper length
12. Blacken the bright spots after filing.

I have not completed the list for any parts yet, I have parts for three cars at point 4. I have also tested the drilling of the bolts, but lacking a proper chuck/mindrill I had to use an hand vise, and this was ridiculous slow and I broke several drills in the process. But I got proof that the concept will work, and proper equipment is on the way!

[finescalerr]

As gorgeous as the parts are (and they, along with your craftsmanship, are beautiful) ... there must be an easier way! -- Russ

[Hauk]

As gorgeous as the parts are (and they, along with your craftsmanship, are beautiful) ... there must be an easier way! -- Russ

O yes. Like casting complete sides in resin from 3D printed masters. But then I got those crazy visions of real metal parts and wooden sides made from scale size planks with working tongues and grooves...

Plain and simple, resin models just did not feel right.

This is one of the few areas in life where total disregard of bottom lines, deadlines and total rejection of reason is possible.
So lets be realistic and demand the impossible!

[NE Brownstone]

"So lets be realistic and demand the impossible!"

I like that!

[finescalerr]

... And the converse often is true: Let's be unrealistic and demand the possible! -- Russ

[Hydrostat]

Hauk,

your post processed items don't give any room for improvement. Even the surface looks good to me assuming the cars won't be presented in delivery appearance ...

Volker