Horst Air Filter Printing

[kalbert]

 Being that Sunrise N629 air filters are cast from 99.9% pure unobtainium I've decided to make my own, or rather have somebody at Shapeways make it for me. Seems like a fairly simple shape, and I've got what I think is a Details West HO equivalent to base my guessing on though I did take some liberties with the inside width so it more or less should slide on an Atlas SD9 shell. I also have exceptional Claris Cad skills that turned out to be only marginally useful in Sketchup. The result should be a lump of plastic that more or less resembles a Horst air filter on an SD10 rebuild? I do plan to add additional detail like the top and rear panels but this is the general shape I think. For the big question... I assume this to be relatively pricey if printed solid, should I try to carve a bunch of material out of the back side or would it become too flimsy?

[daniel_leavitt2000]

The real filters were just ducts along the side, so it would be appropriate to hollow them out

[Catt]

To make it more cost effective do them on a sprue in multiples of at least 5 or 6.

[peteski]

We're talking about a small N scale part. Even when rendered as a solid, it couldn't cost all that much. Now if you made a entire N scale loco shell solid, that would cost you quite a bit.

[kalbert]

Good points brought by all. All considered, I guess I hadn't intended to have it function as an air intake or replicate scale gauge sheet metal.. The solid shape comes out to be about .2 cubic cm, seems like price isn't really a factor at all. Sitting here looking at the HO one it seems like solid would be over kill, but I have to keep reminding myself that mine will be nearly half that size! I do intend to stick 5 or so together on a sprue. That'll darn near be a lifetime supply for my needs.

[nkalanaga]

Solid would be a lot simpler to draw, as well as more durable, if cost isn't an issue.  If I only needed one I'd probably use styrene strips, as it looks simple enough.

As of 1974 the BN didn't have any, that I know of, so I don't need them.  But they seem to be very common on other roads, so they should sell well.

[Philip H]

Can you say Paducah-built? I can. A needed part to make some of the older ICG stuff that slumped into IC.

[jnevis]

I had a couple of the Sunrise ones that I gave to Spookshow a while ago.  They were effectively solid, with the ends indented to have the opening right, IIRC.  No need to really go through the effort to make them any other way.

[FEC Railway]

Still have a few of the ones from sunrise...but the paducahs were rounded on top...i'd take some of those

would be really interested in a GP11 conversion kit (sill, and low hood, mainly) and the filters

[milw156]

Solid would be a lot simpler to draw, as well as more durable, if cost isn't an issue.  If I only needed one I'd probably use styrene strips, as it looks simple enough.

As of 1974 the BN didn't have any, that I know of, so I don't need them.  But they seem to be very common on other roads, so they should sell well.

I could stand to use at least 6
Rick

[kalbert]

I think the IC Geeps had a different style that had a more round shape and without the flared intakes, which if I'm not mistaken can still be found via Detail Associates?

I don't think I'll bother trying to make the intake ends be open at all, nobody's going to stick a dentist mirror under there and see that they're plugged and there's not actually a paper filter inside are they? I'm also on the fence about rivet detail, I'd rather have none that have erratic crappy ones. Which brings us to phase 2... Exhaust stacks.

To my knowledge nobody makes N scale early EMD exhaust stacks, and an SD10 rebuild would need at least 2 more and probably require 4 because a guy would want them to kind of match. If anybody knows of them being available I won't bother trying to print them too. I'm no expert at all but I suspect they are probably pushing the limit of what can be achieved. There are 16 of them, and they have .3mm thick bases with .3mm thick stack walls. They are about 1.3mm tall with bases about 4mmx2.5mm. I have no idea if that's "scale" but it's about the size found on an Atlas GP9, which were the best looking ones proportion wise out of all the GP/SD shells in my stash. I'm thinking there should be a few more tacked on because some certainly will be damaged/lost/not turn out right.

[peteski]

The exhaust stacks placed under the filters will have a wax support for the filters built up all around them. That will change their surface texture. Assuming of course that Shapeways will print them as shown in the drawing.  Just giving you heads-up...

[kalbert]

Ahh, good to know. That's the kind of info I was fishing for... Hoping that when I present my idea it would flush out some gotcha's. I'll rearrange them to not be on the inside.

[peteski]

Ahh, good to know. That's the kind of info I was fishing for... Hoping that when I present my idea it would flush out some gotcha's. I'll rearrange them to not be on the inside.

Any part of the printout which does not start at the very bottom needs a wax support to get printed (FUD 3D printing does not defy gravity)    But is is Shapeways who determines the print orientation, so I only made the comment assuming that your design will be printed as shown in that picture.  The wax supports will likely be always present somewhere in your design, regardless of the print orientation.

[SD452XR]

I'd be in for 10. Always wanted to do some Milw Road GP20's. Be cool if some one could make the correct cab (with tall number boards) also.

Steve