1:24 Heywood Wheel & PAP Project...

[Hauk]

Thanks Chuck. Yes, I'm aware of their size limitations. This wheel is just over 1" in dia. and .25" deep. Their limitations will mean I won't be able to have as many centers printed at once, probably no more than three sets of four sprued up. I may just have one set of four done the first time just to see how they come out.

Paul

Remember that the price drops significantly if you print more than one part from the same masterfile.

Regards,
Haavard

[RoughboyModelworks]

I've scaled the drawings to 1:12 (wheel was originally drawn full-scale) and laid up four wheel centers on sprues. The back view shows how the sprues come out of the axle holes on the back of the wheels. The plan is to cut off the bulk of the sprues, then drill out the remainder of the axle hole, thus avoiding having to clean up sprue remnants from any of the visible surfaces. I decided to try just one set of wheels first to see how they turn out. If successful, then I'll layup multiples on the same sprue network for a second go-round.





Next step is to output the STL file and send it off to PAP for their assessment and quote.

Paul

[Craig_H]

Paul,   What will these wheels go on?       Craig

[RoughboyModelworks]

Craig:

These are the wheel centers for the four-wheel Heywood Brake Van, 15" gauge, now in 1:12 scale. Drawings and other info on the van's superstructure are here: http://www.finescalerr.com/smf/index.php?topic=680.0

Paul

[finescalerr]

Please be sure to keep us up to date on this project! -- Russ

[SandiaPaul]

Paul,

I really like the sprue idea, but I seem to recall someone here(maybe Chuck?) tried that and the PAP folks didn't like it for some reason. Or it could be since I turned 50 last month I have CRS disease...

[Carlo]

Paul, and anyone else interested in 1:13.7 up to 1:6 scale modeling,

check out    http://www.7-8ths.info/

It's a forum for these very large scales, and is in sections by scale.
There is a contingent of 1" scale Heywood modelers, and there are some pretty good
scale modelers here, along with assorted live steam nuts, and garden train guys too.

Carlo

[RoughboyModelworks]

Thanks for the tip Carlo. There is a lot of good information available on that forum. I've been able to track down some prototype references through contacts I've made there. Haven't posted much there though, really only time enough to keep up with this one...

Paul

[RoughboyModelworks]

Carlo:

I checked out the link for Talisman Castings. Their Heywood couplers are 7/8ths, couldn't find a listing for them in 1" scale unless I'm missing something. Another company in the UK is making Heywood loco couplers in 1" scale, but they are slightly different than the rolling stock couplers. These are the people I was in contact with previously: David and Paul Bailey at DJB Model Engineering Ltd.  They also produce name plates for Katie in 1" which look very nice in their photos. Their parts are pricey, 10£ plus shipping per coupler, 20£ plus shipping for a set of Katie name and worksplates, but the quality appears to be quite good. I think at those prices, I'll do them myself...

Paul

[RoughboyModelworks]

Based on a discussion with an individual who has used Printapart commercially for the past couple of years, I made some changes to the layup file for the wheel centers. As you can see I've stacked the centers vertically, separated by approx. .060" - the lowest wheel center is raised about the same amount from the x-y plane base line to prevent any resolution problems on the lowest surface. This setup greatly reduces the overall volume of the printed piece.





I did find out that Printapart.com is part of Fineline Prototyping which specializes in industrial rapid prototyping. Essentially Printapart is a business venture aimed to jewellery designers and hobbyists used to fill in the open spaces in the printer around the industrial parts being prototyped. They have a wide range of materials available and can also colour, texture, plate, soft-touch paint the RP parts and produce clear parts.... this may be an answer to produce clear glass globes for gasoline pumps Chuck, though I expect it's a little more pricey than the regular PAP product. They can also do things like micro stereo-lithography with the ability to produce exceptionally tiny parts - resolution in the 30-40 micron range  . Exciting stuff...

Paul

[finescalerr]

Does that mean they have the ability to produce parts to higher resolution than we have seen? -- Russ

[Hauk]

Does that mean they have the ability to produce parts to higher resolution than we have seen? -- Russ

Yes. But the price is way higher.
I posted some comments on the online quoting and prices  at the end of this thread:
http://www.finescalerr.com/smf/index.php?topic=979.45

I havent gotten around to look into the matter that Chuck rises at the very end of the thread.

-Haavard

[RoughboyModelworks]

I've created another variation of the STL file for Printapart. I had been informed that since the part was actually an assemblage of multiples of the same part (4 wheel centers), a sprue and base weren't necessary and removing that component would reduce the printing cost some. I also filled in the axle holes as boring them out in the lathe will result in greater accuracy. The centers are separated by .050" and the entire assemblage is set approx .030" above the x-y axis baseline to insure accurate printing of the back face of the lowest center. The overall dimensions for the assemblage are 1.0787" dia. x 1.19117" H. The file as submitted was accepted at Printapart, no apparent errors. The print cost however is somewhat higher than I expected at $76.00 Economy (compared to $78.00 with sprue). That translates to a per wheel cost of $19.00 - such is the price we pay for historical accuracy.





Paul

[finescalerr]

I can see how the printer would lay up the resin to create each wheel but how did you devise a way to break apart the printed wheels? Does the center core thin down enough to slice with a razor? Did you create very small pillars between each wheel center? Or is there some other arcane device you concocted? -- Russ

[RoughboyModelworks]

No, nothing arcane. The wheels are not attached to each other except electronically. According to my PAP guru, the PAP process fills voids between parts with a waxy substance, supporting the part during printing. After printing they remove the bulk of this material before shipping. In this case, after removal of the wax, I should be left with four individual centers. The only reason to use a sprue would be in the instance when you are printing several tiny parts (such as Marc did on his latest venture) to prevent anything from being lost.  These wheel centers are fairly large compared to the other parts we've seen printed on the forum. How much cleanup there will be is the question, but since the wheels can be spun in the lathe, it shouldn't present a problem. Will just have to wait and see how they turn out...

Paul