Engine detailing: Thinning parts (fan belts, fans, etc.)

[jean-lloyd]

Hi all

So, I've been getting more into detailing my engines to look more realistic. Obviously, the injected mold parts in most kits leave a lot to be desired.

I'm working on thinning the fan belts in order to make them look better in relation to the pulleys and such. Also, the fans that come with kits are always way too thick in scale. 

I've been having decent luck with just using a triangle needle file to thin the belts out, although it dawned on me tonight that I should also be thinning them down from the outside of the belt as well, to show a little bit of inset in the pulley groove. 

Thoughts, ideas on better/faster ways? Also, thinning down the cove area between the belt and the pulley gets tricky. I've been just using a sharp #11 blade to 'notch' out a sharp triangle after thinning the majority of the flat, but that gets really dicey.

Here's an example of one that I'm working on, still attached to the sprue (the left side of the belt is thinned, the right is still stock). I haven't cut it away yet, and I always get a little sketchy about which part to nip through first so I don't compress the thinned belt to the point of breakage, but that's easy enough to figure out after a couple of "OOPS!" tries. lol

Any helpful input would be much appreciated, thanks!

 

Edited July 13, 2018 by jean-lloyd

[BubbaBrown]

Some guys just cut the belt off and use narrow masking tape thats been hit with black magic marker.

[landman]

I use some very fine styrene strip. However one has to be careful when bending it.

[Exotics_Builder]

I will usually replace the belts, but have, on occasion, used a Xacto No. 11 to scrape the belt to make it thinner.

[BigTallDad]

You can make your own fan belts

http://www.modelcarsmag.com/forums/topic/102506-fanbelt-tutorial/

[Casey]

15 hours ago, jean-lloyd said:

Hi all

So, I've been getting more into detailing my engines to look more realistic. Obviously, the injected mold parts in most kits leave a lot to be desired.

I'm working on thinning the fan belts in order to make them look better in relation to the pulleys and such. Also, the fans that come with kits are always way too thick in scale. 

I've been having decent luck with just using a triangle needle file to thin the belts out, although it dawned on me tonight that I should also be thinning them down from the outside of the belt as well, to show a little bit of inset in the pulley groove. 

Thoughts, ideas on better/faster ways? Also, thinning down the cove area between the belt and the pulley gets tricky

You've got all the info you need to be honest. It's a tedious process, and getting the belt between the pulley lips recessed just enough (and evenly) is the really tricky part, but that detail really makes all the difference. Most of the recommended methods gloss over this important and very visible detail, so I think it's very much worth the extra time and effort to get it right. Just make sure you don't break the (now) super-fragile belt. 

I've only made it one-third of the way through thinning this one, so we'll see who finished first. 

[FredRPG]

Don't forget older fan belts were just as thick as they were wide and the cross section was tapered towards the inside.  These were on any car that had a standard deep groove pulley, unlike the modern grooved pulley with flat grooved belts.

[jean-lloyd]

Great info, Casey and Fred!

Casey, your point about recessing between the pulley lips is exactly what I was thinking as well. It seems like all of the kits I've ever worked on, the belts run flush with the outer radius of the pulleys (if not even proud of the profile!). I've been looking through my needle files to find something that has the right width to be able to mill around the outside of the pulleys and give that recessed look. I think I have a couple, but will need to experiment with them a bit. I've also been wracking my brain to figure out how to micro-mill something like the back of a #11 blade to add some tooth that could consistently remove material without compromising the circular integrity of the pulleys. 

If I were brave, I bet I could use the outer edge of a thin Dremel cutting/sanding/grinding wheel, but even at low speed, that would take a monstrously steady hand.

Fred has a great point as well, the older v-groove belts (vs. the modern serpentine, wide/flat belts) were often deeper than they were wide, if not merely a 1:1 ratio. That means that along with thinning the belts, for complete accuracy, we should be narrowing them at like a 60-70 degree angle from the outer width to the inner width.

I picked up a couple of different X-Acto blades this evening to help with cutting down the coves between the pulleys and the belts. 

As I get older, I fear that I've been gaining a greater understanding of the need for those bench lamps with the big magnifying lenses attached to them. 

I'll post more pics and thoughts as I practice and play more with building accurate belts.

Thanks to all for the helpful replies!

Edited July 15, 2018 by jean-lloyd

[MrObsessive]

This is a bit time consuming, but here's a cheap way to make pulleys and what I use for realistic belts.

If you go here and start with pic #122, I go through a mini tutorial with my Shelby buildup on how and what to use. Just another thing to consider if you're not happy with the kit's molded in belts and pulleys.

Edited July 15, 2018 by MrObsessive

[MeatMan]

9 hours ago, MrObsessive said:

This is a bit time consuming, but here's a cheap way to make pulleys and what I use for realistic belts.

If you go here and start with pic #122, I go through a mini tutorial with my Shelby buildup on how and what to use. Just another thing to consider if you're not happy with the kit's molded in belts and pulleys.

Excellent tutorial Bill, thanks for sharing it!

[Flat32]

What about the fans? How does one improve a kit fan?  How do the scratch builders make them?

[Casey]

13 minutes ago, Flat32 said:

What about the fans? How does one improve a kit fan?  How do the scratch builders make them?

It depends upon the type of fan, but since most are stamped from thin metal, replacing them with photoetched or handmade, then assembled, pieces of scale thickness metal would be ideal. The aftermarket flex-blade style are available from the aftermarket, but you might have to hunt a bit to find a specific factory style fan.

[Flat32]

Examples are shown for belts and pulleys.  Any examples of the various ways for fans? Really most interested in seeing detailing what came in the kit box more than what you could replace it with like photoetch, resin cast or 3D printed.

[Casey]

23 minutes ago, Flat32 said:

Examples are shown for belts and pulleys.  Any examples of the various ways for fans? Really most interested in seeing detailing what came in the kit box more than what you could replace it with like photoetch, resin cast or 3D printed.

What makes the kit-supplied fans unrealistic to you? Usually the blades are a bit too thick, so thin the edges of each blade with a file or sanding stick until they look correct to your eyes. If you're limited to using the kit parts, you can only thin the blades so much and still maintain enough strength. Try it and post your results.

Just to note, most modern era (~'90+ or so) kits have fairly realistic fans, with thinner (and often tapered) blades compared to older kits, so sometimes sourcing a fan from a more modern kit of a similar make (say Revell's '68/9 Charger R/T fan to use in place of a Monogram '70 Dodge Challenger T/A fan) does the trick.

Edited December 30, 2018 by Casey

[Flat32]

My primary model subject interest is Flathead Ford V8 engines and scale accuracy which I find challenging at 1-25 scale for thin and small details. Thinning an exhaust pipe is easy, but a fan has front and back equally visible in an out of the car display.  Actually my parts will be printed resin and designed to be thinned afterwards in some fashion that I imagine a styrene kit part would be thinned. In effect I have to thicken so as to be easily thinned afterward. In styrene would you sand the convex front siide or carve/sand the concave side?

[BigTallDad]

You can always make your own fan belts...

http://www.modelcarsmag.com/forums/topic/102506-fanbelt-tutorial/

 

[Casey]

11 hours ago, Flat32 said:

In styrene would you sand the convex front siide or carve/sand the concave side?

I think it would be a case-by-case situation, depending upon what each fan for each model or model year/engine looks like.

Have you looked at the Flathead parts from the Revell '40 and '48 Ford kits? Both are modern era kits with better detailed parts than the '60s era AMT and Monogram kits, but you'd need to see all the parts to decide if they'd be worth your time an effort versus using a printed resin part you (presumably) would design to your own specifications.

[sbk]

As Casey said, it depends on the model.

I think I thinned both sides on this AMT '50 Ford. I know for sure that I used small files & sanding sticks on the back side. 

 

Also, the belts on the painted version are made from 3M fine line tape with the adhesive removed, painted flat black.

 

This fan is from the Caddy engine in the Revell 1949 Merc. kit. This photo shows one blade at kit thickness & the others in the process of being thinned. All work was done on the backside of the fan with small files & sanding sticks.

 

Although it's still not as thin as it should be in scale, it's much better than straight from the box.

Edited January 2, 2019 by sbk

[Flat32]

Exactly what I was looking for.  Many thanks to all who responded.

Beautiful job on the belts too. Very nicely detailed spark plugs and acorn nuts, but there are a few nuts missing.  Should be 24 of them. Carbs are recognizable as Holley 94's and that's a mighty fine fuel pump.

[rsxse240]

Belts from the Detroit diesel I built in an AMT GMC Astro 95.