GI: Crank Journal Brace for FE engine

[FE3-323]

[mx-3_4evr]

I might be up for one of these in the future

[STW]

Okay, after clearance issues and design evolution, the final form is taking shape. Now it's like this:



There might be tiny adjustments here and there, but nothing too great.

There are few issues I must point out:

The fins in an aluminium sump needs to be cut 10mm lower at the width of 150mm;

The oil pickup needs modifying. I originally planned the brace to have a cutout to clear the pickup support, but it turned out the cutout would have to be so big the integrity of the brace would be compromised and it would make both casting and machining the piece more difficult. Thus I decided it would be better to modify the tab of sheet metal instead. I hope this isn't an issue with anyone.

The shape is now symmetric. It saved a bit of weight and IMO made the piece better looking.

The weight now is 1.4 kg (3 lbs).

[STW]

I got the price for machining and casting, and they were reasonably close to what I expected. However, and this part sucks bigtime, since I pay by €uro, the exchange rate did a dirty trick on my cost estimation. The part will cost about 130€ without shipping and duties. Thus the part price generously overshoots the $150 estimate I first gave, it's $185. (130€) Shipping through mail will make the final price tag to 235$. If i can find a cheaper method for shipping, I will use that but 235$ is the price I'm set on unless I can go lower.

[therieldeal]

IMO for what you are making here, that price is still extremely reasonable. nice work!

[jesiotrot]

We'll take 2 shipped to Aus, how much????

[STW]

Aus (and NZ) has a bit higher shipping fees than europe and north america (but not as high as africa and antarctica!) so the set of two should be between 370-380€.

[STW]

Alright, here's the update on what's happening with this thing:



Got some rapid prototype parts for the brace. These are patterns to make patterns... I will take five resin copies of each half and build the mold pattern around those. The top half will be embedded into the pattern base, the final cap won't be 35mm high! The bridges connecting the caps will be assembled from individual pattern pieces, this allows some last-minute adjustments if necessary.

[FE3-323]

looks like progress

[STW]

Due to circumstances I've been forced to postpone on the production of this item. I'm very sorry about it but I'm expecting improvement in April-May, so if anyone's interested by that time, feel free to contact me at later time.

[FE3-323]

STW, i've been following as much as i can. understand Just come back & let us know updates as things come along

[STW]

I'm hopeful mys ituation with this project gets better soonish, here's a recap and disclosure of what's happening.

Here's the finalized shape, I only adjusted it a tiny bit since:



A wooden mockup was used to check clearances on the brace:



The 94mm crank has no clearance issues.

The methos of production is sand casting. The method requires patterns from which the sand molds are pulled. The construction of the patterns is wood and plasti, here's a look how they look in CAD:


The base material is plywood. Two 12mm sheets are used for stiffness, the patterns for stringers are pinewood. The more complex parts forming the bridges over bearing caps are made with cast resin parts. Here's where they're at right now:

First, a master pattern was created. I got some SLS parts at our office as "samples", they came out looking like this:




SLS method leaves a bit rough surface, I smoothed it out a bit with primer and sanding.



The holes were clayed up, because it would later hinder the copying process.



The part was attached to the bottom of a mold box and sealed with modeling clay. A cabinet tray served well here.



Pouring in the mold RTV silicone. It's very important the part is anchored, otherwise it may start to float in the silicone and the batch is ruined.



And here are the molds. The white mold was a sort of disaster, I had put too little catalyst in the silicone and it took four days to cure. When I removed the "bottom" part, the silicone gave way and broke (you can see it's distored in the white mold). Thus I had to do the red mold.



Clear casting resin was used to obtain five copies of each bit. They need to be finished by sanding each to exactly the same size, and the to be attached on the mold. A keen eye tells the design on the "top" bit (the one that seats against the cap) got changed a bit in design. This is to increase strength and help with casting. The original shape was due to having the fifth bearing cap as reference, and that has a protrusion that needs the extra clearance. Obviously the clearance needs to be cut for the fifth cap before finishing the patterns.

So, I'm not quite done with the patterns, but not too far behind the "schedule" either. I'm pretty sure once my financial issues get better, my patterns will be ready for production.