Clearly, a Penn 49

[oldmanjoe]

 

[oc1]

One thing that i see is the use of a pressure pot to help eliminate air bubbles. 

Wow, thanks Joe.   I've never seen resin foam like that under vacuum but have never seen a thick casting that big cure without getting too hot either.  It's time to find that old pressure cooker.  It's here somewhere.  If I don't report back then come scrape me off the walls.
-steve

[oldmanjoe]

One thing that i see is the use of a pressure pot to help eliminate air bubbles. 

Wow, thanks Joe.   I've never seen resin foam like that under vacuum but have never seen a thick casting that big cure without getting too hot either.  It's time to find that old pressure cooker.  It's here somewhere.  If I don't report back then come scrape me off the walls.
-steve

I don`t know if i trust this , but here it is
 

[Crow]

Interesting !  That's what I had figured on using for a vacuum chamber .

[Gobi King]

the pressure chamber which looks like a pot, what is that?

neat way to get em bubbles out

[jurelometer]

Great progress!

I think the sideplates are pretty good already.  I seem to remember seeing photos of the clear Newell sideplates and knobs that had a bubble or two.   But  if you want to press on in the pursuit of perfection,  here  are a few more points to consider:

1. Using a pressure chamber for casting does not remove bubbles, it just compresses the bubbles that are there to make them smaller, resulting in a part full of bubbles of highly compressed air.  The mechanical properties of the cured resin, wall thickness, the amount of trapped air, and how transparent the final part may be will determine whether pressurizing is a good idea or not.  the upside of pressurization is that the resin will not boil out of the mold, but everything else is downside.

Pressurization is popular for doing stuff like casting opaque mini Star Wars action figures.

It sounds like you are not that interested in pressurized casting, but since the topic came up, I thought that I should mention these caveats.

2.  Boil over under vaccuum has to be planned for by providing enough capacity to contain the resin during the boiling period. I haven't used a vacuum chamber for casting myself, but I have been told that if the resin does not set too fast, boil over can be minimized by slowly ramping up the vacuum, instead of cranking it up to 28 right away.

It is also recommended  to have a clear window into the vacuum chamber to observe the process. 

3.  Using the wood mother mold as a sealing surface is a problem.  It helped you to minimize the amount of silicone needed, but you will have a problem getting a good seal.   Better to have around 3/8 inch of silicone past the edge of the part. Once the mold is clamped, you will have a good seal.  You can also build the alignment pins/ holes into the mold.  A good seal also helps deal with resin shrinkage during cure, as more resin will be drawn into the mold from the sprue  instead of air from the seams.

4.  If you go the gravity route:  All gravity molds fill from the bottom.  Pouring into the top of the part is convenient and works in many cases,  but the resin has to get from the top of the part to the bottom  without entrapping any air, which is difficult for thin wall parts or parts with overhangs.   For these type of parts, it may be better for the resin to slowly enter from the bottom of the part and drive air out the top.  The sprue goes down alongside the part, and then underneath the part to a gate ( channel) that enters the part from below . The diameter of the gate restricts the filling of the mold  to allow the level to rise slowly  and allow the mold to fill without turbulence.

The ideal sprue/gate design creates a reservoir underneath the gate(s)  that will fill easily without turbulence, so that you do not introduce bubbles when filling the mold.   Gravity molds can  include risers (I think that is the right term), which are sort of vents to nowhere.  Risers allow a place for trapped air to go that cannot make it to a vent. 

The downside for this type of mold is that it requires a much larger mold relative to the part size.

5.  Using a large syringe to pressure inject a mold is a neat trick that I have used,  but extra pressure can   generate more turbulence (turbulence causes bubbles),  so the gate design has to be very good, and/or you must inject a large amount of extra resin into the mold to push out  all off the resin that may have trapped air.   I prefer to use the syringe for vaccum assist to help pull the resin into areas of the part that are too small or thin walled to fill easily.  This is much easier for controlling turbulence.

6.  The bummer is that the casting technique used determines the  sprue/ gate design, which determines the mold design.   A change in casting method usually means a new mold.  Switching over to a smaller reel to save on materials  might be a good idea until you hone your technique. 

Thanks for posting your progress!  This is much more interesting and useful than a just a final result.

-J

[Ron Jones]

I have wanted to see this happen for years. Started going down the rabbit hole myself once. My reasoning is a bit different, though. Theoretically, if you get this working, you can cast the sideplate of two reels and swap centers to make a new gear ratio assuming the pinion fits (they swap on a lot of reels.) You could end up with a 49 with Jigmaster guts (I think,) etc. I hope I am making myself clear.

This is awesome

The Man

[Crow]

  Some good points, there, Jurelometer ! I'd already started puttin' on the thinkin" cap about "filling from the bottom".....I figured that the mix...trickling in from the top...was causing extra bubbles, but I HADN'T thought about the syringe causing turbulence ! By using a "long sprue" (or fill port), the mix would also have a lot better chance of "shedding bubbles", before actually entering the mold.

   Ron, I see what you're getting at.....a plate could be "modified"...using whatever methods were needed (grinding , cutting, and gluing back together, to get the correct clearances , then used as a "master> to make a mold to cast a "finished, one piece plate ....I'm only jut beginning THIS project...and I *smell* another , coming right behind it

[oldmanjoe]

the pressure chamber which looks like a pot, what is that?

neat way to get em bubbles out

It is a pressure cooker, something like this.
     https://www.walmart.com/ip/Presto-Aluminum-6-Quart-Pressure-Cooker/931856