Patterns

[Trainman4602]

Just my production for last week
Patterns.

The front frame spreader two molds from original made by Charlie Pipes finished by me. Molds for them and duplicates mounted and gated. ready for the foundry.

I also managed to make a brake cylinder pattern with the front and rear heads. and a cross head for the 0-4-0 camelback along with the core box for it.

I have been turning out patterns for the camelback. I will slowly bring it back.

Take note that I use filler blocks to reduce the amount of repro I need to fill the mold at $87.00 per gallon you dont want to waist it. These molds took the whole gallon unit. I managed to get the two patterns for the front and two brake cylinders and four cross heads with the core box.

When I buy the repro I usually get two gallons units. This saves me one has mat charge.

[Pipescs]

Awesome Dave.

Can't wait to see the part. This was the last hurdle in being able to bolt up the frame members.

[Pipescs]

Tried it, Liked it.

Wanting to be able to cast the journal box covers two at a time without having to make individual molds. Expensive to do this for the amount I will eventually cast but really I just wanted to try it.


Built my mold box out of a piece of old Cherry Wood I had. The part and box are brushed with a wax provided by BCC. It comes in a quart size can so it will last me a life time.

Used the traditional Solo Measuring Cup.

No Waste this time around.

Followed you lead in that I popped the master out while the Kwick Kast was still pliable. Then laid it out on the Surface plate to dry flat

Am planning on drilling a hole in the box lid area on the mold to be able to push the parts out with a dowl. Is 3/16" rod big enough or should I go to 14"

[Pipescs]

Morning Dave

I assume you wax the mold for every part you make.

Also do you push the part out while it is still soft or wait until it is hard?

Hope to try this today.

[Pipescs]

Drilled qtr inch hole in the pattern area that will be machined out later. This to be able to put a rod thru to knock the piece out of the mold.

Waxed up the mold and poured in the plastic. Thirty minutes later even though it was still pretty soft I pulled it out to finish drying up on the surface plate.

Lesson learned: When people that have been in the hobby longer than you give advice you will save money and time following thier guidance.

(NOTE for Fender and Trainman that I did not say old guys or old timers, Just senior members of the group)

[SteveM]

Lesson learned: When people that have been in the hobby longer than you give advice you will save money and time following thier guidance.

You can learn from your mistakes, or from the mistakes of others. The latter is much less expensive.

BTW, nice work both of you.

Steve

[Trainman4602]

Looks good Charlie

I usually wait until the repro starts to get warm. That’s the reaction of the chemicals.
If you pop it out to soon it can get distorted. It will take a set and be ruined.

Try putting some filler blocks in the mold frame. BTW you don’t have to remove the frame I generally leave them on. Also you only need to have about ¼ of an inch around the pattern edge and about ½ inch above the highest part of the master. This will also help cut down on repro usage.

[SteveR]

Thanks guys for a very interesting thread. What are the original patterns made of? They look like plastic, but they could be made of anything, correct?
Steve

[Pipescs]

As you can see by my work I am a beginner at this.

The frame spreader was originally made from Plywood. I grew frustrated with it as I had made the parts straight sided thinking I could add the draft later with Bondo.

Dave tells me this is a common mistake by beginners. I had grown frustrated with the pattern and Dave asked me to send it to hem where he spent I am sure many hours fixing it.

It would have been beter to have started with the flat plates out of plywood but to have added each vertical piece with the draft already cut in.

Patterns can be anything based how long you want it to last. My most successfull ones have been plastic

There are many books out on the enternet that cover patternmaking from the 1920-1940 period. Make for good reading. Dont try and reinvent the wheel

[steamin10]

In patterns it is the shape, filleting, and draft angle for successful pulls. Machining wood can be tiring if you aren't a cabinet builder, and wood maybe the standard for most one-off projects, but a slick pattern of plastic of whatever type works out to be supperior in life and copying abilities, if made correctly to begin with. By eliminating the bad variables of breakage and draft in the first place, you go down a long road to success, in consistant castings.