The Bucket Foundry

[husaberg]

A few more.

Never trust an engineer without a Beard...........

[Flettner]

A few more.

May I comment?

[Michael Moore]

Neil, I'm hoping you will. We want all the "it would work better doing it this way" comments we can get since we have very limited experience. We'd rather leverage other people's experience which is why it has taken a year of studying to get to this point.

The one that wasn't so nice may be due to Jeff putting a bead of paste across one gate. It wasn't sealed off but it was choked. You can see the groove on the gate in the one photo. The other photo shows a bit of variance on the surface of the fin which is actually quite smooth on the pattern. The others don't have that, and the surface isn't quite as nice. Could that be a "too hot" issue?

cheers,
Michael

[Flettner]

Neil, I'm hoping you will. We want all the "it would work better doing it this way" comments we can get since we have very limited experience. We'd rather leverage other people's experience which is why it has taken a year of studying to get to this point.

The one that wasn't so nice may be due to Jeff putting a bead of paste across one gate. It wasn't sealed off but it was choked. You can see the groove on the gate in the one photo. The other photo shows a bit of variance on the surface of the fin which is actually quite smooth on the pattern. The others don't have that, and the surface isn't quite as nice. Could that be a "too hot" issue?

cheers,
Michael

Hey, we are all learning. Two things, those molds look far too nice I'm a bit ashamed of mine now. Second, I imagine that the runners should fill the head along the fins not across as you have done (heads at 90 degrees to what they are now). I think I remember my 350 heads I cast were run that way, along the fins. Finish is a funtion of sand surface, you might have damaged the surface slightly taking the pattern out or perhaps the sand mix was not quite as good in that spot?
The short run in the last head, temp dropped too much by that time? I dose look like a cold short. Do you use magnesium powder on the risers after pouring?

[Michael Moore]

It is hard to tell but I think my Webco CT-1 head was gated from the ends (at the base, not the end at the tips) of the fins. Since Jeff has his patterns screwed to the match boards we'd already discussed rotating things 90 degrees to feed from the ends of the fins the next time we try pour some heads.

We didn't have any exothermic or insulating devices. Chastain's book talks about making plaster risers/sprues to help insulate the metal there from the sand and we will probably try making some of those. I've seen that even putting an insulating board on top of the sprue/riser can be a help in reducing radiated heat loss, maybe a piece of sheetrock would work for that, and I've got some scraps on hand to try.

There are jacking screws at the four corners of the flasks which made it much easier to pull the patterns. But I don't think Jeff was fully withdrawing the pattern with them, just bringing it up an inch or so and then lifting it off, so he may have scraped a little on one of them. I think some alignment pins in conjunction with the jacking screws would be a good thing to have.

The ChemBond mixes very easily with the sand. You mix the catalyst with the sand first then add the binder and mix some more. It doesn't start to set right away and the sand is free-flowing. It gives a much more even cure than the CO2/NaSiO2 we tried, and eliminates keeping another gas cylinder around.

What have you found is a good minimum thickness on a hard sand mold? 1" or closer to 2"? It would be nice to not use more sand than is really needed.

thanks for the comments,
Michael

[Michael Moore]

I just finished making 120" of cylinder head fin stock for my Yamaha 175cc race head pattern.







The draft angle is 1.4 degrees per side. It was taking 2:30 minutes per side of machining time X two sides per 8 pieces and about 2 minutes to swap a part out or flip it over and reinstall it. I could have eliminated nearly 1 minute per side if I'd put my bowl router bit in instead of the ball end mill, as the face mill needed to take a second pass about .15" wide. The flat center of the router bit would have taken care of that, and also saved me the minute per side of sanding needed to knock down the small cusp between the two tools. I'll modify the code to use that router bit and then it will be ready to go the next time.

I'm already hating fine sawdust. Even with the shop vac held right next to the tool I could still see plenty of sawdust floating around (and bigger dust sitting on the mill).

Once I got going it went pretty quick and I know what to do the next time.

cheers,
Michael

[Flettner]

Thank you, I'm interested in your head pattern construction method. I was thinking of somthing similar to build an air cooled cylinder (for my F9 Kawasaki) . My air cooled heads have only been copy cast from originals with the combustion space filled up.
By the way your head castings look great, get them heat treated and they will machine real nice.
The finish on my copy cast heads are certainly no better than your castings, you've done a good job.

[ken seeber]

MM,
Gotta agree with Fletto...great patterns and that I see a cold shut. Either from pouring too slow, temps too low or less than ideal ingate flow direction.
We measure melt temp with an immersed ceramic sheath with a Type K thermocouple down the inside. This then going to a temp controller. All cheap stuff really. I'll take some pics tomorrow and post them.
As to heat treatment, we go for 8 hours for both the solution phase and another during the aging. As this is for pistons that are relatively light and with thin section, I do wonder if we could reduce the durations. Something to follow up. I guess one gets to a stage if it works, then don't stuff it up especially given that any possible gains from changes might easily be outweighed by the loss of a batch or part failure in the field.

[Michael Moore]

Jeff put a lot of work into those head patterns. But then neither of us is a woodworker so we're having to learn to deal with wood along with everything else.

There's some photos in

http://www.eurospares.com/graphics/metalwork/foundry/

that show Jeff's CAD model and the fins being done before gluing them together into the head.

The Webco head seems to have been designed to be easy to make the pattern. There is pretty much a flat surface at the base of all of the fins, with just a lump in the middle for the spark plug. The stud nut seats are lightly countersunk into that surface. That plane is raised enough to allow some finning on the underside. My OEM Yamaha MX175 head has that plane near the gasket surface and so needs bosses for all the studs as well as a much bigger lump for the outside of the chamber and the plug. Jeff's head is more along those OEM lines.

We've got immersible t-couples and have been using them in the melt. I think that one head was mostly due to the gate being choked by the paste. If anything they were all poured a bit hot.

Jeff needs to make Kawa F3 cylinders that don't break the base flange off. They have cast-in supports between the fins and he realized that could be done by drilling through the hardened sand after pulling the pattern. We were having a hard time figuring out how to pattern that until he saw that it didn't need to be part of the pattern.

cheers,
Michael

[Flettner]

Thanks Michael, I'm in contact with Jeff now. It would be good to post the F3 cylinder build project on here,

[AndreasL]

This is very impressive work done by you all!

"Simple" but still so much of a success is in the details. Like a 2 stroke more or less.

Tempting, but glad I haven't tried myself.
Many hours of hard work behind a finished part.

Keep posting! It's very interesting to follow your progress.

[husaberg]

Jeff put a lot of work into those head patterns. But then neither of us is a woodworker so we're having to learn to deal with wood along with everything else.

There's some photos in



that show Jeff's CAD model and the fins being done before gluing them together into the head.


Michael

Michael your friend Jeff, is this him here?http://www.highwaymanbikes.com/ I have linked some of his work before.

[Michael Moore]

Yes, that's Jeff's website.

[Flettner]

Quick trip up to Heat Treatments thismorning to pick up the cast parts, all ready to machine now in T6 state. Ken I'll get your parts in the post Monday.
The different colours? Some parts are LM13 some CC601 and some LM25.
If the weather plays ball I'll have another cast tomorrow. Nearly out of CC601 I see, didn't realise I'd cast that many parts.

[Yow Ling]

There is foundry work in here, the gentleman who produced all this work died last week. His work is pretty amazing, engines models and wimsical things http://birkpetersens.blogspot.co.nz