# Making a 10cc Whippet pattern



## bmac2 (Jun 15, 2015)

* * * WARNING! * * *
If you are looking for a fast paced, exciting thread that ends with a great model engine making that iconic first run . . . this isnt going to be it. This is going to be about trying to make the pattern and about as fast paced as watching paint dry. But it may have molten metal, sand, clay, smoke and fire!

Ive been messing around with casting for a few months now and for the last while Ive been concentrating on pattern making. I got inspired by fourstrokes (Dougies) Side Valve Engine build (http://www.homemodelenginemachinist.com/showthread.php?t=24250) and thought it was time to to try casting some engine parts. Reading Dougies thread (a few times) has provided me with answered to some of the problems I was having getting my head around the patterns and the cores.

I started working on a set of patterns for the 10cc Whippet. Id seen copies of the plans on the internet and liked the engine but most seemed to be missing something. I guess this all started when I realised I had the original articles in Model Engineer No. 3221 to No. 3228. I have seen Whippets built from bar stock but these are inevitably people with CNC equipment and that is just never going to happen in my little shop without a Lottery win. This left either ordering the castings kit, £118.50 to £189.00 ($227.00 to $362.00 Can.) or making my own castings. Ive read more than one build article where they mention the castings where not great having soft or gummy spots. I thought I can probably make my own bad castings so homemade it is. The added benefit is that if/when I mess one up I can toss it back into the pot and just make a new one.

One of the first challenges I ran up against was that the drawings and construction notes assume you are working from there casting set so a lot of the external dimensions are not given. The only way I could think of to get around this was to model everything that had dimensions in CAD, so basically all the working parts.


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## bmac2 (Jun 15, 2015)

Turn that into a solid lump and subtract it from a solid block. Assuming a wall thickness of 3/16 I then carved out the areas where the drawings didnt give any measurement. There is probably a way more efficient way of going about this but hey its a hobby and its not like theirs much on TV.


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## bmac2 (Jun 15, 2015)

Damn those electrons are free machining. A couple weeks of fit, fiddle and adjusting and I finally ended up with this.


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## bmac2 (Jun 15, 2015)

By overlaying this pattern with my original drawing of the innards I could see that it just might work. It was time to make some chips, wood chips.8)


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## Swifty (Jun 15, 2015)

Off to a great start Bob, I will be following your progress.

Paul.


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## Blogwitch (Jun 15, 2015)

You are quite right in making the castings yourself.

I built one from the original casting sets, and after reading what trouble people had with the new ones from Hemingway, nothing had changed at all besides them saying that it had been remastered. Exactly the same problems were found with both old and new.
The engine looks filthy in these pics, but it had just had an hours running in and hadn't been cleaned off.











If I can help you in any way with your build (not the casting process), then ask away and I will see if I can remember anything about it.

One of the major failings with the castings was with the head area, if you drilled down using the dimples provide on the castings, the holes ended up going into the cast iron sleeve, plus on mine, I had to deepen the heart shaped squish area by a fair amount, otherwise the valve heads hit the inside of the head. I used a bit of blutak on the valve heads to make sure I got the correct clearance after machining.
As you are making these yourself, double check the drawings and strokes, just in case.


John


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## bmac2 (Jun 16, 2015)

Hi Paul. It might get dusty but welcome aboard . . . get it . . . Its a marine engine . . . sorry.

Thank you John. I think its going to be a while before I start building anything. Your Whippet looks great and dont apologise for an engine with some dirt and oil on it. If we all wanted pretty, clean, and shiny engines to sit on a shelf plastic model kits would be easier and cheaper. I feel that it a great shame that the Whippet engine seems to have a bad reputation for poor quality castings. In the videos Ive seen of the Whippet it looks like a good, solid running little engine. The Model Engineer magazines I reading are from 1963 and when I think about the size of the RC equipment available at the time it probably would have been a great choice for a lot of boats. Back then people had real skills and hobbies. Being water cooled It could have been a real contender. Of course now kids just download the app.

_ Yo Kidz! That app isnt going to do you any good after the zombie apocalypse, youre going to need real skills!_ *knuppel2*


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## bmac2 (Jun 16, 2015)

My first crack, Pattern 1.0 was an attempt at making it using MDF. The idea was to sandwich two pieces together and just carve it out. This was a total failure and I feel its best for all if we dont speak of it again.


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## bmac2 (Jun 16, 2015)

Pattern 2.0 was done the same way as the first attempt but this time using pine.  The pine was better but still just wasnt going to work. The grain in the pine is just too coarse. For a different type of casting this would be great but for this engine the concept is just wrong.


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## bmac2 (Jun 16, 2015)

So this past weekend I got going on attempt No 3. Went back over Dougies build and looked at the pictures of his patterns. Also went back and looked at the thread Making a set of Wallaby castings by jasonh (http://www.homemodelenginemachinist.com/showthread.php?t=23701). I saw both are built up more like a layer cake. Ive never made a layer cake, but I have eaten one. Spend some quality time with my CAD slicing it up and I now had a plan I think will work.


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## bmac2 (Jun 16, 2015)

As it turns out I only need three thicknesses of wood so after selecting some clear(ish) pine I planed it down to what I needed. The Blue Beast wont do a thou but it can do 1/64. The Ear guards? Oh ya, this thing is my revenge on my neighbours 72dB air conditioner.


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## bmac2 (Jun 16, 2015)

I ripped the stock down the middle and glued them back together with a strip of newspaper. Treating this more like a scroll saw project I glued the patterns to the wood using the dark line of the newspaper to line up on the center line of the patterns. Then I just roughed them out on the bandsaw.


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## bmac2 (Jun 16, 2015)

I drilled a ¾ hole using a forstner bit at the center point of each of the four top pieces to help with alignment then I took them down to the pattern line on the belt sander. I might have to redo the part (middle right) that will be where the timing cover mounts. Its a loose piece or ram-up core and I have to be able to remove it after molding. 
I havent tried this but I read about it once in a book. Thm:


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## bmac2 (Jun 16, 2015)

Im pretty happy with this one. Stacked up loose it looks like it just might work.

Thanks for looking in.


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## fourstroke (Jun 16, 2015)

Looks good so far Bob, hi build auto primer will help hide the wood grain

Dougie


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## Blogwitch (Jun 16, 2015)

Before going any further, I would suggest you read up on this site. There are corrections for dimensions for faults in the engine that you might already be incorporating without knowing it.

Go to this page

http://modelenginenews.org/index.html

On the LHS about half way down, you will see a search button, click it and then enter 'Whippet' in the opened box.

On the generated results, about half way down, click on #19. This will take you to the start of the build. Go to the top of that page and on the LHS you will see 'whippet index' , click on that and you can then access all about it.

I just don't know how to get a link to take you straight to that page, maybe someone else can show a way.

John


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## bmac2 (Jun 16, 2015)

John thanks for the link I'll check it out.
Man I hate typing on this I-pod


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## Blogwitch (Jun 17, 2015)

Worked it out, this should now get you there more easily

http://modelenginenews.org/projects/whippet/index.html#toc

John


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## bmac2 (Jun 18, 2015)

Thanks Dougie 
Picked up a can of the Scratch Filler Primer (same stuff) at good old Canadian Tire the other day and tried it out on some different wood scraps. Ive got to say Im impressed. Ive only used regular oxide primers before and can think of a couple of other places this would come in handy. Thm:


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## bmac2 (Jun 18, 2015)

I got time to make up a split dowel to replace the solid one I was using for alignment. Attempts to rip a dowel on the band saw using V blocks and a couple of jigs I saw on the internet just werent giving me what I wanted. Also the guy at the plant in China that made the ¾ forstner bit I used must have a deal with a guy down the block making digital calipers because its a bit oversized. 
In the end I ripped two 1 strips from the wood Id planed down to ½ and glued them together. The newspaper creates a dark line at the glue joint so its easy to center it on the lathe. Turned it down oversized then used a sanding block to take it to + ¾ I wanted. This turned out to be way faster and a lot more accurate than trying to rip a solid dowel. 

_What a riveting thread . . . Ive made a stick!_


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## bmac2 (Jun 23, 2015)

I got the pattern for the loose piece worked out (I think) and got everything glued up. All thats left is to form the fillets on all the edges and sanding so I have no sharp corners. The glue has set and the little beast is starting to look like something. I must admit Im tempted to pour the block solid but I just see nothing but shrinkage problems and this is supposed to be my exercise in pattern making.


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## bmac2 (Jun 23, 2015)

In CAD this was easy a few round bits on a basically square bit. Now Ive made the jump from the cyber space onto the meat world and things got difficult. I need to make a negative mold to get a positive cast of the sand core so Ill have the correct negative (hollow) in the engine casting. This is what I want to end up with.


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## bmac2 (Jun 23, 2015)

You just have to love the warm feel you get from real wood siding, and stain, and ladders. Despite that I got a chance to sneak away from painting the house over the weekend and got some work done on the core mold. Coming up with a plan for the basic mold shape was piece of cake. Coming up with a plan for a mold the correct size that Ill be able to get the sand core out of . . . without breaking it, was a different ballgame. After slicing it up in CAD for the last week or so and I think I have a plan thats worth giving a try and got some wood sized and cut down to what I needed.


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## bmac2 (Jun 23, 2015)

Then I temporarily glued everything up and checked that it was sitting square so I could drill a pilot hole through everything for the cylinder and water jacket.


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## bmac2 (Jun 23, 2015)

Split it up and drilled out the holes, ¾ for the cylinder and 1 ¼ for the water jacket. Then I cut out the opening for the body of the core on the bandsaw. The cut where I entered the block I filled with a small strip of wood veneer. Cleaned the residual newspaper off everything with the belt sander and glued it back together.


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## bmac2 (Jun 23, 2015)

Once the glue was dry I split the mold and gave it a quick cleanup. I think that once I had a plan actually roughing out the pattern didnt take long at all. What takes time was coming up with the plan . . . and watching the glue to dry. 
Looking at it really makes me want to melt something :noidea: but its nowhere near ready for that yet.


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## bmac2 (Jun 29, 2015)

Blogwitch said:


> Before going any further, I would suggest you read up on this site. There are corrections for dimensions for faults in the engine that you might already be incorporating without knowing it.
> 
> Go to this page
> 
> ...




AAaarg! So close! 
Blogwitch I should have read that article (more carefully) before I started the core. 
I remembered seeing it a while back and thought I was using the corrected measurements, but I missed this one. 
Oops.:shrug:


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## bmac2 (Jun 29, 2015)

Its Just as well. I dont think I had allowed enough for the surfaces that have to be machined. As an exercise in getting the _basic_ form right I think Ill give myself a passing grade but as far as workable pattern goes its a fail.


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## bmac2 (Jun 29, 2015)

So it was back to the CAD last week to tweak it a bit and start over. Good thing I have full scrap bin of woods and an understanding wife.

Correcting the pattern turned out to be as simple as scaling the 2D drawing up a bit and changing the thickness of some of the pieces. I didnt take any pictures while making it. If you want just look at the pictures of the last one and imagine its a little bigger.
 I did take a riveting video of splitting the pattern with a putty knife with my hand in the way. Thm:

[ame]https://www.youtube.com/watch?v=eKf3Pk56dDs[/ame]


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## bmac2 (Jun 29, 2015)

Im feeling good about this one so I gave it some paint. The holes for the locater pins are drilled before splitting the pattern.


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## bmac2 (Jun 29, 2015)

I messed up and painted the loose piece before I sanded off the edges so Ill have to get something on it to protect it. I still have to add the water inlet and the nub for the oil cap but I want to make sure it will pull from the sand before I move on.


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## Blogwitch (Jun 30, 2015)

Don't worry about it B, we all make mistakes.

What would the world be like if everything turned out perfect all the time?

But just to put a few things right about that build I pointed you towards.

I had followed it from the very first words, and nodded my head every time a mistake in the castings came to light, I had been through the same routine a few years before when I used the Woking Precision casting set.

Luckily, after a lot of bodging workarounds (even to the point of getting some metal added by welding to certain areas), I managed to get mine built and running, whereas the two that they built never did. I think it was given up on because it was such a bad job. So much for Hemingway remaking the patterns and selling good quality castings.

As far as I am concerned, they lie like a cheap Chinese watch.

And I don't think it is just Hemingway either. From the feedback I have had from various people, it is suspected that Stuart Turner are using castings as patterns, and so there are lots of undersized casting sets out there that really are difficult to make unless you are a very experienced castings modeller, and you will get no help from ST when the problem is raised with them.

Keep up the good work

John


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## fourstroke (Jun 30, 2015)

Thats turned into a really nice pattern
It will feel really good when you break your first mould and see the casting emerge
Dougie


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## Charles Lamont (Jun 30, 2015)

Blogwitch said:


> Luckily, after a lot of bodging workarounds (even to the point of getting some metal added by welding to certain areas), I managed to get mine built and running, whereas the two that they built never did. I think it was given up on because it was such a bad job. So much for Hemingway remaking the patterns and selling good quality castings.
> 
> As far as I am concerned, they lie like a cheap Chinese watch.
> 
> ...



I hope you are prepared to defend all this libelous speculation in court?

The reason why Ron Chernich never completed the write-up on the Whippets was his failing health.


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## barnesrickw (Jun 30, 2015)

I'm not sure expressing an opinion on a private forum constitutes a libelous situation.  And if so there are many, many people, including myself who are about to end up in court for posts about Harbor Freight and the like.


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## Blogwitch (Jun 30, 2015)

I hope you are prepared to defend all this libelous speculation in court?

The reason why Ron Chernich never completed the write-up on the Whippets was his failing health.

I wish people would replicate the whole post rather than just part of it, the whole context was lost, and yes, I would challenge Hemingway to come to the fore and try to explain why their castings were still no good when even Ron admitted they still had major problems, exactly the same ones I came across when I built my engine from original Woking castings.
I would challenge anyone to attempt to make this engine from Heminway plans and castings, making the parts as drawn, using no intermediate bodges and trying to assemble it at the very end. It is guaranteed 100% that it wouldn't even fit together never mind run.


John


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## Charles Lamont (Jun 30, 2015)

barnesrickw said:


> I'm not sure expressing an opinion on a private forum constitutes a libelous situation.



I think there is a difference between reporting poor service or quality and calling someone a liar, which is what Blogwitch did.

Drawing errors are ETW's, or the Model Engineer tracer's, probably stemming from trying to maintain publishing deadlines, and remembering these were mid-20'th century drawings - no CAD, no calculator, even. Hemingway had corrected the errors they knew about.

Where does Hemingway claim to have remade the patterns?

Tackling a casting kit requires care, checking things out and thinking them through - which is what makes it an interesting job. Expecting perfection from small size, small batch, sand castings is asking too much, and Ron Chernich says as much. I am (slowly) building a Hemingway Seagull, and some of the castings are not easy to get a good part out of, but I have not found it impossible.

Any supplier should be happy to replace a faulty casting. Has Blogwitch had any dealings with Stuart Turner since they were taken over by Bridport Foundry? They told me at an exhibition that they had to throw out much of the stock of castings they acquired from the run-down Guernsey business.


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## barnesrickw (Jun 30, 2015)

There have been cases where libel against individuals have gone to court for damages.  I have yet to find anything relating to a business.


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## bmac2 (Jul 1, 2015)

*HAPPY CANADA DAY/ DOMINION DAY!*





What better way to celebrate Canada Day than playing in the sand. I helped my wife this morning doing _pink_ work so Ive earned enough shop credits to go hide in the garage for a while. Thm:
This thing has to pull from the sand or this is a total waste of time . . . . fun, and a least for me educational, but a waste of time.


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## bmac2 (Jul 1, 2015)

My sand is still not quite where I want it but its what I have. Had to spray it down a bit as it has dried out since I used it last and rammed up the pattern.


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## bmac2 (Jul 1, 2015)

After carefully pulling the pattern I could see that I needed clean up the draft on the back edge and around the one foot.


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## bmac2 (Jul 1, 2015)

Worked on cleaning up the pattern and rammed it up again. It pulled better but needs a little work around the core print. Im having trouble with the green strength of my sand. It always seems that by the time I have it where it will hold the pattern its too wet.


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## bmac2 (Jul 1, 2015)

Mulled the sand and tidied up around the core print some more and tried it again. I felt confident in the pattern this time and rammed up the drag as well as the cope. The two nails are to keep the sand out of the holes that locate the loose pieces.


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## bmac2 (Jul 1, 2015)

After ramming it up I dug down to the pattern using the pencil marks on the cope. Put in the loose pieces and rammed it up again. I guess this is more like a false cope process than a true loose piece but I dont want to have to make a second core, I think it should work.


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## bmac2 (Jul 1, 2015)

Split the flask and the drag pulled great. The edges are clean and the resolution is about as good as this sand is going to give me.


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## bmac2 (Jul 1, 2015)

The cope on the other hand just fell apart. The pattern pulled ok and I have now proven to myself that my loose piece idea will work but the sand is just falling apart. Ive been thinking that I might add a bit more bentonite.


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## bmac2 (Jul 1, 2015)

This was the first time I tried a pattern in my snap flask. It works but I think its a bit small. The idea is that when I do pour I want to do at least 3 if not 4 of each so if/when I mess something up machining I can just toss it back into the pot and grab a spare. ;D


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## bmac2 (Jul 5, 2015)

After reading NameThatGreen Sand Casting Defect! (http://www.afsinc.org/files/20020203A.pdf) an article from the American Foundry Society web site, last night I decided to add 100g of bentonite to my 50lbs of sand and mulled the crap out of it. Now with the lid on tight Ill just let it sit in the sun for a day or so. . . . . . . After watching it for a while I found it just wasnt very interesting so I got started on the new mold for the core. I wasnt really happy with the first one so while going over it to correct the dimensions I made a couple of changes that I think will make it easer to remove the core. I got the wood cut to size and glued up with newspaper then mounted the patterns to the 4 pieces that will make up the bottom part of the mold. Clamped the bottom parts and drilled the holes for the bolts that will hold everything together when its finished.


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## bmac2 (Jul 5, 2015)

On the first mold I used my band saw and I think now that may have been a mistake. I had predrilled the corners to avoid having to cut the tight radius but even with the table tilted I had to file/sand the draft in the corners and I was never really happy with it. This time I opted for the scroll saw and with the table tilted a couple of degrees cut out the patterns. This just felt right. As long as I cut in the right direction I knew I would have plenty of draft angle in the pattern. I then replaced the blade with a strip of cloth emery (I hate sanding) and it was a breeze to clean up.


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## bmac2 (Jul 5, 2015)

With everything cleaned up it was ready for glue. The 1 dowel in the upper left has a taper on one end and I wrapped it with sandpaper to get the draft in the big hole for the core print.


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## bmac2 (Jul 5, 2015)

Bolted everything together and used a ¾ dowel to help align the parts and waited for the glue to dry.


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## bmac2 (Jul 5, 2015)

Once the glue was set I cleaned it up on the belt sander and split it apart. Then filleted the edges in the area that makes up the water jacket with a _five-point-trowel_. 
With a bit more sanding it was ready for paint.


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## bmac2 (Jul 5, 2015)

All painted up Im feeling pretty good about this one. Once the paint has dried for a day or so check it with some green sand. If that works it should be no problem with a sodium silicate core.


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## Swifty (Jul 5, 2015)

Really looking forward to you pouring these castings, I've got my fingers crossed for you that it will all come out OK.

Paul.


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## RichD (Jul 5, 2015)

Looks good to me. I'm learning. Thanks


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## bmac2 (Jul 6, 2015)

Hi Paul Im actually feeling good about the patterns so far, its just the condition of the sand that keeps me up at night reading articles with chemistry I barely understand. The one thing I have learned since I started messing with casting back in November is that if I can get the hole in the sand right I can fill it with aluminum. Ive got my fingers crossed too.


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## bmac2 (Jul 6, 2015)

Rich, I think the reasons I decided to post this slightly odd thread was that I found it frustrating to find much information on pattern making that I could relate to. Dont get me wrong there is a ton of good information available out there but most of it is related to commercial foundries and other than _with aluminum make your pattern 2% bigger than you need_ and _provide adequate draft_ most of the examples shown, I think because of the diversity of patterns, are pretty general . So if one person can take away something from this I am very happy. Thank you.


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## bmac2 (Jul 6, 2015)

On with the show. 
I jumped the gun a bit today and decided to try out the core mold. I justified this to myself by thinking that if it needs more work Ill have to repaint it anyhow and if it does work I want to paint it in something smooth and high gloss anyway. So with a total disregard to the relatively fresh paint I rammed it up.


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## bmac2 (Jul 6, 2015)

The back of the mold came off as just as planned. The small button is only about 1/8 high with a filleted edge so I wasnt expecting any drama. My idea here was to expose as much of the core as I could. If I bake it this will help it to dry out and if I gas it with Co2 I should get a good flow through the sand with the 1 opening on the front that forms the core print.


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## bmac2 (Jul 6, 2015)

There is no way in . . . . well you know the place. . . that I was going to be able to pull a 1 diameter ¾ long plug of green sand so what I did was hold it in place with a dowel and slide the front piece up. The sand crumbled a pit around the edge but there is no way this would have worked before I added that 100g of clay. My sand is better but not there yet. More reading and mulling . . . . :wall:


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## bmac2 (Jul 6, 2015)

_Gently_ tapping the mold I _CAREFULY_ got it open. Not perfect but this is green sand so actually it worked out better than I expected. Of course next I tried to lift if out of the mold and it just crumbled back to what it is . . . sand. Im feeling great with the way this has turned out and cant wait to give it a try with sodium silicate. 
And the paint job survived! ;D


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## Cogsy (Jul 6, 2015)

I'm learning a lot and it looks like a heap of fun, but I'm still stuck at the point of getting bubbles in my aluminium. I just bought some washing soda so I need to make a degassing plunger and have another go. When the weather dries up a bit I'll drag everything out and have another play.


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## bmac2 (Jul 9, 2015)

Cogsy I feel your pain. What type of aluminum are you using? I know I have more trouble with extruded than cast. If you can get just about anything auto related the aluminum is very nice. The better it is when you start the better your castings will be. Ive messed around with degassing using washing soda a bit and one thing Ill pass on is Dont Fill Your Crucible the first time I tried it lets just say the bubbles got very aggressive.

From what Ive read the major culprit for pinholes and porosity is hydrogen from any moisture present anywhere. Pre heat everything, the stock youre melting and all of your tools to drive out/off as much moisture as you can. I wait until my crucible is just starting to turn color before I add any metal. High humidity can affect the casting but if everything is hot you dont get condensation forming. Pour as soon as you can and try not to overheat the melt. The longer the aluminum is in a liquid state the more hydrogen is absorbed. With me its my sand, I still havent found that magic balance of sand, clay and water. Ive read that if you think your sand is a bit wet you can run a torch over the impression in the mold before you close it. 

Its only rained once since May so here humidity isnt a problem.  Having a good chunk of western Canada on fire . . . now thats a problem. I heard on the news that they brought up a bunch of fire fighters from Mexico and now are looking to Australia. To the guys in the states sorry about the smoke.


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## bmac2 (Jul 13, 2015)

Yesterday I made up some SS cores. Ive had trouble with cores off gassing in the past so I thought Id try hollowing it out and running a 1/8 vent up the cylinder part of the core. I filled the pattern halves and baked them open faced in the toaster oven for a half hour or so at ~250 degrees.


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## bmac2 (Jul 13, 2015)

Once the core felt dry I took it out of the mold and glued the together with regular carpenters glue and put it back into the oven at 350 to dry out.


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## bmac2 (Jul 13, 2015)

The core came out a little crumbly around the edges. Im still messing around with the ratios. Most of the info Ive read on SS cores use a 6% sodium silicate to sand ratio (by weight). I got my sodium silicate from a pottery supply place so its not foundry grade. The foundry SS is a brownish color, thick, and hard to come by in my area. I found one place that had it in small quantities but it worked out to $86.52 for a gallon plus shipping. The stuff I have from the pottery supply is clear, thinner, and you have to use more of it to get a strong core. The up side though is the place is about 8 km from me, open Saturday, and the sodium silicate costs $7.00 a litre. 
Mixed up a second 100g batch of core sand this time at 10% SS and just rammed it up solid in the mold and slid a 1/8 rod the length of the core for a vent and baked as before. It cured solider than the hollow one so Ill try them both.


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## bmac2 (Jul 13, 2015)

Today Id mowed the lawn, cleaned up the garage, and fixed the little lights my wife has in her flower beds. I have a mostly finished block pattern and a couple of almost serviceable cores and my wife had left me on my own recognizance for the day. 
I should have gotten back to finishing the pattern but I just wanted to melt something.;D

Rammed up the drag and then filled the cope about half way and dug out the space for the timing gear mount and rammed it full.


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## bmac2 (Jul 13, 2015)

I split the flask and the patterns puled ok but again the sand was looking weak but I decided to give it a go just too see what happens. The two pieces that make up the timing gear mount stay in the mold when I pull the block. The larger one is rapped and just lifted out. The smaller one slides into the void left by the first.


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## bmac2 (Jul 13, 2015)

Got the hollow core snuggled in to the drag and the fit looked pretty good.


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## bmac2 (Jul 13, 2015)

The pour went good filling both of the riser extensions so I assumed it filled. Now I just had to let it sit for 5 or 10 minutes and I could finally see what I got.


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## bmac2 (Jul 13, 2015)

As I expected there is a lot of flash. The general surface finish isnt horrible in most areas and the core cleaned out well with a little extra work in the cam shaft area.


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## bmac2 (Jul 13, 2015)

The biggest problem or lesson learnt on this was that a hollow core will/can float. The dark patch at the top right is just some sand but the bottom left is a hole from the core floating up.


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## bmac2 (Jul 13, 2015)

The undercut worked out pretty good though it looks like a lot of loose sand was washing around in there.


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## bmac2 (Jul 13, 2015)

I use to feel funny about the next step but now I almost look forward to it.
 Cutting it up in the band saw the aluminum is very nice. Not soft and gummy at all with the blade clearing of chips with no problem. The outline of the casting looks terrible but that is mostly due to the fact that I used the flash as a guide line for the cut. The inside finish on this half is a bit rough but not as bad as some Ive made.


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## bmac2 (Jul 13, 2015)

In the cope side the inside is very rough. Im not sure but this could be from sand washing loose from the core (it did feel soft) and moving around or gassing. The three big black spots in the upper right are actually in the flash so they wouldnt have been a problem.


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## bmac2 (Jul 13, 2015)

Looking at the pictures again Im starting to think that its a gassing/moisture problem with the core. If you look at the cylinder part of the core its good. Its the larger part of the core thats bad. Ill try baking them longer and perhaps hotter to see if there a difference. 

Im actually feeling pretty good about this one. The basic shape of the core turned out almost exactly the way I wanted it to. This was the thinnest wall I have tried and it worked (sort of). And I now know that hollow cores can float. 

Im going to add another 200g of bentonite and work my sand some more. I want to see if I can find some fine sand to add to help with the finish. For this one its going to be back to the bin to be melted down again.


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## RichD (Jul 13, 2015)

Looks like good solid progress to me.


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## fourstroke (Jul 13, 2015)

Hi Bob
They look good castings apart from the problem with the cores.
Like you I discovered that the cores move, that particular trouble cost me 4 or 5 pours, in the end I used a nail to hold the core in place. I pushed a hole into the core through the crankase boss before I set it with co2, then used a long nail to push through the core and into the sand mould and that stopped all the trouble I was having with the core moving
Hope this helps
Dougie


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## Swifty (Jul 13, 2015)

bmac2 said:


> Its only rained once since May so here humidity isnt a problem.  Having a good chunk of western Canada on fire . . . now thats a problem. I heard on the news that they brought up a bunch of fire fighters from Mexico and now are looking to Australia. To the guys in the states sorry about the smoke.



Hang in there, I read in today's paper that a couple of hundred firefighters are on their way from Sydney and Melbourne.

Paul.


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## Swifty (Jul 13, 2015)

Your castings look well on their way to being right, I'm impressed with your efforts.

Paul.


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## bmac2 (Jul 13, 2015)

Swifty said:


> Hang in there, I read in today's paper that a couple of hundred firefighters are on their way from Sydney and Melbourne.
> 
> Paul.



 Paul thats great news. In theory its an 18 hour direct flight but those dont exist so with 1 stop its more like 24 hours to get to Alberta from Melbourne. So Then If I have my math right thats:

  (GovernmentA + Government-B) / 24 hour Flight = Murphy s Law

  So by the time they get here it should be raining pretty hard. Rof}

  Thank you RichD 
  I find that working on the pattern gets frustrating at times but a lot of the problem is that I over think it. While in a way I am working on a model engine the patterns really dont have to be that exact. All in all its been fun and interesting even if my learning curve gets a little steep at times. But when I get frustrated its always fun to just melt something. 

  Hi Dougie
  Thats a great idea. I was thinking of something along those lines myself but I was over complicating it. What sort of SS did you use for your cores? I might try for a video on my next pour. I havent done one for quite a while because I just dont want the distraction.


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## fourstroke (Jul 14, 2015)

Hi Bob
I used the foundry grade, the dark brown stuff you mention. I mixed it with kiln dried sand from the local builders merchant at a rate of 3% by weight and the cores came out of the mould rock solid in a couple of minutes. 
Are you using co2 to set it?

Dougie


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## bmac2 (Jul 16, 2015)

fourstroke said:


> Hi Bob
> I used the foundry grade, the dark brown stuff you mention. I mixed it with kiln dried sand from the local builders merchant at a rate of 3% by weight and the cores came out of the mould rock solid in a couple of minutes.
> Are you using co2 to set it?
> 
> Dougie



I just bake them in the toaster oven when Im just messing around like this. If I am planning a pour I stop and pick up some dry ice and use that. Id like to setup up a small Co2 system and looking around the paintball tanks are $30-$50.00 (12oz to 24oz) and cheap to fill but I think Id have to bodger up the fittings and get a regulator together to make it useful.


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## bmac2 (Jul 16, 2015)

Swifty said:


> Hang in there, I read in today's paper that a couple of hundred firefighters are on their way from Sydney and Melbourne.
> 
> Paul.



Hi Paul
Looks like the Australians are all going to British Columbia (my second favorite provinceThm, has to be one of the prettiest places on earth. 
On the news tonight they were showing some fire fighters that are up here from New Zealand getting their _introduction to the local wildlife and what to do if you see one_ training. Id never thought of it before but I guess in New Zealand you wouldnt worry about it.

Swan Hills grizzly weigh from 140 to 450 kg (300 to 1000 lb.)
Average length of male cougar 1.7-2.7 metres, 60-100 kg (130 to 220 lb)


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## Swifty (Jul 16, 2015)

Bob, there's not much in New Zealand that's going to bite you except sand midges, which are a real pest, they don't even have snakes. But us Aussies are certainly use to seeing snakes around, that's about the only thing trying to bite us, just try to avoid them.

Paul.


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## fourstroke (Jul 16, 2015)

Hi Bob
I use the co2 bottle from my mig welder with a short piece of hose cut from the gubbins inside the unit, the regulator lets me adjust the pressure to whatever I need which is usually pretty low
Dougie


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## bmac2 (Jul 17, 2015)

Fourstroke : Ive got a small mig welder but its flux core only. The dry ice setup I use works its just I have to plan ahead. With the sodium silicate I have the cores come out hard after gassing but feel wet so I have to bake them to make sure they are dry. One day Ill find a deal on a bottle with normal fittings and get things setup. I know that most places around here wont fill anything if it looks at all dodgy.

Paul: Yep, thats the difference. Getting a bite and getting eaten. 
Oh. And our weather forecast . . Murphys Law . . Were getting rain on and off for the next week, starting tonight.


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## bmac2 (Jul 18, 2015)

As it turns out, like everything else not all bentonite is the same. There are three main types sodium bentonite, calcium bentonite, and potassium bentonite. And there are probably an infinite number of grades within each type. What you want and what I have for green sand is sodium or western bentonite I just dont know what grade it is. When I mixed up my first batch I went with the ratios from the Myfordboy blog. I think that any recipe you decide to use is only good as a guideline unless youre using materials from the exact same source. Ive been slowly adjusting the ratios in my sand mix over the past 5 months (casting is nothing if not fast paced) and adding that additional 200g of clay this week has made an amazing difference in the overall feel of the sand. Im going to have to go back through my notebook and work out just what my ratio is now. With the sand feeling this good I had to try it so I grabbed my little snap flask and rammed up the block pattern as before giving it a generous dose of venting.


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## bmac2 (Jul 18, 2015)

As soon as I opened the flask I started getting excited. When I pulled the patterns I could see a major improvement. The edges are much sharper and the surface of the sand looks clean and smooth. I also changed the runner and gates this time. I dont know if it makes much difference but Im really starting to like to ram in the runner and gates. I also like to scratch a number in the sand in case my pictures get mixed up.not that that could ever happen.


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## bmac2 (Jul 18, 2015)

The undercut for the cam gear mount pulled smoothly and the edges came out nice and sharp with only the slightest bit of tearing. I was feeling pretty good at this point. I even when and got my wife to show her the results. She was thrilled and said That looks nice and went away but brought me a sandwich. Always a good sign.


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## bmac2 (Jul 18, 2015)

I put the core in the toaster oven at 475 (as high as it would go) and fired up the troll. I really have to get to work on the new furnace one day.


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## bmac2 (Jul 18, 2015)

Once everything was up to temp and melting nicely I got the core positioned in the mold. I thought of trying to get a nail into it to keep it from shifting like Dougie suggested but was afraid of damaging it so I just go it in position as best I could and closed up the flask


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## bmac2 (Jul 18, 2015)

I tried to get a video of the pour and only got about 45 seconds before the batteries died. I thought I had a short pour as the risers didnt fill but I could just see some metal at the bottom. The blob beside the riser was the vent Id put in for the core. It worked well at first with a lot of smoke from the core coming out until it filled with aluminum. Ill have to work on that. Looks like the snap flask got its first battle scar.


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## bmac2 (Jul 18, 2015)

If nothing else the shakeout with a snap flask is well . . . a snap. Pop it open and everything just falls out. Melting things is fun and pouring is just cool but the shakeout has to be my favorite part of casting. 

[ame]https://www.youtube.com/watch?v=h9KcMn2SYmA&feature=youtu.be[/ame]


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## bmac2 (Jul 18, 2015)

This one came out a lot better and the core didnt go walkabout on me. The finish is better with (to me) an acceptable amount of flash but it looks like my sand may have been a bit wet. Over all this one could have been a keeper if the pattern was finished.


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## bmac2 (Jul 18, 2015)

The overhang came out nice with a sharp edge. I am very happy with that and the inside looks cleaner.


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## bmac2 (Jul 18, 2015)

I didnt do any setup for this I just wanted to see how it would finish up so I hit it quick and dirty with an end mill on the surfaces that need to be machined. 4L Nissan is nice stuff. It machined easily and the finish is pretty good considering the mill I was using. There are a lot on tiny pinholes but nothing that I think would make it unusable.


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## bmac2 (Jul 18, 2015)

The flashing cleaned up fast and easy with no sign of the file clogging up. It looks like a lot of gas entrapment in the top in the valve guide area. This may have been from the core but the top of the core looks clean so I dont think so. It may be that it was too close to the sprue so it stayed liquid longer and had more time for gas bubbles to form. If this was a casting I was going to use I dont think it would affect anything but next time I may try degassing the melt. The inside looks a lot better but Im going to rethink that venting in the core to keep it from filling with aluminum.

Thanks for checking in.


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## bmac2 (Jul 19, 2015)

I decided it was time to stop playing in the sand and get back to work on the pattern today. I need to add a flange for the water inlet and a spot for the oil filler plug.


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## bmac2 (Jul 19, 2015)

I only need a little over ¼ for the water inlet but the shape looks so handy I made a piece about 5 long. I did this like all the rest by clueing two strips tougher with newspaper then glued the pattern onto each end and forming it on the belt sander. I cant think of any project Ive made where Ive used this sander more than on these patterns.


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## bmac2 (Jul 19, 2015)

To get it to match the radius of the block and set the downward angle I dug around in my sanding stuff drawer and came up with a 1 ½ drum sander that was close enough in diameter to the block pattern and sanded it in. All that was left was to glue it on and added a fillet to smooth everything out.


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## bmac2 (Jul 19, 2015)

The Filler plug was added basically the same way and once everything was set and dry I rammed it up in the sand to make sure it would still pull then gave it a couple coats of paint.


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## bmac2 (Jul 22, 2015)

You just have to love summer in Alberta. It&#8217;s 27c with a nice cool breeze and I have the day off with nothing to do that can&#8217;t wait. With a day like this I thought I&#8217;d do some more pattern work. 
For the cylinder head and cover I sliced up my CAD drawing and printed the parts in 2D scaling it up 2%. Glued them to the wood and cut out the inside and outside profiles on the scroll saw leaving enough for sanding.


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## bmac2 (Jul 22, 2015)

Then I cleaned the paper off and glued them up. With the draft angle set on the belt sander I then took it down to the final shape. For the cover I drilled the holes for the dowels and glued them in before cutting out the profile. With a bit of filler and some sanding they were almost done. Id left the dowels in the cylinder cover long thinking Id just sand them down to what I wanted and it looks like the maple didnt appreciate it.


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## bmac2 (Jul 22, 2015)

Added the boss for the sparkplug and after a bit more fiddling I gave them a quick coat of the scratch filler primer Dougie (fourstroke) introduced me to. I like this stuff a lot. Fills nicely, fast drying and sands easy.


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## bmac2 (Jul 22, 2015)

All that was left was to see if it would pull from the sand. With the sparkplug boss I have to dig down along that face to create a parting line along its centre. The tape is to cover a small hole in the pattern that a screw goes into when the part is pulled. The pattern came out smoothly and I think I might finally be getting my green strength about right. 
If you look closely in the last picture you can just make out the impression left in the sand from the masking tape and a small dimple from the screw hole.


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## bmac2 (Jul 22, 2015)

Just to finish it up I gave them a coat of the blue and set them aside with the block. Theres got to be nothing better than a beautiful day with nothing to do but work on a hobby I enjoy. 
Oh and some quick drying paints and fillers. Thm:


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## Swifty (Jul 22, 2015)

I have no current intention of ever casting anything at home, but I'm still enjoying your thread. I'm always interested in how things are done.

Paul.


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## bmac2 (Jul 27, 2015)

Woohoo its raining. My wife got a nomination for a local _Yards In Bloom _award so if I have a free minute I think Im supposed to be out grooming a plant of dusting a tree or something, but it raining. woohoo1
This means I got to work the Main Bearing. Ive decided not to cast the detail on the inside (left side) of the casting and just make sure I have enough meat in the casting to machine it.


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## bmac2 (Jul 27, 2015)

I started out by cutting a disk from ½ plywood with my ridiculously out of balance circle cutter then used the newspaper and glue trick to attach it to the work plate on my little wood lathe using the tailstock centre to line things up. Used the hole in the disk to mount a length of 3/4 dowel and took this down to just over 5/8 diameter (small end) with a slight taper going back to the disk and a 1 long stub on the end so it can be chucked in the lathe.


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## bmac2 (Jul 27, 2015)

I was tempted to leave off the three little wings that go around the bearing mount thinking that it would be ok and I could just redo the pattern making it beefier if needed. Part of this was that I just didnt feel like getting out the thickness planer (its heavy) to make up some 1/8 stock. 
Then I remembered all the stir sticks they gave us when we picked up the stain for the house (post #23). These things are a nice straight grained wood and close enough to 1/8 for what I want. 
Cut three pieces from the stir stick and glued them tougher with newspaper then just eyeballed the pattern for the wings and shaped them on the belt sander. With that done I split them apart and sanded some draft angle into them.


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## bmac2 (Jul 27, 2015)

I dont have a tailstock chuck for the wood lathe (I know, I should make one) so I took it into the house to drill a ½ hole in the back for a second 1 stub and add a little thickness. This has got to be the first time I have ever use a Forstner bit I the Myford. 

The bonus I discovered after doing this was that Id put the wood into a three jaw chuck that made 3 evenly space marks for the little wings. Who would have thought that clamping something too tight in the chuck could be beneficial. Thm:


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## bmac2 (Jul 27, 2015)

I was a little concerned because the pattern finished up about 2 long with very little draft. Nothing to be done but ram it up. As it turns out my sand held just like in the books so the bearing pattern has earned some blue. Adding that extra clay has really made a world of difference. ;D


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## barnesrickw (Jul 28, 2015)

You are a good man bmac. If you had been nominated for hobby machinist of the year, would she help you clean your shop?


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## bmac2 (Jul 28, 2015)

barnesrickw said:


> You are a good man bmac. If you had been nominated for hobby machinist of the year, would she help you clean your shop?



*Aaaaaa. NO!* 

Actually she did that once. She&#8217;d been laid off and after we talked about it decided she should just take the summer off. One day I&#8217;d called her from work and she told me she was _&#8220;tidying up my work shop for me&#8221;_. When I got home after what felt like *the longest afternoon in my life* I found she&#8217;d done a pretty good job of it. I was amazed that she&#8217;d dumped out my catch-all bins and managed to sort all the miscellaneous nuts, bolts, screws, oddball electronic parts and printer guts into bins without really knowing what she was looking at. I guess you just can&#8217;t underestimate the tenacity of an accountant with a German heritage.

I don&#8217;t mind the extra bit of yardwork. After all we will probably have snow on the ground by late October and that leaves me with not much to do until April. woohoo1


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## barnesrickw (Jul 28, 2015)

She's a keeper.


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## bmac2 (Aug 2, 2015)

I have been thinking about this timing case for a while now its a relatively small part but from the standpoint of a casting pattern its a complicated little piece of kit.  
I had 3 options.

- Make it solid and just machine out the back. 
- Make basically the same thing and make a core for the inside.
- Pattern it after the finished part with a hollow back.


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## bmac2 (Aug 2, 2015)

I think the option with a core has the potential for the greatest detail but it seems a bit over complicated for a part thats not much bigger than my thumb so In the end I decided to try to do it with the hollow back. Before I could cut it out I wanted to get the bosses in. Id run out of dowel but they are under an inch long so I dug out my set of plug cutters. One advantage to these is that they cut a tapered plug with the small end at rated diameter so the draft is built in.


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## bmac2 (Aug 2, 2015)

To make dowels you just mount the wood vertically so you are cutting along the grain and plunge the cutter in. Then just mark the board 1 inch in from the end and cut it off on the table saw. I liked to use these with furniture because you can use a cut off from the same board to match the grain and colour making the plugs almost invisible.


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## bmac2 (Aug 2, 2015)

With the bosses rammed in and the scroll saw set for the draft angle I cut out the inner and outer profiles. Made the top from my new found stock of 1/8 paint stir sticks and glued it in place. With the bosses I couldnt use the belt sander so I had to dig around and find my small detail hand sanders.


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## bmac2 (Aug 2, 2015)

After I ran some filler around the inside and cleaned up the top I wanted to make sure it would pull before I finished it. I did feel like I was getting a bit cocky on this piece. Its not terrible but it looks like I need to work some more draft. 
No worries the forecast for tomorrow is clear and 29 so I can think of worse things than sitting in the shade sanding this thing.


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## stevehuckss396 (Aug 3, 2015)

This is really cool. I'm enjoying this one.


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## bmac2 (Aug 3, 2015)

Thanks Steve, glad to hear it. I think I must be getting close to a record for the most saw dust on a machinist forum.Rof}


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## bmac2 (Aug 4, 2015)

It was a hot day in the foundry (by Alberta standards) 30 degrees and I&#8217;m stuck sanding draft angle into the timing cover. I had to setup the tent just to get some shade. Brutal, sand a little check the angle, sand a bit more check the angle. If it wasn&#8217;t for the breeze, a cool drink now and then and that nap that snuck up on me while watching some bees I don&#8217;t know if would have made it.


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## bmac2 (Aug 4, 2015)

But I persevered and the pattern is now pulling from the sand. I had to add a lot of filler to get the inside to pull but finally got it working.


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## bmac2 (Aug 4, 2015)

I add the two nubs for the crank and camshafts and it still pulled well so I gave it a quick shot of filler primer and then the blue to finish it off.


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## bmac2 (Aug 4, 2015)

There&#8217;s something about this part that I really like so I was anxious to see if how it was going to pour. It&#8217;s already hot, I know, a lot of you are thinking &#8220;_Bob 30 degrees isn&#8217;t hot&#8221;_ but I have a couple of other things I want to try. I also wanted to check out some changes I&#8217;d made to the burner so I thought I&#8217;d fire up the Troll.


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## bmac2 (Aug 4, 2015)

I had a couple of ideas for the gating I wanted to try so I rammed up the pattern in a small snap-flask. For anyone thats interested a snap-flask allows you to ram up the pattern and then by undoing the hasps open it just leaving the sand. Great for when you want to do multiple pours and dont have room for, or just dont want 5, 10, 20 flasks kicking about.


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## bmac2 (Aug 4, 2015)

Now I know I took pictures of both gating setups but since the last OS update my i-pod has started putting the picture into random directories with incipits names and I cant find them. 

Thank you Apple I needed that.


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## bmac2 (Aug 4, 2015)

Oh ya. 
Back in the first post Id said But it may have molten metal, sand, clay, smoke and fire! This time I remembered to check the batteries in the camera before I started. Not much action Im afraid but when youre talking about 3 lbs of aluminum at 671c, 1240f action and drama is the last thing I want.

[ame]https://www.youtube.com/watch?v=24ot6urhnps[/ame]


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## bmac2 (Aug 4, 2015)

The first one I poured is just a lid for a little compost canister we have in the kitchen. 
The original lid was wooden . . . wood for wet veg kitchen scraps? *bang*

Out of the two timing cases one was a total fail. The gate or channel that carries the melt from the runner to the pattern had shifted out of place and the aluminum never reached the pattern. Dumb mistake and I should have caught it. The second one worked out pretty good and despite some pin holes and loose sand I think is a keeper. Finished the small bolt bosses are only 1/32 high and the two larger ones finish up at 1/16 and 3/16 so no worries there. Id only let it cool for 10 or 15 minutes so that shake out was still pretty hot!
One of the best things about the shake out is you get to lose most of the leather.

[ame]https://www.youtube.com/watch?v=p_ziIQQL4cs[/ame]


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## bmac2 (Aug 4, 2015)

Cut off the spure and did a quick cleanup on the belt sander. I havent melted the better of the two castings I did of the block thinking I could use it to check that parts are coming out close to the right size. Back in the sweatshop it looks like all the bolt holes should line up. 

Again  Thanks for dropping by

Now whered those bees go . . . ?


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## Swifty (Aug 4, 2015)

Great job Bob, you will be in to machining it in no time.

Paul.


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## SmithDoor (Aug 4, 2015)

I like the snap flask
th_wav

Dave


bmac2 said:


> I had a couple of ideas for the gating I wanted to try so I rammed up the pattern in a small snap-flask. For anyone thats interested a snap-flask allows you to ram up the pattern and then by undoing the hasps open it just leaving the sand. Great for when you want to do multiple pours and dont have room for, or just dont want 5, 10, 20 flasks kicking about.


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## barnesrickw (Aug 5, 2015)

Nicely done.  I purchased castings not nearly as nice.


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## bmac2 (Aug 15, 2015)

With my sand finally holding together I decided to work on to see if I could improve the surface finish. My first batch of green sand (about 8kg) I made was with instructions off the internet using sifted Home Depot play sand. It was fun and I learned a lot about patterns and molding but I didn&#8217;t think the surface finish of the castings was good enough. Looking at it now it looks a bit like gravel and the only reason I can think of to use play sand is that its silica free and only costs about $5.50 for a 25kg (50lb) bag. I&#8217;ll be using it on the ice this winter.


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## bmac2 (Aug 15, 2015)

The sand Im using now is a 50/100 blasting media (also silica free) that cost me around $7.50 a bag. Ive been getting a pretty good finish but I want to see if I can get it a bit better. If you want to try casting and make up your own green sand spend the extra 2 bucks and skip the play sand.


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## bmac2 (Aug 15, 2015)

I&#8217;m still pretty new at this so this is just from what I&#8217;ve picked up reading. Course sand is great for venting with lots of air gaps between the partials to allow steam and gasses to escape but gives a surface finish like 80 grit sand paper. If you made green sand with just fines it would give a great finish but steam and gasses would be trapped in the mold and generally nothing good would happen to the casting. From what I&#8217;ve read what&#8217;s best is a mix of sand. One way to think of this like the jar filled with golf balls, then BB&#8217;s, then sand and finally water. So I don&#8217;t want the golf balls and you don&#8217;t want the water.
&#8195;
With all this in mind I stopped off on Friday and picked up a bag of 100/200 blasting media, this stuff is like flour.


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## bmac2 (Aug 15, 2015)

I started by weighing out 8kg of the 50/100, 2kg of 100/200 and 1.2kg of bentonite clay. Mixed everything together dry (yes dust mask on) before adding just enough water to get it to pass the squeeze test. This is where I wish everything was a different color so it would be easy to tell when it was blended. 

It looked like green sand and it felt well sort of soft and silky scratch.gif so I let it sit in the sun for a couple of hours to rest and then mulled the crap out of it before giving it a try. Ive been having trouble with the head cover so I used it to test the new sand. I set up a couple of different gates arrangements all with the pattern filling from the bottom and one using a knife gate. A knife gate is just a wide thin gate running the length of the pattern. I also messed around with the venting going from next to none to something that looks like the back wall at the gun club.


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## bmac2 (Aug 15, 2015)

Fired up the Troll and poured the covers.

[ame]https://www.youtube.com/watch?v=UTxDN8iFs7Q&feature=youtu.be[/ame]


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## bmac2 (Aug 16, 2015)

This came out better than I had hoped. Two out of the three head covers came out with a very nice fine finish and the bad one is still useable but has some pitting. Not much difference between the first two and I dont think the knife gate made any difference in a pattern this small. The venting on the other hand I think did the most with the last picture being the one that had the least. 

All in all a good day. Learned something, got to melt stuff ;D and now have 2/3 good castings that Ill clean up and this time keep.

Hope you enjoyed this as much as I did. And thank you for your comments


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## bmac2 (Aug 27, 2015)

I thought it was time for the family photo even if one member missing.


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## bmac2 (Aug 27, 2015)

This last family member has been the red haired bastard step son. I dont know how long Ive been looking at this drawing and I dont know if I will ever use it but seeing as it is a casting in the kit I thought Id try. The contact breaker is _not_ very big and has a lot of convoluted little corners so the only thing I could come up with was to attempt to make a split pattern for it.


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## bmac2 (Aug 27, 2015)

I started with the round part at the bottom that mounts over the upper boss on the timing case. This section makes up the lower half of the body but is only 5/8 in diameter and a total 1/4 thick. With the pattern being split this means that I need two pieces at 1/8. There is no way I could keep a square edge on these and keep all my fingers so I trued up the end of a dowel, cut off a disk a little long, glue the disk back onto the dowel to sand them to the 1/8 I needed.


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## bmac2 (Aug 27, 2015)

To make the tapered top part I picked through my pile of paint stir sticks and picked out the one with the straightest grain I could find and planed down to 3/32. Rough cut it and glued two of the pieces together with a 1 to 1 print of the pattern. Then I drilled holes to match the radius of the 5/8 bottom disk and the ¼ boss at the top, sanded it to shape and then split it.


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## bmac2 (Aug 27, 2015)

The arm that the blade mounts onto is 1 ½ long, ¼ wide and needed to overlap the 5/8 button so I clamped it to a piece of scrap and drilled an offset recess about 3/32 deep then added the two bosses for the blade mount and push rod bushing. 
To make the round bolt (little screw) boss at the bottom I just sanded off half of some ¼ dowel and used a round file to form the recess for it to sit in. With newspaper between the two halves I got everything glued up, put in some alignment pins and gave it a quick shot of primer.


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## bmac2 (Aug 27, 2015)

This is definitely the smallest pattern Ive tried, and I dont know if Ill use it but after some fiddling and sanding I got it to where it would pull from the sand. The tapered top part is not very thick so I wanted to see if it would cast.


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## bmac2 (Aug 28, 2015)

This was a fun little piece to do and all in all it didnt come out half bad. It has a lot of flash but a quick cleanup with a file and its not terrible at all. 

Hum. I dont remember turning on the date in that camera. 
Actually Im not sure _how_ to turn on the date. scratch.gif


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## Roboguy (Sep 24, 2015)

Hi bmac2 

Given it looks like this thread has come to it's end, I just wanted to say thanks very much for sharing this with us. It's been extremely interesting, informative and motivational! 

Looking forward to the build thread for this engine. 

Cheers, 
James


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## bmac2 (Sep 25, 2015)

Thanks James.
The thread isnt quite dead yet its just been on sabbatical for a bit. Between work and getting ready for winter (We usually get our first snow in Oct.) I havent had much free time. I hope to get the castings done in the next week or two and post a few videos.
I needed to make up some more cores before I could go any further so Ive been messing around trying a few different setups. The biggest problem I have is the Co2. Id like to use a paint ball cylinder but a new 20oz. one is around $50.00 and Im too cheap to lay out the cash for something Im just not sure Id use that much so Im on the scrounge for a used one. 

Until then this is my latest incarnation of _Budget Sodium Silicate Cores_. If you only are working with a small core, the one for the Whippet takes 130g of sand so its pretty small. Or if you dont think youll make a lot of cores, or just want to try it this could be a viable way to go with minimal cash outlay.

Small quantities of foundry grade sodium silicate are hard to come by but you can get wood stove gasket cement in almost any hardware store in a 2oz bottle for around $3.00 ($2.99 Can Tire). According to the MSDS its 47% sodium silicate and water. With 1 bottle I made 3 cores and have a bit left over.


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## bmac2 (Sep 25, 2015)

The standard Crosman 12g Co2 cartridges work out to be about $0.85 each and it took one for each of the cores. I dont know what they cost but a buddy of mine gave me this bicycle tire inflator that was leaking. A rubber grommet, quick and dirty mod with a piece of tubing and a dollar store funnel and its a Co2 dispenser. Now this thing REALLY NEEDS a regulator. You can control the Co2 with the trigger but I wore one of my cores when I squeezed it just a bit too much.:fan:


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## bmac2 (Sep 25, 2015)

The sand I used was a mix of HD play sand and 50/100 blasting media. My thinking was that the larger partials in the play sand would allow the Co2 to penetrate the core better and that any surfaces that need a good finish are machined anyway. 
I did the cores open filling each half of the mold and setting it with the Co2 before putting them in the foundry toaster oven at around 250f for half an hour to dry them out. One advantage to doing it this way is I can cut in venting that would be impossible any other way. 
Ive tried a couple of things as release agents and what I did this time was put on a thin film of Vaseline followed by a good dusting of talcum powder. It sounds like a weird mix but the cores just dropped out of the mold when I took them out of the oven. Thats right my _manly-man_ foundry smells like a babys bum. ;D
Following Dougies (fourstroke) suggestion I put a nail through the core print before gluing the two halves tougher, hopefully this will keep it from going walkabout on me. I think I may have used too much SS in the mix because these are hard as a rock. It might be a ***** to clean them out but if I soak them for a day or so it shouldnt be that bad.


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## fourstroke (Sep 25, 2015)

Glad your back on the case Bob, Im looking forward to seeing this little engine run
Dougie


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## Richard-Vanderpol (Nov 21, 2021)

what do think of this one? ENJOMOR 10cc Whippet Flathead Water-cooled Gasoline Engine Pre-Order


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