Pattern wood?

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stevehuckss396

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I am going to make a pattern and cast an engine part. I was just going to use some pine but am not sure how well it will hold up. I only plan to pour about 8 or 10 pieces so an expensive wood might be a waste of money. I have never tried this before so some wisdom is needed here. What type of wood would be best for a small quantity wood pattern?

 
I have used pine. The castings came out great! The only thing that I don't like about it is after sanding the grain becomes more pronounced because of the hard and soft grains. In my castings you could see the wood grain very clearly. I use Popular for most of my patterns now. Usually the grain's are about the same hardness. I also like that recycled plastic lumber that people make decks out of. It machines great and no grain at all.
 
IIRC the older pattern making books recommend cherry.
I think for hobby work anything will work even MDF.
I like the idea of the plastic wood as well.
Tin
 
I just checked "Wood Pattern Making" by McCaslin 1923 and he states that white pine is the most common pattern wood. He sugests that mahogany, cherry or maple should be used for patterns that will see rough service or make a lot of castings.

Dan
 
Pine is fine for patterns that are not going to be used hard or often.

Mahogany is a good bit better....but you pay for that....it's expensive.

Dave
 
I use pine wood & paint the patterns with white epoxy paint & then sand the paint smooth. The sand doesn't stick to my patterns at all. :) I also use Renwood for patterns, it is a composite wood substitute.
 
I have been using MDF. Easy to work with, cheap, no grain, and when painted, it will last very well through low volume castings.
 
Hi Steve, simply use whatever you have at hand as long as its stable and doesnt twist or bend when its completed. MDF (if you want to) but pine is fine... I seal mine and if its a major part, epoxy coat, but mostly a couple of coats of whatever colour I have laying around. I have yellow plugs, blue ones, white, red... ::)

Sealing is the important part, stops the moisture soak and therefore sand adhesion.... ;)

As a last note..I hate MDF.. I do use it sometimes but am pretty careful with it.... good luck and enjoy....
 
Some 20 years ago I had the opportunity (created by some innocent trespassing) to walk the pattern houses at the abandoned Ross-Meehan (ie, Meehanite) foundary in Chattanooga TN. The overwhelming majority of the large patterns were some species of pine and the small patterns, those needing to be attached to matchplates, were in mahogany.

Most of the patterns I have made have been in musical instrument grade hard maple or mahogany, because I had a source of scraps. The maple works beautifully as it can almost be machined like metal, but if the pattern is too large and made of a single piece of wood (instead of built -up in sections or laminations) there is the tendency for a turned pattern (ie wheel, flywheel) to warp across the diameter.

I recently considered making a pattern for a cast smokebox front for a locomotive and was in a Home Depot where I found their product called hobby "whitewood." Some of this was obviously soft, but some of it looked and felt like a good dense maple and would have made good patterns. I ended up not making the pattern as at the last minute I discovered I could buy a slice of the right-sized cast iron bar for a fraction of what the pattern-making and casting exericize would have cost. The other problem is foundaries . . . they're drying up one by one.
 
Cedar, if you can find it in suitable sizes can also be used for patterns. It is reasonably dense and has a nice closed grain. It does not have a tendency to 'run' along the grain if you carve it.

BC1
Jim
 
I believe jelutong used to be the preferred wood, but an old experienced foundryman told me he uses MDF almost exclusively now, with pieces glued with pvc glue.
 
You said g-code? If you're going to machine the wood with metal working tools like end mills use cherry or walnut. I've machined lots of cherry and some walnut. Both machine fuzz free and you can feed it really fast. Pine might be ok for large pieces but its hard to hold detail in pine.
 
jpeter said:
You said g-code? If you're going to machine the wood with metal working tools like end mills use cherry or walnut. I've machined lots of cherry and some walnut. Both machine fuzz free and you can feed it really fast. Pine might be ok for large pieces but its hard to hold detail in pine.

Good point Jim. I might go to the Woodcraft store and see if they have some small pieces.

 
Steve, should have checked to whom I was posting. Didn't realize it was you.
When I was teaching early on both the kids and I were learning 3d programming together and none of us were to sure how our code was gonna turn out.
To save metal and tools we'd cut a lot of 3d trials in wood. Cherry cut so good we took lots of our wood toolpath trials to woodworking contests and won a number of awards along the way.
dsc00619.jpg

Here's an example in cherry of a student's work we eventually turned into aluminum. As you can see cherry mill pretty well. The base is seperate from the flag. The flag and pole are one piece.
 

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