Cretors popcorn engine

[steamer]

Not from me it's not!

Dave

[black85vette]

It occurred to me that not everyone knows what this engine looks like.   So here are some pics of engines offered by Cretors to run their popcorn carts:


engines by black85vette, on Flickr

I am building the #1 cart engine and here is how it looked running a popcorn cart:


cart1 by black85vette, on Flickr

These were used from the late 1800's to the early 1900's when electricity was not always available.  Plus the carts were very portable and able to go where the crowds were.

[steamer]

I've actually worked on one with a tempermental governer at Mystic Seaport...some years ago....

Governer always stuck!

Dave

[black85vette]

Need some input.  Next items up include lapping the guide and starting the cylinder.  First question:

How smooth does the crosshead guide need to be?   It is not a cylinder and has no compression.  It is well oiled and just has a sliding part.  Do I need to make it mirror flat and smooth?  Something less?

Here is the cylinder.  Bore is 1.5" and 6" square is in the picture.


IMG_5615 by black85vette, on Flickr


Question 2; where do I start on the cylinder and what order to I follow to keep it all square?

[Maryak]

Need some input.  Next items up include lapping the guide and starting the cylinder.  First question:

How smooth does the crosshead guide need to be?   It is not a cylinder and has no compression.  It is well oiled and just has a sliding part.  Do I need to make it mirror flat and smooth?  Something less?

Something less so there is provision for oil retention e.g. nice mill/turned finish.

Question 2; where do I start on the cylinder and what order to I follow to keep it all square?

IMHO the critical thing is that the cylinder bore will clean up. I would try and ensure this is so by using inside and outside calipers and finding the area of least wall thickness. Then add to this a machining allowance of say 0.010"min. 3/4" - 0.010" (or whatever machining allowance you can get, bigger is better), is where the cylinder centreline will be. Now plug the cylinder with a piece of wood to which each end has a piece of shim brass attached and mark off and "pop" the centres.

Using these centres, set up the casting in the mill so they are horizontal and the steam chest face and the cylinder base are as close as possible to right angles then machine the two areas of the base to clean up. You now have a datum face from which the rest of the machining can be carried out.

Hope this helps.

Best Regards
Bob

[black85vette]

IMHO the critical thing is that the cylinder bore will clean up. I would try and ensure this is so by using inside and outside calipers and finding the area of least wall thickness. Then add to this a machining allowance of say 0.010"min. 3/4" - 0.010" (or whatever machining allowance you can get, bigger is better), is where the cylinder centreline will be. Now plug the cylinder with a piece of wood to which each end has a piece of shim brass attached and mark off and "pop" the centres.

Using these centres, set up the casting in the mill so they are horizontal and the steam chest face and the cylinder base are as close as possible to right angles then machine the two areas of the base to clean up. You now have a datum face from which the rest of the machining can be carried out.

Best Regards
Bob

Thanks Bob.   I did some initial checks and it looks pretty good.   The three walls measured at the center of the cylinder are all about .400" so it is close to center.   The bore as cast is 1.380" and will need to be 1.5".   So not a lot of cutting to do.   .120" diameter so .060" off each side should leave .340" thickness all around.   I will need to get some wood to make the plug.

[black85vette]

Holding off the cylinder until I get back from an extended weekend trip.   Looking at the crosshead guide and thinking about the clean up process.   Since this is my first casting project I am in new waters here.   I am assuming that there will be a ton of hand filing on this thing.   I did some initial cleanup with some small sanding discs that I use for car body work.  That was just to get the worst of the rough casting smoothed out some.   Do I just start with my set of files and get finer and finer as I go?

Plan for this part is to paint everything except the rails that the slide runs on.  So I will not need to get it as shiny as the flywheel, just smooth enough for painting.

Suggestions / tips?

[black85vette]

Cleanup underway.   Made a mount to hold the crosshead guide.    Turned the face of the mount to fit into the opening of the flange so I could turn the outside concentric to it.   Then drilled and tapped the mount to hold the guide.  Here is what I got done tonight.


IMG_5616 by black85vette, on Flickr



IMG_5618 by black85vette, on Flickr

[black85vette]

Made a pilgrimage this weekend.  Took a trip to visit the Mecca of Cretors engines and carts.  Went to meet Bob Pearson at his shop in Olathe Kansas.  Got to see some original carts restored and being restored.  But the best part was getting to see original engine parts and how they were made.  Also got some great insight from Bob on how some of the parts worked.   Decided to change some of the Cole's design to make the parts more like the original.   Turns out they took some short cuts in their design.

While on that subject I should point out a couple of key points.  First is that the Cole's castings were not made from the original patterns but from actual machine parts.  With shrinkage from the casting process it means that Cole's parts are about 15% smaller than the true Cretors parts.   So they are not interchangeable.  The other major thing I saw was that the quality of the Cole's castings are far rougher than the originals.  A number of the original parts just needed some cleanup on the flat or mating surfaces.  The Coles parts are so rough you might as well make them from bar stock since you cannot leave the cast look to them.

Finally, I picked up some parts from him that do not come from Cole's or I wanted to replace.  I got the castings for the whistle, the oil cups and caps,  and the pulley for the belt on the governor.  The supports for the main shaft looked so much better I picked up a set of them.  The connecting rod from Cole's is cast as one piece.   It is actually 3 pieces; the two ends and a shaft with nuts so you can adjust the length of the rod.   Here is my treasure box;


IMG_5679 by black85vette, on Flickr


Maybe the best part was getting to visit for an extended time with Bob about how he got into steam engines and building Cretors carts.   He is a storehouse of information and a delight to visit with.

So it was a great trip and a tremendous help in making my build much more authentic.

[zeeprogrammer]

Lucky you! That sounds like a great and fascinating trip.
Always a pleasure to talk to people like that.

[black85vette]

Making progress on the crosshead guide.   Starting to look a little more like an engine part.   Here is what it started like:


IMG_5531 by black85vette, on Flickr

Lots of deep, tough, rough, crust.   Here is where it is right now;


IMG_5697 by black85vette, on Flickr



IMG_5698 by black85vette, on Flickr

Had to spend hours hand filing.  The flange was a PITA to get flat and even.  There were lots of compound curves to deal with also.  Fortunately there was a time that my entire "machine" shop was a grinder, hand drill, hacksaw and set of files.   Guess learning to use files was not wasted time.

Got the channels that the slide runs in pretty much done.    Made a lap out of an old ash baseball bat.

Not done at all but it is now funtional.  It can be installed and checked and then do the final filing and clean up before paint.

[DavidF]

that looks damn good

[steamer]

Hell it looks great!

Dave

[jonesie]

   looking real good . looks like you got some real nice replacement casting also,that will make working with them easier.   jonesie
 

[black85vette]

Set the guide aside to start the slide for it.

I took minimal cuts off the slide crosshead on the mill to just get it squared up a little so I could get it secure in the 4 jaw chuck.   It centered up nicely and I got the stem (right term??)  turned, drilled and reamed.   Then moved it to the 3 jaw and held it by the stem end.  Put a shaft thru it and using the live center to keep the shaft lined up I made the cuts to the outside diameter.   Here is the setup:


IMG_5699 by black85vette, on Flickr


Some adjustment to the plans.  I started on the slide crosshead.   When the casting was made they took a grinder to it to remove some flashing.  Problem is they took off too much.   Both the diameter of the entire piece and the stem were too small.   The slide crosshead needed to be 1.5" and by the time I cleaned up the grinder marks it was about 1.4"      Same with the stem.   It should be .5" and a slight flange on the end of it.   I didn't even get the grinder marks removed and it was already .45" and no material left for a flange. 

There is a bright spot for recovering.  Fortunately Cole's took some shortcuts and made the slide crosshead out of a single piece.   The actual part by Cretors had two removable shoes that could be shimmed to allow for wear.    I will turn the slide down some more and then fabricate the shoes to attach to each side.  Then turn it to size with the shoes installed.