Model Engine Maker
Engines => Your Own Design => Topic started by: gbritnell on August 22, 2012, 01:26:41 AM
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Gentlemen,
I posted the drawings for this engine in the drawings section.
I am building one for a fellow so I thought I would start a build thread on it as the original wasn't documented because it was pre-digital.
This is the start of the base and sub-base made as one piece. It is being made from 12L14 mild steel.
gbritnell
https://www.youtube.com/watch?v=tcfrKsOaDNw
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George I will be tagging alone with you. All of your builds are superb. I look forward to you documentation and photos.
Don
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The machining is straight forward, just small. I figured while making one I might as well make two. The blocks of steel were cut to 1.00x.562x.500. The bottom was relieved leaving an .08 wall all around. I roughed it with a .187 end mill then finished it with a .125 end mill. While I'm making the parts I am also making a drawing that will have stop points, step points etc. for the build. As I develop them I will post them for the group.
After the bottom was relieved the block was turned over and the bearing pockets and side profiles were cut.
gbritnell
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These photos show the finish profiling of the base.
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The last 3 photos for today show the center drilling (#00) and drilling (.029) for the 1.0x.25mm threads. Although the video in this thread shows the comparative size relative to a tire valve cap I am showing the 2 bases relative to a penny. The corner radii will need to be filed on and the bases polished up with some fine emery paper.
gbritnell
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I am also making a drawing that will have stop points, step points etc. for the build. As I develop them I will post them for the group.
George, thanks for showing this build and the stop drawing will be very helpful to see the sequence better.
Dan
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Pulling up a chair for this one! It's like a minute version of my Stuart :D
Simon
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I like it very much :whoohoo:
I find making small parts very satisfying, so will be watching with great interest.
Stew
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George
Will be following this one also.
Vince
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This is a great build George....Like it a lot!
Dave
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George,
I am looking forward very much to this build. I really have a hankering to try one too, but I have a backlog of hankerings. And a real job...
--Tim
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OK George, I got my magnify glass and I will be watching to.
Ray
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Also following along to see this one take shape.
Ray
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:Love: small engine builds.
Alan
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Interesting build, George. I love these tiny little reciprocating steam engines. Thanks for taking the time to share with us.
Chuck
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This installment will be the machining of the column. It's just over .90 long and .95 wide across the legs. It is also made from 12L14 steel.
I chucked up a piece of 1.00 bar stock, faced and center drilled it.
The next step was to drill it undersize for the crosshead guide followed by a very small boring bar.
I calculated the distance between the legs at the top and bottom and opened the bore up to the required dimension by first plunging to depth with a .25 end mill followed by a drill.
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The next step was to put a counterbore into the bottom of the legs for a witness to cut the following taper of 25 degrees. The compound was set over and the small boring bar was also used for the taper.
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The diameter of the part was then reduced to 2 diameters, one for chucking in the mill (.625) and one for the lower flange that matches the lower head (.475). With this finished the part was cut off from the bar.
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I cleaned the mill table and then mounted the rotary table with the dividing head bolted to it. A test bar was inserted and indicated to get the rotary table parallel with the -x- axis. The handwheel was set to -0- and the part was clamped in the chuck. I didn't show it but the part was rotated and set true using the dial indicator. The next step was to find the center and the end of the part so I put the .200 dia. edge finder in because of the limited space.
With the digitals zeroed I was ready to start cutting.
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There's probably several ways to attack the cutting operations. I started by qualifying the width of the legs. By doing this first it left the stock closest to the chuck heavy enough to support the cuts.
The next step was to cut the crosshead window. After finishing this piece I found that I had less to cut with the .125 endmill if I cut the outer crosshead diameter first so that's what I did to the second piece.
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I changed from a .125 two flute end mill to a four flute for the finish machining operations.
First was to qualify the width across the bottom of the legs. This would give me a tangent point to cut the 25 degree angle on the inside of the legs. This is why I roughed out this area on the lathe so I wouldn't have so much stock to cut with the small end mill.
With the witness cut I rotated the rotary table and cut the inside of the legs.
Once the angles were cut I put the rotary table to the starting angle and cut the bottom surface of the crosshead guide, sneaking out till I just touched the taper on the legs.
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The next steps were to cut the support ribs on the legs. These are .086 thick. I put in a .125 endmill with a .045 radius on the corners. Using the digital readout for all of my tangent points sure makes life easier. I roughed the legs and trunk of the crosshead staying up about .01. I then rotated the part and did the same on the other side. I miked the thickness of the rib and adjusted the quill for my final cut. It looks pretty ugly at this point but once all the witnesses are cut the blending cuts smooth everything out.
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Gee! George you have been busy. Thanks for the step by step, that is real interesting. keep the photos coming.
Don
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The final machining was done with a .094 ball mill. I set the depth to the trunk diameter witness and then by rotating the dividing head created the circular shape on the trunk.
The chucking lug will stay on so that I can set it up to drill the holes in the bottom of the legs. Once that's done I can part it off and finish face the bottom flange.
I guess at this point I should have taken a picture of the finished crosshead after detailing it with burrs, stones and files but I didn't think until I started putting all this together.
I did set the finished column on the base so you can see that it's starting to take shape.
Tomorrow I'll finish up the second column, remove the dividing head and while the rotary table is still in place I'll do the shifting links for the valve straps.
gbritnell
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George, Your work is incredible! Thanks for sharing with us. I was wondering, do you work with a print? And is the design your own, or just the scale?
Davyboy
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George, amazing work thanks for sharing.
Davyboy the prints are here.
http://www.modelenginemaker.com/index.php/topic,569.0.html
Dan
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Beauty George! Boy it's real easy to loose track of the size of this thing - until you drop another penny :o
PS - how do you like that six jaw chuck, I've never used one. What diameter?
Cheers Garry (following closely)
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Very educational George
Steve
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Mind boggleing George....as usual!
:NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy:
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Hi Garry,
The six jaw chuck is 5" diameter. I found it used and in perfect condition many years ago. It's not so much that it has six jaws but that it's a set-true type chuck, that's the great part. Even though it's very accurate (going from one diameter to another) it can still be tweaked to get it dead concentric. I wanted to buy the other set of jaws for it but they cost a king's ransom.
gbritnell
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This is brilliant George - when I saw it I thought, another Stuart, I won't bother ... then noticed the scale of things! I thought the column was fabricated too, some interesting machining operations there :ThumbsUp:
Nick
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It's time for the next installment.
Today I will be making a flywheel.
As with the base and column the flywheel is 12L14 steel. The O.D. is .900 and the width of the flange is .150.
I started by chucking up a piece of 1.00 steel, facing and turning the O.D. to size. On one side the hub sticks out .038 so I cut this with the facing tool I had installed. On the second flywheel I realized I could cut this hub with the necking tool so I eliminated this step.
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The next 2 steps were to center drill and drill the crankshaft hole. I drilled it undersize followed by the finish drill which has never been sharpened so with a little cutting oil gives a nicely sized hole.
This diameter is .089.
The next step was to part it off leaving .01 for finishing to size.
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The next step was to make a step collet to hold the flywheel for facing and counterboring the other side.
I had an aluminum disc in my scrap box so I chucked it up, faced and bored it to the O.D. of the flywheel. You'll notice a reference mark on the face of the collet and the chuck jaw. I have found that when I make these types of collets if I register the collet with the chuck when I take it out to split it and reinsert it the runout will be negligible.
The blank was then inserted and the collet clamped. The second side was then cut to the proper width and the recess cut.
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I finished the second flywheel and then went to the mill for the next machining steps.
First up was to indicate the rotary table.
Next was to clamp the collet with flywheel installed into my small 4 jaw chuck. I use this chuck strictly for rotary table work. The chuck is mounted to an aluminum plate with a flange that extends about 1.00 beyond the chuck, this way I can hold irregular pieces and offset them for radial cutting.
I left the clamps loose and inserted my conical mandrel into the spindle. I then located the flywheel by inserting the mandrel into the crank hole and then tightened the clamps. I have found I can get within .001-.002 by this method. If it's something that needs to be exact I will follow the mandrel with a dial indicator.
I had already made a location chart for the holes so it was just a matter of going to the proper coordinate and center drilling and drilling the corner radii.
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The next operation was to cut the material from between the spokes.
I inserted a .062 high speed 2 flute endmill and started cutting. My new mill goes to 2500 rpm which isn't exactly fast enough for this size cutter but given the thickness of the web it wasn't a problem.
I roughed the material out staying about .005 away from my finish dimensions. First was to cut along the spokes from the inside to the outer radius on both sides of the spokes. The next step was to cut the radius using the rotary table. With all the webs cut out I then went to my finish dimensions and cleaned up the spokes and radius.
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The final step were to chamfer the corners of the spokes and the radii. I used a very small white grade conical mounted stone in my Dremel grinder flex shaft followed by small files and emery cord. All that remains is to drill and tap for the set screw, oh yes and to finish the second wheel.
gbritnell
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I really enjoy watching your work, George. The machine work, of course, but seeing and reading how you finish
off a piece like the flywheel, too. Makes all the difference.
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George, you are a true master. It is a joy to follow you with your project. You make it look so easy and you photos and documentation is superb. Keep um coming.
Don
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This installment will cover 3 parts, the shift link, the cylinder and the steam chest.
When making small parts, even those that would normally be made from a sheet of steel, I prefer to make them out of a piece of round or rectangular stock. This way there is always something to chuck or clamp onto. The profile or drilling is completed and then the part is sliced off or parted of depending on how is was made.
With the link I I used a piece left over from making the base and chucked it into the 4 jaw chuck that was still set up from the earlier operations. I drilled the link holes and the corner radii deep enough to get 3 pieces. I then removed the extra materiel with a .062 end mill and then sliced them off with a .025 slitting saw.
From here it was just a matter of filing to put the corner radii on. As all of the fasteners on this engine are 1.0x.25mm the link slot is .04 wide. The thinnest file I have is .047 so I took an older one and ground the back side away till I got it about .034 thick. This allowed me to file the curvature into the link.
gbritnell
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Next up was the cylinder. As mentioned I started with a piece of round stock large enough in diameter to encompass the external shape of the of the part. I chucked it in the lathe, drilled and bored the bore (.300 dia.) and then transferred it to the mill where I had remounted my vise and dividing head.
I indicated the part to get it concentric and then milled the valve face first. Next I rotated the part and cut the 2 side angles. From there I rotated the part and cut small facets around the curvature. These were filed smooth before the piece was parted off in the lathe.
In the last picture you can see that the upper and lower heads had already been made. I didn't show the steps for these as they were just turning exercises.
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There was an operation that I did before removing the 4 jaw chuck from the mill. That was to drill the mounting holes into the lower part of the column legs. The parts still had the chucking lug so I clamped it into the chuck, indicated and drilled it.
Here's an aside to the drilling of this part. On my initial setup of the rotary table and 4 jaw chuck I had indicated the center of the rotary table and set my digitals to -0-. When I cut the spokes in the flywheel I naturally indicated the wheel blank to center.
Now to drill the legs on the column I clamped it into the 4 jaw and with an arbor inserted into the crosshead bore I indicated it to center, first. I then rotated the rotary table to get the sides of the legs parallel to the axis of the mill. That seemed like the proper progression. The only problem was in moving the jaws in and out to clamp the part the true center of the chuck wasn't on the true center of the rotary table and longer. It was only when I got ready to center drill the first hole that I noticed it looked out of place. How could that be? I had indicated the bar true and set my digitals. It then occurred to me that I should have indicated the part square first and then picked up the center because by doing it the other way the part had rotated off center when I squared up the legs.
Calamity averted.
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The final piece in this posting is the steam chest. Once again I started with a piece of round stock. The valve guide hole in the chest is offset so the needed diameter was calculated and chucked. I drilled the guide holes but didn't show the steps, center drilling and drilling.
From the lathe it was over to the mill and chucked into the dividing head.
The outside flats of the chest were cut first followed by the drilling of the mounting holes and inside corners of the chest. The remaining stock was removed with a .062 endmill working out to the pre-drilled holes.
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On the sides of the steam chest are 2 holes, one for the steam/air inlet and on the opposite side the mounting hole for the reversed lever. These were now drilled.
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George you have been a busy fellow, that is some superb work and love how you show the setup.
Don
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The part was removed from the mill and put back in the 3 jaw chuck in the lathe to turn the upper valve stem boss. A tool with a small radius was mounted and I slowly cut the material away given the extra loading of the radius tool and the fragileness of the part. Once I was close to the proper diameter I took the final side cut to establish the height of the part (.400) and finished the boss.
The part was then cut off of the bar.
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The final operation was to remove the 3 jaw chuck and mount the 4 jaw chuck so that I could form the radius on the end of the valve boss. The part was clamped lightly so as to not mark the finished surfaces of the chest and was adjusted to center with an indicator. The radius was filed onto the boss and then polished with emery paper.
gbritnell
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I don't post much in your threads...but I always read them.
Excellent work for me to learn from.
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George you are a man of few words, but dog gone up do excellent work.
Don
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Beautiful George......George showed me some of his art work he's working on at the moment yesterday.....it's everything you could possibly imagine!
:NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy:
Dave
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I like to print out the drawing pages and hold the relevant one in my non-mouse hand as I follow along with the pictorials here.
--Tim
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My hat is off to you George :NotWorthy: :NotWorthy: I have just followed this thread through and your work is stunning.
Jo
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That realy is a master class of maching small parts George
:NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy: :NotWorthy:
I've learnt a lot by following your thread, thanks for showing.
Stew
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Might have to have a go at this one George, once I get the Ericsson finished. Its the small size and reversing gear that really sets it off i think...good project for the Sherline equipment too!! Now if only I can find the stronger diopter lens for my magnifying hood ;D. Great work and documentation as always !!
Bill
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With the cylinders bored and machined to shape it was time to put in all the ports and bolt holes. The ports were done with the cylinder clamped in the mill vise. They (intake ports) were too small for any cutter that I have (.025 wide) so a series of holes were drilled and then with a sharp utility knife I cut away the steps between the drilled holes. The same was done for the exhaust port but I was able to get a small file in to clean up the edge.
Now it was time to put in all the holes for the cylinder heads and cut the recess for the ports at the cylinder ends. I found a fixture plate in my stash of plates and turned up a boss to locate the cylinder. With the cylinder mounted on the boss I then used one of my tiny clamps as a stop so that the subsequent operations would all be square and true. The holes were drilled and the notch was milled.
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The next part would be the crankshaft. For this part I used some 1144 steel. Normally I use this material for it's non warping properties but in this small size it's not really an issue. The O.D. of the discs is .375. I started by facing and center drilling the stock. The next step was to turn the main shaft to .089 diameter. With this done on 2 pieces of stock it was time to make a fixture block to hold the blank for offset turning of the throw journal. I squared up a piece of aluminum and then centered it in my 4 jaw chuck. I put an -X- as register mark to locate the block to the #1 jaw in the chuck so that the bored hole would always be square to it's original setup.
With the block made and a tapped hole put in to hold the crank I put it back in the chuck and offset it with a dial indicator to get a reading of .250. With this done I cut the throw journal by plunging in with a necking tool. The tool was a little wider than 1/2 of the slot so once the first cut was made I could take the remaining stock from the chuck side with no worry about the crank twisting off. To finish off the crank I put the it into a collet and turned the other main down leaving .010. I thought I took pics but apparently not. The second main shaft was made .25 longer than the required length so I could clamp to it while supporting the outboard shaft with a live center. The remaining stock was removed and the crank was cut off to length. The bearing blocks had been made in another operation that I didn't document, just milling and reaming to the proper dimensions.
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The next part is the connecting rod. This was all basic machining but in a much smaller scale.
I started by facing a piece of .25 square brass rod. The next step was to cut the yoke end with a slitting saw. Now I could center drill and drill the hole for the crosshead screw. I did this next so that the stock would still be heavy enough not to flex while drilling.
Now I cut the yoke area to size.
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With that part of the milling finished the stock went back into the 4 jaw chuck to cut the shaft. This is .062 diameter with small fillets at each end.
From the lathe it was back into the mill to cut the area for the big end of the rod.
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I then cut the rod blank from the stock. It was too hard to square the rod in my big mill vise so I used my small Sherline vise for this operation. I squared it up on my layout plate with an indicator and then clamped the small vise into the large one. The end was milled flat and then the screw holes (1.0x.025mm) were drilled.
The cap was then cut off with a jewelers saw and it and the rod were milled square and cut to size.
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I have some screws on order but not wanting to wait for them I made up 4 screws to hold the caps to the rods so that I could finish the crank holes.
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With a little polishing and fitting the rods fit nicely on their journals. I had made the crosshead and connecting screws so I assembled the parts to check the fits. Once all the parts are made they will be properly radiused and cleaned up.
gbritnell
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That is some awesome bit of work on the small scale. You just keep inspiring me every time I read.
Now I have enough on my plate now and this is one I need to try. Thanks George for you continued photos and documentation.
Don
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Beautiful work George and as usual a thread full of excellent information.
Hope you don't mind a couple of questions...
You used a jeweler's saw to cut the cap off. Could this be done using a slitting saw in the lathe?
After cutting the cap off, did you (re)drill the holes in the cap?
Thanks
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It just keeps getting better and better George. Thanks for all the updates and excellent pictures.
Bill
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Hi Zee,
When I cut the rod from the bar I used my bandsaw. This left an uneven surface. I then put the rod in the vise and squared it up. I then took a clean up cut on the end so that the surface would be finished and square to drill the holes for the screws. The lower end of the rod was around .200 long at this point. It would be .15 when finished. After drilling through with the tap drill I counterbored with the clearance drill. With no good way to hold the rod to use a slitting saw to remove the cap I just used my hand jewelers saw and cut the .200 in the middle. Cleaning up the cap wasn't a problem. It needed to be .075 wide so I put a thin parallel in my vise that allowed .062 clamping surface and milled it to thickness. The rod on the other hand posed a problem. I couldn't clamp it on the wide surface because the yoke end is wider. I couldn't clamp it one the narrow surface because I was afraid that there wouldn't be enough friction and the part might move when milling. What I ended up doing was to take a piece of square brass bar, reaming a hole through it lengthwise, splitting it with a .015 slitting saw and then using it to clamp the shank part of the rod in the vise. I made sure that the end mill approached the rod from the narrow surface thinking that if I came in from the long edge there would be more leverage applied to the rod and it might twist in the little fixture block. It worked fine.
I apologize for not giving a more descriptive explanation but it takes a lot of time to make parts, take photos, edit photos and post the text and pictures so some of the machining steps are overly simplified.
gbritnell
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Thanks very much George. This was very helpful.
No need to apologize. I'd rather you keep doing what you're doing.
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George, I didn't get the sense of the minute scale until you showed the coin! I would love to try one of these but think it's beyond my skills. I like the way you did the cylinder though, drilling the angled holes is always something that puts me off a bit - having them straight and milling a pocket makes more sense to me. :ThumbsUp:
Nick
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Today I made the eccentrics. I reused the fixture block that I made for the crankshafts. I moved the set screw hole to the edge so that once set to the proper offset I could rotate the part without having to remove the block.
I turned and reamed the stock for the crankshaft diameter and the nose boss. I then offset the fixture block .032 (total of .064) in the 4 jaw chuck. The part blank was mounted and the set screw tightened on the first flat. (one flat for each eccentric offset). The first eccentric was turned to size.
The stock was then rotated to the other flat and the rear eccentric was cut with a small parting tool. The piece was then cut off the bar. The set screw hole will need to be drilled and tapped.
gbritnell
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The 'D' valve was machined on the end of a piece of .25 round stock. I faced and center drilled the stock on the lathe. The recess is .031 deep so by putting the recess in with the center drill it kept me from having to plunge the .062 cutter into the stock.
The part was then indicated to center.
The first cutter was the .062 end mill. I went right to depth and walked around the inside cavity staying .004 away from the finished size.
The second cutter was the .031 end mill. It only needed to clean up the side walls and reduce the fillets in the corners. I have a high speed spindle for my mill but the setup time for a small job like this just isn't worth it. My mill will only spin 2600 rpm so a gentle touch was needed with this cutter.
The third cutter was a .125 end mill for qualifying the outside of the valve. The overall size of the valve is .175 square.
Once the part was milled the valve rod and set screw holes were put in.
The last picture shows the valve chest assembled on the cylinder.
gbritnell
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Looking good George, I am still following with interest here. I wish you would have put a penny next to the eccentric, it has got to be little. Making an engine of that scale has to work on the nerves. Don't you get some ???%# moments?
Don
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There's good things and bad things about working in this size. The bad thing is the size. The good thing is the parts are so small that if you mess up something you just make another.
For instance. I had made 2 'D' valves. They have a .037 diameter hole for the valve rod and a 1.0mm tapped hole to secure the valve to the rod. While trying to make the small set screws to hold the valve to the rod I must have lost 3 of them. (.039 dia. x .07 long) It was then that I decided to open up the tapped hole to 0-80 because I have some stainless set screws that size. I drilled the threaded hole bigger by hand, stepping up to the tap size for the 0-80 thread. The first one went fine and when I started on the second valve I had one of those senior moments. The holes are so small that it was hard to tell the difference in them so when I started to open one of them up for the 0-80 tap I had picked the wrong hole. Time to make another valve!
I only have a few pieces remaining but the only part I'm cringing at is the final tapping. I have 2 - 1.0mm taps, high speed steel, 2 flute, one starter and one plug. The only place that I can find them is through Travers Tool and they're $32.00 each and it's not even so much the cost of replacing the tap it's having to make a new base if one snaps off.
gbritnell
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George,
You have my sympathy, your taps are the same size as the 14BA's I have had the missfortune to have to use from time to time. Thankfully their use so far has been with success. When I use these small taps I use my pillar drill, with a pointed sprung loaded plunger, as a tapping guide and a very small flat light weight tap holder.
I also have some 16BA :Doh:, which so far I have been able to avoid by using alternative fasteners.
Jo
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Gentlemen,
I have the first of the two new engines finished. I found a few drawings disparities along the way, have fixed them and will be reposting the new files.
The engine runs well so the new owner should be pleased. I have taken a few pictures of the new along with the old from several different angles.
About 2 more hours and I should have the second engine finished.
Thanks for watching.
gbritnell
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George that is some superb craftsmanship. Thanks for sharing you work in progress with us. I loved the photos. They look great for being so small. All of the engine that I have seen of yours are superb in all respects.
Don
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I finished up the third engine this morning. I thought I would take a picture of the trio before I send two of them off to a good home. One is already spoken for and the other is listed on Ebay.
gbritnell
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A very enjoyable build, George. Thank you for sharing.
--Tim
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Thanks George for the journey and all the new things I learned on the way.
Vince
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It went fast George!
Thanks for taking us along!
Dave
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Wow, I must have blinked. That was briliant, thanks George :cheers:
I am wondering if one of these Tiny engines would be a good thing to make as a demonstration piece at our Model engineering show next year using my Cowells :thinking:.
Jo
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THanks for allowing us to watch the build George. I will keep an eye out for the updated drawings as I still want to have a go at one of these soon.
Regards,
Bill
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Gentlemen,
I have posted the updated drawings to the drawings section.
gbritnell
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Thanks George, and again, beautiful work on your latest two!!
Bill
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George is the one engine still on ebay, could you post a link?
Regards,
Gerald.
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Very enjoyable George. And excellent work.
Thanks again for the earlier help.
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Hi Gerald,
I'm sorry I didn't get back to you quicker. It was sold almost as quickly as I posted it so I'm going to build some more.
gbritnell
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Hi Gerald,
I'm sorry I didn't get back to you quicker. It was sold almost as quickly as I posted it so I'm going to build some more.
gbritnell
If you don't mind saying what did it sell for or how much will you ask for future ones?
Regards,
Gerald.
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Hi Gerald,
Email me direct and I'll tell you the particulars about the sale.
gbritnell
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Hi Gerald,
Email me direct and I'll tell you the particulars about the sale.
gbritnell
PM sent
Gerald.