Mark's Build of Rupnow Vertical IC Engine

[mjonkman]

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[Brian Rupnow]

Mark--that looks fabulous!!

 

[Herbiev]

Turned out great.

 

[Brian Rupnow]

Any updates, Mark?--I'm still waiting for the first running vertical engine.---Brian

 

[mjonkman]

Sadly no. I haven't had a chance to be in the shop thus week. Might get an hour in thus aft if I'm lucky. I got a month and 3 days of vacation plus holidays to take before end of year so my target is by Dec 31st.

 

[mjonkman]

No update again this week, work has taken over for the next two weeks.

 

[mjonkman]

Back in the saddle again

Finally after what feels like ions of time, I finally got back into my shop and will be out there approximately every other day for the rest of the year if I can help it.

I got out there last week, made a couple of arbors and finished setting up the horizontal mill (had to cut keys for the tailstock of the dividing head) and I cut the gears. I'd say I did it perfectly the first time but I'm guessing no one would believe me I almost got it right on the first attempt. after much research and watching youtube videos and doing the calculations etc I felt pretty confident. Decided to do the smaller gear first (less material to waste). Well despite double checking everything I somehow had the plunger pin engaged with the 19 hole ring on the plate vs the necessary 18 hole. How or why I did that I have no clue. Sometimes I baffle myself. Anyhow it was evident on the last tooth that I had messed up. One look told me my mistake.

Created a new blank set the plunger right and made a second gear and it came out perfectly. Same with the larger gear. The only headache I had was that it was very difficult to measure the gear while still on the mill. But I only have a 3 jaw chuck and tailstock so I didn't want to remove the gear until it was complete. When I finished the larger gear I miss measured and stop a few thou to shallow. Had to put it back in tonight and take an extra cut. Seemed to work out perfectly.

Mounted the gears up in the engine frame to check fit and after a minor adjustment (skim cut) off the larger gear. It all fit perfectly. the gears mesh nicely and the crank and cam gears spin with no interference and very little backlash. I'm really tickled pink at how they turned out.

I'll be concentrating on any missing parts for the cam shaft and the crankshaft then move back to doing the remaining parts of the head and lap in the cylinder. Once that is all done I start moving towards the rest of the stuff like carburetor and fuel tank and so forth.

I got the spark plug, points and condenser sitting in my drawer of parts. I still have to figure out the what else I still need on that front.

I didn't take many pictures of the gear cutting because it was kind of awkward to get a good picture and poor lighting.

 

[Brian Rupnow]

Great stuff Mark. thank you so much for the update. Gears can be a real pain in the head if you lose track of your "turn count" any time during the machining.--Brian

 

[mjonkman]

Well I never got as much time to do machining as I expected over my 3 wk vacation. Seems like everyone wanted a slice of my time and unfortunately my wife's grandmother (oma) passed away so she went to Holland so I had to be Mr. Mom as well for the first 10 days of my vacation. My "apprentice" used up a lot of shop time as well trying to finish a Stirling engine before he takes off to China at the end of this week. Then of course Christmas showed up - hey on the bright side my loving 14yr old daughter gave me this awesome present of a beautiful black rock with heat generating capabilities (then she wanted me to buy her an iPhone 7 the very next day...) Overall it was a great time, my son flew in from Fort Sam Houston so I got to see him for the first time since he graduated basic on July 1st.

That aside, I did do some work on the engine.

I spent a morning lapping the piston into the cylinder and it now has a very nice fit. Might need a tad more lapping as it slides through with a gentle push but does not fall through on its own weight.

I silver soldered the small gear onto the hub and drilled and tapped the set screw holes.

I made the starter hub.

I finished the flywheel, broaching the keyway, drilling the big hole pattern and the holes for mounting the starter hub. The only slight screw up was when I broached the keyway, I put the shim in and it wasn't required for the 3/32" broach, so I had to machine a 1/8" key to 3/32" width to get a proper fit. I wish Dumont would include at least some instructions in the kit... or maybe I should have read the 1/8" stamped on the back of the shim...

I also made the cam and mounted it to the larger gear.

Made the little hub that the points ride on.

Tonight I made the Valve seat cutting tool that Brian suggested to use for cutting the valve seats.

I didn't take a lot of pictures along the way. I was mostly trying to get time in the shop and didn't want to stop to do a lot of picture taking as it does consume some time.

Most of the pictures I did were around making the cam. Not knowing exactly how to tackle the problem I went with the following:

I machined a length of rectangular aluminum and drilled and reamed 3 by 3/8" holes in a row, parallel to the edge of the work piece. The outer 2 holes were for hold down bolts in my rotary table and the middle was for an alignment pin that goes into the center slug of my rotary table and also the 3/8" reamed hole in the cam blank. A forth hole was drilled directly above the center hole and counter bored to allow the socket head cap screw head to sit below the surface of the material.

The cam blank was then machined to size and the 0.375" hole reamed in the middle and the holding screw hole drilled and tapped.

I then mounted the cam onto the fixture block I had previously made. With the rotary table mounted and set at 0, I locked the fixture down making sure the edge of the fixture was dead in line on the x-axis of the main table. I then centered the rotary table under the spindle with a coaxial indicator. Then it was a really simple process of calculating the correct angles in degrees, minutes and seconds and using the offsets I cut the two angles. and finally I cut the bottom radius to match the drawings. The top radius was already made as part of the blank.

Making the fixture was 90% of the work. Cutting the cam probably took maybe 5 min.

I reused the same fixture plate later with new holes drilled to hold the starter hub in such a way as to make it really easy to drill and ream the 0.125" hole.

Finally a picture of all the parts that I've made to date.

I had really hoped to have this done and running by Cabin Fever but looks like I'll be showing up with the a bunch of parts again... wonder if anyone think I'm nuts for having 2 engines in progress and only 1 complete engine....

 

[Brian Rupnow]

Very nice work Mark. That cam is a very "forgiving" cam. as long as you are somewhere "close" the engine will run okay.---Brian

 

[mjonkman]

Here is are a couple of pictures of my engine at Cabin Fever. I had made the valves, valve cages and lapped them in last weekend. I had also made the push rod guide and started on the push rod. Obviously I didn't make my year end goal of having it done nor my goal of having it running for Cabin Fever Expo.View attachment ImageUploadedByModel Engines1484491945.920281.jpgView attachment ImageUploadedByModel Engines1484491959.522077.jpgView attachment ImageUploadedByModel Engines1484491983.237825.jpgView attachment ImageUploadedByModel Engines1484492001.303984.jpg

 

[Brian Rupnow]

Just lovely, Mark. Herbie seems to be stalled out on his build, so you may still have the first runner of 2017.---Brian

 

[Herbiev]

Looking really great Mark. The weather here cooled down a bit over the weekend but the leader of the opposition brought home a heap of garden seedlings so that was my shed time gone. Hopefully this week I should have my engine running with a bit of luck.

 

[mjonkman]

That means I need to get out in the garage and work all night to see if I can build enough parts to get this thing running if I'm going to outrun Herbie... Then again common sense says I need to get a bit of sleep and start working off all the money I spent this weekend.

 

[mjonkman]

Got a little bit of work done the last two weekends. Could only manage sneaking a couple of hours last weekend, and a few hours yesterday and today.

Basically I finished the push rod - cut the slots, drilled the cross hole etc.

I made the rocker arm support bracket and the rocker arm - lot of machining steps in those two pieces.

Didn't take any in process pictures but here are some of the pictures of the finished items.

Sorry its not much of an update but wanted to let folks know I'm still working at it when time permits. Next weekend I'm off to Colonial Williamsburg for the Woodworking in the 18th century conference learning how to make chairs. So don't expect an update for at least 2 weeks.

 

[Brian Rupnow]

Looking good Mark. Glad to see you are still working on it.---Brian

 

[mjonkman]

Yesterday I spent the day in the shop, the goal being to make a jig to wind springs and to make the two valve springs. I've looked at various ideas on how to wind springs on the lathe from various sources over the years but I've never done it myself. I figured the first thing that needed to be made was some form of wire guide that I could put in the quick change tool post to guide the wire while the lathe turned. I took a rectangular piece of 1" x 5/8" cold rolled steel, 2.5" long. I milled a chunk off - 1" by 0.5" along the length. Making sort of a L shaped piece. I drilled a 1/16" hole through the remaining part, then drilled and tapped a 1/4"-20 hole at the front end to interchangeable offices (can't think of a better name) that is sized appropriate to the wire I'm using - at least that was my plan until I realized how hard it would be to drill a 0.015" hole. Since I had a couple of hundred or so carbide 0.033" drill bits I decided to make a single orfice with that and see how it went. I also drilled a 3/32" hole down from the top to intersect the 1/16" channel. I counter drilled and tapped a portion of that hole to take a 10-32 screw. The idea was that the wire would feed through the 1/16" hole into the custom sized orfice. The top screw would have a small brass extension that would be able to add variable amount of tension to the wire as it pulled through the channel. Probably doing a crappy job explaining it. I had planned on adding a brass shoe to a steel screw then realized that was way too much work and simply made the whole screw from brass. The pictures might make more sense then my words.

The next step was to make some spring winding mandrels. Simply just a straight rod with a small hole drilled in one section so that the wire could be fed into it.

Having never done this before I figured a 3/16"mandrel (0.1875") might do okay for winding a spring with a center of 0.195".... wrong!! I tried winding the .022" wire on it and was successful but when I removed the tension on the spring when I cut the wire from the wire guide, it sprung out to 0.245". The first attempt I hadn't added the tensioning screw to the jig just using a gloved hand for tensioning. I then added the tensioning screw and retried and got a small amount better maybe 0.005" difference on internal diameter. Then I cut a piece of 1/8" drill rod as a mandrel and tried again. This time I got a spring with a center diameter of 0.145". If there is a mathematical equation to describe the right sized mandrel its beyond me. I then made a 0.165" mandrel and tried again, this time I got a 0.205" inside diameter - I figured this was close enough. The other thing I noticed that I had to use a 11 TPI pitch on the lathe to wind up with a spring with a 0.1" pitch (which should be 10TPI) so i guess there is spring back on that dimension as well. I made two 0.022 wire diameter springs.

Then I moved on to the 0.015" wire for the other spring (intake). Thinking I could just use the same mandrel I wound the spring and when I cut the wire it sprung out to 0.240" internal diameter.. ugh. Tried a 0.125" mandrel and got too small. Finally I made yet another mandrel at ~0.145" mandrel and got another 0.205" inside diameter spring. The other headache I hit was that the tensioning screw tip wasn't long enough to contact the 0.015" wire so I had to use a pair of needle nose pliers to provide the tension. So I need to solve that another day.

Being the first time making springs, I was really surprised at the amount of spring back and other less then predictable results.

The picture of the springs on the valves has the springs reversed - heavy spring on intake and light spring on exhaust.. oops.

 

[Brian Rupnow]

Mark--Thank you for the update. I have wound my own springs in the distant past, and it certainly is a "hit and miss" effort to end up with the diameter you want. Did you temper the springs after making them? I tempered mine because I was told that without tempering the springs will eventually lose their "springiness".---Brian

 

[Brian Rupnow]

I found the original thread which shows how to heat treat (temper) the springs.
http://www.homemodelenginemachinist.com/f25/springs-things-7552/

 

[mjonkman]

I haven't yet but plan to. Haven't read the link you posted but another site
http://www.deansphotographica.com/machining/projects/springs/springs.html suggested about an hour at 450F. I'll have to fire up the barbecue next weekend and cook up some springs.

Mark