Kerzel Hit and Miss

[Brian Rupnow]

Weez--That looks really great!!!---Brian

 

[weez]

Thank you Brian. Today I made the rocker arm pivot. After milling the stock to size I milled out the profile.


Then drilled the mounting holes.


Then drilled/reamed the pivot hole. When a hole crosses a slot I like to drill the hole before making the slot to keep the drill bit from wandering.


Now milling the slot.


Mill down one side.


Flip over and mill the other side.


And here is the finished part.

 

[weez]

Today was another first for me. Today I cut my first gear. I must say it was fairly easy. I bought a set of Mod 0.8 cutters from CTC Tools. I went with Mod 0.8 as it is close to the 32 pitch that the plans call for. First I turned a chunk of 12L14 to the proper dimensions.


Then without removing the blank from the 3-jaw chuck, I removed the chuck from the lathe and mounted it on the rotary table. After setting the involute gear cutter right on center, I used a sharpie to blacken the blank. I then turned the mill by hand and slowly moved the cutter towards the blank until it just skimmed the color off of it. I zeroed my DRO and then moved the cutter in the appropriate amount (I hope).


I don't have dividing plates for my rotary table so I just moved 18 degrees between each cut, double checking that I moved the correct amount each time. Half done, looks good so far.


Here is the finished gear. It looks right to me but I won't know for sure until the bigger gear is done to see if they mesh well.

 

[gus]

Hi Weez.

Welcome to the ''HMEM Gear Cutting Gang''. And you got thru with no one half-tooth. Congrats.
A few of us ''eager beavers'' have a good collection of 1/2 tooth DIY paper weights.

 

[gus]

Hi Weez.

Welcome to the ''HMEM Gear Cutting Gang''. And you got thru with no one half-tooth. Congrats.
A few of us ''eager beavers'' have a good collection of 1/2 tooth DIY paper weights.

 

[weez]

Up next is the big gear. I deviated from the plans a little and made the gear and cam one piece. I started with a chunk of 1 1/2" 12L14 round bar in my 4" four jaw chuck. I turned the end down to 1" so that it will fit in my 3" three jaw chuck.


After switching to the 3 jaw I turned the blank to size.


Without removing it from the chuck, mounted on the rotary table. After cutting the teeth on the gear I moved on to cutting the cam profile. I used http://modelenginenews.org/design/CamTable.html to get the coordinates for cutting the cam, making a cut every 2 degrees.



And the finished gear/cam. I still need to clean up the cam a little but for my first cam I think it turned out good.


The two gears seem to mesh well. And Gus you will note that there is no half tooth.

 

[gus]

Hi Weez.

Those are great looking gears. And is this your first attempt???

 

[gus]

To cut noise your may have to lap them togethers. After lapping they are quiet quiet.

 

[weez]

Up next is the regulator arm pivot. After turning to size and drilling/tapping the end to 6-32, I mounted it in a v-block and drilled the hole for the pivot pin.


Then rotated the v-block in the vice and milled the slot.


And here is the finished part.

 

[weez]

Next is the cam slide bearing. First I drilled a 1/8" hole for the inside radius of the corner.


Then mill the profile.


Mill the slot.


Then drilled the mounting hole. I had to use a center drill for the countersink as my countersinking bit is too wide to fit in the slot.


After rounding one end with a file, here is the finished part.

 

[Brian Rupnow]

Still following and still looking great.---Brian

 

[weez]

Here are the push rod bearing and push rod.

 

[weez]

Still following and still looking great.---Brian

Thanks again Brian. You have mentioned in some of your build threads that after a while it seems as though you are posting in a vacuum. I think that this thread is at that point. I only have a few more parts to make before I can try to run it (not in hit and miss mode), then things should get more interesting.

 

[Brian Rupnow]

Weez--It's probably not a great idea to have a brass rod sliding in a brass block. Anytime you have two pieces of metal sliding or rotating against one and other, it is better to stick to dis-similar metals. There is not a heavy load on the pieces you just posted, but it is something to be aware of. And yes, it isn't much fun to post about your project when people have stopped commenting on it. Your "visits" counter keeps going up, but that's not much consolation. It's a lot nicer when folks stop by and say Hi.

 

[gus]

Weez--It's probably not a great idea to have a brass rod sliding in a brass block. Anytime you have two pieces of metal sliding or rotating against one and other, it is better to stick to dis-similar metals. There is not a heavy load on the pieces you just posted, but it is something to be aware of. And yes, it isn't much fun to post about your project when people have stopped commenting on it. Your "visits" counter keeps going up, but that's not much consolation. It's a lot nicer when folks stop by and say Hi.

Its true I had the bad experience when overhauling a Scale Pit Pump hundereds of miles away from Singapore. No matter how much grease I out in it did not slow down the scoring.

 

[Swifty]

As stated above, similar metals will score and gall up when worked together. When I as designing press tools to pierce and form stainless steel, the normal high carbon, high chrome punches were no good, we had to use HSS for this type of material.

Paul.

 

[weez]

Brian, Gus, and Swifty,
I am aware that it isn't a good idea to use the same materials on sliding parts. I didn't give it a thought as the plans call for brass for both parts. I am going to leave both pieces brass and see how it goes. Worst case scenario I that I have to remake both simple pieces.

Here are a few more finished parts starting with the cam follower.


Pivot pin.


And finally the push rod lock nut.

 

[weez]

Here is my next part. Within this Swiss cheese looking chunk of brass is a rocker arm. I drilled a hole at every inside corner and on a tangent line of each face.


First I milled the side profile.


Then I used drill bits in two holes to locate the piece at the correct angle to mill the first face. I used two #60 bits under each larger bit to act as parallels.


After removing the bits, I milled down until the holes disappear.


Then set up and mill the next face.



Repeat this process for the remaining two faces.



And after rounding the ends with a file and locktiting a ball in one hole, here is the finished part.

 

[weez]

I am going to use an electronic ignition with a hall sensor. Here is the magnet disk before locktiting the magnet in and the hall sensor mount.


I used heat shrink tubing to attach the sensor to the mount.


I also completed the spark plug. I hooked it up to the ignition and I am getting a nice blue spark.



I completed the carburetor but forgot to take a picture. Here is the engine to date. Hopefully I will attempt to run it tomorrow.

 

[weez]

Alright, ready for the first run attempt. Set the ignition timing to a little after TDC. Carb needle valve one turn out. Spin flywheel by hand a bunch of times. Nothing. Open needle valve another half turn. Spin by hand. Nothing. Another half turn and hand spin, still nothing. Arm getting tired. Why didn't I make a drive dog for the drill? Too late, I need to see this thing run. Repeat opening valve and spinning flywheel. Finally a pop. Keep spinning and adjusting, getting more pops but no sustained run. Why am I getting bubbles between head and the cylinder? Oh, I forgot to tighten the head bolts. After tightening try again. Spin flywheel, pops. Keep spinning, more pops. More spinning and finally a short sustained run. Keep tweaking carb and get it to run for longer periods. Play around with ignition timing. Advance it to about TDC. Engine takes off. Almost too fast. Quick shut it off. Set carb a little richer and try again. Running pretty good, and a little slower. Turn needle in a little and engine takes off again. I think I found the sweet spot. Here is the video with it running a little rich. I didn't want to run it too fast. It does run better if I lean it out but I will wait until the governor is complete so that I don't over rev it.
http://youtu.be/F1rl6jZ9yI0