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Old 03-22-2015, 10:50 PM   #1
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Default TB2 build Elmer's #46 Comber - back from the dead

Having gotten the Muncaster engine to the initial run state I have decided to revive my example of the Comber engine, Elmer's #46. The parts have been sitting is a storage drawer in my shop since 2008. One reason I didn't continue is that I didn't get parts from everyone on the team, and as well got interested in other projects. I've been thinking of getting it running for CF, so I have about 2 weeks to make the missing parts and get a runner. Personal challenge!

Taking inventory it appears that the parts I need to make are:

Two heads
Two rollers
Two pins
Air inlet barb

The hard parts are in hand, although attention will need to be paid to fitting, esp. with the bearings.


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Old 03-23-2015, 08:01 PM   #2
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Today's first project was to make the heads/cylinder covers. 1" brass rod in the lathe, face, and turn 1/4" boss.



I did this on both ends of the rod so as not to have to change the lathe tool. Then parted off both enns. Next fasten spigot with a collet and face to form a 3/8" x 1/32 spigot to match the cylinder opening.



Now over to the mill with the collet and collet block to drill mounting holes and trim sides:



Mounted on the cylinder the piston rod slides freely.



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Old 03-23-2015, 10:07 PM   #3
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End of day test assembly. On the original build the flywheel was my part assignment as I was using a school shop. Looks as if it could use some attention.

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Old 03-26-2015, 11:19 PM   #4
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Got everything made and assembled. Assembly takes some dexterity since to get the second fork in place it has to be installed without the roller, and then have the roller, pin, and cotter added.

Engine doesn't yet run. Lots of air leaking out the main bearing hole. I can feel some resistance when turning the cylinder opposite to the run direction, so air is getting into the cylinder. I'll keep playing with it as time allows.
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Old 04-02-2015, 08:55 PM   #5
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I've been playing with trying to get it to run, but so far the best effort has been about 4 rotations with 80psi air.

The engine is very low power and any friction is death. The most obvious problem is the forks around the rollers rubbing on the cam ring sides. I think the slots are a bit narrow; add to that the cam ring being slightly misaligned with the plane of rotation and the difficulty of keeping the slots square with set screws. The piston rod is also slightly too long, and will rub one of the rollers if not adjusted just so.

Tomorrow is my last day to fiddle with it before leaving for CF, but I'll haul it along and fiddle with it if it still doesn't work.
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Old 04-02-2015, 10:54 PM   #6
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Keep at it. Mine runs great on 5 to 10 pounds of pressure with lots of power. Even with some friction about the forks yours should run well also. I would suspect the valving may be off because of the low power.
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Old 04-03-2015, 04:13 AM   #7
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Just to remind you that they really do run well.
https://youtu.be/f_KaGygrND0
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Old 04-03-2015, 09:03 PM   #8
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Remade the axle, which was misaligned, and got it to run:

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Old 04-03-2015, 10:14 PM   #9
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Congrats. Lots of work finally pays off.

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Old 04-03-2015, 10:18 PM   #10
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Thanks, Gail.

Can't really claim "lots of work" since I just started the missing pieces and assembly a few days ago. But a runner is always satisfying.
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