Gallery, Projects and General > How do I??
Stainless Oscillating Pistons?
bogstandard:
David,
You have to look at the material you are using.
If you drill it, and force something into the hole, it deforms the material.
After time, the stresses in the joint will try to keep expanding the material. With something like ali or brass, that stress stays in the material and so doesn't allow the part to expand.
The reason for drilling and tapping is to prevent that internal stress build up, so you get no further expansion of the material.
You should find loctite will be plenty strong enough to hold the threaded joint.
John
Stilldrillin:
John,
You`re right, of course. :thumbup:
Darren`s way was chosen cos` I have knurling ability, but no decent tap/ die combination. ::)
Order for 1/8 whit. despatched to Arc this morning......... :wave:
The loctite experiment went ok......
The double drilled hole was a couple of thou undersize, probably soft material springing back.
I made the rod a sliding fit, & assembled with a spot of loctite.
After 6hrs it was a struggle to pull the rod out. 24hrs curing should be ok. :thumbup:
All proceeding nicely. :clap:
David D
Stilldrillin:
Yesterday saw the first run of a PTFE piston.
I have a Mamod SE2 single cylinder engine, ideal as a test bed.
It ran perfectly on air. :thumbup:
STEAM was another story, the piston expanding to grip the brass cylinder...... ::)
After 3 trips to the lathe it finished up some 2thou or so undersize, very baggy when cold, but the engine ran very well! :clap:
After running, everything was clean! No orrible steam cream to clean up! :clap:
Very pleased.
Now to finish machining a set for the Triple...... :wave:
David D
bogstandard:
Now you know what your running clearance should be David, you should have no further troubles.
You're now cookin' on gas, and the only wear you should get is on the pistons themselves. Don't forget to put a spot of lube on your pivot points.
Now you know the exact size, you can make a few spares, then when the time comes, shave the old one off with a stanley knife and stick a new one on.
John
Stilldrillin:
--- Quote from: bogstandard on April 21, 2009, 03:44:53 AM ---Now you know what your running clearance should be David, you should have no further troubles.
You're now cookin' on gas, and the only wear you should get is on the pistons themselves. Don't forget to put a spot of lube on your pivot points.
Now you know the exact size, you can make a few spares, then when the time comes, shave the old one off with a stanley knife and stick a new one on.
John
--- End quote ---
My thoughts exactly, John! :wave:
Thank you for your guidance...... :thumbup:
David.
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