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| sbwhart:
This will be the last post on this job, for over a week going to have a house full of kids and grand kids. I decided to make the crank shaft with a disc throw, quite a few of the popcorn engines I've seen [ics of have this set up so thought I'd give it a go. With a chunk of steel in the chuck turn the od and centre drill, then centre it on the mill a off set it by the throw and drill with a number drill just below the size of the crank pin so its a tight fit. One thing they do with this type of crank is maching out a curve oposite the crank pin to balance the crank so using the rotary table mill a 60 deg curve. Then still in the chuck back to the lathe and drill out for the crank shaft again using a number drill so that its a tight fit. Then skim it off to correct thickness, the material I'm using is tool steel used to make draw dies from, high carbon with bits and bobs of other things in it, I'm familiar with this steel and know it turn well with high speed tools, but it produces wicked razor sharp snakes of swarf. Glue the shaft and pin in Turn up the main bearings and glue them in. Time for a few hows it looking shots. Not bad. Stew . |
| saw:
Nice, I realy love youre flywhile :D |
| Stilldrillin:
That ensemble is really nice Stew! :clap: :clap: :thumbup: "a curve oposite the crank pin to balance the crank". Is the curve filled with lead, or summat Stew? Surely, the crankpin area needs lightening. That area needs to be heavier...... Dunnit? Or am I missing something....... :scratch: David D |
| sbwhart:
:doh: Yes your right Dave the bit oposite needs to be heavier, or the bit behind lighter. Never mind its only for show :D Stew |
| Bluechip:
--- Quote from: Stilldrillin on October 03, 2011, 12:08:51 PM ---That ensemble is really nice Stew! :clap: :clap: :thumbup: "a curve oposite the crank pin to balance the crank". Is the curve filled with lead, or summat Stew? Surely, the crankpin area needs lightening. That area needs to be heavier...... Dunnit? Or am I missing something....... :scratch: David D --- End quote --- I'm with you chief ... I reckon there should be added mass there to balance the big-end and the bit of the con-rod which is considered to be rotary.. Often the 'shoulders' of the crank disc either side of the big end are cut away .. Hmmmm... BC Stew nipped in quick .. poke it in anyway ... |
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