Model Engine Maker
Help! => Machines, Tools and Fixtures => Topic started by: Ratchap on January 06, 2019, 11:02:50 AM
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morning all I have come accross an article on making a 2 cylinder steam engine with a rotary valve that uses no castings.I have no idea where it came from its just called RoataryValveEngine.PDF. I plan on having a go at it
but to make the crankshaft it says the cranks is made from 1 " dia 4 inch long cold rolled steel that is mounted in one pair of off set centres could some one please point me to how this is done
happy new year all Nigel
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Hey Nigel
The "offset centres" refers to the center holes which are drilled off center. (but the same amount on each end of the bar). So if you take these center holes between centres on your lathe, you can machine the crankpin since those offset center holes are drillet to be the center of the crankpin.
Now there are different approaches on how to machine a crankshaft from barstock and as one piece - but I guess this can be found in the forum. (for example have a look at a building thread of Geroge (gbritnell)
Florian
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Hi Nigel,
may be this will help you to imagine the process.
http://www.modelenginemaker.com/index.php/topic,7395.msg173109.html#msg173109
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many thanks guys it now makes sense i need a lathe dog and drive plate
I knew some one would come through with the way to do it
Nigel
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Nigel,
Is this the plan?
http://www.john-tom.com/MyPlans/Steam%20Engines/RotaryValveEngine.pdf
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many thanks guys it now makes sense i need a lathe dog and drive plate
I knew some one would come through with the way to do it
Nigel
Hey Nigel, there are many ways to set up on centers. The center could be a piece of stock held in a chuck with the 60 point turned "insitu". To drive the piece you could use a bolt sticking out from the end of the part bearing on one of the chuck jaws. My point being, before you spend money on tooling, talk to us and maybe we can get come up with a set up based on what you have.
What lathe do you have?
Dave
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Heres a double throw crank between centers on my lathe Notice the use of the 3 jaw chuck with a piece of stock turned "Insitu" for the center.
Dave
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Nigel,
Is this the plan?
http://www.john-tom.com/MyPlans/Steam%20Engines/RotaryValveEngine.pdf
Indeed it is
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[/quote]
Hey Nigel, there are many ways to set up on centers. The center could be a piece of stock held in a chuck with the 60 point turned "insitu". To drive the piece you could use a bolt sticking out from the end of the part bearing on one of the chuck jaws. My point being, before you spend money on tooling, talk to us and maybe we can get come up with a set up based on what you have.
What lathe do you have?
Dave
[/quote]
Cheers Dave i have seen various ways of DIY driving but being a H&S manager i am more inclined too increase my tooling supply. I have a Generic Chinese mini lathe , its been stripped down cleaned scraped honed polished to within 0.025mm of its life lolso far i have added a tailstock DRO and QCTP with home made locking lever and a tachometer
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Hey Nigel, there are many ways to set up on centers. The center could be a piece of stock held in a chuck with the 60 point turned "insitu". To drive the piece you could use a bolt sticking out from the end of the part bearing on one of the chuck jaws. My point being, before you spend money on tooling, talk to us and maybe we can get come up with a set up based on what you have.
What lathe do you have?
Dave
[/quote]
Cheers Dave i have seen various ways of DIY driving but being a H&S manager i am more inclined too increase my tooling supply. I have a Generic Chinese mini lathe , its been stripped down cleaned scraped honed polished to within 0.025mm of its life lolso far i have added a tailstock DRO and QCTP with home made locking lever and a tachometer
[/quote]
H&S for between centers regardless is really about the same as for any lathe. All the same safety precautions apply. Safety is an attitude,
Same set up with drive dog and center
Why two set ups? I didn't have a soft dead center, that I could true up. That allowed a small amount of error to exist in the work. That said, I changed the set up to a 3 jaw with a piece of tool steel in the chuck that I machined to a 60 degree point, like a standard soft dead center, and drove it off one of the jaws with the dog.
Dave
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How do you take a piece of round stock and get the two sets of center holes aligned ??? I see for a rectangular piece it's no problem.
...lew...
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How do you take a piece of round stock and get the two sets of center holes aligned ??? I see for a rectangular piece it's no problem.
...lew...
clamp it to a rectangular piece - V block, block, even a vise if its the sort that be mounted on its side. indicate to centre the dia, offset, centre drill, flip 180 and repeat. It can also be via manual layout with V blocks, centre punching and drilling in the drill press