Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.
Moderators: Harold_V, websterz, GlennW
- Posts: 4515
- Joined: Sat Aug 18, 2007 10:58 pm
- Location: The Land Of Oz (Ahhh, Kansas!)
Jose Rivera wrote:Bill, I have never done a crank yet, but seeing videos of people that are machining cranks for small engines they create the off-set by putting four center drill spots, one on each end, and machine between centers.
In this way it will repeat exactly at ever set-up change.
Another of my two-cents !!
I don't quite understand. (Normal, for me.) Did you mean two on each end?
You are what you write.
- Posts: 3803
- Joined: Wed Feb 21, 2007 9:21 pm
- Location: Vallejo California
Yeah, one on center and second with the amount of off-set, same on the opposite end at exactly the same vertical axis.
What you are making will "work" with a relatively short crank, where you don't need to support the other end with the live center in the tail-stock.
Also the overhang that your fixture will case it may not feasible to free-air machining because of ( chatter ) and end support would be necessary.
Now, being lazy by nature ... I have not read all the postings and since you've been wanting to make steam engines, I assume that is the why of your creation.
So if I am shooting blanks please forgive me.
Here is a video that shown what I know about machining a crank. http://www.youtube.com/watch?v=3YfTtGCsiD8
There are no problems, only solutions.
Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa
- Posts: 1933
- Joined: Fri Jan 10, 2003 1:00 am
- Location: Molalla, Oregon
Jose if you had read the post you would have saw that he was making a crank with multiple throws and the slide fixture is to ensure perfect 180 degree offsets of each throw.