Best way to fit these parts together.

[Jmanb13]

I have a bar that is ~.55 inches in diameter. I have a hole that is currently drilled out to 3/8 with drill bit.

I want to turn down the bar and or enlarge the hole so that have a tight fit that is accurately centered and will resist radial forces. I assume that I would probably want to use a key to prevent slipping.

What would be the best way to go about doing this?

I do not have access to a mill or press.

 

[Wreck™Wreck]

Turn OD, bore ID and key both with a matching keyseat, done deal. Shafts and bores have been keyed together for well over 100 years.

Otherwise crossdrill and pin together, you appear to have no other options.

 

[Jmanb13]

Turn OD, bore ID and key both with a matching keyseat, done deal. Shafts and bores have been keyed together for well over 100 years.

Otherwise crossdrill and pin together, you appear to have no other options.

Would boring or reaming the hole be a better idea in this situation? Keep in mind i'm still new to this, so I don't know when its better to bore vs ream a hole.

 

[coffmajt]

If you want a true hole then you must bore first, then ream to the diameter you want. Running a reamer through a hole that is not centered or true just gives you a smooth untrue hole == Jack

 

[Wreck™Wreck]

Would boring or reaming the hole be a better idea in this situation? Keep in mind i'm still new to this, so I don't know when its better to bore vs ream a hole.

Boring is more accurate then reaming if you have the tools, if not ream away which will get you close enough for general purposes.

 

[chips&more]

If you want the best amount of strength out of the joint/marriage. Then you would want the bar to remain its nominal size and not turn it down at all.

 

[scwhite]

Turn OD, bore ID and key both with a matching keyseat, done deal. Shafts and bores have been keyed together for well over 100 years.

Otherwise crossdrill and pin together, you appear to have no other options.

As small as those shafts are
You might consider drill and roll pin them together
Instead of keying
It all depends on how much force you plan on putting on that joint .
Both of my machines the lathe and the mill
Power feed is roll pins
Bore your hole with a tight fit
Heat the one with the hole in it .
And freeze the other one that is turned down
Push them together. Then drill a 1/8 hole and drive a roll pin in the hole .

 

[scwhite]

Turn OD, bore ID and key both with a matching keyseat, done deal. Shafts and bores have been keyed together for well over 100 years.

Otherwise crossdrill and pin together, you appear to have no other options.

I don't think he has the ability to put keys in ether piece . Even if he did the key would have to be so little about 1/16" .
Roll pin might be best for him

 

[Jmanb13]

As small as those shafts are
You might consider drill and roll pin them together
Instead of keying
It all depends on how much force you plan on putting on that joint .
Both of my machines the lathe and the mill
Power feed is roll pins
Bore your hole with a tight fit
Heat the one with the hole in it .
And freeze the other one that is turned down
Push them together. Then drill a 1/8 hole and drive a roll pin in the hole .

I don't think he has the ability to put keys in ether piece . Even if he did the key would have to be so little about 1/16" .
Roll pin might be best for him

I'm fine with using the roll pin as well. This is probably the best solution with my current tool capabilities . Would secure the shaft in both radial and axial forces plus the shrink fit of the actual shaft should be plenty strong.

Any suggestion on oversize/undersize on the hole to make the fit nice and tight with the shrink fit?

This is 1018 steel btw.

 

[scwhite]

I'm fine with using the roll pin as well. This is probably the best solution with my current tool capabilities . Would secure the shaft in both radial and axial forces plus the shrink fit of the actual shaft should be plenty strong.

Any suggestion on oversize/undersize on the hole to make the fit nice and tight with the shrink fit?

This is 1018 steel btw.

No more than .0005 press .001 is probably to tight
You could just heat it a little and push it together
Nice and tight. .0015 little more heat and even tight