Removing Slight Amounts (0.005") from Round Bar Diameters Quickly?

silverhawk

silverhawk

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Hello.

I have an application where I am changing out round bars. The tool is an old Craftsman Port-Align that I am abusing into use as a drill and subsequent reamer tool so I can keep things lined up and get definite measurements on the reamer sizes of un-labeled reamers in my possession. It has a sled/guide on top that runs along two round bars. Those round bars are originally 0.498". I'd ordered some round bar (one of the few times I was hoping for undersized) and ended up with a stainless steel that is 0.504" in diameter.

Is the best way to reduce the diameter of the bar to go between centers on the lathe and use emery cloth? Should I set it up to take a skim pass on the lathe and do that with the lathe cutters instead?

I would prefer not to cause more permanent damage to the tool itself, so rather than boring the guide out, I'd prefer bars closer to original diameters. And, current medical conditions forces me to not be at the lathe for "long periods of time" (I might get about 20 minutes at a time - and if I have to do each bar in segments, that's what I'll do).

Joe
 
What the type of material is, especially when it is stainless really matters. The different stainless steels have a wide variance in the machinability index. If it is a 300 series stainless, that will generally be more difficult than a 400 series. Even in the 300 series, a 304 will be easier to do than an 316. What type of SS material are you working with?

Second question is what tolerance can you live with? If you are good with 0.498 +/-0.001, then that is much less demanding than 0.498 +/-0.0005.

Next question, how long are the bars? So a 3" long bar is much easier to achieve the target size than if the bars were 12" long and 36" long is even more demanding (if you are to lathe turn it, tool push is real and something that has to be managed, if the tolerance matters).

More details please.
 
Chipper5783 said:
What the type of material is, especially when it is stainless really matters. The different stainless steels have a wide variance in the machinability index. If it is a 300 series stainless, that will generally be more difficult than a 400 series. Even in the 300 series, a 304 will be easier to do than an 316. What type of SS material are you working with?

Second question is what tolerance can you live with? If you are good with 0.498 +/-0.001, then that is much less demanding than 0.498 +/-0.0005.

Next question, how long are the bars? So a 3" long bar is much easier to achieve the target size than if the bars were 12" long and 36" long is even more demanding (if you are to lathe turn it, tool push is real and something that has to be managed, if the tolerance matters).

More details please.
Click to expand...
The original bars are what appear to be a mild steel. I thought just moving to a 304 would be a good lifetime choice for the replacement stainless steel.

Tolerances might be a tad more attrocious. I'm thinking even +/- 0.002" .

The bars are 17" long to be able to allow me to clear longer reamers along with a different chuck (the original 3/8" chuck would only allow me to ultimately gauge half of my unknown reamers).

I do have an ER40 collet chuck at my disposal, or the old 5C adapters, so I can potentially slide the rods along, too.
 
silverhawk said:
The original bars are what appear to be a mild steel. I thought just moving to a 304 would be a good lifetime choice for the replacement stainless steel.

Tolerances might be a tad more attrocious. I'm thinking even +/- 0.002" .

The bars are 17" long to be able to allow me to clear longer reamers along with a different chuck (the original 3/8" chuck would only allow me to ultimately gauge half of my unknown reamers).

I do have an ER40 collet chuck at my disposal, or the old 5C adapters, so I can potentially slide the rods along, too.
Click to expand...
oh, I thought maybe you were looking to make long rods.
I have a bigger issue with the bushing for the spindle . I need to replace mine with a tighter one sooner or later. I picked up another portalign for my son... great tools... not like the **** out there today.
 
A three-foot-long piece of precision O1 drill rod in exactly .500 dimensions costs $14 plus shipping. I would do that.

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I'll be interested to see what works.
0.005 is a bit much to take off with emory. I usually think of that for the .001 or less type adjustments. Cutting tools will be a bit challenging, stainless is not the easiest to machine. Getting a 17" rod turned without deflection issues on a .5" rod isn't trivial, I'd be trying a follow rest.

I think I'd go with buying some precision rod like @7milesup mentioned, either O1 or any other precision ground steel and if necessary ream out the mount plates
 
TGP might be an alternative, also.

Stainless is corrosive resistant, not tough.......
 
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