3/4" Raritan 2-4-0 build.

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Harold_V
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Re: 3/4" Raritan 2-4-0 build.

Post by Harold_V » Tue Feb 23, 2021 2:19 am

shild wrote:
Mon Feb 22, 2021 9:47 pm
NP317 wrote:
Mon Feb 22, 2021 9:32 pm
Your last photos seems to show the reamer not aligned with the hole.
Parallax error or a real misalignment?
The tailstock should be adjusted so its center aligns with the center of the main lathe spindle.
RussN
Indeed it is. But this reamer is 6 inches long so the error is exagerated over that much distance.
Wrong. A reamer MUST be in alignment with the bore it creates. If it is not, you can expect bellmouth and taper. You will struggle with size and straightness. A floating holder is highly recommended. If you don't have access to one, DON'T GRIP THE REAMER DEEPLY IN THE CHUCK. Hold it by only about ¼" of the end length, so it can freely move about in the chuck jaws (it will seek center easily that way). That will provide the best possible scenario for the misaligned reamer. Mean time, get the tailstock aligned as best you can, to limit the error the reamer sees.

One more thing, and if you are already doing it, forgive me. I don't have enough time at my disposal to read the entire thread again, and I don't remember. Don't drill, then ream. The hole you create is likely to not be on location or straight unless you bore before reaming. Best scenario is to not ream at all, but bore to size.

In the post above you said the reamer quit cutting, although you fed it deeply. It didn't "quit cutting". It ran out of material to cut because you hit the back side of the wheel. The length of deposit in the flutes represents the depth of the part, and does NOT represent how deeply you fed the reamer.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Greg_Lewis
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Re: 3/4" Raritan 2-4-0 build.

Post by Greg_Lewis » Tue Feb 23, 2021 6:05 am

Harold_V wrote:
Tue Feb 23, 2021 2:19 am
... Don't drill, then bore.
...

Harold:
I think you mis-wrote. Didn't you mean, "Don't drill, then ream,"?
i.e. Drill and ream = bad.
Bore and ream = good.
Bore to size and don't ream = best.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

shild
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Re: 3/4" Raritan 2-4-0 build.

Post by shild » Tue Feb 23, 2021 12:11 pm

Thanks Harold, Thanks Greg. I'll put the reamer in the chuck only 1/4 the way next time. After I finished reaming both wheels I put the indicator touching the inside of the holes and ran it and they were well within a thousandth. Now I've turned the wheel around and faced the hub and it's now time to make an Arbor to put the wheels on. Maybe I should make it out of 3/4" stock so that I can put it in a 3/4" collet consistently?
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Harold_V
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Re: 3/4" Raritan 2-4-0 build.

Post by Harold_V » Tue Feb 23, 2021 3:33 pm

Greg_Lewis wrote:
Tue Feb 23, 2021 6:05 am
Harold_V wrote:
Tue Feb 23, 2021 2:19 am
... Don't drill, then bore.
...

Harold:
I think you mis-wrote. Didn't you mean, "Don't drill, then ream,"?
i.e. Drill and ream = bad.
Bore and ream = good.
Bore to size and don't ream = best.
Heavy sigh!
Thanks, Greg. I have corrected the statement. Yep, I said the wrong thing.
Ain't old age grand? :roll:

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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NP317
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Re: 3/4" Raritan 2-4-0 build.

Post by NP317 » Tue Feb 23, 2021 3:34 pm

Harold wrote:
"Ain't old age grand?"

Some days I can't remember...
Russ

Harold_V
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Re: 3/4" Raritan 2-4-0 build.

Post by Harold_V » Tue Feb 23, 2021 3:45 pm

shild wrote:
Tue Feb 23, 2021 12:11 pm
Thanks Harold, Thanks Greg. I'll put the reamer in the chuck only 1/4 the way next time.
Not ¼ of the way. ¼" maximum. The short engagement will allow the reamer to move about, seeking center. Do keep in mind the error isn't gone, so the reamer attacks the bore at an angle, and that's not good.
After I finished reaming both wheels I put the indicator touching the inside of the holes and ran it and they were well within a thousandth.
And that's the problem. A thousandth shouldn't be there, it should be zero. And it may or may not be consistent, as each hole will start differently from the previous hole, so each wheel will have some degree of error unless you are very fortunate. The error is likely due to the bore not being in alignment with the spindle centerline (it's not just eccentric, it's also at an angle), so when you mount the wheel on an arbor that runs true, the error translates to error in perpendicularity, so the wheel now has wobble to the sides. Boring before reaming eliminates that problem, as the bore will now be in dead alignment with the spindle. It may still have slight taper, however, due to the misalignment of the tailstock.

Note that I did not say what you're doing won't work. It will. It just introduces error that is not necessary. In the end, the results are in keeping with those who don't really understand the ramifications of making bad choices. That can be avoided by using good shop practice.

A thought. If you bore, leaving only a couple thou to ream, the depth of cut of the reamer is so slight that it most likely will simply follow the bored hole. You'll limit the amount of taper simply because the reamer isn't doing much. As chucking reamers are cylindrically ground, the margins will pilot the reamer so it will follow the now straight bore. With a heavier cut, that may not be true.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

shild
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Re: 3/4" Raritan 2-4-0 build.

Post by shild » Tue Feb 23, 2021 6:05 pm

Harold_V wrote:
Tue Feb 23, 2021 3:45 pm
shild wrote:
Tue Feb 23, 2021 12:11 pm
Thanks Harold, Thanks Greg. I'll put the reamer in the chuck only 1/4 the way next time.
Not ¼ of the way. ¼" maximum. The short engagement will allow the reamer to move about, seeking center. Do keep in mind the error isn't gone, so the reamer attacks the bore at an angle, and that's not good.
After I finished reaming both wheels I put the indicator touching the inside of the holes and ran it and they were well within a thousandth.
And that's the problem. A thousandth shouldn't be there, it should be zero. And it may or may not be consistent, as each hole will start differently from the previous hole, so each wheel will have some degree of error unless you are very fortunate. The error is likely due to the bore not being in alignment with the spindle centerline (it's not just eccentric, it's also at an angle), so when you mount the wheel on an arbor that runs true, the error translates to error in perpendicularity, so the wheel now has wobble to the sides. Boring before reaming eliminates that problem, as the bore will now be in dead alignment with the spindle. It may still have slight taper, however, due to the misalignment of the tailstock.

Note that I did not say what you're doing won't work. It will. It just introduces error that is not necessary. In the end, the results are in keeping with those who don't really understand the ramifications of making bad choices. That can be avoided by using good shop practice.

A thought. If you bore, leaving only a couple thou to ream, the depth of cut of the reamer is so slight that it most likely will simply follow the bored hole. You'll limit the amount of taper simply because the reamer isn't doing much. As chucking reamers are cylindrically ground, the margins will pilot the reamer so it will follow the now straight bore. With a heavier cut, that may not be true.

H
Thanks for the lessons Harold. If the bore is off so wheel wobbles side to side a couple thousandths, doesn't that clean up since the wheel tread and flange is done on the arbor? I've seen engines with wheel wobble and thought it might have happened when the wheel was pressed onto the axle. I've got another question about good shop practice. I'll want to make a hole with the mill/drill so after I've marked a part with a caliper and put the part in the vice I'll lower the mills head with a center drill until it just barely touches it then raise the head back up so I can see it better and check. I'll usually be satisfied but when I lower the head again to drill with the center drill much deeper, as it loads up the head nods up under load a little so hole ends up a few thousandths closer to me than I had hoped. The gib for the head is tight. What can I do about this?

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LVRR2095
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Re: 3/4" Raritan 2-4-0 build.

Post by LVRR2095 » Tue Feb 23, 2021 6:24 pm

shild wrote:
Tue Feb 23, 2021 6:05 pm

I've got another question about good shop practice. I'll want to make a hole with the mill/drill so after I've marked a part with a caliper
A vernier caliper is a measuring tool and NOT a layout tool. You don’t mark the parts with calipers.
I would suggest that before you start on a complex machining project like a locomotive that you enroll in a night school class and learn proper metal working techniques.

shild
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Re: 3/4" Raritan 2-4-0 build.

Post by shild » Tue Feb 23, 2021 6:46 pm

LVRR2095 wrote:
Tue Feb 23, 2021 6:24 pm
shild wrote:
Tue Feb 23, 2021 6:05 pm

I've got another question about good shop practice. I'll want to make a hole with the mill/drill so after I've marked a part with a caliper
A vernier caliper is a measuring tool and NOT a layout tool. You don’t mark the parts with calipers.
I would suggest that before you start on a complex machining project like a locomotive that you enroll in a night school class and learn proper metal working techniques.
Doesn't that really just mean I don't want to use expensive calipers to do it? And this is my night school class where I try to learn proper technique.

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LVRR2095
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Re: 3/4" Raritan 2-4-0 build.

Post by LVRR2095 » Tue Feb 23, 2021 6:49 pm

No, while help here is nice, you learn by doing under the watchful eye of an instructor.
And the reason you don’t use calipers for layout work is because they are not designed to do that and you won’t get accurate results.

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Greg_Lewis
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Re: 3/4" Raritan 2-4-0 build.

Post by Greg_Lewis » Tue Feb 23, 2021 7:22 pm

The bottom line is that you want the wheels to run true to the axles. I like to put center holes in the rough axle stock and then turn the axles between centers for the wheels. I leave a shoulder on each end of the axle so the wheels will seat at the proper back-to-back distance. Then I press on the wheels and make a finishing cut on the wheel treads and flanges with the axles set between centers. Thus regardless of what's happened before, they will run true.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

shild
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Joined: Mon Jan 22, 2018 11:58 pm

Re: 3/4" Raritan 2-4-0 build.

Post by shild » Tue Feb 23, 2021 9:54 pm

Greg_Lewis wrote:
Tue Feb 23, 2021 7:22 pm
The bottom line is that you want the wheels to run true to the axles. I like to put center holes in the rough axle stock and then turn the axles between centers for the wheels. I leave a shoulder on each end of the axle so the wheels will seat at the proper back-to-back distance. Then I press on the wheels and make a finishing cut on the wheel treads and flanges with the axles set between centers. Thus regardless of what's happened before, they will run true.
Been thinking about that too. Do you have problems with rigidity when you do that? Problems with it slipping?

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