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Need Advice For Using a Chucking Reamer

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Nogoingback

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#1
I need to ream a 1/2" hole inside a 3/4" diameter piece of 12L14, 3 inches in length. I have a 1/2" chucking reamer to do the job. What diameter hole
should I drill/bore prior to using the reamer? And, should I ream under power a little at a time, or do it manually on the lathe without power?
 

dpb

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#2
I would drill it 31/64”, and run the reamer at 1/2 the rpm of the drill, fairly quick feed, no stopping or pecking. All the way in, all the way out, done.
 

Norseman C.B.

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#3
What he said with lots of oil......................
 

Karl_T

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#4
To be totally correct, a floating reamer holder is needed. Without it, the bore will be slightly bell mouthed. How much depends on the machine.
 

Nogoingback

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#5
I would drill it 31/64”, and run the reamer at 1/2 the rpm of the drill, fairly quick feed, no stopping or pecking. All the way in, all the way out, done.

The only problem is that my tailstock doesn't have 3" of travel: it's more like 2 1/4 - 2 1/2". My lathe is a 10" Logan. Could I ream as far as
possible on the first pass, reset the tailstock position towards the chuck, and start it up and finish?
 

Nogoingback

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#6
To be totally correct, a floating reamer holder is needed. Without it, the bore will be slightly bell mouthed. How much depends on the machine.
Not sure I understand why that would be. If I ream on the same lathe with the same setup, why wouldn't it just follow the hole? How much
bellmouth are we talkin'? A few thou?
 

markba633csi

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#7
I think the bell mouthing would normally be only a few tenths, from my experience anyhow. I disregard it on the rinky-dink stuff I do
m
 

mikey

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#8
The only problem is that my tailstock doesn't have 3" of travel: it's more like 2 1/4 - 2 1/2". My lathe is a 10" Logan
You could always bore it. If you need an accurate 1/2" hole you would either need an slightly undersized reamer to come in dead on size or you can bore it accurately. A 1/2" reamer will give you a plus-sized hole.
 

Bob Korves

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#9
You could always bore it. If you need an accurate 1/2" hole you would either need an slightly undersized reamer to come in dead on size or you can bore it accurately. A 1/2" reamer will give you a plus-sized hole.
Listen to Mikey. If you need to ream the hole instead of just drilling it, there is usually a reason for doing so. Are you attempting to achieve a press fit or a sliding fit, or what? To really be helpful, we will need to know exactly what you are trying to achieve with the reamer.
 

Norseman C.B.

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#10
The only problem is that my tailstock doesn't have 3" of travel: it's more like 2 1/4 - 2 1/2". My lathe is a 10" Logan. Could I ream as far as
possible on the first pass, reset the tailstock position towards the chuck, and start it up and finish?
Yes you can do it that way, I have when necessary, the finish wont be as clean but
reamed finish is not that great any way and what Mikey, and Bob said what
is the fit and finish your looking for............
 

mikey

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#11
Lucky for us, we can often ream a hole and then make the part to fit the way we need it to. There are advantages to being a hobby guy who is making one off parts. :)

On the other hand, it is good to know how your drill and reamer choices can be done on a more informed basis. I often use the Yankee guide I'm attaching below; hope it helps.
 

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Nogoingback

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#12
DSCF7425.jpg

OK, here's what I'm making. I bought a boring bar holder off ebay to use with 1/2" boring bars, and need to make a reducing
sleeve for it. So, I need a 1/2" hole to match the boring bar diameter. I thought I'd use a reamer since it would be more accurate
than drilling, and I happen to already own a reamer. Boring would be fine, but I'd have to bore 3 inches deep,
which seems a stretch for a boring bar that fits down a 1/2" hole. mikey, when you say a plus size hole, how much are we talking?
Since the holder "pinches" the sleeve down, I would think I've got some leeway here.
 

DoogieB

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#13
Why not just use a tool holder with a V cut in the bottom? Usually marked 250-102 on the cheap imported AXA holders.
 

mikey

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#14
Oh, okay. A sleeve needs a clean finish and should ideally be bored to the pre-reamer size to ensure the hole is straight before you ream it. However, I understand that boring a 3" long hole is difficult if you lack the proper bar (5/16" or 3/8" carbide bar). When I made my boring bar sleeves, I drilled and reamed it and it works just fine. And you're right; you do not need a super-precise fit because you're going to slit the side of the sleeve anyway.

Assuming you are using mild steel, then the correct pre-reamer drill would be about 31/64". The way I did mine (I've only done 4 of these sleeves but I've reamed many holes and the principles in the Yankee paper work well) was to spot drill, then pilot with a drill that spans the web of a 29/64" drill. Then I drilled with a 29/64" drill to bulk out the hole, then drilled with the 31/64" drill. This gives me a pretty clean and straight hole. Then I used a 1/2" reamer.

I have found that sulfur-based cutting oil works well. Reamers cannot take a lot of material off so the way we use them matters. What works best for me is to chamfer the entrance hole, then coat the reamer and the hole with cutting oil. I set speed at about 100 - 200 rpm and make a single pass manually so I can feel a slight resistance to feed all the way down the hole (teeth are cutting continuously) until the reamer tip emerges on the other side. I shut the machine off and withdraw the reamer. I have tried many ways to ream - low speed, high speed, withdraw under power, etc. I have found that my reamers cut more accurately, produce a better finish and stay sharp longer by doing it as above, or at least this works best for me.

I think you're doing it right. A finely reamed finish in the holder reduces chatter in the bore so reaming the sleeve is the way to go if you cannot bore it.

I also suggest that you make two lengthwise cuts on your sleeve; one through cut and one expansion slot opposite the slit like in the pic below. This allows the sleeve to clamp easily without cracking the sleeve.

sleeves.jpg
 

Nogoingback

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#15
Why not just use a tool holder with a V cut in the bottom? Usually marked 250-102 on the cheap imported AXA holders.

That's what I've been using, but the boring bar holder should be more rigid and that frees up another tool holder for normal lathe tools.
I got the boring bar holder cheap since it was missing the sleeve that normally comes with it.
 
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Nogoingback

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#16
Thanks for the detail Mike. The only 3/8 boring bar I own isn't carbide, so I'll drill it per your suggestion. My usual cutting
fluid is Rapid Tap. Not sure if it has sulfur or not, but I usually get good results with it and I can slop it on. My biggest concern is that
my tailstock won't make the full pass. I was thinking I could back up the reamer a small amount, stop the machine, reset the tailstock,
start it up and finish the pass, but I don't know if that would grab when I start it up. Or, I could finish the last 1/2" or so manually
with a tap handle to keep that from happening. What do you think?
 

mikey

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#17
You'll do fine with Rapid Tap. Just be generous with it.

I would do as you suggest - stop the machine at the limit of your tailstock ram and back the reamer out of the hole. Retract the ram, clear the reamer and hole of chips, re-lube, advance the reamer into the hole and back up so the tip is just clear of the contact point. Lock the tailstock down, restart the machine and then finish up. The reamer cuts only at the tip and creates it's own chamfer; it will self-center when you resume and it won't grab. The flutes will also help center the reamer in the hole so you should be fine.

Just for future reference, if you have a QCTP then you can buy or make a tool holder with a drill chuck attached. It takes more to set up and get it on center but you can then use the saddle to give you all the travel you need when using this tool.

You got this, brother - go for it!
 

P. Waller

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#18
This is a wedge tool holder correct?
If so it will not hold well if the sleeve is not slit.
 

Nogoingback

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#19
I'm planning slitting the sleeve. Thanks for bringing it up though.
 

hman

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#20
My biggest concern is that my tailstock won't make the full pass.
I don't know if this idea would work on your lathe. It's a modification I made to my Grizzly 9x20 for deep drilling. The pin on the underside of the door hinge screwed to the tailstock can be hooked into the T-slot of the carriage. I can then use the carriage to drive the tailstock back and forth. Disadvantage: The tailstock lock has to be released, or at least loosened, so centering accuracy might suffer. But then, a chucking reamer shouldn't be rigidly positioned anyway ... should be allowed to find its own center.

HPIM2578.JPG HPIM2579.JPG HPIM2581.JPG
 

Nogoingback

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#21
Interesting idea that I've never considered. I think I'd want to experiment with that a bit before trying it out on a
part that counts. Or, as mikey suggested, set it up on the QCTP, and just use the carriage itself.
 

Nogoingback

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#22
IMG_1720.jpg

Sleeve drilled 31/64"and reamed. Came out great, with a sliding fit to the boring bar, yet with no slop.
Just have to slit it and I'll be done. Thanks to all of you that made suggestions!
 

Brento

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#23
Just for future reference, if you have a QCTP then you can buy or make a tool holder with a drill chuck attached. It takes more to set up and get it on center but you can then use the saddle to give you all the travel you need when using this tool.
I've always been curious but how do you indicate that? Do you pu a DTI in the spindle and move it slowly around the cutter?
 

mikey

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#24
I put a center in the spindle and the chuck, then stick a razor blade between them and sight it until the blade is square. A pain but it gets me close enough.
 

Brento

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#25
Ok sounds like a decent idea? I’ve never seen it done to make the drill or even the endmill on center. I feel like it is a practice that i should know.
 

Nogoingback

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#26
Since I don't own a milling machine, I had to give some thought to how I would slit the sleeve. I decided the cold saw would do the job,
since I have a vice that can be clamped into it. I first pressed a 1/2" OD length of aluminum rod into the sleeve, to keep it from pinching
as the saw cut through. Worked great.

IMG_1721.jpg

The part was cleaned up and, as usual blued and oil finished. Done.

IMG_1722.jpg
 

mikey

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#27
That turned out really well - good job!
 

Nogoingback

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#28
Thanks Mike, I appreciate it.
 

rwm

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#29
Very nice! When I made mine I just drilled with 1/2". The inside is not as smooth as yours must be but it seems to clamp down fine. I wonder if there is any difference in rigidity when holding a boring bar? Perhaps I will remake mine and ream it!
Robert
 
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