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??? Reamer Holder ????

 
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  #1  
Old 06-12-2010, 10:53 PM
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??? Reamer Holder ????

OK, I've read everything I can find on the internet about reamer holders so now I'm in need of more help than I was before!

Here's what I'm know so far, I need some kind of reamer holder, I want to get or build a quality one as I don't like screwing around, do it once do it right!

I have gone over the lathe that I'm using and I'm thinking the best thing for me to do is to get a 3MT tool holder and chamber with the tool post instead of dealing with the tail stock which is way out of wack. I used a ground rod and put it into a tool holder and centered it to the spindle bore then moved the carriage several inches and I could see no movement on a .001 dial indicator, so it looks like it's movement is real good to me. By the way I have a .0005 test indicator en route.

Any links or advice would be greatly appreciated!
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  #2  
Old 06-13-2010, 07:30 AM
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Re: ??? Reamer Holder ????

Quote:
Originally Posted by bigngreen View Post
OK, I've read everything I can find on the internet about reamer holders so now I'm in need of more help than I was before!

Here's what I'm know so far, I need some kind of reamer holder, I want to get or build a quality one as I don't like screwing around, do it once do it right!

I have gone over the lathe that I'm using and I'm thinking the best thing for me to do is to get a 3MT tool holder and chamber with the tool post instead of dealing with the tail stock which is way out of wack. I used a ground rod and put it into a tool holder and centered it to the spindle bore then moved the carriage several inches and I could see no movement on a .001 dial indicator, so it looks like it's movement is real good to me. By the way I have a .0005 test indicator en route.

Any links or advice would be greatly appreciated!
I would recomend using the tail stock because most reamer holders use the tail stock.

You need to correct the tail stock anyway . I had the same problem and bought a precision
alignment bar 1"x 12" from PTG and straightened the tail stock.

I am sure there are some that use the carriage for chambering but I like to use the tail stock
And as I said it needs to be centered/aligned anyway.

Just my opinion

J E CUSTOM
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  #3  
Old 06-13-2010, 07:37 AM
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Re: ??? Reamer Holder ????

I have found, over the years, that there is not too much that hasn't been tried, at one time or another, when it comes to gunsmithing. I suspect there's a reason why most use the tail stock. It seems the natural way to do the job (the end slide or tail stock). I never remember using a 'round' tool mounted on a 'side' slide, in the years I worked in job shops, not that it couldn't be done on the right machine, I guess. I'd make sure the lathe is level (with an engineers level) and then straighten out that tail stock. That's part of owning a machine, knowing how to adjust it when it gets 'out of wack'.I know, it takes time, but, you'll want to use that tail stock for other jobs too, and it will need to be true to the spindle. And, you will learn more about your lathe in the process. No need to over complicate what should be a straight forward machining operation. Think about it for a minute,,,,,, if you are going to make a reamer holder the tail stock needs to be trued to the spindle anyway! Just my 2 cents
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Last edited by shortgrass; 06-13-2010 at 07:43 AM.
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  #4  
Old 06-13-2010, 09:06 AM
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Location: Carlisle, PA
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Re: ??? Reamer Holder ????

This is a shamless copy of some I saw on one forum or another, or maybe more than one. I'm not sure who made the first one or I'd give them credit for it right here. The bottom line, it was free because I made it out of metal I had in my "metal archive", and it works essentially perfectly for chambering barrels.

This piece in the tail stock pushes on face of the collar that holds the reamer. That face of the collar that holds the reamer was machined in the same setup where the center hole was bored so the plane of the collar face is dead nuts orthogonal to the bore axis, which means it is also as perfectly orthogonal to the axis of the reamer as I can practically make it. I made a collar instead of a tap holder type because I couldn't see any way to guarantee both faces of the tap holder were in exactly the same plane, which as is discussed below, is key to how a pusher like this functions.

The pusher itself is a piece of mystery metal, from a drop rack in a metal yard far away, machined to have a MT #3 taper on the back end. This was then put in the headstock of my 9" SB, parted, faced and drilled out 29/64". The important point is that the plane of the pushing face is dead nuts orthogonal to the axis of the pusher. As will become evident, this is key to why it works well.



While I've seen the pictures, I've never seen an explanation of why this design works so well, so I thought about it a while before I made this one. I wanted to machine it controlling as exactly as I could what ever the critical parameters were that made it work. I came up with the following hypothesis to explain why I think it works as well as it does.

It, and the Manson my friend the "real" gunsmith with the borescope has, work on pretty much the same principle, and tend to create forces that react against the pilot to drive the back end of the reamer in the direction to correct for parallel axis misalignment between the spindle centerline and the reamer centerline.

My tail stock ram CL is right in line with the lathe spindle front to back as close as I can measure it. It is about 0.002" high with the tail stock clamp torqued down as tight as I can reasonably get it using the handle it came with (I plan to take it apart and weld a square drive socket on it so I can use a torque wrench - but it won't get any closer even with a cheater bar, I tried, but didn't over do it). The important part is that the tail stock spindle axis is "parallel" to the spindle axis, but offset ~0.002" above it. This parallel offset is probably found to one degree or another on most of the lathes used for chambering. That being the case, if the reamer is pushed square to the axis it will self center parallel with the lathe axis.

Why will it self center?

If you had a pencil lying on the desk with a cross stick glued to it, you could push it with two fingers and it would stay pointed in the direction you are pushing. If you push on the eraser with one finger, when the pencil gets a little off line, it will tend to go further off line.

The first case applies to this and the Manson pushers. The pushed surface on the collar is orthogonal to the reamer centerline, and the push surface of the annular ring that does the pushing is orthogonal to the tail stock centerline. If the reamer tries to tilt out of parallel with the centerlines, the ring acts on the side opposite to the direction of tilt and tries to push it back to parallel. This moves the back of the reamer to stay in line with the pilot so it remains parallel to the spindle centerline.

Even though a reamer cuts on the side, it seems to want to be inherently self centering on the bore left to it's own devices. My theory for thi is that for small deviations from parallel with the bore, the reamer presents a greater frontal area off set on the side in which it is out of alignment. This greater frontal area will tend to react against the pilot to push the back end of the reamer back into into alignment with the axis of rotation. This correcting force from the front of the reamer is apparently stronger than the destabilizing force from the offset push at the back, (for small deviations - it isn't for large ones), so within limitations of small deviations it overcomes the inherent instability of the pushing scheme. And that is why I think the Bald Eagle reamer holder works (and I proved to myself that a pusher based on that principle does work just fine) inspite of the inherent instability of it's design.

With the correcting force from the front of the reamer, and the inherent correcting force on the back of the reamer from the annular (or planer in the case of the Manson unit) pusher, the reamer should follow right along a path parallel to the lathe axis if the bore is centered on the lathe axis. This emphasizes why it is so extremely important to have very precise bore alignment with the spindle axis in the area where the chamberi is being cut. This may seem obvious but it is important because it means the floating holder will "not" compensate for the bore being misaligned with the axis, on only compensates for the reamer being misaligned with the bore.

Given the principles involved I could have made the annular pushing surface larger in diameter (keeping the center hole the same size - 29/64" for a 7/16" reamer shank) but it seemed to me the increased surface area might somehow add friction to the system, make it sticky, and impede it's operation, so I didn't do that. As it is, it works just fine.

I've seen no indication that I need to add a second handle on the other side to maybe get a more symmetrical torque reaction, but I could do that if I had to. I didn't use shoulder bolts in the collar and slots in the pusher for torque reaction like the Manson holder has because I think that if the bolts and slots were not precisely aligned on a diameter that would tend to push the reamer off center. I wasn't sure how to do that as precisely as I needed to so I stuck with the handle.

Finally, when I hold the handle my thumb is right over the set screw that is tightened on the reamer, my fingers under the handle to resist torque reastion. This "grip" effectively eliminates side force because it is a torque couple. You can demonstrate this to your self if you use a long extension on a socket wrench. If you just pull on the handle the thing will move sideways. if you put your thumb on the rachet head and counteract the finger pull on the handle you can apply torque to the wrench with no side force. That's how I hold this reamer holder. It works just fine and the torque couple is why.

In know, I know, I'm putting some to sleep, and others think I'm regrinding flour into molecule sized dust particles (the smallest particles that are still flour), but I like to know why things work. I don't seem to be able to resist trying to figure things out. My engineering gene made me do it.

That's my story and I'm sticking to it.

Let me add, I've no indispensible ego attached to any of this, I'm just looking for the truth of it, so if you have a different view of the physics at work, please share it.

Fitch
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  #5  
Old 06-13-2010, 10:33 AM
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Join Date: Nov 2008
Location: SW Montana
Posts: 4,257
Re: ??? Reamer Holder ????

Thanks for the replies guys!!!! Double that for Fitch, I hope your fingers stop cramping soon

The was a great write up, I'm very inclined to make a holder/pusher like you have. I like real clean and simple things as they usually work the best. The extra why it works and how it works really helps.
The reason I want to use the tool holder over the tail stock is that I get .004 of up movement in a 4in movement of the tails stock spindle. I have also check how repeatable it is and I'm not liking it, granted it is probably better than I think and I'm being nit picky.
My other reasoning is the fact that when I was building my action truing jig I was able to turn the outside and bore the inside very accurately, actually surprisingly so. So why wouldn't I want to use the most accurate, repeatable means of holding a reamer that I'm trying to run perfectly down the barrel? I check the repeatability of the carriage to come back to an exact position by recreating the movement that would be happening with removing the reamer,cleaning and lubing then going back and take another cut and I was able to easily return to that spot with accuracy that I couldn't even see on my .001 indicator.
That and I think Chad Dixon has said a couple times to do it with the tool holder. This may not even require a floating holder but an adjustable fixed holder.
I'll tinker with it more today!! A lathe is one of the best big boy things ever
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  #6  
Old 06-13-2010, 10:47 AM
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Join Date: Jul 2004
Location: Texas
Posts: 5,192
Re: ??? Reamer Holder ????

Quote:
Originally Posted by Fitch View Post
This is a shamless copy of some I saw on one forum or another, or maybe more than one. I'm not sure who made the first one or I'd give them credit for it right here. The bottom line, it was free because I made it out of metal I had in my "metal archive", and it works essentially perfectly for chambering barrels.

This piece in the tail stock pushes on face of the collar that holds the reamer. That face of the collar that holds the reamer was machined in the same setup where the center hole was bored so the plane of the collar face is dead nuts orthogonal to the bore axis, which means it is also as perfectly orthogonal to the axis of the reamer as I can practically make it. I made a collar instead of a tap holder type because I couldn't see any way to guarantee both faces of the tap holder were in exactly the same plane, which as is discussed below, is key to how a pusher like this functions.

The pusher itself is a piece of mystery metal, from a drop rack in a metal yard far away, machined to have a MT #3 taper on the back end. This was then put in the headstock of my 9" SB, parted, faced and drilled out 29/64". The important point is that the plane of the pushing face is dead nuts orthogonal to the axis of the pusher. As will become evident, this is key to why it works well.



While I've seen the pictures, I've never seen an explanation of why this design works so well, so I thought about it a while before I made this one. I wanted to machine it controlling as exactly as I could what ever the critical parameters were that made it work. I came up with the following hypothesis to explain why I think it works as well as it does.

It, and the Manson my friend the "real" gunsmith with the borescope has, work on pretty much the same principle, and tend to create forces that react against the pilot to drive the back end of the reamer in the direction to correct for parallel axis misalignment between the spindle centerline and the reamer centerline.

My tail stock ram CL is right in line with the lathe spindle front to back as close as I can measure it. It is about 0.002" high with the tail stock clamp torqued down as tight as I can reasonably get it using the handle it came with (I plan to take it apart and weld a square drive socket on it so I can use a torque wrench - but it won't get any closer even with a cheater bar, I tried, but didn't over do it). The important part is that the tail stock spindle axis is "parallel" to the spindle axis, but offset ~0.002" above it. This parallel offset is probably found to one degree or another on most of the lathes used for chambering. That being the case, if the reamer is pushed square to the axis it will self center parallel with the lathe axis.

Why will it self center?

If you had a pencil lying on the desk with a cross stick glued to it, you could push it with two fingers and it would stay pointed in the direction you are pushing. If you push on the eraser with one finger, when the pencil gets a little off line, it will tend to go further off line.

The first case applies to this and the Manson pushers. The pushed surface on the collar is orthogonal to the reamer centerline, and the push surface of the annular ring that does the pushing is orthogonal to the tail stock centerline. If the reamer tries to tilt out of parallel with the centerlines, the ring acts on the side opposite to the direction of tilt and tries to push it back to parallel. This moves the back of the reamer to stay in line with the pilot so it remains parallel to the spindle centerline.

Even though a reamer cuts on the side, it seems to want to be inherently self centering on the bore left to it's own devices. My theory for thi is that for small deviations from parallel with the bore, the reamer presents a greater frontal area off set on the side in which it is out of alignment. This greater frontal area will tend to react against the pilot to push the back end of the reamer back into into alignment with the axis of rotation. This correcting force from the front of the reamer is apparently stronger than the destabilizing force from the offset push at the back, (for small deviations - it isn't for large ones), so within limitations of small deviations it overcomes the inherent instability of the pushing scheme. And that is why I think the Bald Eagle reamer holder works (and I proved to myself that a pusher based on that principle does work just fine) inspite of the inherent instability of it's design.

With the correcting force from the front of the reamer, and the inherent correcting force on the back of the reamer from the annular (or planer in the case of the Manson unit) pusher, the reamer should follow right along a path parallel to the lathe axis if the bore is centered on the lathe axis. This emphasizes why it is so extremely important to have very precise bore alignment with the spindle axis in the area where the chamberi is being cut. This may seem obvious but it is important because it means the floating holder will "not" compensate for the bore being misaligned with the axis, on only compensates for the reamer being misaligned with the bore.

Given the principles involved I could have made the annular pushing surface larger in diameter (keeping the center hole the same size - 29/64" for a 7/16" reamer shank) but it seemed to me the increased surface area might somehow add friction to the system, make it sticky, and impede it's operation, so I didn't do that. As it is, it works just fine.

I've seen no indication that I need to add a second handle on the other side to maybe get a more symmetrical torque reaction, but I could do that if I had to. I didn't use shoulder bolts in the collar and slots in the pusher for torque reaction like the Manson holder has because I think that if the bolts and slots were not precisely aligned on a diameter that would tend to push the reamer off center. I wasn't sure how to do that as precisely as I needed to so I stuck with the handle.

Finally, when I hold the handle my thumb is right over the set screw that is tightened on the reamer, my fingers under the handle to resist torque reastion. This "grip" effectively eliminates side force because it is a torque couple. You can demonstrate this to your self if you use a long extension on a socket wrench. If you just pull on the handle the thing will move sideways. if you put your thumb on the rachet head and counteract the finger pull on the handle you can apply torque to the wrench with no side force. That's how I hold this reamer holder. It works just fine and the torque couple is why.

In know, I know, I'm putting some to sleep, and others think I'm regrinding flour into molecule sized dust particles (the smallest particles that are still flour), but I like to know why things work. I don't seem to be able to resist trying to figure things out. My engineering gene made me do it.

That's my story and I'm sticking to it.

Let me add, I've no indispensible ego attached to any of this, I'm just looking for the truth of it, so if you have a different view of the physics at work, please share it.

Fitch
Very good information.

I took a different approach (One of many) and instead of building a different Mouse trap I
just fixed the one that I had, by truing the lathe with as near perfect alignment as possible.
with the instruments on hand ,(they read to .00005) I have been very happy with the
Manson reamer holder.

I have found that the tail stock requires consistant torque to reach zero. (It always started
out .001 to .002 thousandths high)until I found a torque value that brought it in perfect.

Sense aligning the tail stock, chamber run out has been immeasurable using the Manson
reamer holder. also there is another one that uses a ball socket but I dont know much
about it I think Specweldtom has one and maybe he can add to this post.

I make a lot of my special tools also but this one worked so well I decided to go with it,

It is a very good place to start if the lathe is true.

Just some more information.

J E CUSTOM
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Last edited by J E Custom; 06-13-2010 at 10:52 AM.
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  #7  
Old 06-13-2010, 12:00 PM
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Join Date: Aug 2009
Location: Carlisle, PA
Posts: 478
Re: ??? Reamer Holder ????

Thanks guys.

While I'm at it I should include some critical data on the pusher and how I use it.

The hole in the pusher in the tail stock is about .020" larger in diameter than the reamer shank and deep enough that the end of the reamer won't bottom in it. I didn't want anything but the front face to contact the reamer assy. This gives me enough play to accomodate the hight variation between my tail stock and the spindle, yet limits the reamer's movement which makes it easier to get it started.

I feed with the tailstock wheel and use a dial indicator mounted like this to watch the depth:



I've found that by doing some "practice landings" where I use the go gage, pick a new depth, mic it, then try to hit that new depth using the dial indicator, I have no trouble hitting the mark within the line width on the indicator face, and it will mic at the desired depth will within half a division.

Making cutting passes:

I can feel the torque and regulate the feed to keep it smooth - holding the reamer handle in my left hand, turning the tail stock feed wheel with my right hand. Normally the feed is smooth, there is no jerking to speak of, and I can easily regulate the feed to maintain a constant torque. I can tell essentially instantly if anything is amiss in the chamber. The one time I had chatter begin to start I was able to immediately let go of the handle, back off the tail stock, turn off the spindle, clean the reamer, relube it, and use a couple of patch restarts which corrected the chatter problem before it turned into a real problem. Chatter won't self correct, it will just get worse.

When I see chips show up, or I've gone about .025" in depth of cut (which ever come first), I let go of the handle, back off the tail stock quill enough turns (the same every time) to clear the reamer shank, turn off the lathe spindle, and remove the reamer. Letting go of the handle and letting it spin avoids galling from a chip getting under a reamer flute that might happen if I tried to remove the reamer with the spindle still turning. Removing it with the spindle stopped makes that a complete non issue.

Note: It's important to have a short enough handle that it can spin clear of the cross slide and compound if the compound is in place when chambering. Mine is.

I use the lathe carriage as a tail stock stop - i.e. I position it against the tailstock and tighten the clamp to lock it in place when I know where the tailstock is to be located. That way I can pull the tail stock back after retracting the tail stock spindle half an inch or so and withdraw the reamer straight out of the chamber and easily move the tailstock back to the same location.

Once the reamer is out I use a rubber tipped air nozzle to blow the chips out of the chamber (and look in there to be sure they are gone), rinse chips off the reamer in a container of paint thinner, blow it dry with compressed air, dip it in the cutting oil, and reinsert it into the chamber. Then I run the tail stock back up, clamp it, then advance the tail stock quill with the hand crank to get it back over the shank of the reamer. I can tell from the dial indicator almost 'exactly" when the reamer will start cutting again. When I'm close I start the spindle and begin the next cut.

Fitch

Last edited by Fitch; 06-13-2010 at 12:04 PM.
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