What is that Black Box on the GreTan Reamer holder in these Pics

[hoz53]

can anyone identify this —Thanks

 

[Nightraider]

View attachment 1182073 View attachment 1182074 can anyone identify this —Thanks

It's an offset, it's a dovetail alignment tool.

 

[hoz53]

It's an offset, it's a dovetail alignment tool.

thank You — but I think I’m still confused— What needs aligned here. Is it aligning the tailstock center to spindle center? It looks like there is an offset there. So this has a dovetail in there that slides back and forth to align things? When I go to the GreTan Site the reamer holders have Morris taper shanks on them I bet not many people use these in their chambering activities

 

[GenePoole]

Is this from Gordy Gritters' video? I remember wondering about that too. Apparently it is used to get precise alignment of the tool in the tailstock. Since the video was sponsored by Grizzly and Gordy kept praising the Grizzly lathe, I imagine Grizzly didn't want it described as it would seem to take away from the perception that Grizzly lathes were perfect.

I believe the tool is actually for moving the tailstock effective center for taper turning, but will also work in the opposite mode by recentering an offset tailstock.

Maybe this?

http://www.lathecity.com/Tools/ToolsDocuments/AdjustablePrecisionTailstock.pdf

 

[hoz53]

Is this from Gordy Gritters' video? I remember wondering about that too. Apparently it is used to get precise alignment of the tool in the tailstock. Since the video was sponsored by Grizzly and Gordy kept praising the Grizzly lathe, I imagine Grizzly didn't want it described as it would seem to take away from the perception that Grizzly lathes were perfect.

I believe the tool is actually for moving the tailstock effective center for taper turning, but will also work in the opposite mode by recentering an offset tailstock.

Maybe this?

http://www.lathecity.com/Tools/ToolsDocuments/AdjustablePrecisionTailstock.pdf

yes it is and i was thinking the same thing as you. surprised they would even show it if thats what they used it for. i think youre right about the tool though- in another view i saw what looked like a micrometer barrel on one end if it. I looked at your link and thought it kind of funny it says "for China Import Lathes". Kind of a cheap taper attachment then? wonder how much it costs -- not that im buyin but some people use boring heads for this. I have a grizzly lathe so needing this is understandable to me

 

[paperpuncher]

It would adjust the effective tail stock height. I have noticed on most lathes I have had they are a bit high. Tailstocks can be adjusted left,right and even up(by shimming). Lowering the tailstock would be a bit more involved, my guess is that this device is made to address that. Curious if it indexes in the tailstock quill somehow to allow for repeatability after removal and re-installation

 

[hoz53]

It would adjust the effective tail stock height. I have noticed on most lathes I have had they are a bit high. Tailstocks can be adjusted left,right and even up(by shimming). Lowering the tailstock would be a bit more involved, my guess is that this device is made to address that. Curious if it indexes in the tailstock quill somehow to allow for repeatability after removal and re-installation

right i am in the process of adjusting my lathes tail stocks. i hope i wont need to resort to this gizmo. if you go to the link left by GenePoole you can see it just has a taper and a center that moves back and forth so doesnt look like any indexing to me. Thanks

 

[Walt Krafft]

I can understand the need for it sometimes. But, why is it needed with a floating reamer holder?

 

[hoz53]

I can understand the need for it sometimes. But, why is it needed with a floating reamer holder?

well its not really a floating reamer holder as it has a center for the reamer from the tailstock- like a pusher-- it just holds the reamer up with the springs and disc

 

[hoz53]

It would adjust the effective tail stock height. I have noticed on most lathes I have had they are a bit high. Tailstocks can be adjusted left,right and even up(by shimming). Lowering the tailstock would be a bit more involved, my guess is that this device is made to address that. Curious if it indexes in the tailstock quill somehow to allow for repeatability after removal and re-installation

thinking about that a little more that must index somehow like you said otherwise the offset wouldnt necessarily be going in the right direction--Thanks

 

[tobnpr]

If you read Greg's info on the holder, it will not correct radial misalignment, only axial:

https://www.gretanrifles.com/product-page/3-reamer-holder

IMO, it's easy enough to correct horizontal, radial misalignment (with the usual adjusting screws on the tailstock)- but getting vertical, radial misalignment dead nuts is very difficult.

As noted, tailstocks on new machines are (generally) a few thousandths "high"- this allows for some of the inevitable wear, where the tailstock will eventually wear down to perfect alignment, and then continue wearing and getting lower, until one needs to shim to get it back to correct height. The alignment fixture behind the holder in the picture I would presume is for this purpose.

Tailstocks on both of my machines are within a thou on vertical height- but trying to get better than that would be very time consuming and difficult. How close is close enough for this holder, would be a question for Greg.

Being able to correct axial misalignment- which pushers can't do (I use a Manson pusher) is an advantage IMO- esp on older machines like mine. Tailstock bases wear unevenly- more wear at the front due to chips and slide pressure, which causes axial misalignment. Extending the tailstock ram fully, and running an indicator down it's length (locked, and unlocked) will show the extent- then add the length of the holder, and reamer- and it's easy for this to add up to several thou over the full length.

With my older machines, this uneven wear is alleviated with different thickness shims front and rear- but still not "dead nuts" to within a couple of tenths.

 

[BoydAllen]

Before he took the time to tune his headstock height, a friend did something that worked very well, in terms of making reamer sized chambers. He would push the reamer with a center and then switch to a simple pusher, to finish, leaving enough to finish with the pusher to clean up the whole chamber to the size of the reamer (at the back of the chamber.

 

[hoz53]

Before he took the time to tune his headstock height, a friend did something that worked very well, in terms of making reamer sized chambers. He would push the reamer with a center and then switch to a simple pusher, to finish, leaving enough to finish with the pusher to clean up the whole chamber to the size of the reamer (at the back of the chamber.

Hi Boyd- its good to hear from you these days-- i hope youve been well-- Thanks for that info- that seems like a good idea.

 

[hoz53]

If you read Greg's info on the holder, it will not correct radial misalignment, only axial:

https://www.gretanrifles.com/product-page/3-reamer-holder

IMO, it's easy enough to correct horizontal, radial misalignment (with the usual adjusting screws on the tailstock)- but getting vertical, radial misalignment dead nuts is very difficult.

As noted, tailstocks on new machines are (generally) a few thousandths "high"- this allows for some of the inevitable wear, where the tailstock will eventually wear down to perfect alignment, and then continue wearing and getting lower, until one needs to shim to get it back to correct height. The alignment fixture behind the holder in the picture I would presume is for this purpose.

Tailstocks on both of my machines are within a thou on vertical height- but trying to get better than that would be very time consuming and difficult. How close is close enough for this holder, would be a question for Greg.

Being able to correct axial misalignment- which pushers can't do (I use a Manson pusher) is an advantage IMO- esp on older machines like mine. Tailstock bases wear unevenly- more wear at the front due to chips and slide pressure, which causes axial misalignment. Extending the tailstock ram fully, and running an indicator down it's length (locked, and unlocked) will show the extent- then add the length of the holder, and reamer- and it's easy for this to add up to several thou over the full length.

With my older machines, this uneven wear is alleviated with different thickness shims front and rear- but still not "dead nuts" to within a couple of tenths.

Thanks for all that info- i do have an older machine with quite alot of tailstock wear on the bottom that will need shiming-- ive got a newer one to and its not perfect on the tailstock alignment either so i will need to be working on it also. I did read the description of the reamer holder on Gretan Site before. He says in there how a test bar will never work to align centers for chambering so Im left wondering what he means will. I think i know what i need to do to align them. If i can get alignment good enough i will be able to use the gretan holder- if not ill have to stick with my floating holder. But i dont think i will be using one of the sliding devices either way- i coild change my mind though.

 

[tobnpr]

He says in there how a test bar will never work to align centers for chambering so Im left wondering what he means will.

Perhaps he's referring to the axial alignment.
IMO, this can be the toughest to troubleshoot, and correct.
A precision ground test bar, fitted to the spindle taper is one way (pricey, and I don't have them). This will indicate whether the headstock/spindle is in perfect alignment to the bedways. If it's not, it may or may not be able to be corrected. Larger lathes have jacking screws to tweak the headstock up/down/sideways for adjustment. Older 'Merican iron like my SB and Sheldon do not- and adjusting the headstock can be done only with shims and scraping.

A typical test bar between centers will only show whether the end of the centers are in alignment at any given point on the bed depending on the length of the test bar(s). They're not capable of indicating the actual axis of the spindle.

 

[Dusty Stevens]

Just get a bald eagle pusher

 

[hoz53]

Perhaps he's referring to the axial alignment.
IMO, this can be the toughest to troubleshoot, and correct.
A precision ground test bar, fitted to the spindle taper is one way (pricey, and I don't have them). This will indicate whether the headstock/spindle is in perfect alignment to the bedways. If it's not, it may or may not be able to be corrected. Larger lathes have jacking screws to tweak the headstock up/down/sideways for adjustment. Older 'Merican iron like my SB and Sheldon do not- and adjusting the headstock can be done only with shims and scraping.

A typical test bar between centers will only show whether the end of the centers are in alignment at any given point on the bed depending on the length of the test bar(s). They're not capable of indicating the actual axis of the spindle.

Ok thanks thats alot of good info- one machine ive got is a Grizzly and there is something way off between spindle and tailstock centers . they tell you in their manual to use a test bar between centers and machine collars at each end to align the tailstock front to back.. they dont give you direction on how to do it top to bottom which is the more difficult as you have said. Ill keep working with it Thanks Again

 

[hoz53]

Just get a bald eagle pusher

i looked at them and im thinking about doing that Thanks Dusty

 

[tobnpr]

they tell you in their manual to use a test bar between centers and machine collars at each end to align the tailstock front to back.

The "two collar test" is beneficial to determine if you're turning without taper, but doesn't tell you "why". Could be the lathe bed has twist, could be the headstock/spindle out of axial alignment- but has nothing to do with the tailstock as it's not used in this "test".

Take a long piece of at least 3/4" drill rod (MUST be perfectly straight). Drill a center in each end.
Then at one end, take a couple of light cuts over the last inch or so of the rod to get it concentric.
Place it between centers (no chuck, no collet...), with the turned section at the headstock.
Indicator base on the saddle. Depending whether you want to indicate horizontal or vertical tailstock alignment, preload a tenths indicator lightly onto the top of the turned section ahead of the center. Set to zero.

Lightly support the tailstock end, withdraw the tailstock ram enough to remove the bar WITHOUT DISTURBING the indicator at the headstock.
Run the saddle with the indicator (again- do not disturb the indicator) down to the tailstock, so that the indicator is positioned just ahead of the tailstock center, then after flipping the test bar end for end, place the unturned end into the spindle center, and carefully lift/place the turned section under the indicator and extend the tailstock ram into that center. If you're indicating relative center height, it will show how much you need to shim the tailstock. On the side, how much you need to adjust with the tailstock adjusting screws.

I like this method because it allows you to adjust your tailstock to the bed at whatever section you might use most- bed wear means it will be different, in different locations. Right at the headstock, you can use (or make) lathe "buttons" to check for alignment (just Google them...).

 

[hoz53]

Thats alot of great info -- I never heard of a two collar test done that way. I think it will help me. Ive got a short 1" bar but ill get a longer one and try this. Thank You I appreciate it.