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Chris S.
10-19-2011, 01:43 PM
A buddy Bud (not a pun) sent me this ebay link (ground test bar with centers) this morning..

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=270830472697&ssPageName=ADME:B:WNA:US:1123

...and it made me wonder why the HSM couldn't make his own from drill rod.

(1) Using a 4 jaw, chuck up the rod and zero it with just an inch or less protruding.
(2) Face off the end and Single point a counter sink.
(3) Repeat 1 & 2 on the opposite end.

Am I missing something?

legendboy
10-19-2011, 01:59 PM
Assuming your talking about a test bar and not a tailstock barrel you posted a link to:

I had one made at a shop close by out of 1.5" drill rod

I could not center drill accurately with my tailstock being out of alignment and also needing to be shimmed.

I paid $30 bucks for the test bar. Had my tailstock shimmed, dialed in .001 over 12" height wise and side to side in about 20 mins.

Toolguy
10-19-2011, 02:41 PM
To answer the question - yes you can make your own as you described. There is no reason why not. Would it be accurate to millionths? Probably not, but plenty good enough for nearly any normal work.

Metalmelter
10-19-2011, 03:43 PM
Here's a little trick I read about and tried and it actually works.

Go find an old large printer to tear apart. The old tractor feed models or similar. The print head rides on a nice thick stainless round bar that is rather straight. Use that as your alignment bar. Now I don't remember where I read about that but I did at the time have at least 3 old style printers to play with. I found one at least an inch in diameter and at least 20" long. Turns out the bar truly is rather straight and I keep it tucked away for the day lathe alignment comes into question ;)

Highpower
10-19-2011, 04:32 PM
A buddy Bud (not a pun) sent me this ebay link this morning..

http://cgi.ebay.com/SOUTH-BEND-10K-LATHE-TAILSTOCK-RAM-SPINDLE-PT201KR2-/370527042141?pt=LH_DefaultDomain_0&hash=item564521fa5d

...and it made me wonder why the HSM couldn't make his own from drill rod.

(1) Using a 4 jaw, chuck up the rod and zero it with just an inch or less protruding.
(2) Face off the end and Single point a counter sink.
(3) Repeat 1 & 2 on the opposite end.

Am I missing something?
Did you mean one of these? Lathe Test Bar (http://www.ebay.com/itm/3MT-LATHE-TEST-BAR-3-MORSE-TAPER-LATHE-/370542487356?pt=UK_Home_Garden_PowerTools_SM&hash=item56460da73c)
The problem is drill rod is not perfectly round.

Chris S.
10-19-2011, 04:50 PM
Sorry guys, I posted the wrong link! I edited that post but here's the link anyway. It's no wonder I was getting such odd replies! :rolleyes:

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=270830472697&ssPageName=ADME:B:WNA:US:1123

As you can see, it's a ground test bar with centers. Scroll down the page when you get there..

Chris

Chris S.
10-19-2011, 05:00 PM
Did you mean one of these? Lathe Test Bar (http://www.ebay.com/itm/3MT-LATHE-TEST-BAR-3-MORSE-TAPER-LATHE-/370542487356?pt=UK_Home_Garden_PowerTools_SM&hash=item56460da73c)
The problem is drill rod is not perfectly round.

No, I'm aware of this technique and this test bar. It's used for checking bed twist - leveling and way wear. It's not used for TS alignment,.... unless it has centers.

No, I didn't know that drill rod is not perfectly round. I was under the impression that drill rod was ground to dimension. When you say "not perfectly round", to what degree are you talking about?

Chris

Chris S.
10-19-2011, 05:39 PM
Did you mean one of these? Lathe Test Bar (http://www.ebay.com/itm/3MT-LATHE-TEST-BAR-3-MORSE-TAPER-LATHE-/370542487356?pt=UK_Home_Garden_PowerTools_SM&hash=item56460da73c)


I should have mentioned that this is a very good price if the shipping doesn't kill ya... and yes, this does have centers.

Chris

Highpower
10-19-2011, 06:09 PM
Chris, most drill rod I have seen shows a max T.I.R of .005" for the "standard" tolerance. Drill or reamer blanks usually fair better than that I believe, but then you are limited on length.

And the shipping (Royal Mail) on that test bar is quite cheap actually. I think I paid less than $15 when I ordered mine.

Forrest Addy
10-19-2011, 06:15 PM
You really don't need anything precision ground to determine error in the tailstoock quill. There a couple of simple tests:

1, Droop. Fully extended the quill. Register and indicator on the end and set a zero iin the vertical plane. Scan the extended length of the quill and note the sweep. Any amount of "droop" is characteristic of taistock wear. The front edge of the tailstock base wears more rapidly than the rear. Return to the extended end and note if the zero repeats.

1a. Do the same side to side and note any error conditions. Push the end of the taistock quill both ways. Reading discrepancies more than 0.0005" indicates wear. Bi-stable (the tailstock does not recover from the push) indicates moderate to severe wear on the V way. It's not automaically centering. Mixed in with the reading of excessive clearance of the quill in the quill bore. Conduct tests to separate with wear conditions.

2. Determning parallelism error. Machine a stub the same diameter as the tailstock quill and leave it in the chuck. Set up and zero an indicator on it to register in the vertical plane. Extend the tailstock quill. Crank the carriage so the indicator contacts the extended tailstock quill and note the reading. On any but a new lathe this should register some out of parallelism. The amount of error should be recorded on a sketch. Go back to the headstock and register the indicator on the stub without disturbing the setting for a repeat zero. If the zero repeats your out of parallelism reading can be recorded for posterity or used to determine the amount of shim used to raise the tailstock up to alignment with the headstock.

This is simple machine tool survey technique and needs no special fitted tapers or precision ground bars. Don't get me wrong. Certified proof bars are a great convenience but it's a use-once item. They take many hours of time to make of cost several hundred dollars to buy. Once used they sit on a shelf, a white elephamt. They are needed about once a generation in any but a professional rebuild shop.

If you need to conduct a partial survey for spindle tailstock alignment, the two collar tests and plug tests are as accurate and only a little more time consuming than using a certified proof bar.

I've surveyed and run test sheet checks on used and rebuilt machine tools. A few cases my results were challenged and my use of two collar tests etc disparaged. After some time and expense a cetrified test bar was acquired and the test re-run by another. Funny thing: we both got the same results recognizing small descrepancies inherent when working to the limits of the test apparatus.

Worn out is worn out.

Note, I deliberately glossed over and inserted petty errors in part of the above post. This is something I seldom do but I did this time thinking a few of you may enjoy finding the dubious and erroneous and pounding on them.

lane
10-19-2011, 08:44 PM
My question will be this . Just how many of you Have a perfect Lathe any way . I have only ran a very few brand spanking new machines in my life time . Most of the lathes I have ran were worn out to ever ones slandered here. And I was still able to make good parts. So what gives.

Chris S.
10-19-2011, 09:12 PM
My question will be this . Just how many of you Have a perfect Lathe any way . I have only ran a very few brand spanking new machines in my life time . Most of the lathes I have ran were worn out to ever ones slandered here. And I was still able to make good parts. So what gives.

Well, that wasn't my question; was it? This is an alignment/setup aid, just like a machinists level and just as relevant.

Chris

Boucher
10-19-2011, 10:08 PM
A test bar is not that hard to make. The procedure is described in one of our sponsorers lathe videos. It is well past happy hour here but I will try. Take a 12" bar about 3/4" dia and drill new centers in both ends. Don't fret about the accuracy. Put a center in the headstock and if you want to fret about something take a truing cut on the center. Install the bar between centers and turn about 1" next to the headstock center. Put an indicator in a tool holder and take a reading on the test area that you turned true. It is important to stay at the centerline height. Reverse the test bar between centers so that the good surface is now at the tailstock end. Move the indicator and read the position of the test bar. Move the tailstock to get a zero reading. The video also details how to make a good holder for this.
Hope this makes sence when I read it tomorrow when I am sober.

Chris S.
10-19-2011, 11:20 PM
A test bar is not that hard to make. The procedure is described in one of our sponsorers lathe videos. It is well past happy hour here but I will try. Take a 12" bar about 3/4" dia and drill new centers in both ends. Don't fret about the accuracy. Put a center in the headstock and if you want to fret about something take a truing cut on the center. Install the bar between centers and turn about 1" next to the headstock center. Put an indicator in a tool holder and take a reading on the test area that you turned true. It is important to stay at the centerline height. Reverse the test bar between centers so that the good surface is now at the tailstock end. Move the indicator and read the position of the test bar. Move the tailstock to get a zero reading. The video also details how to make a good holder for this.
Hope this makes sence when I read it tomorrow when I am sober.

Well, I must confess that I've read threads using the 2 collar method more times than I care to remember but this technique is a first for me. I reserve the right to not judge it until you're sober. :D

Chris

rkepler
10-19-2011, 11:50 PM
No, I didn't know that drill rod is not perfectly round. I was under the impression that drill rod was ground to dimension. When you say "not perfectly round", to what degree are you talking about?

I've got a chunk of 1.25" O-1 that mics pretty close, but stick it in a V-block with an indicator and it'll set the needle moving pretty good when turned - it's lobed from centerless grinding into a trichordal form. Naturally I trusted the micrometer when I tried to put it into a 1.2500 hole, figured it out when rotating a piece between centers and the indicator showed it "lumpy".

Chris S.
10-20-2011, 12:29 AM
I've got a chunk of 1.25" O-1 that mics pretty close, but stick it in a V-block with an indicator and it'll set the needle moving pretty good when turned - it's lobed from centerless grinding into a trichordal form.

Good to know. I now know that drill rod is not a precision piece of stock.

Thank you.
Chris

jugs
10-20-2011, 01:49 AM
I've got a chunk of 1.25" O-1 that mics pretty close, but stick it in a V-block with an indicator and it'll set the needle moving pretty good when turned - it's lobed from centerless grinding into a trichordal form. Naturally I trusted the micrometer when I tried to put it into a 1.2500 hole, figured it out when rotating a piece between centers and the indicator showed it "lumpy".

Not only that, you'll often find that form is on a helix http://smileys.on-my-web.com/repository/Surprise/surprised-005.gif:mad:

For round you need it center ground ;)

lynnl
10-20-2011, 12:01 PM
A few years back I got some really nice such bars from the piston rods out of shock absorbers, or maybe it was McPherson struts.

Don't know if the stuff was chrome plated, or just highly polished; but it was mirror smooth and shiny. Very hard on the outside, but soft enough to cut easily, once you got through the outer case.

Was perfectly round, to the best of my measuring abilities.

Boucher
03-18-2012, 07:40 PM
I have revised my earlier post to clarify.

To quickly center the tailstock you need a test bar and an indicator. A test bar is not that hard to make. The procedure is described in one of our sponsorers lathe videos. Take a 12" bar about 3/4" dia. and drill new centers in both ends. Don't fret about the accuracy. Put a center in the headstock and if you want to fret about something take a truing cut on that center. Install the bar between centers and turn about 1" next to the headstock center.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0252Small.jpg
Put an indicator in a tool holder and take a reading on the test area that you turned true. It is important to stay at the centerline height. Reverse the test bar between centers so that the good surface is now at the tailstock end. Move the indicator and read the position of the test bar. This shows that mine is about .002 off center.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0254Small.jpg
Move the tailstock to get a zero reading.

The on center indicator holder is easy to make. Here is what mine looks like. http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0251Small.jpg
Mill out the block that has a bottom tab that fits the T- slot in the cross slide. The indicator hole is drilled using a drill in the headstock. This assures that it is on center. The diameter corresponds to the diameter of your indicator. Two holes are drilled and tapped from the top one to hold the indicator in the block. The second positioned to lock the block in the T-slot.


Boucher



Boucher

oldtiffie
03-18-2012, 07:58 PM
Some are making too much out of very little at all.

This should work just as well if needs be. Its served me well enough often enough - and I have all the "good gear" if needs be:

http://bbs.homeshopmachinist.net/showpost.php?p=752131&postcount=2

http://bbs.homeshopmachinist.net/showpost.php?p=752137&postcount=3

http://bbs.homeshopmachinist.net/showpost.php?p=752141&postcount=4

Ron of Va
03-18-2012, 08:39 PM
I am no expert by any means, but this is how I align my tailstock. I use a gage pin the same diameter as the end of my live center in the lathe chuck. I then zero the dial indicator at the lathe chuck. I then run down to the tailstock and check for zero. If not zero, then I adjust as necessary.
http://www.hunt101.com/data/500/medium/TailstockAlignment.jpg

I check the tailstock height in a similar fashion.
http://www.hunt101.com/data/500/medium/TailstockAlignment2.jpg

This method seems to work ok for me. I am not sure how orthodox it is. You could also use a drill chuck in the tail stock and swap the gage pin to the drill chuck. But I don't think it would be as accurate.

oldtiffie
03-18-2012, 09:07 PM
A true tail-stock test bar is precision ground between centres and has both a parallel section as well as a Morse Taper (MT) to match the MT in the tail-stock quill.

Put the MT in the tail-stock quill MT and run an indicator along the parallel section. Any angular misalignment between the tail-stock MT and the lathe bed will soon become evident. It should be zero in both the vertical and horizontal planes.

Same apples for the lathe head-stock MT with its test bar.

http://lprtoolmakers.auctivacommerce.com/LATHE-ALIGNMENT-TEST-BAR-2MT-HIGH-PRECISION-GROUND-BAR-P1422224.aspx

oldtiffie
03-19-2012, 12:06 AM
All of these tool & cutter grinder adaptors - with a 3MT bore or adaptor - need a test bar to align the spindle axis to the table axis in 3 planes: left-right (rotate); and up/down (tilt) as well as the universal table (left-right).

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo10.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo9.jpg

There are others around the shop including the 3MT tapers in my mill spindles.

oldtiffie
03-19-2012, 02:46 AM
I have revised my earlier post to clarify.

To quickly center the tailstock you need a test bar and an indicator. A test bar is not that hard to make. The procedure is described in one of our sponsorers lathe videos. Take a 12" bar about 3/4" dia. and drill new centers in both ends. Don't fret about the accuracy. Put a center in the headstock and if you want to fret about something take a truing cut on that center. Install the bar between centers and turn about 1" next to the headstock center.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0252Small.jpg
Put an indicator in a tool holder and take a reading on the test area that you turned true.


Reverse the test bar between centers so that the good surface is now at the tailstock end. Move the indicator and read the position of the test bar. This shows that mine is about .002 off center.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0254Small.jpg
Move the tailstock to get a zero reading.

The on center indicator holder is easy to make. Here is what mine looks like. http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0251Small.jpg
Mill out the block that has a bottom tab that fits the T- slot in the cross slide. The indicator hole is drilled using a drill in the headstock. This assures that it is on center. The diameter corresponds to the diameter of your indicator. Two holes are drilled and tapped from the top one to hold the indicator in the block. The second positioned to lock the block in the T-slot.


Boucher



Boucher


It is important to stay at the centerline height.

Not so.

If the diameters are similar it will neither matter if the indicator is above or below centre (say +/- 0.050") or tilted (+/- 5 to 10 degrees) so long as it is used in the same position on each turned diameter.

The indicator is used solely for "zero-ing" and as a comparator - not necessarily for measuring.

Jaakko Fagerlund
03-19-2012, 06:08 AM
If you want a complete story from the tailstock, you need to measure along the extended quill to see if it is parallel to the ways AND take a measurement from a Morse tapered test bar held in the tailstock to see that the Morse taper is also pointing straight.

oldtiffie
03-19-2012, 06:31 AM
That's true.

But several readings along the outside of the quill - top and side - with the quill both clamped and not clamped - are required.

Martin0001
03-19-2012, 07:25 AM
A buddy Bud (not a pun) sent me this ebay link (ground test bar with centers) this morning..
Am I missing something?
Bedways & Tailstock allignement (I assume that you have already aligned headstock with bedways):

1. Take a section of 1 inch BDMS about 1.5 ft long and drill centers on both ends.

2. Turn 2 "bobbins" 2 inch in diameter with 1 inch hole and locite it on your BDMS bar about 1 - 1.5 foot apart.
Bobbins are best to be made of nicely turning material giving good surface finish.
Say brass, bronze or aluminum.

3. Install soft centre in the journal and turn it fresh to 60 deg angle.

4. Install your bar between centres with barrel of tailstock *withheld*.

5. Take a light, finishing cut under power on 2 bobbins and measure diameters.
Carriage should go 1 way during cuts.
In ideal world which does not exist they would be *equal*.
In normal world they won't be but it is acceptable for a one closer to tailstock to be *larger*, say by 1-3 thou per foot.
If that is not the case add some packing under one or second foot of the lathe at the *rear* and retighten down bolts with torque controlled spanner.
This is causing twisting the bedways one way or another.

6. Repeat measurements and repeat procedure until you are happy with accuracy level.
I got down to better than 0.0005 thou a foot.

7. Remember that it is not acceptable for the bobbin at the tailstock end to get smaller than one at headstock.

8. Now extend tailstock barrel to the end and repeat cuts.
There should be the same difference between diameters as the one recorded during first test.
If not, offset tailstock accordingly.

9. Now turn half turn tailstock (hard) centre and repeat cuts & measurements. They should show exactly the same error like before.
If not, particularly with significant discrepancy, then tailstock socket is damaged (possibly because it was used as a *bearing* by careless operator etc and now needs reboring.
Assuming that headstock is aligned well and its socket is true you may advance a bit a good quality, spiral flute tapered reamer from the headstock down the tailstock barrel to correct the error (usually in form of burrs and groves) but if you don't know what you are doing, you may cause furher damage.

Make sure that your tailstock centre (hard one) is very accurate, from reputable maker before attempting it and of course tailstock socket cannot be harder than 50 - 55 HRc for success to occur.

Note:
Described test will align tailstock in horizontal plane.
Correction with reamer will make it true in horizontal *and* vertical plane, that assuming that bedways are not worn.

Breaking centre drills despite of proper alignment done as described above are suggesting error in vertical plane.
This is usually due to bedways wear and bedways must be scrapped in or ground again before any reboring of tailstock.

Hope, it is clear enough.