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Bob Fisher
12-31-2012, 01:13 PM
Anyone tried the tram with 2 dial indicators as offered by MSC ? If so, whar are your thoughts? Bob.

Rich Carlstedt
12-31-2012, 02:48 PM
Personally, I think using two indicators is a mistake.
You then have to consider that they may not be the same in setting.
You could wind up reading only one , or be confused with two.
When they don't match, you have to rotate the spindle anyway to set them, so why complicate the issue?

Tramming is easy if you follow this Procedure, and you don't need a big Ring or double indicators.
Start with the spindle in the full up position and tram left and right ONLY !
When you feel it is pretty good, drop the table and fully extend the quill and repeat.
The extended quill acts as an amplifier and you can fine tune the L & R settings because of increased sensitivity to head movement.
After L & R, then you do the front...period
Never rotate front to back, only rotate front to one side ( 90 degrees).
If the right or left are plumb, then all you need is to balance the front with one side.
This is much faster and prevents going the wrong way . It doesn't matter if the dial changes, which it will when doing a tilt correction.
All youy have to do is make sure the front matches a side..
When you are done, you can dop a 360, but be aware that 3 points determine a plane , so L, R, and F are all you need.

Rich

EVguru
12-31-2012, 04:38 PM
Personally, I think using two indicators is a mistake.
You then have to consider that they may not be the same in setting.


There is a pad under each indicator and these pads are machined to be at 90 degrees to the spindle axis. You rest the instrument on those pads and zero the indicators.

It's fast and involves the minimum amount of cranking the knee up and down.

Boucher
12-31-2012, 04:48 PM
I have one and I love it. Much easier to use than the DTI. The proof of the pudding is the ability to easily tram accurately enough to get that perfect fly cut finish. They are a little expensive for the component cost and the ease that one could make their own.

Carld
12-31-2012, 04:52 PM
I don't see the need for the double indicators. It doesn't take that long to just use one indicator and the standard method. I like having tools but sometimes tools come along that are not really needed.

If you have a lot of spare money and like to buy any tool that comes along I see nothing wrong with it. For that matter you can make one for yourself at way less than those sell for.

When I sweep my head in I seldom move the knee more than a few thousandths up or down to get it done. I don't understand why you have to crank the knee up and down so far.

BigJohnT
12-31-2012, 05:00 PM
I'm glad someone else thinks that is a gadget, my wife would buy one though...

I might add to your procedure: Use a machinist square on the extended quill to get it close to square before you mount the test indicator.

John

Dr Stan
12-31-2012, 05:09 PM
+1 on the DTI

BTW I was taught to tram the head with the spindle fully retracted as that is where it should be when you are milling.

Mike Amick
12-31-2012, 05:45 PM
I think that most modern tools you can buy .. there is a previous method/tool that can be used
that takes just a little more effort/time to use. There will always be people that resist
change. I say take those darn DRO's off .. whats wrong with the dials !?

The people using these easy trams all say they love them .. seems strange to say nonsense without
even trying one.

bborr01
12-31-2012, 05:54 PM
Training wheels for your mill.

Brian

BigJohnT
12-31-2012, 06:10 PM
The problem I have with unitaskers is well they only do one thing... I can tram my head with a test indicator heck I can even tram the mill head with it as well as align my vise, check material... well you get the picture. I'm sure it works fine but that is all it does... and I don't have enough drawers for every unitasker out there.

Just to be clear I'm not saying it doesn't work!

John

Ron of Va
12-31-2012, 07:26 PM
I made one and I like it. They are not hard to make.

With a single dial indicator you go to align the head, you tap a little this way and that way. I am ashamed to admit it, but with a single dial indicator, I frequently tap the head the wrong way before I get my brain wrapped around it. With the two indicators, I know exactly which way to tap the head. I really donít know why it is like that for me.

I still use a Starrett indicator with the plunger on the back most of the time because I donít want to dedicate two dial indicators to the tool and leave them in the drawer. So I have to go get two indicators from their magnetic bases and switch them to the tramming gizmo. Then put them back on the magnetic base. All that is a pain.

(And I would never buy it from MSC. They can be found much cheaper elsewhere.)

uncle pete
12-31-2012, 07:27 PM
Each to their own opinions I guess, I've got two spare indicators brand new still in the box and could easily make one. I just don't see much point if you've already got a DTI. And for the same reasons already mentioned. But they obviously work, just not quite as accurate as a 10ths reading DTI though. Probably in a commercial shop they would speed things up enough to be well worth it? I really am a tool whore and love even single purpose tools. And I still can't justify one.

Pete

Lew Hartswick
12-31-2012, 07:30 PM
I made one a couple years ago (whenever they came out) and haven't used it
since the initial trial. A big truck brake disc and a single dial indicator with a
large swing to match the disc is so easy to use it's a no-brainer.
...lew...

dp
12-31-2012, 09:31 PM
I made one a couple years ago (whenever they came out) and haven't used it
since the initial trial. A big truck brake disc and a single dial indicator with a
large swing to match the disc is so easy to use it's a no-brainer.
...lew...

Like this?
http://www.youtube.com/watch?v=ZfioLDhBNBQ

KiddZimaHater
12-31-2012, 09:58 PM
Do you REALLY need one?
I mean, just how often are you tramming your mill?
It's once in a blue-moon when I need to tilt the mill's head.
Then, it's a quick 15 minutes to tram it back in the 'old-fashioned way', and It's set for another long while.
I have the feeling the EZ-TRAM will be a dust collector.

MichaelP
12-31-2012, 10:21 PM
Isn't EZ-Tram a ring platform with three legs that you rest on the table to tram your mill? Or the dual indicator device uses the same name and just shifts the hyphen one position to the left (E-Z Tram)? :)

darryl
12-31-2012, 11:14 PM
I generally do my checking with the quill extended about 1/2 inch. Within that half inch up or down, nothing's going to change much. With it fully retracted, you might see some error induced from the 'bump ring'.

In any event, it's interesting to check the performance of the mill at other extremes, once you have it dialled in. You might find that it's out when the head is raised (or the table lowered) or the quill extended most of its travel. It's good to know if anything changes when you operate the machine over more of it's capabilities.

By the way, I've been thinking of making my own test instrument. It would be sonic. With its own speaker and a built in pair of oscillators, you set up a beat frequency in the audible range. Moving the probe alters the frequency of one oscillators, and it doesn't take much deviation of the probe to create a change in the beat frequency. You don't look at anything besides the obstacles that the probe might come into contact with as you rotate the spindle. As you adjust, you hear the change. When the note doesn't change, you have it right on.

rode2rouen
12-31-2012, 11:54 PM
I find a large bearing cup (10.25" OD) works a treat for tramming.
No cracks about the table, please. It was already fixed up when I bought it.


Rex

http://i721.photobucket.com/albums/ww216/bjorn_toulouse/tram1.jpg

Boucher
01-01-2013, 12:51 AM
That mill has been rode rough also.

bborr01
01-01-2013, 12:56 AM
I find a large bearing cup (10.25" OD) works a treat for tramming.
No cracks about the table, please. It was already fixed up when I bought it.


Rex

http://i721.photobucket.com/albums/ww216/bjorn_toulouse/tram1.jpg

The bearing race idea is something I would use if I ever came across one. I'm pretty sure that they are precision enough and would make an indicator glide like silk. My mill tables are not new either.

Brian

GNM109
01-01-2013, 01:19 AM
I have both a DTI and a Coax and I use a spare brand new front brake rotor. They are excellent for tramming your mill.

bborr01
01-01-2013, 01:53 AM
I have both a DTI and a Coax and I use a spare brand new front brake rotor. They are excellent for tamming your mill.

I never thought about tramming the head with a coax indicator and a brake rotor or a bearing race. That might make tramming real easy.

Brian

darryl
01-01-2013, 03:19 AM
Table- what table? That's the surface of Mars, complete with craters and canals. Funny that the canals are all parallel-

That's a seriously large bearing ring- biggest one I've been able to find is about 6 inches across. That's what I'm using.

BigJohnT
01-01-2013, 09:05 AM
I just use a 6" x 6" x 3/4" piece of ground plate in the vise... easier to find at McMaster Carr than a truck brake disk that ain't worn out.

John

JCHannum
01-01-2013, 10:03 AM
I do feel the dual indicator tramming device is overkill for its occasional use. If gadgets are your downfall, buy or make one. It would make an entertaining project if you have a couple of extra dial indicators you can tie up for the fixture.

As far as using bearing races, brake discs or other flats for tramming, make sure they are flat and parallel. Clean the table and stone any bumps or lumps that might interfere with the flat. If using a vise, it is not a bad idea to tram to the floor of the vise.

This post by J Tiers discusses bearing races;
http://bbs.homeshopmachinist.net/threads/51840-Bearing-race-face-flatness?highlight=bearing+race

I won't rehash the use of a coaxial indicator for tramming other than to state that the longer the probe and the farther it is extended in a plane at 90 degrees to the spindle, the less sensitive the indicator becomes.

rode2rouen
01-01-2013, 12:49 PM
The bearing race idea is something I would use if I ever came across one. I'm pretty sure that they are precision enough and would make an indicator glide like silk. My mill tables are not new either.

Brian


For grins, I had it checked by the inspection lab where I worked at the time.......flat/parallel < .0003"
New in the box from Ebay, IIRC, $18.00.


Rex

Danl
01-01-2013, 09:24 PM
My little brother has owned an operated a precision machine shop for about 30 years. I asked him about dual indicators and he said if time didn't matter they wouldn't be needed, but he can tram his mills in a fraction of the time it takes using the old fashioned methods. hmmmm.....

Ridgerunner
01-01-2013, 10:08 PM
I have one and love it. Previously, I had purchased a brand new rotor and when I checked, it was .001 out. With the dti reading the one side was OK, but I had to stick my beard in the chips to see the dial when I rotated it. With this I just put it in a 1/2 inch collet and it is ready to go.

http://i1122.photobucket.com/albums/l539/ridgerunner1212/Tram.jpg

EVguru
01-02-2013, 06:51 AM
The question has been asked, 'How often do you tram your mill?'.

The question in some ways should be, 'How often do you avoid angling your milling head due to the hassle of re-tramming it?'

LKeithR
01-02-2013, 10:20 AM
The question has been asked, 'How often do you tram your mill?'.

The question in some ways should be, 'How often do you avoid angling your milling head due to the hassle of re-tramming it?'

Exactly!! There are many projects where the simple approach is to tilt and/or nod the head but many people avoid doing so, not because the setup is difficult, but because it's a pain to re-tram the head after. Anything that makes the latter easier is a bonus in my opinion...

bborr01
01-02-2013, 12:16 PM
The question has been asked, 'How often do you tram your mill?'.

The question in some ways should be, 'How often do you avoid angling your milling head due to the hassle of re-tramming it?'

Exactly never.

Brian

Tony Pratt
01-02-2013, 01:29 PM
I'm with Brian, if the head needs to go over it goes over. Tramming the head is really not difficult folks, the more practice the quicker it will become. I normally use a long L bar which spans the vice, indicating on a precision block or slip placed on the table either side of the vice, 5/10 minutes max should do it.
Tony

Rich Carlstedt
01-02-2013, 02:22 PM
Interesting, that there is a new post on this forum about a problem reading a dual dial traming unit called a Pro-Tram.

In response # 2 on this thread , I outlined a fast and simple method to tramming a mill.
but I want to inject some concern here as I read some postings that you do not move the milling head because it then has to be trammed.

First, if you do lots of fly cutting, and thats usually means a "finish" surface, a properly trammed head is critical.
Those that do not flycut, mill or boire to shallow requirements can pay no heed to routine tramming .
Note I said "routine" tramming !
Besides rotating the head for angled cuts, a mill head can loose tram every time you take a heavy cut, or when you pull a piece of stock out of the vice.
It happens !
The other missing element here, and not mentioned is that when ever you tram a knee mill, make sure the knee clamp is locked !
if you don't lock your knee, when tramming, then you cannot lock your knee during PRECISION cuts .

Off the soap box
Rich

J.Ramsey
01-02-2013, 02:44 PM
but be aware that 3 points determine a plane , so L, R, and F are all you need.Rich

I agree with you 100%, that's the way I was taught.
Left
http://i.imgur.com/jPf7w.jpg
Right
http://i.imgur.com/uqwyT.jpg
Front
http://i.imgur.com/OKDuO.jpg

Most BP and their clones have a pair of notches on the casting at the front, they work excellent for rough tramming the head with a carpenters square.

http://i.imgur.com/ykPYw.jpg

Rich Carlstedt
01-02-2013, 02:47 PM
Most BP and their clones have a pair of notches on the front of the down feed, they work excellent for rough tramming the head with a carpenters square.

http://i.imgur.com/ykPYw.jpg

You're right !
Forgot about that !

Rich

MichaelP
01-02-2013, 06:10 PM
I agree with you 100%, that's the way I was taught.
Is it a brand new machine? The table looks uncomfortably mirror-like. :)

J.Ramsey
01-02-2013, 06:29 PM
Is it a brand new machine? The table looks uncomfortably mirror-like. :)

Bought new in '02.

MichaelP
01-02-2013, 06:54 PM
You didn't use it since then or used very rarely?

loply
01-02-2013, 07:15 PM
How easy it is to tram the head depends on the mill.

On my RF45 clone it's a nightmare to do with one indicator as the head rotates in a badly fitting bore and moves when you tighten the bolts. You tap it to adjust one side and both go the same way, then when you tighten the bolts it shifts by a different amount each time. You can literally spend 30 minutes nudging it back and forth hoping it lands just right. It's a nightmare.

Being able to watch both indicators at once as you progressively tighten the bolts, and bang the head around as it goes, would make it a lot easier, as the tram rotates unpredictably.

uncle pete
01-02-2013, 07:52 PM
Funny enough I've read a few past posts on this forum where people didn't know it's SOP to regularly check any mills tram. Some didn't even know they weren't perfect when brand new right out of the crate and have never trammed in their mills head. And I do know a little bit about Rich's past experience, so it's highly unlikely I would ever disagree with him about what's correct. If the works accuracy demands it? Then it sure doesn't take long to double check that everything is correct and in tram within what your willing to accept. And yeah, I wouldn't hesitate to rotate or nod the head. That can be a drawn out procedure to do it with any kind of accuracy and correctly though. Anything real accurate would require you to set the head against at least a fairly good sine bar, gauge blocks, and a dial indicator. Tilt the head, then do the work, and then retram everything back in. Ok, sometimes the work might be long enough or for various other reasons the head does need to be moved.

Nope it isn't the cheapest way to do it, but I bought a fairly cheap set of Chinese gauge blocks and a sine bar, I later upgraded to far better, so I then repurposed the lesser equipment just for work like this. Those are my shop grade gauge blocks. For the shorter work, I can set work at a single angle in the vise using that setup a lot faster, and I still don't need to retram my mill's head when it's done. IMO? Flop the head over to whatever angle is needed when it's needed. But I'm just too damn lazy to go look for extra work. Especially so when a couple of hundred bucks will get you the tooling to do the above. I just don't use my Mitutoyo gauge blocks for work like this though. The angled steam passages to the valve port openings are a no brainer, fast, accurate, and easy doing it that way for just one example.

Pete

Ridgerunner
01-02-2013, 09:27 PM
I wonder if a person could easily do some minor angles with the dual gauges?

Randy
01-03-2013, 12:48 AM
I made one. I like it a lot, and I'm going to use it whether the old school scolds who've never tried one approve or not.

OK. Sorry for getting a little snarky. A single DTI works fine, and for real critical work a tenths reading DTI is probably better. But for most work I find this easier to use, especially for straightening up the nod. And as noted before, sometimes the head shifts a tiny bit when you cinch down the bolts. That's not always readily visible with a single indicator. I find it's instantly visible with two indicators. I also find this works nicely for setting the head at an angle with a sine bar.

http://img.photobucket.com/albums/v21/rykrisp/tram-o-matic_2000_5.jpg

LKeithR
01-03-2013, 04:01 AM
So how do you "zero" the tool? Put a gauge block under each end of the bar? Some of the tools I've seen have a raised flat on either end for setting up...

uncle pete
01-03-2013, 06:01 AM
Keith,
They come with a small magnet. You place that under the first indicator tip on the mills table, zero the dial, rotate the whole unit 180 degrees and do exactly the same for the second indicator. That gives you a flat plane between both indicator tips when there at zero.

Pete

oldtiffie
01-03-2013, 06:13 AM
All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

jcaldwell
01-03-2013, 11:33 AM
A question a bit off of the main discussion: I saw a picture of a milling table that had been scraped to be perfectly flat. Would the peaks and valleys of the scraping causes problems when tramming? More so with a tenths indicator than a thousandths indicator?

EVguru
01-03-2013, 11:54 AM
All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

Your mill is knackered.

dian
01-03-2013, 12:52 PM
All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

right. what do you folks tram to exactly?

Boucher
01-03-2013, 01:10 PM
There seems to be some misunderstanding of the principals involved. To set up this tool you only need a flat surface. Before you install it in the spindle you just set it on the flat surface and adjust both indicators to the same reading. (I use the ground top of my mill vice) Install it in the spindle and you are ready to go. The functional requirement is that the bottom surface of the pads under the indicators be flat in the same plane perpendicular to the rotating axis. Very simple to make one. Install the spigot in the lathe headstock and take a facing cut. These are functionally simple and very easy to use.

dian
01-03-2013, 01:19 PM
please choose:

- tram to table
- tram to x-y plane
- perpendicular to spinde axis
- perpendicular to quil movement

are there any others?

edit: sorry not spindle axis but z-axis i mean.

derekm
01-03-2013, 03:01 PM
All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

tiffie wrong end of stick holding

As the measurement is back to the same point it doesnt matter. (almost)
any errors are due to either differences in the radius from the axis of rotation of the two tips or errors in rotating exactly 180 degrees
However, any remaining error is attentuated by having the axis of rotation close to perpindicular.

if think the maths is :
If the off perpindicular angle is dp
the off 180 angle is dq
the error in rotation radius of the tip is dr
the rotation radius is r

then the total error dz = r(1-cos(dq)).sin(dp) + dr.tan(dp)

I think :)

MichaelP
01-03-2013, 03:21 PM
Derek,

Tiffy is right. If the pad is not parallel to the indicator's plane of rotation, the tip of the indicator will climb or descend to/from the pad. You will notice it as a changing value shown by the indicator while it slides across the pad. This will not allow you to find a base point for calibrating the other end. Unless, of course, you're willing to play with the "from-to" range or, as you mentioned, have a way to rotate the spindle exactly 180 degree. Putting a mark where you want your base point to be may be a perfectly acceptable compromise unless the table is a way off, and your mill is useless.

In this respect, the pad should be spherical, but this will introduce some other problems such is a neccessity to find the highest point or need for identical lengths of arms. This wouldn't be a good solution, IMO. Besides, it will hide the fact that your table is off. :)

MichaelP
01-03-2013, 03:32 PM
There seems to be some misunderstanding of the principals involved. To set up this tool you only need a flat surface. Before you install it in the spindle you just set it on the flat surface and adjust both indicators to the same reading. (I use the ground top of my mill vice) Install it in the spindle and you are ready to go. The functional requirement is that the bottom surface of the pads under the indicators be flat in the same plane perpendicular to the rotating axis. Very simple to make one. Install the spigot in the lathe headstock and take a facing cut. These are functionally simple and very easy to use. Byron,
You lost me here. How do you set the indicators BEFORE the fixture is in the spindle?

Ron of Va
01-03-2013, 03:46 PM
The feet donít have to be in perfect relationship to the shaft.
All you have to do is make sure you zero the dial indicators independently of each other in the same spot. The attached photo shows how I used a ĺ inch parallel bar to zero one indicator. Then I spun it around and zeroed the other indicator in the same spot (using a little mirror). Now both indicators are properly zeroed. If the shaft and pads were in perfect relationship, then there would be no need for this, then it would work great, but mine are not perfect. The $150 SPI unit is good to go. This one is home made.
http://www.hunt101.com/data/500/medium/SpindleSquare2.jpg

derekm
01-03-2013, 04:54 PM
Derek,
, ...the tip of the indicator will climb or descend to/from the pad. You will notice it as a changing value shown by the indicator while it slides across the pad. ..)
tiffy isnt right ( and you dont move the table, you rotate the gauges 180)
That error is specifically allowed for in the error analysis( i.e. r(1-cos(dq)).sin(dp) term ) thats why you need a marked point on the pad to keep dq (the error in the 180deg reversal) small and close to the maxima.(solstice)

lets do this with some real numbers

lets say the dial gauges are 100mm apart.
the head is tilted by 1 degree
the error in rotating the head by 180 degrees is 1mm accuracy in matching marks at the solistice point
the tips are unequal in their radius from the axis of rotation by 0.1mm. (0.004")

RESULT:The error between the dial gauges is 0.017 mm ~ 0.00068 "

only 0.00006" come from the 180 reversal error
the biggest contributor is the radius error at 0.00063"

let go devils advocate and carelessly put the patch at the point of maximum change (equinox). That will give an error of 0.02mm from the reversal error which is still only 0.0008"

MichaelP
01-03-2013, 05:58 PM
Derek,

I see no contradiction between what you, Tiffy or I said. We do need to check both sides in the same spot.

Boucher
01-03-2013, 09:35 PM
The SPI spindle square is shown here:
http://i109.photobucket.com/albums/n50/boucherbyron/TramToolSmall_zps292eef85.jpg
As mentioned previously it is calibrated by just setting it on a flat surface and zeroing the indicators. The spigot which is perpendicular to the plane of the pads under the indicators is installed in the quill and the indicators are set on the table and the head rotated to zero the indicators resulting in the head being trammed.
After viewing the Edge Technology video I realized that all tramming tools are not made to work the same way. I have been very pleased with the results and ease of use of the SPI tool. No connection just a satisfied user.

MichaelP
01-03-2013, 10:02 PM
I got it. Thank you Byron. So as long as you're 100% sure the stems of the indicators are parallel to the spigot, and the arm base is perpendicular to them, you're OK.

oldtiffie
01-04-2013, 12:49 AM
This is my post that caused some concern here to some previously in this thread.


All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

It is easliy resolved to see if the top of the table is in fact parallel to the "Y" face the saddle moves on. Just put an indicator on the say front of the table with the table at the end of its "Y" travel/traverse. If the indicator remains at zero when the table is traversed to the other end of the "Y" travel, all is OK.

If it isn't then it seems that the table top is not parallel to the "Y" slide.

Tramming is setting the spindle mutually square to the "X" and "Y" using the table top assuming it is parallel to the "X" and "Y" slides.

This has virtually no effect in "X" but it will result in "saw-toothing" if multiple (say) fly-cuts that are made in "X" and are parallel and over-lapping are made. The amount will be small but will proabably leave a small "burr" that may need to the stoned/honed/filed off.

This can be eliminated (after the event) by moving the table in "Y" half the width of the over-lapped fly cuts and taking another fly cut at the same setting.

There should be no similar result if fly-cutting in "Y".

A "tilt" (in"X" or "Y") of say 0.002" over a tramming swing of say 8" is 0.002/8 = 0.00025" per inch. So 2"is not so bad but perhaps 1" over 8" = 0.000125" per inch - (or better) might be better.

Tramming can be lost just by varying the torque on the quill and or knee clamps (happens with tail-stock quills too). It can be lost by too heavy cuts or "crashes".

My quote at the start of this post was to point out that if and as you are using the table as parallel to the "X" and "Y" slides as a reference that that is the case and if not due allowance may have to be made.

Note that in that quoted post of mine I did not say what anything is or is not - I merely posed the question.

oldtiffie
01-04-2013, 12:53 AM
Originally Posted by oldtiffie

All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?


Your mill is knackered.

Possibly maybe even probably or certainly or perhaps it can be "lived with" or "worked around".

But you will never know unless you check it for your self.

derekm
01-04-2013, 07:46 AM
This is my post that caused some concern here to some previously in this thread.

...Note that in that quoted post of mine I did not say what anything is or is not - I merely posed the question...

Ok then I got the wrong end of the stick you were waving...
please machine a more obvious handle on the stick :)

Tiffie, a long time since we last traded posts ... hows it going?

Rosco-P
01-04-2013, 09:18 AM
All of this presumes the table top is flat and is parallel to the X and Y slides.

What if it isn't?

It also presumes that the hole in the bar which holds the indicators was drilled/bored perfectly perpendicular to the bar. If not, you are already introducing error. As a reference/alignment tool, it's no more accurate that the machine it was made on.

goodscrap
01-04-2013, 09:27 AM
these devices make no account for the accuracy of what you hold it in, if you have a rogue collet with a bit of swash you'll get false readings, or as in the photo on the previous page holding it in a drill chuck will almost certainly give an error (not having a go at you just stating what i see).

In my mind using a single dial for tramming will give more accurate results, yes - i suppose you could use these devices to get close, but if you want it spot on, then a single dial has got to favoured in my book. This way you are setting it all up to the rotation axis of the spindle; the same axis the cutter sweeps.

Brian

bborr01
01-04-2013, 11:29 AM
I saw a picture in this thread of an easy tram like device in a drill chuck. If your drill chuck is not perfect, you will not get a good tram unless you calibrate the easy tram every time you use it.

When you tram the head of a mill, you are tramming the axis of the spindle. Meaning that if you put something like the easy tram in a collet or a drill chuck that is not perfectly square to the spindle bearings, you will not be square.

When using a single indicator, it doesn't make any difference how you hold the indicator as long as it doesn't move. The indicator will always indicate square to the axis of the spindle.

As to what you are tramming to, you can tram your mill head to anything. Most times you will be tramming to a table or vise, but you can tram to something that is mounted at an angle to the table. The whole point of tramming is to get something square to the spindle axis. Nothing more. Nothing less.

Brian

MichaelP
01-05-2013, 04:26 AM
It also presumes that the hole in the bar which holds the indicators was drilled/bored perfectly perpendicular to the bar. If not, you are already introducing error. As a reference/alignment tool, it's no more accurate that the machine it was made on.

Actually, as long as you use the original method of zeroing (vs. Boucher's method pictured above), the parallelism/perpendicularity of the the indicator stems or the arm relative to the spindle or each other shouldn't matter. As long as you use the same spot to zero both indicators initially, you'll be fine. The indicators may not show you the true distances when you're tramming, but as long as you reach zero on both of them, you know the head is trammed. In this respect, your travel indicator just starts working as a test indicator.