PDA

View Full Version : Tramming a round column mill



71CJ5
12-23-2010, 08:48 PM
I'm having a little issue in determining how to properly tram the swivel of the head on a round column mill. This is the mill I have:

http://cdn7.grizzly.com/pics/jpeg500/g/g1126.jpg

As you can see the head tilts side to side but has no ability to "nod". I understand how to tram the tilt of the head to the table.

How do I verify that the head is perpendicular to the x-axis of the table when looked at from above. Below is a very rudimentary drawing of what I'm trying to accomplish. Thanks

http://i937.photobucket.com/albums/ad211/JKSebring96/Misc/Mill.jpg

Astronowanabe
12-23-2010, 09:19 PM
not being flippant but, why does it matter?

no matter where it is the y-ways that will determine the line that is cut.

darryl
12-23-2010, 09:59 PM
Your mill is different than mine, but the adjustment of the column on the base is the same- tilt and nod. You'll need a dial indicator of some kind, and a cylindrical square. Because there are 4 areas where an error could be, you'll need to approach this properly. To start, it would be good to check the table slides to be sure they are free of foreign material, and that both axis can be adjusted to eliminate play. No good adjusting things higher up if the table is going to rock and roll as junk gets excluded, etc. If that's well taken care of, carry on.

You can tilt the head side to side, and you have a zero there. You don't know yet whether the zero is in the right place, but that's your only reference so far. Set it there, and engage the pin or whatever, if there is such a thing, before clamping it tight. A note here- is the mounting surface behind the head and on the casting that rides the column clean and flat? If that fit isn't cleaned and lightly oiled, you could be wasting time going any further. It should have no rocking motions, in other words it should be a nice flush fit with no gaps at the edges. Any cosmoline that isn't cleaned out is a menace.

Now you mount a dial indicator to the spindle and arrange to indicate against a cylindrical square mounted to the table. You'll be checking for nod to begin with. With the quill snugged to the point of having some resistance to down motion, check for variation on the indicator as you run the quill up and down. Make note of how much variation and over how much vertical distance.

Here's where it gets tricky- you need to check for tilt, but the error could be with the column tilt, the head adjustment, or both. Loosen the head on the column and rotate it 90 degrees to one side or the other. Adjust the spindle mounted indicator so it can ride the side of the cylindrical square, and run the quill up and down again. Note the variations and the vertical distance travelled to get those variations, same as with the nod test.

This should give you a side to side column tilt figure. Now rotate the head on the column back the 90 degrees and run the indicator on the side of the square again. If these figures match the first side to side error figures, then the head tilt zero setting is right on. If the figures are different, both the column and the zero setting will need to be tweaked.

If the column is leaning in any direction, it will have to be shimmed to be as close to upright as available shim stock will allow. If this needs to be shimmed, then you have to backtrack a little. You'll have to unbolt the column from the base, make note of any existing shims at the bolt locations, and make note of any paint, etc that might be pinched between the base and the column flange. You might have to clean this all to bare metal, remount the column, and run the tilt and nod tests again.

Are you tired of me yet? It will pay off in the long run to set it up properly once right from the start, so it's worth the effort. In my case, I was able to rig a hoist between the exposed rafters above the mill, so I had an easy way to lift the head and column assembly off the base. If you don't have any way to handle that, you can loosen the flange bolts, but not remove them. This will let you tilt the column to check the gap cleanliness without having the thing fall over on you. You will probably remove one bolt at a time to clean that corner, then put the bolt back loosely and move to another corner, etc.

At any rate, now you measure the bolt pattern and mark it on paper. The previous error figures are now compared with the bolt spacing, and you'll get the thickness figures for the shims. Say you got an error reading of one thou over three inches, and the bolt hole spacing in that direction is six inches. That means a two thou shim there, etc. This is just math, and mental coordination. One corner will have no shims, and three corners will need something. I made my shims L shaped so the flange rests on about an inch of shim length on each side of each flange corner, and they don't have to have a hole for the bolt to go through. Up to you how you want to do this.

Anyhow, I'm here and you're there, so I'm assuming at this point that you've got the flange shimmed and bolted down, probably with some grade 8 bolts. The column is now upright with respect to the base. Run the side to side tilt test again, and these results will tell you if the zero adjustment needs to be changed. Once you make whatever corrections are required there, the mill should be in tram. Now you test that with a dial indicator reading against the table surface, while you rotate the spindle by hand, taking care to not have the indicator tip dropping into the t-slots. If you had a large outer ball bearing race to lay on the table, you can arrange the indicator so the tip rides the entire up side of the race. You'll get a full 360 sweep with less hassle that way. Any deviations front to back will mean the column nod setting is off, and any deviations side to side will be because of a possible combination of head tilt error from zero, and the column side to side tilt.

darryl
12-23-2010, 10:11 PM
TomC, it matters because if you are facing a part with the cutter shown, any errors will translate into scalloping on the face of the workpiece. If you are milling edges with the side of an end mill, you won't be getting the edges square to the face. It's up to the operator to determine how much of an error is acceptable, but wouldn't you generally want it to cut true?

I've recently found with my mill that the x and y axis are not at a true 90. This is something else again that is not a part of tramming, and for the most part I can't see a way to correct this short of having the block of cast between the base dovetalls and the table dovetails re-machined. My tablesaw cuts more squarely than the mill can - to say that irks me is an understatement. But it's a round column mill, one I could afford, and I have to live with it. I could possibly make up a pair of very slightly tapered shims and add them to the dovetails- hmm.

As far as the mill being accurately aligned, it sure is nice to see the leading and trailing edges of the cutting tool marking the facing work equally. If you can crank the workpiece around under the cutter, and it doesn't get dished and gouged, you'll be a happier camper.

Tom, I see you're in Mouldy, Or. You probably have the same cold rain as we do here. Not to minimize the plight of those out east, but this is dreadful.

luthor
12-23-2010, 10:18 PM
The head has no traverse so why does it matter???

darryl
12-23-2010, 10:28 PM
Hmm. If the tram is out, an endmill held in the chuck will not be parallel to the table- a facing cutter like the one shown will have a low spot that all the cutters will dip to as the spindle rotates. If you crank the table back and forth forever, you'll get that low spot everywhere, so the surface becomes sort of flat, but it will be full of little scallops. You'll have a whole bunch of alternations between conventional and climb cutting- why not set it up right to begin with-

71CJ5
12-23-2010, 10:32 PM
TomC, it matters because if you are facing a part with the cutter shown, any errors will translate into scalloping on the face of the workpiece. If you are milling edges with the side of an end mill, you won't be getting the edges square to the face. It's up to the operator to determine how much of an error is acceptable, but wouldn't you generally want it to cut true?

This is what I'm getting at. I need to cut a 45* chamfer on some 1" plate. I was planning on tilting the head 45* and moving the y-axis to make the cut. This is why I want the head as perpendicular to the x-axis as possible.

I was just seeing if there is an easy way to check this since I'm an amateur when it comes to milling.

luthor
12-23-2010, 10:39 PM
Darryl, did you see what the OP is trying to achieve? What he is trying to do will have little to no effect on how the machine cuts.

rode2rouen
12-23-2010, 10:40 PM
How do I verify that the head is perpendicular to the x-axis of the table when looked at from above.


Seems to me that a pair of 1-2-3 blocks, spaced equidistant from the center of the table, would give you the info you need.

Mount the blocks 3" either side of table center. Place a drill rod in the spindle.
Center table under drill rod. Zero the X axis dial and crank the table to one of the blocks. If you have traversed 3" (less the radius of the drill rod), the head is centered. If the measurement is more/less than 3", moving the head right or left will get you centered.


Rex

Arthur.Marks
12-23-2010, 11:05 PM
luthor has obviously never used a boring head on a round column mill/drill. :) Basically, without reading the above responses thoroughly, you need to shim the column mount at the base casting to adjust for any error. I bought a roll of .0005" thick shim stock to do this. I just used a dial indicator mounted in an arm extension in a collet. Swung the head around and trammed that way. Yours is easier than mine... I've got an RF31 that has no swivel adjustment on the head! Sounds like a bear, but it really isn't that bad. Maybe an hour and shouldn't need to be repeated unless you're doing something unusually critical.

luthor
12-23-2010, 11:12 PM
Arthur and others, please look at the OP's sketch to understand what he is trying to do. For your information I have used boring heads on many types of milling and boring machines from 1/2 ton to 30 tons.

Arthur.Marks
12-23-2010, 11:14 PM
Here's some pictures. You can see some of the shim sticking out on the edge if you look closely. Actually, I have quite a bit left of the shim stock. It was a large roll. If you'd like a holiday gift, I would send you enough to get the job done :) PM me if you'd like some.
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4050.jpg
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4052.jpg

luthor
12-23-2010, 11:16 PM
That's fine Arthur, but has nothing to do with what the OP is asking.

Arthur.Marks
12-23-2010, 11:16 PM
Arthur and others, please look at the OP's sketch to understand what he is trying to do. For your information I have used boring heads on many types of milling and boring machines from 1/2 ton to 30 tons.

Then you know you will produce an oval hole when using a boring head with an out-of-tram headstock in the direction the OP mentions. :) ...or an ugly surface finish with a face mill as previously mentioned.

Arthur.Marks
12-23-2010, 11:20 PM
Doh! :rolleyes: I think we're both right! The OP's drawing indicates a tram that absolutely does not matter. Yet he used the term "nod" to indicate it---which is what my previous response would fix.

We need clarification! :D

luthor
12-23-2010, 11:21 PM
Do yourself a favour and look at and try to understand the original question and accompanying sketch's.

Arthur.Marks
12-23-2010, 11:25 PM
You are right in that whether the head is positioned like this:
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4053.jpg
or like this:
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4054.jpg
...has absolutely no bearing on the X,Y or Z axis movements of the machine.

Arthur.Marks
12-23-2010, 11:26 PM
BTW, this is not called "nod".

rode2rouen
12-23-2010, 11:27 PM
Arthur and others, please look at the OP's sketch to understand what he is trying to do.


Looks to me like he is trying to get the spindle centered with the column.
Please correct me if I am mistaken.


Rex

luthor
12-23-2010, 11:28 PM
You are right in that whether the head is positioned like this:
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4053.jpg
or like this:
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN4054.jpg
...has absolutely no bearing on the X,Y or Z axis movements of the machine.


Thank f--- for that.

71CJ5
12-23-2010, 11:31 PM
Looks to me like he is trying to get the spindle centered with the column.

Ding ding, we have a winner. Arthur's first pic shows what I would like to accomplish. The second pic is what I'm trying to avoid. Imagine the head tilted 45 degrees in the second picture...the endmill would not be happy cutting with the y-axis!

Sometimes its hard to type things out so its easily understood....pictures are worth a thousand words! ;)

Arthur.Marks
12-23-2010, 11:33 PM
Thank f--- for that.
You're welcome! :p I'm a little slow today.

rode2rouen
12-23-2010, 11:34 PM
Arthur's first pic shows what I would like to accomplish. The second pic is what I'm trying to avoid.


See post #9 for the "how to".


Rex

71CJ5
12-23-2010, 11:37 PM
See post #9 for the "how to".

One problem, I have no 1-2-3 blocks. I've been planning on getting a set for some time but just haven't gotten around to it.

I suppose I should mention that this is by no means precision work. Getting it close would work for me.

Arthur.Marks
12-23-2010, 11:39 PM
Imagine the head tilted 45 degrees in the second picture...the endmill would not be happy cutting with the y-axis!

Depends what you mean by "happy". As you move the head around the column, it is true that you lose some travel in the Y axis. Think about it, though... your Y axis will still be perpendicular to your X axis. Your Z axis will also not be changed in relation to the X or Y axis. You might lose a total of a couple thousandths travel in the Y if it isn't "perfectly" centered. I just do it by eye. Always have, and never encountered a problem.

luthor
12-23-2010, 11:39 PM
Deleted double post.

Arthur.Marks
12-23-2010, 11:45 PM
Unless... the real reason is you're perplexed on how to raise or lower the head and retain your exact position. That, my friend, is the point that plagues all of us round column owners! Various people have tried and documented different means. Myself, I just accept that failing in the design and try to plan accordingly by not changing the head's height in the middle of a job if at all possible.

rode2rouen
12-23-2010, 11:48 PM
One problem, I have no 1-2-3 blocks. I've been planning on getting a set for some time but just haven't gotten around to it.




Any pair of similar pieces of material would get you going. 1-2-3 blocks just popped into my head.

For that matter, a steel scale (visualize a 12" scale on the table with the 6" spot at the center of the table) attached with 2 sided tape, and a small drill bit mounted in a chuck would do the trick. You should easily be able to get within 1/64" of "dead nuts".


Rex

oldtiffie
12-24-2010, 12:53 AM
I'm having a little issue in determining how to properly tram the swivel of the head on a round column mill. This is the mill I have:

http://cdn7.grizzly.com/pics/jpeg500/g/g1126.jpg

As you can see the head tilts side to side but has no ability to "nod". I understand how to tram the tilt of the head to the table.

How do I verify that the head is perpendicular to the x-axis of the table when looked at from above. Below is a very rudimentary drawing of what I'm trying to accomplish. Thanks

http://i937.photobucket.com/albums/ad211/JKSebring96/Misc/Mill.jpg

If the milling head is trammed to the table the milling head quill spindle axis is at right angles to the table. The applies equally on a square column mill like this:
http://i200.photobucket.com/albums/aa294/oldtiffie/HF-45%20Mill%20misc/Mill_drill1.jpg

or the OP's round column mill - like this:
http://cdn7.grizzly.com/pics/jpeg500/g/g1126.jpg

It does not matter where the head is swung in an arc left/right on a round column mill or where the table is moved on "X" or "Y" on either type of mill.

Strictly speaking both types of columns should be square in "X" and "Y" to the table and the milling head quill spindle should be trammed as near as practicable in "X" and "Y" to the mill table.

If the column is not all that far out it really doesn't matter all that much mostly.

I tram my mills with the head "Z" slide/gibs clamped as well as the quill. That is my machining condition for milling on the table in "X" and "Y".

Tram your mill with those clamps on and then release them and you may be quite surprised how much tram error there is.

My columns are pretty good so I leave the column base and its bolts alone.

I adjust left/right error on my milling head head and lock it when it is OK. I use the same tilting mechanism to correct "nod" (in the "Y" direction) by shimming the tilting faces. Its quick and accurate and it works. I am careful to place my shims either side of the tilt clamping bolts.

If I had a round column mill and wanted to get the line at which the face of the tilting adjustment was parallel to the slots in the mill table (the slots are in "X") I would put a laser pointer - like this:

http://www.lasercenteredgefinder.com/

into my drill chuck, switch the laser on, pick up an edge of a tee-slot, clamp "X" and "Y", release the tilt clamps, swing the head left say 30 or 45 degrees, clamp tilt and see if the laser picks up the same edge of the tee-slot. If OK job nearly done. Swing head on column to adjust. Re-clamp column. Re-check at vertical and at 30 or 45 degrees left and right. Adjust as necessary. When the laser accurately picks up the edge of the tee-slot at centre (milling head vertical) and 45 or 30 degrees left and right, the plane and face of the tilting faces are parallel to the table tee-slot/s and assuming the mill "X" and "Y" slides are at right angles to each other the milling head tilt is normal to "Y".

But realistically, there is no real need for this procedure.

Just centre the milling head on the column, tram the head and get going.

There is a quick and quite accurate re-set for the swing of the milling head on the round column. I will cover that later if needs be.

darryl
12-24-2010, 02:16 AM
Hmm a big DUH on my part. I just now noticed 'looking down from the top'. Ok, so that's not tram like the title says, so I'm at least partially vindicated. Nod is going to be front/rear tilt of the column, part of tramming but no part of adjusting the point on the column where the head is swivelled to, except for the effect it will have if it's out. There isn't a position of the head on the column which will cancel any errors-

So you want a precisely 'straight ahead' position for the head- do you need to have a means of repeatedly being able to find this position? Say you move the head up or down and lose the positioning (pretty much guaranteed)- are you looking to 'get rid of' the head rotation about the column? I think that's at least part of what you're asking for- the ability to raise or lower the head without losing the left/right positioning. I'm guessing that the absolute position isn't critical, just that it 'stay in line'.

I need something like that on my mill. Some have suggested a keyway up the column- in theory that works, but in practice- not that well. You'd be able to keep relative position within some limits, but it will probably be too broad. One thou of play there will be five thou or more of play at the spindle, and one thou is going to be hard to achieve over the length of the key. What I'm thinking to do with mine is make up two collars that mount to the column, one goes at the top and the other at the bottom. From the collars, a plate goes out sideways and a rod is mounted parallel to the column and spaced away from it- lets say about eight inches or so. Think of a pair of connecting rods- the big end is clamped around the column and the small end is where the rod mounts. The rod has one or two bushings sliding on it, and some connecting arms go from the bushings to the side of the head- the fixed part that rides the column. If you loosen the collars, the head can swivel on the column, but if the collars are tight, the head can only go up or down.

In my case it would fit on the right side, since the crank handle is on the left. The bolts that secure the head on the column would still be accessible. The second column (the rod) would not have to be round- it could be any shape as long as it's stiff and you can make a guide ride on it closely. When you loosen the collars to allow rotation about the column, that guide has to stay parallel to the column, hence the need to have two bushings mounted off the side of the head base. When you swing the head, both bushings move with it, and the guide rod stays parallel.

You have nothing hanging off the back of your mill, so there's easily room for this mechanism. The hard part in your case, as I see it, is mounting some arms to the head base to go out to the bushings. Those arms will have to attach in a way or place that doesn't get flexed when you tighten the 'head bolts'. At the least you'll have to drill and tap some mounting holes.

I hope that's a little more 'on target'.

Ed P
12-24-2010, 08:50 AM
1. Place a piece of straight drill rod in spindle.

2. Rotate head 90 degress so that the drill rod is horizontal.

3. Place dial indicator on table and place its finger on the side of the drill rod.

4. Move table in X axis, adjust head until there is no movement of dial indicator.


Not sure how to get the spindle horizontal in step 2? Here's how:

1. Place spindle as close to 90 degrees as you can according to the scale.

2. Place dial indicator on table and touch the bottom or top of drill rod.

3. Move table so the dial indicator finger is touching near the end of drill rod and move table in Y axis and note highest reading.

4. Move table in X axis so that dial indicator finger is touching drill rod near the spindle. Move table in Y axis and note highest reading, should be the same as in step 3. Adjust as necessary.

Ed P

BillTodd
12-24-2010, 09:08 AM
That, my friend, is the point that plagues all of us round column owners! Various people have tried and documented different means.

A simple wishbone (http://billtodd.dyndns.org/drillmill) really does work...

oldtiffie
12-24-2010, 09:10 AM
1. Place a piece of straight drill rod in spindle.

2. Rotate head 90 degress so that the drill rod is horizontal.

3. Place dial indicator on table and place its finger on the side of the drill rod.

4. Move table in X axis, adjust head until there is no movement of dial indicator.


Not sure how to get the spindle horizontal in step 2? Here's how:

1. Place spindle as close to 90 degrees as you can according to the scale.

2. Place dial indicator on table and touch the bottom or top of drill rod.

3. Move table so the dial indicator finger is touching near the end of drill rod and move table in Y axis and note highest reading.

4. Move table in X axis so that dial indicator finger is touching drill rod near the spindle. Move table in Y axis and note highest reading, should be the same as in step 3. Adjust as necessary.

Ed P


Good advice Ed.

Best advice so far.

71CJ5
12-24-2010, 10:26 AM
Guys, I really appreciate the good advice!



1. Place a piece of straight drill rod in spindle.

2. Rotate head 90 degress so that the drill rod is horizontal.

3. Place dial indicator on table and place its finger on the side of the drill rod.

4. Move table in X axis, adjust head until there is no movement of dial indicator.


My plan of action is to use the above method to get the head aligned on the column and then lock it down. I then have a large outer race from a bearing that I will place on the table and sweep with the DTI. This should allow me to get the tilt zeroed out. Then I will align the vise to the table.

Once again I can't thank you all enough:cool:

luthor
12-24-2010, 06:34 PM
Guys, I really appreciate the good advice!




My plan of action is to use the above method to get the head aligned on the column and then lock it down. I then have a large outer race from a bearing that I will place on the table and sweep with the DTI. This should allow me to get the tilt zeroed out. Then I will align the vise to the table.

Once again I can't thank you all enough:cool:

Are you going to do this every time you move the head? You will soon get sick of doing it, can't you just measure the central position with a tape measure?

ligito
12-24-2010, 07:16 PM
Are you going to do this every time you move the head? You will soon get sick of doing it, can't you just measure the central position with a tape measure?

Wouldn't that reference move, when the table is moved?

ligito
12-24-2010, 07:18 PM
I'd like to mark my column and the collar, so I can have a ballpark reference, for starting a tram.

71CJ5
12-24-2010, 07:21 PM
Are you going to do this every time you move the head? You will soon get sick of doing it, can't you just measure the central position with a tape measure?

No not every time. I'll do it this time and then scribe a mark on the column and then on the head. This will get it close enough for 99% of the work I do.

71CJ5
12-24-2010, 07:39 PM
I was able to get some pictures today of what I'm doing. I want the head "centered" on the column so when I tilt the head 45* to side, I avoid cutting like this when moving the y-axis:
http://i937.photobucket.com/albums/ad211/JKSebring96/Misc/005-1.jpg

This is what I'm after:
http://i937.photobucket.com/albums/ad211/JKSebring96/Misc/008-2.jpg

darryl
12-24-2010, 08:48 PM
Here's another suggestion. Since you would have to make this adjustment every time you change the head position, you could make up some parts to help do it. One part is a reference surface you mount on the table. It lays across the table, front to back, and you key it to one of the t-slots so anytime you mount it, it will go on squarely. With this part made, you mill a bevel on one top edge, and that's it. You'd probably want to face the top edge as well, just for looks.

Second part is a disc with a stub on it that can be mounted in your mill spindle. It gets faced so the surface is true and at right angles to the spindle axis.

To use this setup- mount the first part on the table and the second part in the spindle. Set your head to the 45 degrees, or whatever it is you want. Loosen the head on the column, change the height so the jig on the table can come up against the disc in the spindle. You'll see instantly when the head is rotated properly on the column- you crank the x axis so the disc will contact the bevel on the jig, and when the head is adjusted til the disc makes full line contact- you're there.

The jig that you make for the table can be simply a piece of angle with one side faced to sit flush against the table. All the upright edge really needs is the bevel as the reference surface. I'll suggest about a 4x4 piece of angle, and long enough that it spans all the t-slots across the table. A pair of holes spaced for the outer slots gives a way to mount it securely, and either of the other slots can be used for the key.

This will solve your problem, and with the table jig being 4 inches high, you'll have some range of height over which you can adjust and secure the head on the column. Start by knowing at what height you want it for the machining operation you intend to do. It won't matter for adjustment purposes where the disc contacts the bevel on the jig- it will still let you see when the head is directly lined up with the table axis.

Ed P
12-25-2010, 07:36 AM
Are you going to do this every time you move the head? You will soon get sick of doing it, can't you just measure the central position with a tape measure?

What about permanently mounting one of those cheap little laser lights on the the head? If the light shines across the room at a piece of paper on the wall with a vertical line drawn on it that should be a quick and easy and accurate way to realign the head next time. It won't matter which wall, just as long as it is a couple of feet at least from the milling head.

Ed P

atty
12-25-2010, 12:07 PM
That's one hell of an idea, Ed. Simplicity at its finest, plus a reasonable degree of accuracy.

I raided the cat toy drawer and found one. Temporarily duct taped it to the side of the mill head and shot it 20' to a very convenient, white garage door. At that distance the very slightest movement is clearly indicated on the door.

No offense to Bill and his wishbones, but this is much simpler and serves the purpose very well.

Good thinking, sir. I thank you.