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Tramming Vertical Mill with Articulated Arm question

Joined
May 27, 2009
Location
Leland, NC USA
I am having a difficult time trying to understand how I am supposed to get the rod that goes into my collet to be perfectly straight with the rotational coupler and then to have that extend out in a 90" angle (probably does not matter on that part).

Out of all of the materials and bits and parts I have, I do not have what I feel is a accurate way to tram the spindle of the vertical mill. I am not a professional as of yet but I am working on it as fast as I can. This is a manual mill with a long bed and knee for the Z.

I am attaching photos if anyone can help me so I can start cutting some plastic injection molds for my wife. I have Mitutoyo Digital Dial Gauges, standard analog and several test dial indicators 0.0005" jeweled gauges. I do have a nice Noga magnetic base with the fine adjustment as well if this helps. Thank you for any advice.IMG_6969.jpgIMG_6968.jpg
 
It is unimportant that the indicator arm and body be inline with the spindle. Does not matter at all. To real a mill literally all you need to do is hold an indicator in the spindle.

I find indicating over parallels or better a big ring and only working one axis at a time are very helpful. You don't want the tip to bump badly as it goes over the t slots.
 
You do it just like you have it shown. I put a 123 block under the tip vs letting it ride on the table. Zero on the left, swing to the other side and adjust until the indicator reads half the error. Should only take a couple of tries to get within .001.

It’s faster when you adjust the nod to zero the indicator at the back of the table then come to the front and adjust the nod until the indicator is zero again. Each time will ~halve the error.
 
Ok ... going back outside to give it a go if my full stomach will let me 😂. I hope everyone had a great Thanksgiving Day. I guess I need to get some Allen’s and really lock the knurled knobs down or else it is really out of tram and the guy I bought it from saw sucker on my forehead. Also, are there any good links here to a 3 point leveling for the base instead of just sitting it on the concrete? I read that having the back two corners used as support points and a round stock for the middle front is the best but I am having a hard time believing it. I guess the shimming really comes down to the back to support points. Thank you so much for the fast replies
 
Lately I have been getting jobs where it is easiest to tilt the head of my mill, so I have been tramming the head in a lot.
I bought a Pro Tram from Edge Technologies about a month ago.
After using it the first few times, it only takes me about 2 mins to tram the head back in.
pro_tram_by_edge_technology_bridgeport_milling_machine_angle__08115_1391121124_600_650.jpg
 
...I bought a Pro Tram from Edge Technologies about a month ago.
After using it the first few times, it only takes me about 2 mins to tram the head back in...
View attachment 271273

I bought one of those a couple years ago and it sure makes tramming the mill a lot easier. I love it!

I never liked the idea of using something--brake drum, 1-2-3 block, gauge block, whatever--between
the indicator and the table. There's got to be some introduced error in there somewhere. Before I got
the Edge tool I trammed directly on the table and used a back plunger indicator with a big round button
for the contact point. You can set it so the button skips over the slots in the table without catching on
them...
 

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Lately I have been getting jobs where it is easiest to tilt the head of my mill, so I have been tramming the head in a lot.
I bought a Pro Tram from Edge Technologies about a month ago.
After using it the first few times, it only takes me about 2 mins to tram the head back in.
View attachment 271273

.
double indicator is much faster.
.
and if you zero both to back side of table on a vertical mill raise up and check plate sticking up 1" out of mill vise you can check and or set vise jaw parallel to table literally in seconds too.
 
What others have already posted is correct and the use of a "double" indicator is a personal choice, what you're using is already quite acceptable. I only wanted to point out that you needn't drive yourself nuts striving for .0005 total difference from one side to the other. It's a knee mill, not a jig bore/grinder and working to .0001's is neither possible nor practical. Tram the head to an acceptable level of accuracy per the work you're doing. If the side to side difference is +/- .003 you're .003 out of being perpendicular. If the distance swung (arm length) is 3 inches you've swung a 6" circle. That .003 you're out over 6" means you're out .0005 per inch. That's fine for most general work anyway per the cutting length of the end mill your using. I only used those numbers as an example. When doing work beyond general milling you always want to check/verify your tram settings before you begin a fussy operation anyway because sometimes the head will change from heavy cuts and/or knee position. You're doing fine just don't drive yourself to seek accuracy greater than most used knee mills can give you (+/- .0025). JMO
 
In my opinion the double indicators are not a good setup as they degrade the accuracy compared to a single indicator. The “nod” is the most tricky part and for me it helps to extend the quill and mount my Noga stand to the table and crank the table up and down to indicate the quill for being square. You can’t adjust the y by splitting the indicator reading like you can on the x. Once you get your head wrapped around the offset pivot effect it can be pretty quick. Always sneak up on the correct setting from one side so the backlash and static friction don’t send you to the nut house ;-)
 
You can actually tram the nod just like the tilt, you just have to figure out the ratio due to the offset. So if your nod trams out .010, say, because of the offset (that moves both sides of the indicator tram in the same direction at different ratios) you may need to move the indicator something like .012" rather than .005". You can calculate this pretty easily by taking into account the distance from the pivot to spindle CL and how far from center your tram reaches. Takes a lot longer to type than to calculate.
 
Your setup is entirely adequate for tramming the mill. I keep my indicator point above the table and slip a parallel under the point to gt my reading. If the indicator point touches the table there is a possibility its setting will be disturbed when rotating across a T slot.
 
Thank you to everyone for the advice and knowledge. I am a glutton for punishment so last night I printed a dual gauge traming device and I was going to put the Mitutoyo digitalis in and realized that would be too number memory so I went with cheap dials instead. The punishment is that the .stl I used printer a 20.22mm shaft for the collet and my collets are SAE.
So now my 3/4” is too small and the 7/8” too loose. Now to turn the 22.22mm down to something like 0.750” 😂🧐😥. I am going whole hog. After getting the left and right dead on the nose the front to back is off so now I am going to take my time, three point mount the base, use the 8” machinists level and get the base to table as close to perfect and then wrestle with the nods. Thank you again!
 
What others have already posted is correct and the use of a "double" indicator is a personal choice, what you're using is already quite acceptable. I only wanted to point out that you needn't drive yourself nuts striving for .0005 total difference from one side to the other. It's a knee mill, not a jig bore/grinder and working to .0001's is neither possible nor practical. Tram the head to an acceptable level of accuracy per the work you're doing. If the side to side difference is +/- .003 you're .003 out of being perpendicular. If the distance swung (arm length) is 3 inches you've swung a 6" circle. That .003 you're out over 6" means you're out .0005 per inch. That's fine for most general work anyway per the cutting length of the end mill your using. I only used those numbers as an example. When doing work beyond general milling you always want to check/verify your tram settings before you begin a fussy operation anyway because sometimes the head will change from heavy cuts and/or knee position. You're doing fine just don't drive yourself to seek accuracy greater than most used knee mills can give you (+/- .0025). JMO

2 and a half to 3 out will show concave cuts in the cut direction and steps in the traversed direction. Always tram to as close as you can get to 0/0.
 
Double Indicators

2 and a half to 3 out will show concave cuts in the cut direction and steps in the traversed direction. Always tram to as close as you can get to 0/0.

TO NC RICK Using the double indicators you can check the tram with one of the indicators when you are done by rotating the spindle a half turn. Adjusting the nod is where they really shine.
 
TO NC RICK Using the double indicators you can check the tram with one of the indicators when you are done by rotating the spindle a half turn. Adjusting the nod is where they really shine.

I think the double indicator deal is great. The first time I used one I felt like a regard for a minute or two though lol.

Years ago I made a 409ss plate that I use to tram my head, it's ground flat and parallel to a few tenths and it can fit inbetween a Kurt 6" all the way open if I need a quick check.
 
2 and a half to 3 out will show concave cuts in the cut direction and steps in the traversed direction. Always tram to as close as you can get to 0/0.

-It would if using a fly cutter or large face mill to "deck" the thickness of a plate, it wouldn't if using the side of an end mill to square up a plate. I posted numbers as an example to set tram per how much of a given cutter is modifying the material. The OP was asking questions that suggest being rather new to setting the head with a DTI. I don't feel that the head of a mill "always" has to be set as close to 0/0 as possible if not needed. I feel the OP can decide when/where it's important to get as close to 0/0 as possible. Chasing 0/0 when not needed is chasing the unnecessary. It's about being a Practical Machinist rather than encouraging compulsive habits that add no value. You work your way, I'll work mine, the OP can/should learn to work his/her way too. Your assertion of concave/steps is correct in one type of milling but not always. JMO.
 
In my opinion the double indicators are not a good setup as they degrade the accuracy compared to a single indicator. The “nod” is the most tricky part and for me it helps to extend the quill and mount my Noga stand to the table and crank the table up and down to indicate the quill for being square. You can’t adjust the y by splitting the indicator reading like you can on the x. Once you get your head wrapped around the offset pivot effect it can be pretty quick. Always sneak up on the correct setting from one side so the backlash and static friction don’t send you to the nut house ;-)

.
double indicator works 10x faster as you adj tram you aim for same number on both indicators. final check you just use one indicator if really concerned about <.001", never had any problems getting to <.001" both X and Y and then use to check mill vise, literally use and check tram and vise both in less than 1 minute normally to confirm everything ok
.
also I mounted a spirit level like from cheap combination square. when going from 45 deg to 0 its 10x faster to get level close before looking at indicators. not seen in picture cause picture is old
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type shown are zeroed to same spot, you rotate and bring each indicator to same spot and zero each one indicator at a time. been using many decades without problems. now a days dont have to make as they sell them already made reasonably priced. smaller one is obviously more useful on smaller machines
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many a time I have seen head go out of tram when roughing and its vibrating bad especially if end mill breaks that 3/8 or bigger. thats why I check tram often usually each day as it only takes a minute if everything ok, to adjust it takes maybe 2 minutes at most normally to do tram AND mill vise. for vise usually zero to back of table, never had problems. <.001 just final check with one indicator. literally it takes longer talking about it than to actually do it
 

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-It would if using a fly cutter or large face mill to "deck" the thickness of a plate, it wouldn't if using the side of an end mill to square up a plate. I posted numbers as an example to set tram per how much of a given cutter is modifying the material. The OP was asking questions that suggest being rather new to setting the head with a DTI. I don't feel that the head of a mill "always" has to be set as close to 0/0 as possible if not needed. I feel the OP can decide when/where it's important to get as close to 0/0 as possible. Chasing 0/0 when not needed is chasing the unnecessary. It's about being a Practical Machinist rather than encouraging compulsive habits that add no value. You work your way, I'll work mine, the OP can/should learn to work his/her way too. Your assertion of concave/steps is correct in one type of milling but not always. JMO.

Any cutter that you use on the face of the work piece will show what I described. Why are you trying to give bad info to this guy. If you are ok with it out 3 thou why even bother tramming the head in the first place? Peripheral milliing out of tram will induce taper into the part, more noticable with longer cutters. And if using a cutter to make multiple peripheral cuts you will, again, get ridges.
 
What others have already posted is correct and the use of a "double" indicator is a personal choice, what you're using is already quite acceptable. I only wanted to point out that you needn't drive yourself nuts striving for .0005 total difference from one side to the other. It's a knee mill, not a jig bore/grinder and working to .0001's is neither possible nor practical. Tram the head to an acceptable level of accuracy per the work you're doing. If the side to side difference is +/- .003 you're .003 out of being perpendicular. If the distance swung (arm length) is 3 inches you've swung a 6" circle. That .003 you're out over 6" means you're out .0005 per inch. That's fine for most general work anyway per the cutting length of the end mill your using. I only used those numbers as an example. When doing work beyond general milling you always want to check/verify your tram settings before you begin a fussy operation anyway because sometimes the head will change from heavy cuts and/or knee position. You're doing fine just don't drive yourself to seek accuracy greater than most used knee mills can give you (+/- .0025). JMO

If you are using the quill you will find that .003 tilt moves the cutter a fair ways between quill up and down. I have a 7" diameter tapered roller bearing race that I lay on the table as a track for my indicator. I lower the table and tram with the quill down as this magnifies any error in tram. If the head has been tilted I rough it in with a 9" B&S machinists square before traming. You would be amazed how close you can get it with a square.
 
Yeah .003" is excessive. I usually shoot for less than .001" even on non-fussy work. It doesn't take but a minute.

Now there is a case for intentionally leaving the tram out a bit but that's for special cases. I used to do it on big 90° heads when we were fly cutting interior pockets on the big HBMs, using a big turntable with a slide to cut 18" or so rectangular pockets 8 feet long. Tramming at zero usually produced unsightly steps in the blend of cutter overlap. A couple thou out of tram in the right direction across a 12" cutter head solved that problem nicely.
 








 
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