How do you ensure the milling head is parallel with the table?

Hi all,

Just wondering, on my Bridgeport mill the head can rotate. How do you ensure that the markings on the machine are actually correct.

What I mean here is that I understand how to tram the vice with reference to the head, in each axis.

How are we sure, how do we measure the squareness of the head to the table?

Many thanks in anticipation of many quick replies

Like your comments on another thread, please do not expect instant answers to your many questions at 11.28 pm, it will likely only lead to your disappointment again.

If nothing else, the people that have to get up and go to work tomorrow are probably already in bed and won't be around until tomorrow evening

You can buy tramming plates but personally I would not bother, the best way is use a clock/dial gauge mounted on the spindle with a chuck, collet whichever you choose. Use a bar that will give your gauge around a 6" radius form centre - not an important size -- then swing the spindle through 180 deg using a suitable V block or parallel between the gauge probe and the table. Move the head until zero - zero.
John

You tram a mill twith a dial indicator mounted on an offset extension arm fitted to the spindle and sweep the surface of the table by turning the spindle by hand taking readings every 90 deg of spindle rotation with zero deg being along the x axis centreline so 0, 90 . 180 & 270 deg , if you look up tramming a mill on youtube you will find a million videos on it .

People are not reading correctly my initial post, how do you ensure that the head is 90 degrees to the table?

Edited By Mexican jon on 02/11/2017 23:55:36

What I mean is how do you ensure that the ram and head are 90 degrees to the table.

When we tram our vice for example we adjust it to be in line with the spindle/head

My question is how do we ensure that the table is 90 degrees to the head? Not the Vice!

Or perhaps it is irrevelent, if the table clocks square then thats all that counts?

Gary

The markings on the machine are simply that, just markings. Do as JF & XD told you quite clearly. When the same readings are indicated on both sides of the axis, the head must be perpendicular in that plane. Simple as that.

I guess I have thought through my own answer here, I guess that if you belive the table is square to the saddle by measuring, that you measure the table and align it with the spindle, the vice then that is tramed is irrelevantt as to its position on the table as long as you tram it sure. Does that make sense?

Gary

It will be much clearer if you watch one of the many videos on tramming that are on youtube , a channel called thatlazymachinsts will enlighten you on many aspects of mill set up and metalwork in general .

Gary, it's not so much the table at 90 degrees to the head, as setting the head at 90 degrees to the table, since it's the head angle which is adjustable..

Rather than repeating my previous typings her, may I refer you to my post on this older thread, and in particular to the link I posted there.

It can all be done with one clock gauge, but it's a bit of a pain setting up trying to see the face of the gauge when you've rotated the spindle through 180 degrees.

This solution makes it quick and easy when the device is made, and the clocks are cheap enough from China via ebay.

If you only have the one clock available in the short term, make up an arm to suit and have a look on ebay for a cheap car brake disk for the moving foot of the gauge to slide on, (or a sheet of glass would do as well)

Bil

Thes days i use one of those tramming tools from edge technology and find life is much easier and quicker , you cam make your own version easily enough .

Some use a new brake rotor sitting in the top of the table and sweep the top ground disk surface , this averages out any imperfections or damge on the table , i use two thick parallels to straddle the table top as my table has a small section that is around .0002 low .

From the replies I am not explaining my question correctly.

I want to locate the head correct in the Y axis with ref to the X axis.

SO to conclude I assume that if I believe the measurements I take as to the alignment with the x and y axis are correct with reference to themselves, I can simply run a indicator across the rear surface of the table with reference to the spindle?

Gary

SO to conclude I assume that if I believe the measurements I take as to the alignment with the x and y axis are correct with reference to themselves, I can simply run a indicator across the rear surface of the table with reference to the spindle?

Sorry, but wrong again. The table could be perfectly level and the head at a rediculous angle and the indicator would not change. Try it.

Ok i think i may be beginning to understand what you are asking

On a bridgeport you can swing the entire head and column left or right or offset it in regards the y axis centreline and you want to get it back on centre ?

If so the graduations on the column/ base would be accurate enough to do the job and even if the head was set up so the centreline of the spindle was not directly lined up with the centreline of the y axis it won't affect how the machine operates .

With a bridgeport you can tilt the head left or right and nod it up or down so when you mention the word "tram" that is what most people think of and getting the spindle centreline perpendicular to the table surface in the x& y axis .

Edited By XD 351 on 03/11/2017 07:05:30

To check that the spindle axis is parallel to the table, mount a round bar in the spindle and a dial indicator on the table.

As you move the table/indicator under the bar it should read the same distance, assuming that the bar is straight and concentric with the spindle. (to check slowly rotate the spindle and the reading should repain the same).

Paul.

The OP will need to get his "truing" technique sorted, Bridgeports are notorious for shifting there heads!

John

A lot of people think they are a big heavy industrial machine but they were designed for tool and die makers , the more adjustments or the abillity to adjust the machine components to suit different angles the more chance there is for something to move .that being said i don't know of anyone that wouldn't like to own one - me included!

+1

Versatile, but not the most rigid of machines.

To tram the head in X & Y I use a DTI and four parallels as per JohnF.

Andrew

If the need is to rotate the ram assembly in the xy plane then clamp a suitably sized engineers square (in good condition of course) to the table. Move the table along the x axis to set the square correctly. Then with the indicator on the ram move the ram along the y axis and adjust the rotation of the ram assembly in the xy plane until the indicator shows the ram is running parallel to the y axis.

Martin C