Yes, another Tramming Question!

[Bison9]

Hey All! I am finally to the tramming stage of this mini mill!

I basically took a Harbor Freight X2 Clone (model 44991) mini mill and fit it to the LMS solid kit.. The thing is awesome (See this thread about this: Does the LMS solid column conversion kit make a big difference?).

Ok, so I am first tramming the spindle to the table... I made a nice bracket for my Dial Indicator and it works very well.

I measured at the furthest point to the right side of the table, zeroed the dial indicator, and then swept to the far left side of the table. I was out -.004 in my initial measurement here. So... Based on all the articles I have read out there, I placed a shim HALF this size (so, .002) on the right side of the base (as the solid column kit removes the swivel base of the X2 so it has to be shimmed to square it up). Because I had to basically unbolt the column to put the shim in, I just started the process over again the same exact way. I was off -.002 this time... So, I just put a .004" shim on the right side of the column this time. I do a fresh test and I am pretty much zeroed out....

So... I basically put a shim in that was the same size as the amount I was out of tram on my initial measurement...

Did I do this even remotely correct here??? I don't get the whole "adjust it half the distance you are out" idea here that I have been reading about online... This is totally not my experience here for this.

Any feedback on this would be greatly appreciated!

I have poured literally hours into research and setup of this mini mill and I am so close to making the first chips of my life as a hobbyist machinist!

Thanks in advance for the help!

 

[bazmak]

Hi,if the distance between bolt centres is say 200mm and the difference
between the tram points is also 200mm then shim by the amount out
if the tram centres are 400 then shim half the amount
Its just proportional.Hopes this makes things clear.Regards barry

 

[Swifty]

First thoughts, exactly what Barry said. Also watch the dial indicator as you tighten the bolts.

Paul.

 

[Bison9]

Hi,if the distance between bolt centres is say 200mm and the difference
between the tram points is also 200mm then shim by the amount out
if the tram centres are 400 then shim half the amount
Its just proportional.Hopes this makes things clear.Regards barry

Here's my whole problem with this: So, my "sweep" was initially out to the far ends of the table (so close to 15 inches apart total - meaning 7.5 inches from the spindle on each side). I then took a way tighter sweep at about the distance of the bolts... It seemed that I was off about the same amount in both measurements (which made me scratch my head a lot then...).

Once I shimmed the .004, I was zeroed out in both cases above....

 

[Justmental]

i have fitted a plate to the base of my column and have no more problems with vibration when using a boring tool.
i am about to make a plate so i can fix the top of the column to the wall so it can't flex backwards if putting pressure on it when drilling.
the one thing i have noticed is when tramming along the bed it was 004 thou higher on the left side. but with a vice in the
centre of the table and a piece of aluminium clamped in it 240mm long 85mm wide i get it within 002 thou
but was more front to back but have no found it is lifting in the vice as the plate on the sliding jaw is loose.
it is with in 0005 thou front to back over 100mmm

 

[bazmak]

The way the m/cs are designed and built means you will get a small amount of flex.At the wide extremes you will also get flex in your dial holder
If you are out 2 thou at 100 rad you will be out 4 thou at 200 rad
laws of mathematics.Any variation to these rules is flex.I personally
would tram at halfway point table ctre (spindle) and rad 1/4 of table length
Say on a 100mm rad.Over that dim i would aim for less than 1 thou.Dont for get that the y axis is still proportional but because the spindle is forward of the
fixing bolts it is similar to calculating CofG.I would use feeler gauges as trial and error to get it right then use permanent shims.It will never be perfect and it will never stay perfect. Regards barry