[zerodegreec]

Tramming my head and found that I need to tilt the head back 0.1mm. I was thinking that the best way would be to shim the column at the base. Or is there another way to zero the error? I don't have any proper shims but was thinking I could use Tinfoil.

[HawkJET]

Tramming my head and found that I need to tilt the head back 0.1mm.

You should only shim the column if the column is not vertical. If the column is vertical and the head needs to be tilted, shimming the column may solve the head, but it will make the column no longer vertical.

[zerodegreec]

Thanks, Some times you need to step back for a min before you go down the wrong road. I ran my indicator down the edge of my 6" square that I clamped to my table. Then ran the head up and down the square and the column is dead nuts level.

Then I put the indicator on my spindle and rotated around the table. Front to back has a 0.2mm difference. Leading me to believe its the head that needs to "tilt" back 0.1mm to correct the error.

[zerodegreec]

Solved! The screws holding the gear cover plate were ever so slightly raised and keeping the head from seating properly...

[zerodegreec]

*UPDATE*
Just wanted to update this thread if someone comes across this later with the same problems I HAD

Had some more problems getting the mill trammed in properly (was for lack of a better word leaning forward). I tore the mill down to the base and column... EVERYTHING was pulled apart.

I found the column is in fact vertical. My problem was with the head and not in the column. So I looked at the head and the way it bolts to the Z axis.
What I found was the bottom bolt that "locks" the head from rotating was actually pulling the head down in relation to the Z axis and this was giving me the error.

When I got my mill in the "tool box" was 2 extra T-Bolts that for the life of me I could not figure out where they were intended. When I took the head off the Z slide I figured it out... they were the exact match to the bottom "locking" bolt.

So with the head on my workbench I drilled two new holes for the bolts so that when I tighten down the head it gets pulled equally to the Z slide and is now 100% true to the Z axis.

Problem solved :banana:

Only issue I came up to in the mod was the light mounted in the head. Well it wont fit with the new bolts... Oh well, I will take a 100% squared head over the POS light. I guess I will have to find a new mounting location.

I guess the factory thought that a light was more important than the ability to properly tram the mill.

[hoss2006]

That's what machinechick did too.

http://www.cnczone.com/forums/744780-post313.html

I have the bolts in my toolbox too, it's like maybe they intended to make it use 3 bolts in the beginning
but then some money miser said 1 hole is good enough, screw em.
Hoss

[zerodegreec]

Nice. At least this is good proof that the problem I had is not unique. This obviously is a required Mod for these mills.

[hoss2006]

Yeah, at least they gave us the bolts, wonder if anyone with a mill from other suppliers got them.
We should all definitely do this one.
Hoss

[arizonavideo]

Well it looks like my Weiss 30LV has some extra bolts too.

I thought they were to mount something to the table but I guess not.



I just use it for light stuff but some holes are in the future.

[photomankc]

Oh yeah, they are going on mine too when I take the head down to CNC the Z axis. Going to be my excuse to get a real drill press! I know, I know, it's not required for this but damn it, that's how I'm justifying it!

[zerodegreec]

Found a solution to the light. I picked up a 12v 20watt directional pot light at Home Depot this afternoon for $19. Put a good strong magnet on it and wired it up. Now I get a better light source that's not buried in the bowels of the head. And where I need it. Of course I can still access the head bolts just by giving it a pull...

[hoss2006]

Grizzly intended these T-bolts to be for a vise and such but I think you've found
the best use for them.:cheers:
That's where mine are going now.
Hoss

[arizonavideo]

Hey how come mine didn't come with a light?

I hope I don't start a three page rand about bolts but I don't know if the T bolts are really for mounting things to the table. The heads are so small that they rotate in the slots and they are so long that any vice that would fit the table will have the work hit the bolts.

They do look to be exactly like the bolt on the collar.

Zerodegreec, were the extra T bolts exactly like the ones in the collar?

[hoss2006]

I don't know if the T bolts are really for mounting things to the table. The heads are so small that they rotate in the slots and they are so long that any vice that would fit the table will have the work hit the bolts.

They do look to be exactly like the bolt on the collar.

I gotta agree with you there, they are pretty useless on the g0704 too as table t-bolts.
The size given in the manual matches the bolts but they should rethink the description.
Hoss

[zerodegreec]

Zerodegreec, were the extra T bolts exactly like the ones in the collar?

They were exactly the same. Only thing was the 2 extras had thin washers and the one mounted in the head had a hefty washer and lock washer.

But the bolts were 100% matches.

[archiebald]

I had my quite new BF20L roughly trammed in for some practise work but now decided to tram it in really on the nuts. Here is my experience.

In my rough tramming I had noted that the head seemed to be drooping forward a little but my mill only had the one bolt fitted. So, thinking logically and listening to other's, the first thing was to make the three hole mod. Thanks to Hoss's video and those that inspired him this was an easy one hour mod with a hand drill. In my case, I had no problem with the lamp fitting causing any conflict with the upper two bolts.

1. From there I followed the steps in Hoss's tramming videos, i.e.
First check the head to the column left-right
In principle this is easy but let me just say this - some say that two tramming aids for the head are nice to have (originally only one fitted), but in my opinion they are essential. Makes an annoying little job into a dead simple job.

2. Next, check the head to column front-back alignment.
So now I am thinking the droop will be improved by the three hole mod...wrong!! I measured with the top bolts fully tight and fully loose and it made absolutely zero difference to the tramming - don't let anyone make you think otherwise. Of course it should help a little with rigidity and keeping the head in place but take it from me, it will not correct any front-back tramming issues. On a 200mm test bar the tip was 0.1mm closer to the column that the top (just below the spindle)
So, I tried adding some shim between head and column just below the bottom bolt. Initially I over corrected the situation, but reducing the shim brought me within about 0.03mm (about 0.0008") between top and bottom.
Just want to add that you need to be careful where the shim is placed as I found that as the bolts are tightened, it can distort the head carrier slide so that it tightens up in the dovetails.

3. Check column/head to table side to side.
Slight tap here and there with a mallet and all is good. Very easy.

4. Check column/head to table front to back
Now I find that the column appears to be leaning back. It appears that if I took out the shim between head/column then it would zero out this difference, but if I did this then it means that when lifting the head up down, the head would not be tracking perfectly vertically, even though the quill would be moving in the vertical plain. What would be happening is that the spindle axis of rotation would move toward the front of the table as the Z slide is lowered. It may not be much and would only be noticeable when boring deeper than the quill stroke allows for, but I don't like it. More investigation is required...

This might be difficult to visualize so I attached a hand drawn sketch.

I will be taking my head off again to see if there is anything on the mating faces causing an issue such as the gear cover screws mentioned by zerodegreec.

[archiebald]

Okay, so I now have my BF20L perfectly trammed in. Here is what I found.

There was no problem with the gear cover screws holding the head off the slide base. Also checked for any burrs or bruising on mating surfaces and none were found. Also, as already mentioned, the uppper two bolts made zero difference to head droop when they are fully tight or fully loose. However, tightening the gib locks can make a significant difference even if you have the gibs adjusted really snug as possible without binding.

So, there were no errors and the only way to get alignment was to insert a piece of 0.2mm shim right under the lower fixing bolt. This allowed me to get within 0.01mm when running up and down a 200mm test bar in a collet.

Next, looking at the column to base alignment, the column needed 0.05mm shim at the bottom to make the column lean forward a little.

Now, a full sweep my DTI shows lessthan 0.01mm error. Actually around 0.008mm I reckon. Quite happy now!