G0704 Tramming

[BallisticArmsCo]

Im trying to get my head trammed to the column and i have the left to right set but i cant get the front to back. Using HOSS's tramming technique i zero the DTI on a 3/4 rod, but when i raise the head its at -.005. Is this normal? I drilled and tapped 2 tramming aid holes in the bottom of the head but it moves everything. Any help would be appreciated.

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[archistrong]

Couple of quick questions.

Is your DTI attached to the table or to the column?

If after adjusting the column with the set screw setup that Hoss came up with you are not seeing the head tramming out in the Y axis you might have an issue with the ways on your Z Axis. If the dovetails of the Z Axis were improperly machined you might see this error. One way to isolate this is to attach the DTI to your column rather than the table. This helps to isolate the error to just the column and saddle. If you still have the error with this setup then the geometry may be changing as the head moves up the column.

.005" is a pretty small error for these Chinese mills and could be cleaned up with careful scraping. I ran into a similar issue on my G0704 which had an unfinished section of the column (about 5") which resulted in massive errors as I approached the extremes of head travel and would even jam the saddle if it went too high.



I got in touch with Grizzly and they have decided to warranty the entire mill so I'm still waiting on the replacement.

If the error goes away when you are measuring with the column as your basis then the issue might be with your column / base connection. This adjustment (either with Hoss' set screws or shims) is pretty finicky. Keep at it and you can eventually tram it out.

Hope this helps.

[Fastest1]

Tramming takes patience. No doubt about it.

[BallisticArmsCo]

Let me preface this by saying im not a machinist or very familiar with this process other than browsing the forum, reading a couple of books, and spending too much time on youtube.

The DTI is coming off the column with the tip resting on the front side of the rod. At first it was around -.007 but i adjusted the z-axis gib as much as possible. It is reading +/- .0005 with the head lowered, i zero that and raise the head and it reads -.005 when i rotate the spindle it moves from -.005 to -.0035. Its not the tramming aids on the side of the head. I made 2 aids on either side of the lower bolt through the back of the head against the saddle. I guess i need to examine my ways closer, if im missing something here let me know. thanks

[Connor]

Couple more questions. How high are you reasoning the Z? The Rod, how accurate is it?

[BallisticArmsCo]

Couple more questions. How high are you reasoning the Z? The Rod, how accurate is it?

from the 6 1/2 to the 11 marks on the column. This is the rod that im using O1 Tool Steel Round Rod, Precision Ground, Annealed, 0.75" Diameter, 36" Length: Steel Metal Raw Materials: Amazon.com: Industrial & Scientific.

[Wiggles84]

To me, it sounds like the head is out of tram, between the head and the Z saddle.

I can't remember if Hoss has any aid's to adjust this. might have to use shims.

Andrew

[archistrong]

To me, it sounds like the head is out of tram, between the head and the Z saddle.

I can't remember if Hoss has any aid's to adjust this. might have to use shims.

Andrew

Could be. Does the dial indicator uniformly creep up from .0005" to .005" or does it consistently stay at .0005" and then jump up to .005" towards the very end of travel. If the value is slowly creeping up as you move the head I would agree that the issue probably lies with the head / saddle rather than with the saddle / column.

If the spindle (and subsequently head) is not parallel with the face of the saddle you will have to use shim stock between the head and saddle to bring them parallel. This can happen if the factory did not properly machine the back of the mill head and face of the saddle to be exactly parallel. In very basic terms, if the tip of your precision dowel is angled towards the column you would add shims to the bottom of the head between the head and saddle. Conversely, if the dowel is angled away from the column you would shim the top of the head / saddle area.

If you find that the value on your DTI stays consistent but then jumps up in value on your at towards the end of travel it might indicate an issue with the column or dovetails themselves. I know this is a lot of "if's" but I hope this helps.

CJ

[BallisticArmsCo]

Its a steady decline once the head starts moving up. I didn't get a chance to take a look at the machine yesterday but i will try to get some pictures tonight.

[vertcnc]

I think there is many ways to tram this import machines. They method that worked for me was to use a cylindrical square standing on the table with indicator mounted n spindle. Move the head up and down and measure if the column is tilted front to back or side to side. In my case it was both and shimmed under column to bring it true to table then re-torque bolts. This may take several hours on your first go around. After you have the column square to the table then swing indicate with the indicator in the spindle and rotate the spindle 360 around the table and determine if the head is nodding or tilted to one side or the other. Tilting side to side is the easy fix, just rotate head. If the head is nodding you would need to shim the head at connection to column plate. Patience is the key. Just have to break it down into smaller segments and go one step at a time.I have mine within .0005-.001 in the machining envelope that is normally used.