Accurately setting up z axis cuts

[Ngray]

So I am no machinist, far from it. My new X2 is my first mill. One of the things that I am trying to figure out right now how to take accurate cuts off of the top plane of a simple pie e of stock that I am squaring.

My process goes like this lower the head using the large feed wheel and engage the fine downfeed when the cutter is close. When I have touched off make a note on the fine downfeed and what position my z-axis's is at.

Back my work away from the cutter, twist the fine downfeed, and allow the head to lower down by the appropriate amount and then lock in the z-axis.

however, there is about 20 thousandths of backlash in the fine downfeed, and TONS of stick-slip in the z-axis travel.

How do I make this work?

 

[Dataporter]

I guess the entire head of your machine goes up and down and there is no quill per se? In any event,
you will probably need a dial indicator or a little DRO quill scale to have any prayer of being able to make anything close to fine adjustments. This is a picture of what I'm talking about when I say quill scale


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[Ngray]

After thinking about it, I got all the cosmoline off, and put a little machine oil on it, but I never took it apart. Is it worth taking the head off the gibs and reallly cleaning it out well, and re-oiling?

 

[Walt]

So I am no machinist, far from it. My new X2 is my first mill. One of the things that I am trying to figure out right now how to take accurate cuts off of the top plane of a simple pie e of stock that I am squaring.

My process goes like this lower the head using the large feed wheel and engage the fine downfeed when the cutter is close. When I have touched off make a note on the fine downfeed and what position my z-axis's is at.

Back my work away from the cutter, twist the fine downfeed, and allow the head to lower down by the appropriate amount and then lock in the z-axis.

however, there is about 20 thousandths of backlash in the fine downfeed, and TONS of stick-slip in the z-axis travel.

How do I make this work?

With your current equipment, the conventional wisdom is to always set your z-axis by raising the head. As you have found out, that's difficult to do when touching off to characterize the cutter. The way I have been dealing with the issue is to leave the gib adjustment a bit on the tight side and to always use the gib lock. Having an electronic scale on the z-axis helps take the guesswork out.

A gas support strut from Little Machine Shop would be better than leaving the gibs tight, I'm probably wearing them more than necessary.

http://www.littlemachineshop.com/products/product_view.php?ProductID=4005&category=

Walt

 

[timbertoes]

The expense and trouble of adding a Sino 3 axis DRO has transformed my Mill-Skills from cowboy, to almost machinist......

 

[onecut jimmy]

So I am no machinist, far from it. My new X2 is my first mill. One of the things that I am trying to figure out right now how to take accurate cuts off of the top plane of a simple pie e of stock that I am squaring.

My process goes like this lower the head using the large feed wheel and engage the fine downfeed when the cutter is close. When I have touched off make a note on the fine downfeed and what position my z-axis's is at.

Back my work away from the cutter, twist the fine downfeed, and allow the head to lower down by the appropriate amount and then lock in the z-axis.

however, there is about 20 thousandths of backlash in the fine downfeed, and TONS of stick-slip in the z-axis travel.

How do I make this work?

Ngary I am a machinist with over 70 years expeience.
My advice would be to ask someone who has experience with that same machine how to corect the problem.
If that isn't an option go directly to thr manufactuer or their US representative.
No machine moving parts should stick or slip.
What is the make of your machine and where did you purchase it?I have many contacts and may be able to get you some information.
If you can't get it but do try to contact the company that made it.

 

[Ngray]

Ngary I am a machinist with over 70 years expeience.
My advice would be to ask someone who has experience with that same machine how to corect the problem.
If that isn't an option go directly to thr manufactuer or their US representative.
No machine moving parts should stick or slip.
What is the make of your machine and where did you purchase it?I have many contacts and may be able to get you some information.
If you can't get it but do try to contact the company that made it.

All good advice, and I would take it if I had not purchased it from horror fraught tools.

 

[Walt]

All good advice, and I would take it if I had not purchased it from horror fraught tools.

I agree that it's not likely that Harbor Freight will be of any help to you with this problem. It's also true that you would probably face the exact same issue with gear lash and z-positioning uncertainty if you had bought a similar machine from Micro-Mark, Sieg, Grizzly, etc. They all work the same way, and suffer the same shortcoming.

Have you tried adjusting the gib screws? It's not unusual for these to need some tweaking in a new machine.

Walt

 

[kd4gij]

There is a yahoo group for the X2 mills. You would find alot of good info over there. A lot of them in use.

 

[Ngray]

Just an update on this. I did a few things to tune up my control of the z axis, and it's gone a long way to help:
1) I found that the gibs/ways were not bad. I just re-cleaned them, and added some 80W to make sure. The big crank runs the head up and down pretty smoothly, but as others well know, the torsion arm is inconsistent. I may change it out for a counterbalance at some point.
2) I found a TON of binding in the fine control mechanism itself. The screw was binding in the housing, even when not mated with the gear. I hand-fitted it, and it runs much better. Further, the housing was binding the inner gear pretty badly. Same treatment.

Net result, I have about a thou and a quarter of backlash, and it sticks much less. Very usable now. I still have to use it in anger to see how I like it.