Inspecting new Grizzly mini-mill.

[Cowbell]

Hi everyone. Let me preface this with : I'm a rank beginner, so please excuse terminology or general silliness.

I recently purchased a Grizzly mini-mill and I've started poking around with it to get my feet wet. Grizzly had a dial gauge set with magnetic base for sale which I picked up. I set it up and started twisting dials to see if everything matched. Things appear good - 1 thousandth on the dial comes out as one tick mark on the side wheel dial.

But I noticed one oddity. Let's say I'm twisting the wheel clockwise. As I twist, each tick reliably matches up with a tick on the dial. But when I reverse direction, the dial has a good deal of 'play' before it actually starts moving the table the other direction. As much as 6 ticks on the wheel. This seems like quite a bit.

Is this something normal for a low end mill of this kind? If not, is it something that's fixable without sending it back (*ugh*)?

When working by hand, it would seem that this is something that can be worked around (as long as you have dials). But if you wanted to CNC the thing, 6 thousandths of an inch would amount to a big chunk of error for the motors, no?

Thanks from a rookie!

[phantomcow2]

I have a Sieg x1, but its the same company as the mini mill you have.
What you speak if is backlash, if you do a search on this forum you will probably come up with 100 pages. It is the enemy of CNC, not so bad manually.
This is normal, not just for a low end mill. THe bridgeport I use has significantly more backlash, and thats not a low end machine.
The mini mill should have some sort of backlash adjusting "split nut", try playing with that.
I know for my X1, when i got thrust bearings installed and the backlash nut adjusted, i can get it under .001". Then when you do CNC your software will have some sort of software compensation.
Still, its good for the machine to have as little backlash as possible.

[Cowbell]

Ahhh. Yes, I've seen the term bandied about while lurking. Just never put a face to the name, so to speak.

Thanks for the info. Looks like I'm ready to rock, for my meager purposes

Side question : Of the many forums on this site, what's the best place for a beginner like me to post general machining "how-to" questions? As you may imagine, I've got a bajillion questions regarding proper techniques for setting up workpieces (alignment, zero points, etc, etc).

[phantomcow2]

WEll little machine shop has very good articles that will help you get started. Im assuming you know about little machine shop here. If not, they are the premier importer of goodies for the Sieg line of machines.
You might want to see if you can find a book about machining, they are plenty out there. Read through the metal working part of this website too, search the archives. If your really into it, i've seen plenty of people put ballscrews in their mini mills, that will eliminate most backlash.

[fignoggle]

on your grizzly (sieg x2) you can do a simple split nut mod yourself. i've posted pictures on my website. it takes all of 15 minutes and will really help your backlash situation. one of my pages shows (after a cnc conversion) before and after backlash adjustment using the split nut method.

just take the brass nuts, split them more than half-way down the middle. tap one side, then when you tighten the screws, you separate the halves slightly to create that quasi-anti-backlash nut.

and, check out the various yahoo groups including mini-mill and mini-cnc-mill.

[swarfmacdaddy]

6 thous is pretty good for a grizzly or harbour freight mill. Or pretty average i should say. I had the h.f. folks almost throw me out of the store for bringing a drill press back because the spindles were so bad. I made them them open 5 boxes before i found one that was even suitable for drilling wood. All of the chucks would make a drill rod spin 0.125 t.i.r. and it wasnt that the chuck wasnt square on the arbor. One of them actually said to me " What do you expect for $250?" Well ,semi useable when new would be nice was my answer.