CNC x2 Mill

[Rndmann9]

Ha. I wish. Na I like my job. It just comes and goes in spurts as far as busyness. A hospital is a complex beast when it comes to design. I have to get my mill working again. My game controller program got screwed up so I have to rewrite it. Might be this weekends project.

 

[Rndmann9]

Welp. Been a while. Got the controller program rewrote and the mill working but had binding on the x axis so naturally decided to switch it to a ball screw too.

 

[Rndmann9]

Ball scews are NOT fun to machine. Super hard metal. The first one I ordered wasn’t the right size so I decided to use it and upgrade the z since that one had too much backlash to. Should have it finished tomorrow. Here is some wood I milled to test the x. And you can see the backlash issue with the z. Also some picks of the current state. I should have taken more pics but I was “in the zone” I

 

[Rndmann9]

That’s the old motor position so don’t get confused by it’s weird placement. Lol

 

[Foozer]

Ball sc[r]ews are NOT fun to machine. Super hard metal.

Now you tell me. Doing a goofy winter project with longer than required ball screws. If I hose em up there is always the acme with derlin nuts route . . .
Robert

 

[Rndmann9]

They are just case hardened. Once you get through that armor they arnt too bad. Scratching my head trying to figure out how I want to remount the stepper???

 

[Rndmann9]

Ok time to do some testing tweaking and probably shimming.

 

[Rndmann9]

It is worth noting, it's really hard to work on your mill without your mill. Makes me wish I had two... One day...

 

[Rndmann9]

Couple more pics. Seems to be functioning pretty good. Much better than before.

 

[Foozer]

Curious as to what weight the Z-Stepper has to move and is the Z counter balanced.
Robert

 

[Blogwitch]

It looks like you are taking the route most other people do for the Z axis.

I don't know if you realise that you are taking a large risk.

Because the stepper is only on one side of the head, that will try to cant over the head as it moves up and down, also called crabbing, which will eventually lead to uneaven wear on your Z axis slides and may even sieze up or knock your cutter off line..

The easiest way to cure this is to have a stepper either side running in parallel, so the head has equal pressure on either side.

I brought this problem up a while ago but my own illness and the death of a great friend caused me to abandon the project some time ago.

http://www.homemodelenginemachinist.com/showthread.php?t=24086

If you go to the last post in that link, you will find a link to one of the last articles John S did before he passed away, about the build we were working on together.

John

 

[Rndmann9]

Yeah I thought about that. Mainly was trying to use the material I already had mainly the belts. That and somewhere to mount it. When I first made it I only changed the y axis to a ball screw. Then changed the x. Since I had a 12mm instead of a 16mm ball screw that was ordered inadvertently went ahead and winged it for the z. These mills aren't the stiffest things anyways so I don't ever expect to get great precision. I'd be somewhat satisfied with +~- .005. I plan to get a much bigger mill in the near future ( kinda want to move first so I only move it once). It's more to learn CNC on. the whole project was sort of an impulse project...something to do with some challenge from scratch and was fun. Now I'm giving my lathe dirty looks and temped to jump on it.

 

[Rndmann9]

I got tired of the backlash with no way to compensate for it which drove me to change it again. Here is the first version.

 

[Rndmann9]

I noticed some loose the gas strut or torsion spring. I elected to keep the strut to maybe lesson that effect. I figured at worse the gib will wear unevenly but I plan to replace those with brass as soon as I get some stock that's the right size. The x still has some sticky spots due to the gib. I actually started this in 2016 but finally got motivated and the time to fix it

 

[Rndmann9]

I actually toyed with mounting it centered but decided the extra trouble wouldn’t be justifiable. I also would need another mill. Just didn’t have much space to make it happen. All the screws are 16mm but the z. I have a spare 16mm if this one causes trouble. So far the 12 seems to be doing ok.

 

[Rndmann9]

Curious as to what weight the Z-Stepper has to move and is the Z counter balanced.
Robert

It’s prob 20~25lbs. Gas strut helps some. Motor muscles the rest.