[binfordw]

Hi,

I'm almost ready to make my first cuts with my X3, thought I would ask a few more questions first.

Backlash. I bought kit #4 from CNCfusion. I have heard others mention as well- that the locknuts for the ballscrews are incredibly tight. I tried to set mine about where I thought they should be to preload the bearings enough without being too tight and causing wear/damage. While setting up the motors in the Mach3 software, I noticed .010-.025 of backlash on my dial indicator.

I have read the ballscrews can have .003 or so of backlash, so I assume the rest is likely slop in the bearings- possibly loose mounts?

Where in Mach3 can backlash be accounted for if I still have "too much" after adjusting mounts/bearing preload?




Any tips for fine tuning/ first test run help would be appreciated.

Ben W

[vlmarshall]

Where in Mach3 can backlash be accounted for if I still have "too much" after adjusting mounts/bearing preload?

I can't help you with the ballscrew preload, but In Mach's "Config" pull-down menu there's a section for backlash.

[binfordw]

Thanks-


Another question,

I have a R8 QC collet set from Grizzly.com, and I noticed that the spanner wrench that came with the mill no longer fits when its installed. There isnt a tall enough gap between the quill and the collet holder to fit the wrench in.. Anyone else have this problem?

[Jeff Davis]

Yep, same problem. I use the spanner that came with the collet set when that one is on the spindle. Probably not the best way to do it, but I havent came up with anything else that works.

Jeff

[Crevice Reamer]

That's a lot of backlash. I recommend the near zero backlash deluxe kit, because it's WORTH the extra money for the precision ball screws, angular contact bearings and preloaded ball nuts. I hope you got the G540 option.

If you have the lovejoy type connectors, changing to helicals will help.

CR.

[binfordw]

How do you hold the spindle while you loosen the collet locknut though?

The wrench that came with the collet set fits the collet locknut fine, but I have no way of holding the spindle now. The two holes on the underside are blocked by the collet holder.

[Crevice Reamer]

How do you hold the spindle while you loosen the collet locknut though?

The wrench that came with the collet set fits the collet locknut fine, but I have no way of holding the spindle now. The two holes on the underside are blocked by the collet holder.

You could put a crescent wrench across the spindle splines.

A couple of belleville washers under the drawbar will let you simply hand-hold the spindle while tightening the drawbar. OR, you could invest in some Tormach QC tooling that WILL let you use your spanner wrench.

Here's some basic CNC info that you may find helpful:

http://crevicereamer.com/Page_2.html

http://crevicereamer.com/Page_26.html

CR.

[Crevice Reamer]

Oh BTW, Welcome to the Zone!

CR.

[binfordw]

I have Lovejoy connectors. I'm using a 3 axis kit from Keling, http://www.kelinginc.net/Three34XCNCPackage.html


I had time to play a bit more tonight, I placed a dial indicator at the end of the X screw, and jogged - +. There was some slop, so I'm confident atleast some of my backlash is due to the preload on my bearings. I'll check the X and Y again when I have time.

On the plus side, I ran a few simple programs while I was there, and the machine ran excellent. I cut a circle and some lettering in a piece of pine, and then milled a short piece of flatstock. Loved the results and cant wait to run more complicated parts.

I just finished up a 4-prong Socket in Bobcad to tighten the locknuts on my ballscrews, I'll try to run it tommorrow so I have the proper tool to tighten the nuts. Which btw, love the Bobcad V23, its proving pretty easy to use and a big help!


Also, I actually bought a gasram from CNCfusion but have yet to install it. The Z seems to run perfect as is, it zips up and down without being able to tell it might be straining at all. I'll probably install it before long I suppose.

[Crevice Reamer]

I have Lovejoy connectors.

Helicals are better. If Lovejoys are set-screw, use blue Loctite.

I'm using a 3 axis kit from Keling, http://www.kelinginc.net/Three34XCNCPackage.html

Too bad! You could have used the G540/381/906 setup for less.

[quote]I had time to play a bit more tonight, I placed a dial indicator at the end of the X screw, and jogged - +. There was some slop, so I'm confident atleast some of my backlash is due to the preload on my bearings. I'll check the X and Y again when I have time.

So you are using the X3 stock open thrust bearings? Make sure you lube them with some good grease.

On the plus side, I ran a few simple programs while I was there, and the machine ran excellent. I cut a circle and some lettering in a piece of pine, and then milled a short piece of flatstock. Loved the results and cant wait to run more complicated parts.

Good work! Now you know it won't be a $3K paperweight.

I just finished up a 4-prong Socket in Bobcad to tighten the locknuts on my ballscrews, I'll try to run it tommorrow so I have the proper tool to tighten the nuts. Which btw, love the Bobcad V23, its proving pretty easy to use and a big help!

Best way to hold the ball screw while you tighten nut, is zip cut a slot in end of ball screw for screwdriver.

Also, I actually bought a gasram from CNCfusion but have yet to install it. The Z seems to run perfect as is, it zips up and down without being able to tell it might be straining at all. I'll probably install it before long I suppose.

If it works well without it--leave it out--It will limit Z travel.

CR.

[Jeff Davis]

Ok, I understand your question now. I hold the collet with a large pair of channel locks right now while i use the spanner that came with the collet to loosen tighten. I plan on making a little custom spanner wrench out of 1/4" AL to replace the channel locks with as one of my next projects.

You collet should have a flat spot on each side where you can grip it.

Jeff