Z-Axis Upgrade from CNC4Newbie.com Initial Review


(Jeff French) #1

I’ve had my XXL for coming up to 2 years now. I bought it to help prove out a concept for a retirement hobby business. For the better part of the last year my machine runs 6 days a week and approx 20 hours a day. “She a carving”! Needless to say it’s proven that there is a business out there for what I’m selling. During this time the majority of my scrap has been caused by 1 of the following items:

  1. Improper Feeds and Speeds - basically being too aggressive and over running the capability of the machine… This is pretty much under control as I have gained experience and worked my way through the varieties of wood that I’ll be using.

  2. The Dewalt Router stopping in the middle of a job due to the brushes wearing out. I have tried all the countermeasures listed in the forums. But still manage to wear a set out every 4 to 6 weeks. Currently adding a cheap hour meter to track the time on the brush, but in the next month or so I will be installing a VFD & industrial spindle.

  3. Last Item and subject of today’s Topic. The Z Axis is very weak, it tends to very easily be knocked out of calibration, either by a downward movement and the bit not cutting in fast enough, or rapid upward motion and the bit holding back to much. Had both, but downward is the most predominant. My countermeasure has been slowing down the plunge rates and feed rates.

So I did a lot of research in the forum, wiki pages, web etc. and decided to give the updated Z axis Slider from CNC4Newbie.com a shot.
Shapeoko Slider
It runs around $260 US or $340 Cnd with the current exchange rate.

Here is a Summary of my upgrade activity and thoughts:

  • From order to delivery was about 3 weeks (reasonable since ordered over the holiday period)

  • Product quality & machining was very reasonable for the price, no parts missing, nothing broken or loose. (this comment based on I was an engineer at an automotive factory for 30 years and have purchased many products from various tool shops and can appreciate the cost of top quality)

  • Instructions poor, your pretty much left on your own to research the comments and info from others, but not very difficult to assemble. Only needed a picture of what it should look like and if new hardware not provided reuse from the OEM part.

  • Upgrade took an afternoon. Actual mechanical switch over took 1 hour. The rest of the time was spent learning Grbl-Panel and testing various parameters until I was satisfied.

Summary of Required Changes:

Carbide Motion switched to Grbl Panel ( I asked for advice here on various programs and found Grbl Panel very easy, plus the you tube video very helpful)

$3=2 - Port Direction is different for new Z axis
$20=1 - turn on soft limits
$102=200 - Z axis step/mm
$112=2000 - reduced max speed of Z axis for better movement
$122=750 - Z accel mm/sec
$132=150 - Z max travel in mm (might be able to adjust a bit more but was happy with this)

On the CNC4Newbie website he mentions the option of buying a bigger stepper with more torque. I opened a discussion on this forum and bounced around options for doing so. In the end I did not upgrade the motor and just reused the original one. One of the concerns in that discussion was the slider uses a Leadscrew instead of a Ballscrew which is better using less torque. So far no concerns with the leadscrew in this application with original stepper.

Results of Initial test runs & 1st couple jobs.

1st & foremost you will notice the Z axis is Solid, no play or movement even at the tip of the bit.

2nd - I applied a lot of force against the downward motion & could not stop the unit unless accidental jamming into the spoil board… (very happy with that)

I was able to increase the speeds & feeds by 30% on the first jobs I ran with no repercussions. These jobs ran for 40 hours before and now finish up around 30 hours of machine time. Please note I had overcompensated the slow down before because the job ran so long and I couldn’t afford it to screw up. On my shorter jobs I did run the machine faster because the risk was less if I scrapped one off.

Here are couple pictures of the upgrade and the big job I was talking about. Anyway will update if I have any longer term reliability issues, but so far happy with the upgrade.

Jeff


(Jeff French) #2

Oh Forgot to mention, my Suck It dust boot will work, just needed to make a couple of spacers.


(Jon Anderson) #3

Awesome, thanks for your sharing this. I have a CNC4NEWBIE z-axis as well and ended up installing the new Shapeoko Z-plate onto it. I had to drill 4 holes in it to make it align properly but I liked how the z-axis isn’t counterlevered anymore like both the old z-axis and the CNC4NEWBIE one. It is more solid now and deflects less in aluminum and hard woods.


(Jeff French) #4

I read all the discussions on here about the previous versions, looks like the guy who makes them did too. Product is now very solid on the x axis rail and I couldn’t detect any play. Mind you I’m carving wood, I’m sure the guys that are focused on metal finishing might be able to measure what deviation is there. But very happy with the improvements he made to the design.


(Jon Anderson) #5

Got it, that makes sense. I’m milling aluminum with mine so I wanted the extra rigidity.


(Jeff French) #7

Update on my review after 350 Hours running.

Had a couple of issues pop up during the initial running of the new Z axis upgrade.

  1. After about 100 hours running got a vibration and/or looseness in the operation. After troubleshooting I found that the eccentric nuts would no longer keep the new slider tight on the X-axis rail. I found that the aluminum plate had some premature wear in the hole causing the nuts to become loose.
    The issue is that the shoulder length on the original eccentric nuts to too short. They work fine on the steel plate provided on the original axis, but in the softer aluminum of the new plate the wear in.
    I found new eccentric nuts with a long shoulder for about $2.50 each from https://sienci.com/product/m5-threaded-eccentric-nut/
    After they arrived I installed them and regained my adjustment and was able to tighten up all the play.

Only issue with these new nuts is they are a bit long for the hole in the plate. Overcame this by installing a couple of washers to keep the new Z-axis plate parallel with the X-axis rail.

I believe the root problem was some of my tool paths being too aggressive, I do a lot of peck drilling when I make crib boards some 300+ holes in Maple. I believe with the new rigidity of the Z-axis upgrade all the stress was passed back to the weakest point which was the depth that the eccentric nut went into the aluminum plate.

Side Note: when waiting for the new parts to arrive I tightened up the slop by running a couple of strips of aluminum tape (used for sealing HVAC duct work) on top of the V groves on the X-axis rail, adding a couple mm to the dimensions. Had to reapply ad it only lasts about 50~60 hours as it compresses.

  1. After 250 Hours of operation I had another round of Slop / Vibration . Turned out to be the bolts holding the slider together backed off.
  • Applied Lock Tite & tightened up.

I’ve passed my comments back to the manufacturer hopefully he will improve the minor issues in future revisions.


(Jon Anderson) #8

Awesome write up! I need to check my eccentric nuts and see if that’s why there is some displacement when I push on my endmill. Thanks for putting in this effort.