ACMER Z-Axis Module
I like my ACMER products, even when they require unexpected maintenance. The design is simple enough to figure out, and for the most part well engineered. My Z-Axis Module did not fit in this "most part" category. Still, for the price nothing beats ACMER.
What is great about the Z-Axis Module:
I have to start out with, I do love my Z-Axis Module. It is super easy to use. I can quickly adjust focus, saving me time in setup, resolving any focusing concerns I would have had when adjusting manually. I can still do manual adjustments if needed. I also find the Z-Axis Module gives me greater access to the two lock screws, which have always been a problem for me to get my fingers on. That alone makes it nice, but there is more.
The Z-Axis Module can be used on the P1S Pro, P1, P2, and P3 machines. I have the P3.
When cutting material (right now I cut only wood), I focus the laser half the depth of the material thickness. Without the Z-Axis Module you would have to do this by "guessing", or by using the appropriate number of shim to set height. With the Z-axis module I start with the focusing foot "up", turn the adjusting screw to lower the laser head, I put the focusing foot "down", and slowly raise the laser head using the adjusting screw of the Z-Axis Module until the focusing foot pops into the focus position. Doing it this way is quick.
One oner method may be to start wit the raise the laser head using the Z-Axis Module with the adjusting screw, put the focusing foot down, and lower over a piece of paper, sliding the paper back and forth you turn the adjusting screw to lower the laser head, feeling for when the foot makes contact (from free paper movement to a very slight drag).
I lift the foot up, and turn the adjusting screw to lower the laser head as needed for my half material thickness cut. One complete turn is 1mm and there is a graduated scale with pointer on the side you can look at too that is graduated 0.5 mm.
For those who use the ACMER P-model machines to engrave slate, you know that slate height will always vary. Yes, you can group your slate in height increments for one focus setting (need to do this for multiple slates in one engraving cycle), but with the Z-Axis Module you can now set individual height quickly and accurately.
Side Note 1:
I use two different ACMER laser heads for my P3. The 2-in-1 which is a 10W and a 2W IR laser has a focal distance from the bottom of the laser to the work surface of 5 mm. My other is a 48/24W, which has an 8mm focal distance. For cutting I subtract half my material thickness and set my new height above the material surface accordingly. If the new set distance interferes with my hold downs, all I do is give the adjusting screw a quick turn clockwise to raise the laser head 0.25mm or so to clear. Quick and easy.
I also have a set of shims I bought from ARB Woodworking LLC, that allows me to set height manually and accurately. This was custom designed and made at my request.
What is not so great about the Z-Axis Module:
I installed my module right away and began using it. It felt great having a clean process for adjusting. I did notice that the laser head was not plumb. It was out about 3 degrees. Because I had to make product, the product came out useable, and because I had other maintenance issues to chase on my ACMER P3, figuring out why it was tilted was at the end of my list of things to do.
As time went on, I found a screw sitting on my honeycomb bed. I came from the bottom of the module that connects the adjusting rod to the module frame. I put it back in and tightened. Somewhere along the 3 months I had been using the module, I also lost the bearing at the bottom. I did not know that at the time I put the screw back in (probably fell out with the screw the first time).
A few weeks ago I found the time to investigate the 3 degree tilt. I noticed that I could physically move the head back to plumb, and when I released, it tilted. Physically that was a lot of movement.
My background is engineering and manufacturing. (Now retired from Quality Manager.) I have dealt with tolerance issues the entire time whether engineered or manufactured. It became obvious to me that I needed to disassemble the module and take some measurements.
First were the two guide rods. Both measured in five different places 4.9 mm. Very repeatable. Next, to measure the bores of the top and bottom caps that the rods are retained in. Measurements varied by bore in multiple directions, with the range between 5.0 to 5.2 mm. That is a total tolerance between 0.1 to 0.3 mm, and for those who what to know thousands, that is 0.0039 to 0.0118 inches.
For a free running fit, I believe the tolerance would be 0.022 mm, or for a close running fit 0.028 mm. ACMER confirmed back to me that their design for ease of assembly is 0.2 mm tolerance (barn door tolerance where I come from). Add to this the tolerance stack of the block the laser mounts too, and I end up with about a 3 degree movement.
Through all this ACMER was very kind in their responses. They understood the problem, but did not see it as a problem. Well, it is a problem when the design you purchased calls for mating dove tails. On one end you would be cutting with kerf at one angle, the the mating end the kerf would be cut at the opposite angle, making for an interference fit rather than the designed running fit. Yes, one could flip a part over and assembly with the other side up (in my case), or flip the design around in LightBurn so that the kerf angles will match up when assembled. But why? This is extra work to think of when you pull up a design to cut, "Which way do I have to re-lay this out to fit, or does it not matter?"
In some of my other blogs I mention "process window". The wider the window, the better the chance of making an acceptable item that still shows signs of quality. By not having a plumb laser head, this now reduces my process window, that if I hiccup, I can make scrap or an item useable but of poor quality. Which side of the fence would you rather be on?
I do not believe ACMER is selling this module anymore. You may see it pop up in their advertisement, but I believe that is because they have not updated their website. AliExpress, where I was directed to by the module from, no longer shows this item, so you cannot buy through them.
There are many third part Z-Axis modules out there, some with every adaptive hole you can think of to mount on almost anything. They are more expensive, and how long will they be around? If you end up going through Amazon to research, I would suggest that in this case of the Z-Axis module, that you look at those that have sold the most. The correlation you are hoping for is that if there are many out there, they may be the better unit to buy, and it is likely they will stay in business for support.
ACMER did offer to quote me replacement parts for the lower flange bearing, screw, and washer. Given the shipping cost for such low cost items, I said no thanks, and asked for possible information on them so I can source here in the U.S. ACMER graciously responded with the following that I will pass along:
Bottom adjusting screw connection uses a flat head socket head screw M3 x 8, an M3 x 3 x 1 washer, and a 6 * 10 * 3 flange bearing.
The flat head screw and washer I believe is to offer as much clearance as possible under the module. I chose to use a common socket head cap screw and no washer, and seems to work fine.
For the bearing I purchased through Amazon 10 pcs of a Uxcell MF63ZZ. I tapped it in the bottom block just fine.
To overcome my problem with module tilt, I braced the laser plum and used Loctite 680 Sleeve Retainer just on the bottom block (seen in the above video withe the guide rod moving in the bottom block), which was where most of the movement was coming from. I put a couple of drops in, moved the head back and forth to "burb" the air out as it oozed in, and waited for it to set. I now have less than half the laser head movement than when I started. I did not Loctite the top because this allows me to disassemble if I need to in order to change the adjusting screw and other associated parts.
I only have a couple of hours on my modifications . . . so far so good. I will update this (with a date of the update) should the situation change.
Side Note 2:
There are a lot of laser manufacturers out there. Many have died off because it is a tough market to compete in. Given this tight market, manufacturers do what they need to in order to turn a profit. Hate to say it, but head count (the number of employees) is the quickest and easiest to keep the cost down. Yes, you can keep going after lower material costs, and you can revisit the manufacturing process for opportunities to improve to lower those costs. That however is a fractional cost reductions, whereas headcount will give you bigger numbers.
I have read forums of other manufactured laser equipment, and they all have complaints about service. ACMER is no different, though my experience for whatever reason is they have provided me excellent service. It is like the analogy I made in another blog about cameras, because I am also a photographer. It does not matter what camera make I use, because the photo quality is still controlled by me. Learn about your ACMER machine through your maintenance routine. Understand how it functions. Have patience because ACMER deals world wide, and with that communication is different because of how individually we think across the world. People simple response is, "ACMER needs to hire more service people." Well, yes, and are you willing to pay double for your ACMER equipment now? No, well the other competitors have similar issues as well, and perhaps are hire priced to begin with. The grass is never greener on the other side. Learn you equipment, learn how to communicate with ACMER (in a civil way), and let the grass turn green on the ACMER side of the fence.
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