Aluminum Engraving Problems. Please Help!

[CoreyD]

Hey guys, when I first got my X-Carve I was doing a lot of Aluminum engraving for my side business. Once I got the settings and process dialed-in, I was super happy with the results. But now my quality has completely gone, and no matter what settings I use, I can’t get it to come out the same. If anyone can share their success story or advise on what might be causing my issues, it would be a huge help!

My Machine:
500mm X-Carve, small motors, DeWalt 611, 1/4" Carbide engraving bit from Inventables, 0.1-0.3mm engraving depth, matterial thickness 2-4mm

Machine Upgrades (after successful engraving, before unsuccessful engraving):
Torsional stiffening of X-axis, replaced MDF work bed with 8mm Aluminum plate, added 2mm acrylic side guard things along the Y-rails to stop debris clogging the rail, put the machine on a custom built steel-frame table with heavy wooden top (used to be on a wobbly old school desk), sat machine on rubber to dampen vibrations.

Previously successful settings:
550mm/min, 22000rpm, WD40 fluid manually sprayed in little bursts, full depth of cut (i.e 0.1-0.3mm depending on what i was engraving)

So now, using the same settings, my engraving comes out with very burred edges. I’ve tried brand new engraving bits, even tried the 1/8" bit from the inventables. I’ve tried all sorts of speed and feed settings; every combination of low/med/high rpm and feed rate. Nothing seems to work.

I’ve tried even tried re calibrating the motor current pots, re-leveling the entire machine (every frame joint, every roller), checked and loctited all the pulley screws, re-tensioned the belts. More or less rebuilt it!

So then I thought, it has to be something to do with the machine upgrades I’ve made. But what!? Maybe the Al work bed is too rigid, and that is somehow causing issues…?? So I tried laying down some 3mm MDF to “soften” it. No noticeable change. Surely the the X-axis stiffening isn’t causing problems? People do this all the time!

So basically, I’m all out of ideas and I need some help.

My machine

My table

Successful engraving from the before-time

Test engraving I did today

[B.F]

.090 2024 aluminum
2f down cut Destiny Viper bit .125
Dewalt 611 speed 1
DOC .002 (slow, but turning parts out is better than more test panels stacked up)
FR 25" ipm
PR 10
Single channel (no fluting or widening the channel to relieve heat)
No oil

[DavidWestley]

Are you still using the same bit? Maybe it’s blunt…

[cncrockstar]

Could be runout. Is your collet in good shape? If you have a dial indicator, set it up touching the tool, the rotate it counterclockwise( do it doesn’t dig into the indicator tip) and make sure the tool is straight. Shouldn’t have less that .0005 to get good results.
See if that helps.

[CoreyD]

Thanks everyone for your inputs. So far the leading theory is slop in the Z-axis.

@PhilJohnson I checked the delrin nut. I tightened the screws a little (i don’t think they were too loose though), and found that there is a tiny bit of freeplay in the thread engagement with the lead screw. I can’t find any other slop/freeplay in any other components, other than normal flex in the construction materials. I’ve linked a video showing the freeplay >> https://youtu.be/b8tVdMXa1z0 Does this look too sloppy?? I’ve never lubed it, (didnt want debris to stick to it, and it seemed frictionless enough already) but i wouldnt have expected much wear at this stage anyway. Do they normally wear out quickly? Should i replace the delrin nut? I could try applying grease which may reduce the slop…??

As i was playing around, i remembered that the Z-axis used to be quieter (i think, but can’t remember for sure). So i’ve linked a couple of videos of that too. It almost sounds like something momentarily resonates as the motor is starting and stopping. Does this sound bad compared to everyone elses?? Given that i can’t find any loose parts, i don’t know what this could be. I tweaked the motor trim pot, but no change.

Z-axis 0.1mm increments >> https://youtu.be/7ZSj8DNCdfs
Z-axis 1mm increments >> https://youtu.be/8F6Fb9_d9bY

@DavidWestley I’ve tried many different bits, most of them brand new. Makes no difference.

@PhilJohnson regrading aluminum types; I typically engrave 3 different grades (6061, 5005, 5052). All worked great before. All are terrible now.

@cncrockstar I can borrow a dial indicator from work, so might try this. Honestly if theres something wrong with it already, i would be asking for my money back on the router. It really reeaally shouldnt be worn out yet, and it hasnt had any big impacts or load that you would expect to cause damage. I only got it in April this year.

[JkWestphal]

From the vids, it sounds similar to what mine started doing before i used some PTFE dry lube on the acme screw. the sound was still there but no nearly as pronounced as before the lube. however, this did not affect my operation, but then, I have not messed with machining aluminum beyone a slight bit of tinkering. I have since upgraded my Z axis to a linear rail setup so the noise issue is no longer an issue.

One note on lube, DO NOT USED ANY SORT OF OIL OR GREASE ON THE ACME SCREW. dust and debris can collect in these oil based lubes and gum things up. (and you think you have issues now…)

You can find this in a spray can at home centers and auto parts stores. You dont need much and it can get a bit messy when applied, it turns to a white powder so if you are a neat freak, you may want to shild things behind your target a bit. I works well for alot of other things around the house too.

[AaronMatthews]

@CoreyD

So basically, I’m all out of ideas and I need some help.

Also check the holes for the eccentric nuts on your Z axis as well.
My Z axis suddenly go very sloppy and it turned out the holes for the eccentric nut had gotten damaged and stretched out so the nut would wobble just a bit causing problems.
Replacing the nuts and bolts helped a little, but I wound up replacing the Z axis.

[Earwigger]

I just replaced my z-axis with a linear guide z-axis and when I broke it down, there was quite a lot of slop in the delrin nut (after a year of every-other-day use on average). Just an fyi. It only takes a few minutes to break the whole thing down and check everything real good. It certainly seems like either a z-axis or run out problem.

[CoreyD]

Thanks everyone. I’m going to try replacing the delrin nut, and hopefully that will solve the problem. Everything else on my machine seems ok.

I’ll definitely get some PTFE dry lube as suggested by @JkWestphal. I’ve only have my machine since April and don’t even use it that much, so i’m surprised and a bit disappointed that the Delrin nut would wear out so quickly.

I’m looking into getting some nuts custom made out of a more wear resistant plastic (possibly Ertalyte), since the Delrin wore out so quickly. I’m awaiting a quote today, but i’ll likely have to buy a few to meet their minimum order quantity. If anyone wants one, let me know

[JkWestphal]

Dont be so sure that the delrin nut is worn out just because it is making a bit of noise, as long as backlash hasn’t become an issue the nut is probably still serviceable. I had been running my machine on the standard acme/delrin setup for several hours at a time 2-3 nights a week and on weekends doing an ongoing deck board engraving job and it had been holding up well, though some “binding” noise had developed which was toned down by the ptfe lube. beyond that it was working as good as the day I first set it up.

I only upgraded to the linear z axis because I wanted a more rigid assembly and since I like to tinker with stuff.
Also, somewhere on here i came across a mention of not having the 2 screws the hold the delrin to the z mount plate too tight as it could cause binding issues. If this is true or not I dont know…

[CoreyD]

The machine still works well for my other milling and routing jobs, although i had noticed the Z height had lost some precision when i was leveling the work bed. From memory I think it would lose almost a 1mm if I’d go up and down a few times, which could be explained by the wear I’ve found in the Delrin nut. Anyway it’s the only thing I can find that looks like a problem, so i’ll replace it and see what happens.

[CoreyD]

Hey guys, just a final follow up for anyone who’s interested. I’ve replaced the Delrin nut and the problem is solved! I actually made one out out of Ertalyte instead of Delrin, because it has better wear resistance. I’m also using dry PTFE lube now too. Funny thing is, replacing the Z-nut didn’t quite get me back to 100% quality. It wasn’t until I accidentally snapped the tiniest little bit off the end of the engraving tip (1/4" Onsrud engraving V-bit from inventables store) that it got that last bit of quality that i was chasing.

Also, I’m going to try diamond drag engraving on my anodized parts next. Sounds like a far better way to go, with lots of advantages.

I made bunch of extra Ertalyte nuts if anyone wants one. They’re on ebay, but if you’re outside of Australia, contact me direct and I can work out cheaper postage.