I know the instructions say that anything works as long as it’s rigid. Metal isn’t required.
The dilemma is I have access to 1/4 “ HDPE scrap that I can cut out of or some scrap 1/8” steel that can be cut with a plasma cutter. So both options are the same cost to me (steel would be powder coated after cut).
So which option is better, even if marginally?
Steel is very rigid (good), but adds a lot of mass/weight to the build (bad). More mass results in challenges for accelerating the gantry. It may not be a huge issue if you are running at very slow feedrates, but if you are trying to run faster. you might find that you are skipping steps, even with light or no loads.
Things like laser engraving sometimes work better with faster feedrates, and have a lot of instantaneous direction reversal (acceleration). That might be difficult to achieve with a heavy gantry.
I used two layers of 2mm aluminum from an old road sign for my struts, and it was reasonably light and fairly rigid. The 1/4" HDPE would be pretty light as well, and presumably quite rigid.
TLDR: I’m not sure that steel would be the best choice.
I’d go with steel if it us easily done for you. 1. It is rigid compared to hdpe and it is thin, so while yes, some weight will be added, it won’t make it unusable. It may make it more stable. 2. I dont know of anyone else that has steel so that would be a data point to provide the community more information and 3. powder coating would look awesome. Love to see it when you are done!
Steel sounds like overkill… AWESOME!
Edit: do not ever powder coat conduits!
Or worse… rattle can them. Ask me how I know…
LOL.
most of mty builds are steel, not conduit, though it’s conduit for the ZenXY, which is rattle-can painted. For the Zen,m it’s OK, because the POM wheels aren’t putting enough pressure on the conduit to dislodge the zinc. A coat of primer and one of paint, and it’s fine.
I would not powder coat steel used for the rails if 608 skate bearings are intended to ride on it, the powder coat is liable to crack and peel.
Powder coating the struts though, that would be amazing.
For the material, if I were to use steel, I’d probably modify the struts to be more like the LR3 struts, with a more open latticework design. The steel is going to be super rigid in any event, and the open lattice would reduce mass. Given the choice of materials, though, I think the HDPE would have excellent properties, but I’d want to ground the X rails in order to mitigate the effects of static, in the event of friction with the HDPE.
Yeah. The bearings ate my poor rattle can job pretty quick. So it was a self solving problem, I suppose.
I’d imagine powder coat would hold up better though still not suggesting it’d be a good idea!
I’m curious what @vicious1 has to say. I’m leaning towards the HDPE since that doesn’t have to go through the powder coating process or show scratches or nicks in the paint. I haven’t heard any real benefit to one over the other except for it would look awesome.
I can always switch if I feel like one has a benefit over the other.
Not an easy answer. I agree with everything said above.
Now, If it were me, I would try the steel if your plasma is fairly accurate, which they usually are not. Some of the stiffness comes from a tight fit. I do think I would trade some acceleration for a little extra mass. Mass can come in handy for large long cuts, if you are doing smaller things or a lot of Carving you do not want that mass.
Unfortunately everything is a tradeoff.
I built both of my mp3dp v5’s with acrylic instead of aluminum because it was 45 minutes of cut time instead of hours. The only part i plan to swap for aluminum now are the x mounts. Because you have the option for either, you can try one and if you are not happy with it for whatever reason, you still have options. If you were nearby id be asking for the steel one…. Wanna be my friend? Ill cut you some acrylic.
Machine mass is like salt in food. It’s easy to add more, but difficult to remove.
mmmmmm salt