I’m getting ready to start my MPCNC build, I’ve decided on a 24" x 36" work area with a 3.25" z height. (Will shorten to 24" by 24" if I find it’s not stiff enough.) So that’s 281" total with kerf. Decided on D.O.M tubing because it’s apparently stiffer than SS as well as cheaper. I know this topic has been discussed ad nauseam, but where is everybody sourcing their tubing? I’m getting quotes of $200+ online, got a local quote (via email) of $270 from Metal Supermarkets. Is the secret to get the quote in person? Are these late pandemic prices?
On the topic of print material, has anyone had good luck with PETG? I really want to avoid printing in PLA for a number of reasons, first and foremost because the fumes from printing with it make me feel nauseous and sick / irritate my eyes and sinuses. (Unfortunately I share a 500sqft space with my printers.) My machine will be, at times, exposed to sunlight as well as heat from plasma cutting. Also saw some reports on this forum of PLA cracking from fatigue, which could be avoided due to PETG being more ductile. I will be cutting wood, metals, and eventually plasma cutting, but I’m ok with mediocre results when machining metals. With the dense infill, wont the PETG parts be pretty stiff anyway?
I work for a company that sells structural steel, and the “guy walks in off the street” price for a 20’ length of 1" tube is about $20. I bought 2 in order to build my MPCNC about the same size.
The downside is that we don’t cut it, so I cut to manageable lengths with a hacksaw so that I could put it in my car.
Aside from that, even in DOM there are differences. You don’t need the really spendy stuff, 0.065" wall tube is going to be fine.
As for PETg, it’s more flexible, which does mean less rigid. For a Primo that size, you’re going to get some effects in the result.
Odd that PLA fumes affect you so much, usually PLA is one of the less nasty thermoplastics to print. ABS is notoriously bad (Don’t print an MPCNC in ABS!) PETg is probably the closest acceptable substitute. Still, a Primo that size is going to struggle with metal, no matter what, and PETg isn’t going to make it better.
The printer is 3’ from my laptop which doesn’t help. Once I tried PETG for the first time I never went back to PLA. Bed and layer adhesion is excellent on PETG as well.
I priced out the JEGS stuff, they only had 0.120 wall and it was around $250 shipped for the amount that I need.
I put together a cart with approximate lengths of 0.065 wall that I will have to cut down to size (better than paying to ship 8’ lengths) and the total cost delivered is surprisingly only $129.83
If you live in the areas Rural King is at, they have dom in the welding supply section. That’s where I got my tubes for my mpcnc. They don’t have lengths long enough for a full sheet lowrider though.
This is a general rule of thumb. My biggest recommendation is to get on google, do a search for “steel tube” and call/email each place in the area for a quote on both DOM and Stainless (you can tell them you want what is cheaper) make sure to tell them acceptable wall thickness and that welded SS is fine. Also ask them how much extra it would be to have it cut to length (some places do it for free others charge a hefty price).
I say this because I got 7 quotes from suppliers in the area and all but 1 where ridiculously expensive. The one reasonable quote I got was actually for SS, when I asked about it. They said their SS pieces where cheaper because they use large volumes of 1"SS and very little DOM so they could pass part of their bulk discount on to me.
Depending on where you live you can also check other kinds of stores. Boat supplie stores often carry 1" SS, it is also used regularly for roll cages on ORV/racing vehicles.
edit: I will also note that the best price came from a small, localy owned, metal supplier and scrap yard. So don’t just look at the big names with fancy webpages. Only thing your out by asking if a shop has it is a 5 minute email or phone call (and if it’s email you can make a form letter and just copy/paste )
Got some more quotes today, all were well north of $200. Checked the websites of a couple boat supply shops and their SS was fairly expensive and looked like it was available online only.
Decided to go ahead and order my tubing from stockcarsteel.com instead of dealing with the hassle of tracking it down locally. Specified slightly longer lengths per cut of tube to make sure I don’t end up a few mm short due to cut accuracy. Here’s the price breakdown:
Subtotal
$61.32
Shipping & Handling
$42.33
Extra Fee: Surcharge (tubing over-length fee)
$15.00
Total
$118.65
No tax! I think this price is reasonable considering my time and the aggravation of Seattle area traffic. If I was building a 24" x 24" machine the total would be only ~$92 delivered!
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