I’ve done a lot of searching and just want to get clarification.
I’ve seen some posts where they recommend 1" Outer diameter with a 0.65" ID for stainless, I’ve also seen others recommend something with a thinner inner diameter, and conversely others stating a thicker wall would be even better, indicating a larger ID would be best.
I guess I’m just asking what the latest recommendations are for:
To start, it’s not 0.65" inside diameter, it’s 0.065" wall thickness. With a fixed outside diameter, a larger inside diameter has thinner walls, which is cheaper and lighter but also weaker.
Thicker will be stiffer but it’s diminishing returns. It’s just one of several parts that can deflect, and beyond a point there is no benefit in stiffer rails but there are downsides. Stiffer tubes are heavier, which can make the machine slower because the maximum acceleration without missing steps is lower. Lower feedrates can in some cases also shorten tool life and perform generally worse.
By the time the whole thing is built, the price of increased wall thickness is not that much higher. To me it seems the 0.065" recommendation is not simply a tradeoff between price and stiffness. It’s where stiffness is not really improving and the additional weight (and cost) are not buying anything.
This balance can also be influenced by the build size. Larger machines incur a stiffness penalty that’s larger than the weight penalty, so thicker tubes could make a difference. Smaller machines are stiffer to start with and thicker tubes might offer nothing but downside in weight and cost.
For the most affordable I wouldn’t go below 0.065" but you could get mild steel (non-stainless) and keep it dry. For extra stiffness you could get stainless with 0.12" wall thickness, and while you might never see the difference, you can sleep well knowing that the rails are not the limiting factor in the overall system stiffness.
Jamie that was very well said, thank you. I might need to link that somewhere (linked on the parts page, thanks!).
The bearings have a crazy high point load on the rails. Stainless is a bit harder and rust resistant, for those reasons I chose Stainless. Usually it is not all that much more, if you want to try it the other way It will work, but stainless is a bit better. That might seem like a bit of a half answer but we have no idea how big your build will be, what you plan on using it for, or your expectations.
Yikes. To give you an example, my local metal supplier has 1" 0.65"wall, Stainless-Seamless in 20ft length for around $50. More than enough to do a machine that size. Will Call MOQ of 1 piece (e.g. you must buy the entire 20ft).
I’m from Brazil, and down here I can’t find this OD tube with 0.065" wall thickness.
I have some wall thickness closer to this here, and I’d like to have some tips on which one will be better to follow with this project.
I can buy the 1" with 1,5mm (0.059") wall thickness OR 1" with 2mm (0.0787").
Fala Denis. Ainda nao, no momento eu tenho 2 MPCNC uma com conduite e a outra com 0.065" (1.651mm), Aqui no US e dificil achar tubo de 2mm e tambem tenho todos os componentes para montar a LR o que está me faltando e espaço na garagem. lol
A ta explicado, por isso vc consegue ter o tubo de 0.065" hahaha.
O que você acha das MPCNC? Vale a pena?
Eu foquei na LR por conseguir fazer algo com uma área maior e me pareceu ser mais baixo custo…
This is not what I expected my first post to this forum to be.
I would also like some clarification regarding the tubing requirement.
I think I’ve just ordered $150 worth of useless tubing.
The link on the lowrider-parts page points to “(Online Metal Supply 304 Stainless Steel Round Tube, 1/2” OD x 0.028" Wall x 72" Long, Seamless (3 Pack)) Further reading indicates 1" OD tube is required.
If the link to 1/2" tubing is wrong, I would suggest removing or better correcting it.
If the link is correct, I guess I dodged the bullet.
Ouch… Save your receipt. That is an unfortunate link, as it’s just an example of SS tubing, and not the actual tubing you need, which is linked in the BOM above the link you followed. @vicious1 or @jeffeb3 or someone with the proper skills should either change that link or at least make it abundantly clear that it’s not the actual BOM item.
I’m really sorry that this is your introduction to the community, but like in The Money Pit, your Low Rider build has been pre-disastered!