Using iron angle bar as rail
Hello, newbie here want to make a personal project using GRBL. This is my first project on CNC and would like advice from you guys if is it ok to use angle bar with 3/8 v groove bearing as rail for x and y axis. Googled v groove with angle bar rail, but no luck.
Thanks..
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Re: Using iron angle bar as rail
Hey Alison, I just asked something similar in another thread. Feedback I got so far is that v groove on angled bar isn't as good as there's too much play possible and alignment is more difficult. Just to be clear when I say angle bars I mean 45 degrees profiles, is that what you meant?Originally Posted by alixson
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Re: Using iron angle bar as rail
Yes. 45 degrees profile. Any suggestion for rail? bcos i've already ordered 3/8 v-groove bearing.
Re: Using iron angle bar as rail
You'll find plenty of people that will tell you not to, but you'll also find many people that have done it.
Your first machine will be a learning experience. Build it, and see how it works for you.
Gerry
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Re: Using iron angle bar as rail
word, that's why in the end I'm sticking to skate bearing rails, it's something I wanna try even if eventually I upgrade to SBR rails.
@Alixson, if you decide to go with it I'd love to know how ti works out for you, I'm just starting my own first build and it'd be great to compare notes. what's the rest of the machine going to look like?
Re: Using iron angle bar as rail
Im not finished yet with the rest of the machine. This is how I plan to use it 45 degree angle bar and v-groove bearing.
Re: Using iron angle bar as rail
I searched for it as V-groove track, found some stuff. What about something like this? https://www.ebay.com/itm/131898162874
Re: Using iron angle bar as rail
@jo_ky, I had done a similar search, but I could only find the same exact piece you found which is expensive as hell ($48 with shipping). For that price you can get an entire rail v profile ready to go instead of just a bar to attach to something else. This is $16 from the openbuilds store for 1m + $5 shipping, way better than that ebay piece: http://openbuildspartstore.com/v-slo...0-linear-rail/ . In fact for that kind of money you can almost buy an SBR rail... so yeah, not worthy imho.
Re: Using iron angle bar as rail
It's not a bad price for hardened steel with the tolerance rated (V-groove is not just a low cost approach - for some applications it's much preferred to round rod or profile). But yeah. It looks like this is the website: v groove rail
The aluminum rail + delrin wheel option sounds interesting. If it ends up being steel angle, be prepared to do prep. I think you can flatten that out with emory cloth and some effort.
Re: Using iron angle bar as rail
One thing to realize here is that you are really looking for 90 degree solutions. Once you realize this other options pop up. One of these options is to buy square steel bar and use that instead of angle iron.
So you may ask why square bar, well it can address some of the issues with trying to use Angle iron. With Angle uron you will struggle to get the two tracks parallel and in the same plane. So on an axis with two linear rails you only have to worry about getting the two rails parallel and in plane. Drilling mounting holes will be a pain as you will likely need to drill from corner to corner. Even with mounting though you have options.
These rollers arent ideal when it comes to lateral stiffness. It might help to add rollers at 90 degrees but this isnt trivial to get right.
If you are wondering about the two tracks you need a way to keep the rollers from lifting off the tracks. This usually implies a set of rollers under the first set designed to pull the assembly togther under load.
Do realize that your tracks of soft metal will wear. Most angle iron is relatively soft but that is variable. Common bed rail though is often pretty hard. Ive seen some synthetic rollers that supposedly helps with this. Wear will happen even with the factor specific tracks designed for these bearings.
These bearings are at best light duty and maybe not the best thing for a router. Great for laser and plasma tables where little in the way of reaction forces happen.
Re: Using iron angle bar as rail
I studied the v-wheel, skate bearing rail designs quite a lot in deciding what I wanted to do in building my DIY machine. It's rather sexy to completely build everything including the rails. I decided against it and went with SBR16 rail. Reason one, keeping the bearings aligned and tight against the rail, and two...the number of parts required. You always have to have some scheme to keep v wheel or skate beaings aligned and tight against the rail. Also, it seemed to me that there were quite a lot of parts to have to build to accomplish the rail design which, in my mind, would cause the build be more complicated, costly and time consuming. Complexity in design would also play back into reason number one.
Implementing the SBR16 rail was so much more straight forward and there's just a couple of adjustments needed to take out any slop. My next build will include profile rail...even better!
Re: Using iron angle bar as rail
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Just to be clear, because I really dind't communicate well in my last post, this will not work well at all. You need a solution that prevents the roller mechanism from rising off the rail. At least in a CNC router you do as there are forces acting on the gantry that will twist it, rotate it and otherwise cause the bearings to lift off the rails. This is why I suggested in another post that SBR rails are not really all that more expensive to buy. The only way you can really do DIY linear bearings well is to have access to a shop already or to buy a solution. Here is the thing, you will need a mechanism that preloads your bearings against your homemade rails. This will have to be a heavily spring system because the likelyhood that your rails will be 100% parallel is slim at best and the bores for the bearing will most likely never be on centers to the point that adjustment will not be needed.
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