Sounds good, I'll think about it and rethink everything :)
@Wal: It works in SW :) I just didn't think steel was going to be that heavy x) Obviously this is due to the size of the machine, not much about the thickness of the steel. 1300mm Y travel implies at least 1700mm gantry width. Using 100x100x3 profiles will definitely be the key to lightness :)
Using 100x100x3 profiles will definitely be the key to lightness..Clive
It's nice to design somthing totally bespoke, never seen before and so on but I too really would encourage you to look at this from a different perspective, setting aside what the machine will look like cosmetically, I say cosmetically because we really can't see there is advantage to your rail fixture method and it's just going to serve you a handycap.
Yep, It's not just achieving the consistency in your method that'll give you a problem - the height of the rail will also depend on the torque of the bolts - as such it's going to make measuring for the ball-nut bracket fitment a real pain... You need to be designing around what you know - data that is readily available, not "Oh, I'll just put these rails in using the maddest method I can come up with and then see about my ballnut bracket later.."
Heh, the rails will probably resemble a roller-coaster by the time everything's torqued up anyway. Using this method the ballnut might just move smoothly along a couple of inches of track...
Honestly, don't pursue this inviable method..! It'll be a waste of your time and money. Enough said.
Last edited by Wal; 27-08-2015 at 03:04 PM.
Listen to the sound of bearings moving in this video:
It sounds bad.
Very, very bad.
I'm guessing this video or something like it is where you got the idea for DIY supported rails.
It is a bad idea.
Very, very bad.
The reason why everyone is giving you negative feedback is because it is a bad idea, so ditch it and move on. If it helps any, hiwin rails from hobby machines have a good second hand market value. When you outgrow your machine you can recover a lot of the price by selling them on.
PS I'm the resident village idiot, annoying people with my hair-brained ideas, even I figured out that DIY supported rails was a non-starter.
Hi ! Sorry for the late reply, I've been a bit busy :)
I hear you all, and I will take your advice. I know, DIY supported rails are not the way to go. I hear you. Even if this is not going to work, I think that the profile method was going to work, just not with steel, or made differently with short pieces. I think DIY rail is possible, but you need to get the supports milled from ALU or steel and then tap them. What I am just explaining here is that ROUND fully supported rails don't seem efficient to me cost / strength wise. I've run a couple simulations in SW and that confirmed my idea. You could semi-support a round rail with at least 1/2 of the material used in fully supported chinese rails. Of course, getting those parts machined may be expensive, unless you've got a CNC within hand's reach, or know someone that can get them milled.
That said, supporting the rails with bolts is a silly idea, I agree.
I requested a quote from my seller Kevin and from Fred at BST automation for SBR rails.
Kevin asks for $305, Fred for $345 ;)
Now ask fred if he can get any lower or at the least price match ?
That's an idea :)
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