Personally I hate these bearings they are rubbish.!
There hardly ever flat or square making mounting without binding difficult they go sloppy on the rail in no time, they wear like crazy if you operate them in any reasonably dusty or abrasive conditions.
Do your self a favor and save up for some real profiled rails or at least buy some decent bearings and blocks, to me it's just false economy because if you build a decent machine frame these will quickly become the weak link and you'll want to change them and it's not often a quick swap over job to change to profiled rails.!! . . Spending on profiled rails is one area where I promise you won't regret or begrudge the extra expense.
Hi Dean, I thought about profile and besides the cost, it seems like it would be more fussy about the surface they are mounted on. I don't have the ability to machine the mounting surface 100% flat, so I think the stiff supported rail will help there. I have to say I'm not very impressed by these bearings though. Can you recommend some higher quality open bearing for this type of supported rail?
I must say I'm starting to wonder if I will just use the unsupported rail. The bearings seem much smoother and tighter tolerance! It's all very well having stiff rail, but I can find some places on the supported rail where the bearing will wobble slightly side to side.
lol, you is crazy.
Pardon my French but it sounds like you bought shite.
I await your post showing pictures of your newly purchased profile rails
Said it before many times but If you want real accurecy and longevity then get rid and save for some profiled rails and don't even go the unsupported route because you will regret that path promise you that.!!
Mmmmm sower grapes me thinks????....I love my unsupported rail and never had a problem, maybe that is just me :-)
Reality is you get what you pay for in most cases, if you can afford profile rails and bearings then grab them first. If you can not then anything else needs to be as thick as you can afford to give yourself a chance.If the nagging gets really bad......Get a bigger shed:naughty:
After I looked more carefully at the parts I found one rail was strange, it seemed like it was slightly more narrow at one end because regardless of the bearings used, it was tight at one end and sloppy at the other. So it isn't the bearings so much as a strange rail.
I sent a short video to the guys at CNC 4 U and they called me back to say they are checking their stock and if others are okay they will send me a replacement, without me even needing to return the duff one.
I'm drawing up a plasma cutter with a 2 meter axis on the gantry and I want to use one profile rail, probably the 20mm.
My problem is the spec says they come in two flavours...
1: with slop to allow for slight misalignment between 2 rails.
2: with oversize balls to get a tight fit.
Zapp seems to sell only the sloppy variety and I can't afford twist around the long axial because the head sits quite far forwards, about 65mm ahead of the races.
My question is, how much axial twist do I expect?
Should I add a spring roller running on the rail behind to keep it in tension? That wouldn't be hard because I have to screw the rail from behind so there are no visible holes that might carry abrasive crut passed the wipers.
You can also get the flush plugs for rails mounting from the front and SBC rail might offer a few different options, then there is going over to traceparts and looking up the French/Swiss rails (not much different in price from Hiwin from what I have seen) and seeing what they offer as well. I need to look up th Italian firm that sells different types of rail on the per project basis as most want you to buy way to much. Good luck
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