I want to DIY.. some questions please!

[Tenson]

Thanks I rather thought it might be the case, though good to know open bearings on supported round rail are not a no-no. The HiWin rail is okay priced but the bearings seem a bit steep. How about other brands? RS Components sell one called IGUS DryLin T which for 300mm is quite affordable (GBP14 rail, GBP16 Carriage, I can't do the pound sign on this Korean computer) but doesn't offer longer rails. There are many other brands too.

[Tenson]

Hi Guys,

I got some SBR rail from CNC-4-U with open bearings. The bearings look like they are normal ones that have been cut open. Is this normal? They also have little grub screws in the top that hold the bearing in and when tightened up they close the bearing up on the rail a little. The motion was a little jerky at first but after a quick sanding of the cut endge of the bearing thye are smooth now. They seem a bit home made. Should I be sending them back or are they okay?

[Jonathan]

They seem a bit home made. Should I be sending them back or are they okay?

That's perfectly normal. Same as you'd get from linearmotionbearings2008 on eBay. I ordered some recently from china (not for myself I hasten to add!) and they came in less than a week. The're essentially the same except the grubscrew is now on the side of the bearings, not on the base.

[JAZZCNC]

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.