my router build - advice needed

[JAZZCNC]

Regards unsupported rails and so on. What I learnt from talking to Brian is that its a matter of horses for courses. Supported profiled rails with carriages offer greater precision than unsupported round rails but the lack of "give" in such rails and carriages places a lot more empathsis on a precision build, a tiny mis-alignment or deviation from parallel can result in resistance which can slow the machine down or worse. For my large router bed I choose to go the route of supported profiled rails with carriages but I can see that a future project planned for a plasma table would ideally use a rail set up more similar to yours.

This is very true regards alignment of profiled rails but there's more to it than that really in real world use.! And the Horse's for course's only applies to a point.??

The main problem with the Cheap round rail bearings, whether that be supported or unsupported is the quality. They are very poor and soon become sloppy and inaccurate when used in moderately harsh condition's, often needing regular or constant adjustment to keep good accuracy.
Now has you say horses for courses can apply and for DIY level routers they are Ok to a point but in the long run they are More trouble some and Far far less accurate then Profiled rails so if your wanting or looking long term and accurate then it's worth spending the Money and slight extra care that's needed to use Profiled rails.
For Machines like Plasma you'd say Unsupported are fine because there's no Cutting forces involved but Again Plasma can give off very Harsh dust that will Kill the Cheap Bearings in short order so it would be false Economy and more hassle in the long term.!!

IMO and experience the Round rail are just not worth the Hassle and for just a Few dollars more profiled rail turns mediocre machines into Proper machines. This is also reflected in the Re-sale value.! They add far more Value than the sum of there parts and make the machine that much more appealing and sell-able.!!

[jonnie]

For Machines like Plasma you'd say Unsupported are fine because there's no Cutting forces involved but Again Plasma can give off very Harsh dust that will Kill the Cheap Bearings in short order so it would be false Economy and more hassle in the long term.!!!

Point taken regards dust from plasma but I would not undertake a plasma build without isolating the rails from dust, not only that I would also isolate myself from dust/fumes since (dependent on metal) these byproducts are not very nice for the lungs or general health either. I would follow advice regards rail choice from more experienced builders but at the same time I would always strive to isolate rails as much as possible from dust of any kind as I dont think that bearings and dust are great bedfellows period - ok metal swarf may simply be pushed along as the vee ways on my old Boxford demonstrate but instinctively I would not trust any linear bearing against the ingress of plasma or wood dust without secondary physical isolation.

Thanks jonnie

[JAZZCNC]

I would follow advice regards rail choice from more experienced builders but at the same time I would always strive to isolate rails as much as possible from dust of any kind as I dont think that bearings and dust are great bedfellows period - ok metal swarf may simply be pushed along as the vee ways on my old Boxford demonstrate but instinctively I would not trust any linear bearing against the ingress of plasma or wood dust without secondary physical isolation.

Yes that's good and should if at all possible be done but no matter how well you ventilate or try to protect them there's always a certain amount of dust that gets on the rail and my point still stands in that the cheap round rail bearings can't handle it for very long before getting baggy and sloppy. They wear quickly enough with wood dust but with fine metal powder dust they will run for the hills very quickly.!!

Profiled linear rails have Wiper seals built into them that greatly protect the bearings, infact they are similar to the V wipers on the Boxford (I have one too) but much better. When you experience profiled rails you won't ever build another machine without them.!! . . . . I won't entertain building machine using Cheap Round rail anymore has it's more hassle than it's worth.