Linear bearings

[EricW]

I'm making a new router bridge that, in theory, gets me accurate and repeatable cores. Something that has eluded me so far. Found some poor mans linear bearing that have the added benefit of being able to cope with elevation changes on the rails.

My last one was made of wood and that would be fine if I had Pat Warner's abilities but I don't. Still working on how to actually get the rails to adjust properly. I may switch to round steel rather than aluminum angle. The frame it all sits on is 2x1 and 1x1 steel. Hope this is an idea someone else can use.

[Richuk]

Well done with the bearings!

I'm not sure you are going to get the AL angle to provide the results you require ... you may find that they twist when pushed up from below, especially as you will be pressing down from above.

You can make accurate rails using a strip of wood screwed to mdf. Pass the mdf through the planner on their edges before marking out using a pair of calipers. The bearings won't be wasted, as they will ride the rail and orientate the carriage within the vertically mounted rails.

Hope this helps.

[EricW]

The aluminum angle was just handy at the time. I'm going to use round steel with threaded rod verticals. Thanks for looking out for me though.

[gav wa]

The round rod will work great. The ally angle won't allow you to get good adjustment. You need your table made pretty solid as the load you impart to make the rod bend to your profile can be quite high and I have found it could pull my vac table set up out of shape.
Save the ally angle to make your bridge.

[/img]

This is my set up. I used 8 X 40 flat bar for my rails so I could fit bearing top, sides and bottom.


All very similar to what you have planned. It works great. Just remember that your bearings are following the rails not the center of the bridge so your profile won't be exactly the same as the rails.[/img]

[EricW]

I had not thought of using the aluminum for the bridge. I dig the idea. What to you have shimmed under your router to get it traveling smoothly?

[gav wa]

I used some basic PTFE Teflon sheet we had at work. We use it for cryogenic gaskets but its pretty common stuff and makes for a good slide surface.

[gav wa]

One other thing to be mindful of while you are building such a set up is how high your router ends up sitting above your table and therefore core. Do some sketches and measurements before you get too committed into a design or you can end up with your router quite high above your core and therefore needing quite long router bits.

[MadRussian]

One other thing to be mindful of while you are building such a set up is how high your router ends up sitting above your table and therefore core. Do some sketches and measurements before you get too committed into a design or you can end up with your router quite high above your core and therefore needing quite long router bits.

that's exactly what's happened to me. I didn't expect this problem. In the beginning I used extension router bit. In the end had to rebuild the table.
GW how you make adjustments? I don't see you have any adjustment points this way all components have to be made ABSOLUTELY PERFECT which is difficult to do without assess to machine shop.
building profiling table was most frustrating part of the entire project for me multiple times I was almost ready to give up

[MontuckyMadman]

gav and mad, a plunge router frame would eliminate this issue I think.

[gav wa]

MR - I just undo the bolts holding the flat bar down and I use washers to shim it up in the areas I want. Using shims makes it really easy to get both sides exactly the same.

I was lucky with my router height, a bit high but still usable.

[MadRussian]

@MM
I am using plunge router and it not enough of vertical travel. Basically it's all depends how high rails and bridge sets in relation to the table. My is quiet high. Even now for example bottom clearing router bit is too short.

@gav good for you. I was not that fortunate. Besides table height (which was not difficult to fix) shims method didn't work for me at all. I like your railing with flat stock, I tried it but unfortunately at the time it didn't work for me, I never thought of make the rails much wider. If I would do it again I would make a rails 1/2" by 2 to 3 inches wide flat stock mild steel.