Bolt spacing on THK rail?

[samualt]

I have a 8 foot THK rail rail I'm mounting. The rail is being mounted on 80/20 extrusion. I'm drilling a hole all the through and putting a washer and lock-nut on them. The spacing of the bolts from center to center are 80 mm (3.1496063"). So, does it really need that many bolts? Wouldn't it work just as well putting a bolt in every-other-one? I mean, the rail is steel and isn't going to flex much between bolts if placed every 6 inches...right? Or , is it critcal enough I need a bolt in every slot?

[High Seas]

I can't say how critical it is - But how are you mounting to the 80/20? Drilling into the 80/20 itself? I built (well - hired it out) a set of drilled and tapped rails to slide inside the 80/20 slots and then screwed the thk rail to that. Worked sweat as -- for making parallel adjustments - and I can always reuse the 80/20 as its not full of holes!
Does that help? BTW I did every other hole when I installed the rail - but my longest piece is only 36 inches. AND I do check it every so oftenm to make sure the bolts are tight - guess one day I'll usre that LockTite I bought too.

Jim

[samualt]

Well, it's 1.5"x3" x 10' extrusion. It's laying flat, not on it's side. So, there is no groove for the rail to slide-in. I'm just drilling holes through it. There is no point in tapping the extrusion because it is kinda thin in profile. I have allot of bracing to work around also (because it's on it's side). I think I'll skip every other one and see if it works.

[High Seas]

Yeah - maybe I confused you - or I'm confused??? My 80/20 is also 1.5x3 and is sitting 3 inches tall - the slot on the 1.5 inch side is what I slid the Tapped rail into - Does that make any more sense? Even if it was an the 3 inch side there are 2 slots you could pick from. Here's an idea - check out the Member'sGallery - look for the System2_router_close_up, under High Seas - maybe a picture is worth a few words. You can see (well just barely) the tapped rail thats in the slot and the rail on top. Else I'll have to wait for a picture of yours to better understand - No worries!
Jim

[samualt]

I have looked at your pictures a million times! You have a beautiful router.
I know the extrusion is much stronger on its side, 3" tall. It holds weight better with no deflection. But my machine just didn't work out that way (I did add lots of supports though).
My bearing-blocks are 3" wide , and the rail is laying flat so it's 3" wide (laying flat so it is 1.5" tall). So I decided to mount the rails right in the middle for esthetic reasons (I suppose it's the artist in me just screaming to get out!) It just didn't look right unless it was symmetrical.

I'll post some pictures in about a week.

[anoel]

I think the hole spacing is 60mm on most but you might want to measure yours just in case.

[Cold Fusion]

Mine is 60mm and for a couple weeks I used bolts on every other hole with no problems.