Where can I find supported shaft?

[Cold Fusion]

I have been thinking about using 1 inch supported linear shaft instead of 1.25 end supported. The reason for this is that I think the 1.25 shaft will sag in the middle like Limbo's. Can anyone point me to a good site that has prices listed for pre drilled supported shaft?

[HomeCNC]

http://www.mcmaster.com/ page 947

[wakeboard]

Hey Cold Fusion i checked out the prices and i found out that for 48'' that price on the rail and support are as follows:

ALL THESE PRICES ARE WITHOUT GUIDE BLOCKS

6499K75 Hardened Predrilled Precision Steel Shaft 1" OD, 48" Length..........$137.59


6039K35 Predrilled Support Rail 48" Length, For 1" Shaft OD..........$174.77

also here are the prices for THK rails

6709K432
(Same as 6709K43)

20 mm Width, 1240 mm Length Rail For Versa-Mount Guide Block

$347.20 each
(1240 mm is a bit longer than 48 inches)


This concludes me to which is worth it? SPend the extra money for thk, for stay with supported....or don't go that route at all and go with normal unsopported rails(but form what i have seen they sag)...

[ger21]

If you're not in too much of a hurry, hang around Ebay until you find what you want. It'll save you hundreds of $$ vs new stuff. Also, a good alternative might these, as seen in another recent thread.
http://www.bwc.com/html/dualvee.html
If you must have new, also look at reid tool, http://www.reidtool.com or msc, http://www1.mscdirect.com/CGI/INSRBR.

Gerry

[BeerFizz]

If you are using rail which is supported along its full length, is it necessary to use rail as large as 1” diameter. There is a huge price difference if you go with ½ rail or even 5/8” rail. Perhaps someone out here that understands these things would like to comment

Phil

[limbo]

Cold fusion,

You already bought that 1.25' shafting and bearings I think? Would be a setback . Keep in mind that the supported rails dont eliminate the sagging by themselves, they need to be mounted to something very stiff, for instance thick steel square tubing.

greetings,
John

[buscht]

If you already have the round shaft. The issue is the bearing. The bearings for supported shafts have a cutout to clear the support.

If you have the right bearings, you might be able to use what you have and just make a riser under the rail to support it, just don't fasten it to the rail. 1-1/4" rails are pretty strong.

[Cold Fusion]

Actually I have not bought any parts yet. I found out that this guy can cut his 1.5 inch rods to any length I want for a fairly good price. http://cgi.ebay.com/ws/eBayISAPI.dll...category=11805

Do you think it would sag if I had 40 inch long 1.5 rods on the x axis with an aluminum gauntry and 9 pound router?

[buscht]

Look at page 139.

http://www.thomsonind.com/PDFs/Catal...ures/ALMTG.pdf

They have a deflection caculator for end supported shaft material. If you use their calculations and know your gantry weight and spread of your bearings, you should have no problem figuring this out.

If your application is just straight cutting and drilling then any vertical deflection isn't too important. As long as you cut through your lexan, it doesn't matter if the router cuts .02" past or .01" past.

Good luck
T

[limbo]

On my gantry most of the weight comes from the rods and (steel) bearing blocks. These alone are increadibly heavy. It should be possible to build a much lighter gantry, for instance with rails mounted to an alu plate or profile. Somebody even pointed me to a good quality steel tubes. The ball bearings run smoothly on them, so I could use them for Y and save a lot of weight. Would stay with solid rods for X.
As Buscht said: sagging is not always a problem. I hardly notice it anymore. The table the machine sits on is less straight. I imagine the 1.5' bars to be much stiffer than mine, they seem to be not hardened too.

[CNCadmin]

Here is another source- http://www.nookindustries.com/linear...Assemblies.cfm