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Discussion Starter #1 (Edited)
I'd like to make a jig for a router which will act like a cnc but would be operated by just pulling the router about by hand. I'd like something like this but a little bigger and with the horizontal rail also.

https://www.youtube.com/watch?v=bGbWBDtzydw

Im pretty sure I know what i'm doing in concept, but I really have no idea about the terminology of the parts or what bearing system to use on the rails is best.

Am I right in looking for linear bearing housing for the slider which sits on the rail? Is something like this right?

http://www.zappautomation.co.uk/en/...sbr20uu-open-linear-bearing-with-housing.html

I think ive seen some that have the bearings set up to twist and some to slide up and down a rail but im not sure what the difference in terms is for each? Is this the best option as far as smoothness goes, the ones in the video seemed pretty noisy which didnt seem great.

Perhaps this type is superior?



Thanks in advance.
 

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The ones in the video look like Thompson linear bearings I have worked on some robotics that use these , all they are is a several rows of ball bearings the rod has to be hard and polished. They are much smoother than they sound on video, but its noisy where they are located at work
 

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Old Methane Gas Cloud
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Doesn't Legacy make one? (I think that they are in Utah.) They were very popular exhibitors at the woodworking shows. However I think that their 48" unit was more expensive than a ShopBot.
 

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Discussion Starter #5
I seem to have found a bit of basic useful information.

Apparently the pole rails are easier to align properly, but can deflect a little more under load but not so much as seems to be a big deal with woodworking.

The square rails are stronger but a bit harder to get perfectly set up to enable smooth running.

I was thinking about using just plain steel poles that have hollow centres but looking at things now it seems the more proper way is to use solid bars. I wonder if you could fill a hollow pole with cement to give it more stiffness?

Unless I find otherwise though i'll most likely pay for the solid type, and go for the round bearing mounts as it should be easier for someone who doesnt know what they're doing too well.
 

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If you go to woodgears.ca and look up the buiding of the pantorouter you will see the section on making of the x y axis using full extention drawer glides tha would do what you are trying to accomplish. It is also low profile too. Good luck!
 

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Uberinkerer
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Thoughts

Shesho-
Just so I understand; you're basically looking for something to maintain the distance / depth of cut between the router and workpiece? Are you also concerned with locking one direction so as to allow you to swing a straight line with the router? (Lock the "x" axis so that you can route a line in the "y" axis? This is not an expensive or complicated modification to the 'machine' btw.)

Beware.. this is free thinking, and it's only worth what you're paying to read it....

IF the above is the case, you could build yourself an extended base for the router, and build a "hard" set of guides atop the workpiece. (Of course, this is highly dependent / limited by / on the size of the piece.) A simple explanation: a box without a lid, large enough to contain your flat workpiece. At the top edges of the box, add Teflon flat stock, so that the "skid" for your router slides. To adjust to different heights, make a second box without a top and bottom, just large enough to encase the first. Cut slots, and using thread inserts and wing bolts, build it so you can slide the outer box upwards and lock in place with the bolts. How to get it even? Just use the same thickness spacer under each corner of the outside box. You can also replace the Teflon sheet with a 1/4 to 1/2" diameter steel tube or rod (of course they don't couple completely in the corners,) routed into the center of the inner box side pieces. Ok... before I go off on how you can also add dust removal easily to this... I'll move on.

If you're looking for everything but CNC, then you have to go the route you're talking about. Check out McMaster-Carr online http://www.mcmaster.com/#linear-bearing-shafts/=mn8n1t for their hardened steel rod. I like this one in particular, because the support rail can be used with a riding bearing (you'd have to engineer, very likely,) to prevent perpendicular movement at each axis, among other things,...but it is pricey as heck:


By the way, self-built tabletop CNC is probably very near the point where the average guy can afford to make their own. I haven't done so yet, but between my knowledge of Arduino (programmable electronic modules) and stepper motors, I think the only thing left is checking through NutsAndVolts magazine online to see if someone else was successful yet... http://www.nutsvolts.com/
 

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Wood Snob
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I'm not sure what kind of work you will be doing on this and how smooth the bearings need to be but there are tons of them sold on EBay at greatly reduced prices.

I have used 8020 inc for all me woodworking fixtures and tools and found it all on EBay.

Friends don't let friends use stamped metal tools sold at clothing stores.
 

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