slightly different idea for bearings as slides

[Darren_T]

I've been fiddling with some sketches of ideas for using the roller blade bearings in a slightly different way. I didn't want to have to machine any parts other than what I could accomplish with my woodshop tablesaw, bandsaw, and drill press.

Here is a sketch of what I came up with. Anyone see any problems with this design. It's just a sketch slightly to scale but not perfect by any means. It's just for concept.

I imagine the stock to be sheet aluminum either 3/8" or 1/2". The drawing shows 1/2". The top bearings are mounted at 45 degrees and the bottom bearing is on a sort of swing arm that is tensioned with two through bolts.

[HuFlungDung]

Hi Darren,

I like it pretty well actually. All the wheels should touch no matter what (within reason ) You should also be able to nicely regulate the preload of the trolley so it will roll just right.

Go for it.

[deft]

I've been thinking about the same problem.

I like your through bolt tightening system.

I think you would need to use 1/2" thick stock.

Cutting the miters on a table saw doesn't sound like fun...

if and when I get around to making a machine I'm probably going to use a variation of this method (see link)


http://members.shaw.ca/axxus/m1.htm

The hardest part would be drilling the holes 60 degrees apart and finding the right channel... The slots in the tube aren't critical so they could be drilled out and then filed...

[Darren_T]

Oooohhh. I like that Deft. It looks quite a bit easier than my plan too. I'll probably have to give both a try

Darren

[sol]

Good!... getting about putting pencil to paper; it is a start! My experience with a similar prototype that I made (and dismantled) was...having the tensioning bearing in the center between the other bearing-sets allowed a fair amount of rocking of the axis. When the bottom bearing was tightened to the rail enough to remove all of the play the bearings were loaded too tightly to roll smoothly. I then put the bearings all in the same plane or cross section and everything tightened up nicely. The result has been an X axis that rolls very smoothly with virtually no slop...all made on the cheap. Enclosed is an image of the bearing set I welded up and yeah, it is not of aluminum but I thought the cam tensioning system (a rod threaded off-center into the head of a bolt) was worth the show and tell. Oh yeah... and I left the bottom, rather than a side, open so that gravity was my friend when it came to loading the whole rig onto the rails.

Hope this helps!
Sol

[ehiebert]

I'm just curious why everyone is choosing the more complicated moving gantry designs over the moving table designs? Is space saving worth that much extra effort??



Eldon.

[High Seas]

I was wondering the same thing! Don't suppose its always been that way?

I expect the trade off (excepting floorspace) comes when gantry weight exceeds project weight! Is that why most vertical mills have moving tables? Or because they evolved from a drill-press approach? I don't know - I'm new to all this!

The gantrys I've seen, all have large endplates designed to elminate any "wiggle" as the gantry moves along the x axis. And, at least one member of the 'zone added cross members to his gantry to elminate wiggle along the y-axis.

Earlier a reference to a cnc router offered on ebay showed an approach, between moving table and gantry. The gantry moves but the rails for the x aixs are more or less "in-plane" with the y axis on the gantry. That seems like it could elminate some potential for "wiggle" - and still conserve floor space.

I'm trying out a similar plan in mine - I'll let you know how it goes.
Jim

[ger21]

Mines 5ft long, with 4 ft of travel, so yes, saving space is very important.

Gerry

[ger21]

Take a look at my design here

http://cnczone.com/showthread.php?s=&threadid=1356

It can all be done with a table saw and drill press and is very strong and smooth rolling. I built a wall mounted panel saw with the same basic design which has been working great for the last 8 years.

Gerry

[tekno]

Originally Posted by ger21 Take a look at my design here http://cnczone.com/showthread.php?s=&threadid=1356 It can all be done with a table saw and drill press and is very strong and smooth rolling. I built a wall mounted panel saw with the same basic design which has been working great for the last 8 years. Gerry

was doing a search and found this tread.. would like to see more but we have a link error. can someone help me out?

[jeffs555]

http://cnczone.com/forums/showthread...&threadid=1356

I have found that on a lot of the old links you have to add the /forums/ between cnczone.com and showthread.

[wjbzone]

I stayed with the fixed table because I did not want to limit myself on the workpiece length or weight. I've worked on the end of some long boards where I had to support the opposite end off the table.
Bill