Another version of the coholic table

[tlempicke]

After seeing Andrew Coholics table I decided that I needed one. I made a couple of changes and thought I would write them up in case anyone is interested.

Rather than the 5/16 T slot I wanted 1/4 inch material. The tracks come out to be exactly one inch apart, which makes a lot of things easier. I bought it from the 80/20 surplus store on Ebay. Supposedly it is cheaper than you can buy otherwise, and it is, by about 10 cents per piece. What really was a good deal though was the shipping. It was only $70 for two day UPS. Here is what I ordered. 8020 T Slot Aluminum Extrusion 10 S 1030 x 60 N.
Each piece was 60 inches long and cost $34.95. So the entire table, 20 pieces, 3 inches wide, was $850 delivered.

For the rail and bearings I found, again on E bay, an outfit with the name econvenience1986.
I am including their name because the two rails and bearings cost $270 shipped to me. It arrived in about four days and was shipped via Fed Ex for that price. What I ordered was 2X TBR16-2000mm 16MM SUPPORTED LINEAR RAIL+ 4 TBR16UU Router Bearing
The quality that I got was first rate.

The 1 1/2 by 2 inch angle came from Online Metals. http://www.onlinemetals.com

I sourced the hardware from McMaster Carr. Expensive(relatively) but fast and they do have the stuff. I went with all grade eight cap screws and elastic stop nuts. BTW do not buy T slot hardware from McMaster. I is a LOT cheaper on Ebay.

First step was to make up a drill jig so that I could use the drill press to drill the holes. Made out of scrap aluminum it is a three position deal. Drill the two holes in the center to fasten to the PowerStick, slide left and drill two holes, slide right and drill two holes. The only holes left to hand drill are the ones in the 1/4 thick angle that supports the rail.

I first mounted one piece of the Tslot to the PowerStick track. I then used a dial indicator to make sure that it was dead on parallel to the Y axis. See the picture. After that I re-mounted the indicator and used it to true the piece for flatness and tighten down the pieces that hold the bearings to the sides of the Buddy. Predictably the Tslot was drooping about 70 thousandths from the weight of the rails and of its own weight. I made up a jack out of a piece of scrap aluminum and a bolt to jack each side up so I could fasten down the bearings. After about 20 minutes of fiddling I got the slot within .002 from end to end.

To fasten the rest of the tracks I would move the X axis so that the Tslot being put on was just about over the bearing on that side. This way the bearing is truing the angle for me so that the Tslot is not exerting any force on the assembly.

I fastened down a piece of 3/4 inch ply as a spoil board. The first pass was at zero depth and it shaved a couple of areas of the board where it was a bit thick. The second pass was at a depth of .015 and I was rewarded by having the cutter make a complete cut with no voids at all.

First project was a plastic sign that was engraved .020 deep. Perfection!

This is a worthwhile project that will really extend the capabilities of your Buddy! Thanks Andrew!

[Ajcoholic]

Cool stuff

I am so very happy with my table - just so much better than the MDF I was using.

I am sure you will also appreciate yours, and the more you use it the more you appreciate the accuracy.

More photos please, if you get a chance.

[tlempicke]

Those were taken with a phone camera. Over the next day or so I will take a decent camera out to the shop and get some good photos.

[Ajcoholic]

Those were taken with a phone camera. Over the next day or so I will take a decent camera out to the shop and get some good photos.

Tom, I am seriously interested in your take on the table (more pics that is) if you are still able.

Plus I am sure more lurkers would like to see it as well.

AJC

[tlempicke]

Sorry about that. I got busy and forgot. Here are some more pix taken with a better camera.

[tlempicke]

Here are acouple more pix

[Ajcoholic]

OK now those are better Looks great! Your bearing blocks for the linear rail look like cnc machined bar stock - not like the plain Chinese ones I bought

So far other than that one bad bearing I had early on, things are working very well. I keep my rails clean (good dust collection and use compressed air to keep the rails clean each time I use it) and I hope they will last.

Cool table!

[tlempicke]

No they are just the plain jane chinese bearings. They certainly work well and the table is just as smooth as glass as it runs. I have in mind to put an oiler and wiper right next to each bearing but machining aluminum makes such a mess that I have not gotten around to it yet.

[tomkbud]

Tom, Andrew.....

They say that imitation is the highest form of flattery. Well, you both have inspired me to add an aluminum T-track table to my new Buddy Alpha BT48-12, very similar to both of yours. I am taking a slightly different path, since I also want to mount my 6" indexer parallel to the Y axis, and I want to be able to move the table between the standard powerstick and the 4 ft one (6 ft long) as I need it. I don't have room in my shop to keep the 4' powerstick on all the time, and most of my work will fit OK on the 2' x 4' standard space.

I also went with 8020 aluminum, but used 3075 extrusion (3/4" x 3", with 5/16" slots on 1.5" centers). I am fastening each of them to a piece of 1/4" aluminum 6" wide x 48" long, to in turn fasten to the powerstick under the extrusions. I used my ShopBot to create an MDF jig to square the extrusions with the aluminum plate. Since the tool created the 90, I know it will be dead on parallel to the Y axis when I mount it parallel to the powerstick. I bought the 8020 from the Amazon store, at a total of $596 for 16 pcs, 60 in long. I also got 1.5 x 2 x 0.25 x 4 ft aluminum angle for each edge. I bought 2 sets of 1450mm long 16mm mounted bearing rods including 2 sets of SBR16UU bearing blocks for a total of $200, from the Ten-High Amazon store.
I'm still putting it together. Lots of drilling and tapping. When I get a minute I'll snap some pics and post them.

One note: When complete my table will weigh a bit north of 125 lbs. I checked with SB tech support and they said they've tested Buddy's with 500 lbs on the power stick with no missed steps (on an alpha), so I should be good.

I just wanted to take a minute and thank Andrew and Tom and all that post on this great forum for my their inspiration and help with things like this.

Tom

[tlempicke]

Just quick follow up
Andrew discovered, and now so have I, that you need just a little flexibility where the linear bearings mount to the sides of the Shopbot. I am about to re-make the mounting plates for the bearings and make them a bit longer so that they fasten one notch higher up. This will allow them to flex just a little bit in the "Y" direction. Hopefully this will take some of the transverse load off of the bearings and make them last a bit longer.