aluminum extrusion

[georgebarr]

This is about aluminum extrusion information. I looked into the cost of using aluminum extrusion to build a CNC and found that ITEM Int'l (itemamerica.com) cost between 20-40% more than 8020.net (or futura ind.) cost. However, ITEM has more parts and accessories and is considering as being better in quality and etc. Essentially, ITEM is better in qualify and selection, but 8020 is better in cost savings. My plan is to buy the aluminum extrusion beams from 8020 since it cost less and buy the accessories (e.g. bolt joining accessories, etc) from ITEM. Does anyone know if this can work? That is to mix and match from two different manufacturers. This is of course verifying that the aluminum extrusion beams are of exact (or close to it) dimensions. I believe I read about mixing and matching from alt.machines.cnc but would like to ask anyone here. My first CNC project became a little more difficult since I am trying to optimize performance with saving cost which requires a good balance between performance and cost.

Thanks,

[Klox]

My experience is that extrusions are usually quite accurately made. I don't see a problem, to be honest about the mixing and matching of 2 different manufacturers... i don't know.

Klox

[coherent]

Most all of the aluminum extrusion manufacturers have specifications online or a downloadable catalog or cad drawings of their products. I was thinking doing the of the same at one point and as far as I could find out, most are exactly the same dimentions. There was at least 1 or 2 I found that had better prices on the extrusion itself than 80/20, but I don't have the links handy.
-Marc

[Zephrant]

I came to a similar conclusion regarding prices, but did not find anything that I needed that 80/20 did not have. Of course I will only using their extrusions for the frame, and not as linear slides.

Which parts did Item have the 80/20 did not ? Maybe I missed something I need.

Zeph

[georgebarr]

Any links to cheaper aluminum extrusion is appreciated. The ITEM extrusion catalog had many accessories to build things like cabinets, desks, office cubicles, etc. The numerous accessories that ITEM has shows how versitle their items can be used to build all sorts of things and I heard that they continually add new products. They have linear bearings, proximity switches, etc. I would say ITEM is the leader in extrusions. However, I found that their prices are 20-40% more costly. Instead, I can buy the basic 8020.net stuff and save on shipping cost by picking it up myself at their local LA branch office. The disadvantage is ITEM only sells metric and no fractional sizes. I plan on buying almost everything from 8020.net. There is a "bed place" that ITEM has that 8020 does not which can be used for the top XY table which is nice. Item has this nice fastener that screws inside the beam which requires no holes being drilled and looks better since it is hidden inside the extrusion and does not show. One plan is to buy 2" length samples of each beam I plan to buy from both 8020 and ITEM to make sure their dimensions are a match and buy a couple of ITEM accessories to make sure they work on 8020 stuff.

[kdoney]

I have mixed 8020 with Tslots extrusions and had no problem. www.tslots.com is even less expensive than 8020. There prices are online too.

[Max]

I'm using 80/20 with good results.
The only problem buying any extruded aluminum framing is it's weight and if ordered in long pieces ... the cost of shipping (ouch!)
BTW, I'm building a hot wire machine similar to croma and megablock's
I hope to have some pics in the near future on a web site.

I'm also experimenting with 80/20's linear bearings (catalog pgs. 300 - 320)
Anyone have any results/exprience with using them?
They also have wheels that ride in the t-slot.

Here's a link page for various aluminum extrusion supplies
http://www.robotics.com/framing.html

[kdoney]

When I tried the 8020 aluminum bearings I had to use two of them since they are sloppy parallel to the bearing face (like a lazy susan). If you use 2 bearings 90 degrees off ( say one on top and the other facing out) and tie them together they are very tight until they wear too much. I'm still using the first set but I don't do much work (almost none) on the router.

[Zephrant]

The prices I saw made Tslots identical to 80/20. Since Tslots is obviously copying the 80/20 design, I would expect them to attempt to be cheaper.

???

Zeph

[kdoney]

I've always found tslots to be cheaper since I can get a discount (about 15%). What distributor are you using?

[georgebarr]

kdoney,
How can you get a 15% discount at tslots from their normal prices? Do you have to ask for the special discount? How does it work?

[georgebarr]

This is about the linear bearings from 8020 which uses the UHMW stuff. I posted a question on deja.com and the replies are this. They said it is subject to distortion under load, the slides will wear so you have to replace them but since they are cheap it should be ok, and does not have high accuracy. It seems that people instead use THK bearings instead of UHMW bearings. Also, you can buy shims to make the fit tighter, however the slides will move slower. See the discussion at:
http://groups.google.com/groups?hl=e...om%26rnum%3D10

Thanks