18x18 Linear Rail Tormach Build.

[nateman_doo]

Its been a while since I have been here so I figured I would start posting some pics of the linear rail machine I have been building. Maybe with some motivation (and input) from the community I can finally finish this build I have been working on for what feels like years.

The frame for the machine is 4 x 4 feet. The actual table will be 4 feet wide by 3 feet deep.

I used 3" aluminum I beams (which I just found out are warped) and some 8020 2x4 main beam which I filled with four pieces of 0.5" rebar and 10 lbs of concrete poured in there. It feels like it weighs 50 lbs now and seems unearthly rigid. There will be somewhere on order of 1000 lbs on the table, so I think it will hold up pretty well. Each leg will support 250 lbs, and the rear 8020 which is anchored to the foundation will support the other 500 lbs.

Here is the basic frame:


I made some custom Gusset plates for the 2040 because I couldn't find any anywhere. Let me know and i will post the DXF if anyone wants it.

Unfortunately I found out that the I beams are warped:


I put them down on a granite surface plate and put a level on top of them to show the company I purchased them from how messed up the lot was. They intend to file a claim with the carrier saying it was warped in transit. I just don't see the old UPS guy bending I-beams all Hulkamania style since he is to lazy to even take them to my front door. New ones should be on the way, so the company did OK in my book.

Here is the layer of wood which will be the "underlayment" for a concrete pour:

1.5" of MDF (which will be waterproofed). A 2x8 frame will be boxed around to hold the 10 or so bags of concrete and probably a few threaded rods to keep the generally square shape. 800 lbs should do a wonderful job of dampening for the relatively light machine work that I do.

Feel free to SUBSCRIBE to the thread and watch me learn all my lessons the hard way.

[keebler303]

Could you shim the i beams at the bottom to get them close and then skim the top once the machine is running to get it true?

Looks like a beefy build
Matt

[SCzEngrgGroup]

ANY extruded aluminum piece is going to have very significant dimensional variation, and the larger it is the larger the variation. Things like I-beams are never intended to be "precision" components. If your design depends on the beams being dead-straight, then you've got a serious problem. You will also see VERY significant dimensional variation with changes in temperature, as aluminum has a very high coefficient of thermal expansion, and will expand, and contract, and twist all over the place, even with relatively small changes in ambient temperature.

Regards,
Ray L.

[packrat]

ANY extruded aluminum piece is going to have very significant dimensional variation, and the larger it is the larger the variation. Things like I-beams are never intended to be "precision" components. If your design depends on the beams being dead-straight, then you've got a serious problem. You will also see VERY significant dimensional variation with changes in temperature, as aluminum has a very high coefficient of thermal expansion, and will expand, and contract, and twist all over the place, even with relatively small changes in ambient temperature.

Regards,
Ray L.

Not to mention that they are not good from a "torsion resistant" point of view.

[FannBlade]

I will be watching. I love these types of builds.

[nateman_doo]

Thanks! I wasn't looking for "precision" I-beams, just something I didn't have to over torque screws from the I beam into the wood. I was hoping they would sit flat, and cost less then more 8020 extrusions. The only decent priced extrusions that came in bulk were 40x40mm.

I have most of the table completed, but I still need a way to figure out the motor mount/ball screw/dbl nut situation.

[nateman_doo]

While waiting for the new I-beams I did some leveling, and replaced the slotted screwdriver bolts with socket cap screws:


The leveling results:
Front


Back:

Not sure how "off" the back one is since there is no markings. Debating upon leaving well enough alone, or trying to fix that half a degree or whatever the interval off it is.

[SCzEngrgGroup]

If it makes you feel any better, you'll have at least that much error (probably considerably more) front-to-back, due to thermal expansion.

Regards,
Ray L.

[nateman_doo]

heh... thanks. The basement stays cool year round (obviously more so in the winter).

I just figured trying to level it wouldn't be a bad place to start. I-beams should be arriving this week (I HOPE?!)

[nateman_doo]

new beams arriving friday. Just in time for me to not be able to touch them over the weekend.

[MichaelHenry]

Interesting build approach.

How will this be similar to the Tormach mill?

Mike

[nateman_doo]

Interesting build approach.

How will this be similar to the Tormach mill?

Mike

Because I am using a Tormach V770 Milling head.