Welding Plasma Table...

[tof1]

I'm getting ready to weld my plasma table (5' x 10'). I wanted to ask if it would be a bad idea to weld the table with the linear rails and gear rack pre-installed to help prevent warping? Or would that just tweek the linear rail as well? The steel tube that the linear rail and gear rack will be mounted to is 2" x 6" x 1/8".

[DISCONNECTED]

I would not weld the frame with the rails installed.If the frame warps you will ruin the rails.Rails could always be shimmed later on if your frame warps.Make sure when you weld you always get every thing squared and tacked.Then add (in welding terms) a strong back to the corners.The more bracing you have on corners the better.

[tof1]

Good point, that's what I was worried about. I just don't want to spend all that time drilling and tapping 150 holes and then not being able to get them lined up. Are you saying use clamps after getting the table squared or actually welding the back side?? Any tips to avoid warping? Thanks!

[DISCONNECTED]

Anytime you weld something shrinkage will occur.If you brace the corners by tack welding a sturdy pieces of angle iron you will help keep things square.Also the weld sequence is very important.You do not want to much heat in one area.Jump around, do not weld one complete area all at once.A common welding rule is to weld from the inside out.

[Dustin407]

Tof1,I understand your problem.. What if you weld up the table, then the 2 x 6 that the rails are mounted to leave unwelded. You can bolt the 2 x 6 to the welded frame below, this will allow you to take both the rails and tube and put it on the mill... The only problem with not welding the 2 x 6 to the rest of the table is, does your design allow you to do this?

[tof1]

Tof1,I understand your problem.. What if you weld up the table, then the 2 x 6 that the rails are mounted to leave unwelded. You can bolt the 2 x 6 to the welded frame below, this will allow you to take both the rails and tube and put it on the mill... The only problem with not welding the 2 x 6 to the rest of the table is, does your design allow you to do this?

That's a good idea but I think it would complicate things. The 2x6 rails will be on their sides (2" wide, 6" tall). The only way warping from welding will throw me off will be if the rail bends in a U shape on the vertical axis. I couldn't see that happening... I'm thinking it will only warp on the horizontal axis (if at all) then I can use shims like Disconnected was saying. What do you guys think?

[millman52]

I was afraid of welding the corners together on my table. Below is a pretty good pic of what I done. I figured I could shim the corners if needed. What I actually did was bolt it together, then X measure from corner to corner. I was off just a bit so I temped a turnbuckle from corner to corner, drew the table to square, Then welded in an x brace below the slats.

It also allows for future expansion of the table if necessary.

[tof1]

Bolting it together sounds like a great idea. Did you bolt the legs on or weld them?

[millman52]

Bolting it together sounds like a great idea. Did you bolt the legs on or weld them?

Bolted, There is pretty good detail of it here: Started building new 5 X 10 table today Post #52

The above link will take you to my build log. I don't have a set of plans but most everything is explained fairly well, along with some of my reasoning of why I did it my way.

I don't claim to have the best design. I was attempting to build a good solid table that was still repairable without having to cut things apart. It's still a work in progress. But it has seen 30 & sometimes 50 hrs per week of operation for about 15 months now.

If you have other questions about how or why on my table please ask on my log so I don't have to jump back & forth on the forum. I'll be more than happy to share what I know, or give an opinion.

When you actually begin your build it will help you greatly to do your own build log, Post pictures so others can see what you are talking about & progress. & comment on your work. It's good for ideas you havent thought of & somewhere bound to save you a re-do.

Neil.

[tof1]

Looking at those pictures it seems if you were able to weld those bolt plates in without the rail warping you could of welded the table together instead (although you wouldn't be able to expand as easily).

I'm thinking I might weld the table after all. What do you think about running water over the frame 1-2" from the joint while welding? Just make a little wall out of tape or something to keep the water from contacting the weld. That way the heat is kept to a small area and the chances of warping would be greatly reduced.

Seems like I barely have enough time to work on this thing but I'll try to get a build log started.

[millman52]

Looking at those pictures it seems if you were able to weld those bolt plates in without the rail warping you could of welded the table together instead (although you wouldn't be able to expand as easily).

I'm thinking I might weld the table after all. What do you think about running water over the frame 1-2" from the joint while welding? Just make a little wall out of tape or something to keep the water from contacting the weld. That way the heat is kept to a small area and the chances of warping would be greatly reduced.

Seems like I barely have enough time to work on this thing but I'll try to get a build log started.

It's the weld joint itself that tends to draw things out of square. I'm sure It can be welded. Just tack things together being careful till you get the outside frame tacked up square. Then tack in some X bracing to help hold it square. Then weld up.