Homemade Welding Table

[URracing]

Hey it's been a while since I posted. I'm comin back to school and we're on the midst of finally gettin our University of Regina chapter back into the SAE programs again. (Last FSAE competed in 01). We've had much trouble with consistent dedication and support so it's been tough, but we're lookin to get back into Baja as an easier start to re-establishing the chapter with future plans to finish our FSAE car that was started in 2003.

Besided our weekly "shop-cleanup/organization" sessions we've been having, one major step I'd like to take is getting a GOOD assembly table to weld our frames on. We ended up literally trashing $600 worth of 1" sq chromoly tubing that was welded into a crooked and bulky Formula frame that we were going to use way back in 05.

I checked out a thread on this that was posted three years ago and it looks like an optical table of some sort would be ideal. Only problem is we wanna be cheap and spend max $500 on this item. We're lookin to get a local manufacturing shop to help us out with a 3/4" or 1" thick 4' x 8' steel sheet and have them drill/tap 1/4" holes on a 2" x 2" pattern (approx). I realize a 4 x 8 optical table weighs around 2000 lbs so we're also trying to cut the weight down a little if possible. Because of this we're just curious if an aluminum sheet would be better (realizing it would not stand up to heat as well though). I also realize optical tables use shock absorbence materials and honeycomb construction to absorb impacts and keep a true flat surface. Just curious if we can in fact get away with a thick steel or aluminum sheet.

We went ahead and welded up a simple work table for now using just 1.5" x 1.5" x 1/8" tubing for a frame and 3/16" steel sheet welded to the top of the frame. We were going to put down 3/4" MDF on top of the sheet but unfortunately it bowed up in the middle after releasing the clamps so it's definitely no good for jigging.

I've been trying to explore different types of jigging technigues and I've found using upright jigs bolted to the table is one of our best options. We tried using just MDF sheet with 1" pieces of wood nailed to it to hold a flat plane but when it came to stacking the planes (such as fabbing the bulkheads and welding in the role hoops), there was no way to keep the frame from twisting/bending/warping.

So I'm just curious to get other ideas from anyone who wishes to offer any that has experience with these types of tables. I'm also wondering if we should stick with just mild steel sheet or up it to stainless. Sorry for the long post but I felt it's good to express my situation so you all get a good understanding what I'm after.

[URracing]

Hey it's been a while since I posted. I'm comin back to school and we're on the midst of finally gettin our University of Regina chapter back into the SAE programs again. (Last FSAE competed in 01). We've had much trouble with consistent dedication and support so it's been tough, but we're lookin to get back into Baja as an easier start to re-establishing the chapter with future plans to finish our FSAE car that was started in 2003.

Besided our weekly "shop-cleanup/organization" sessions we've been having, one major step I'd like to take is getting a GOOD assembly table to weld our frames on. We ended up literally trashing $600 worth of 1" sq chromoly tubing that was welded into a crooked and bulky Formula frame that we were going to use way back in 05.

I checked out a thread on this that was posted three years ago and it looks like an optical table of some sort would be ideal. Only problem is we wanna be cheap and spend max $500 on this item. We're lookin to get a local manufacturing shop to help us out with a 3/4" or 1" thick 4' x 8' steel sheet and have them drill/tap 1/4" holes on a 2" x 2" pattern (approx). I realize a 4 x 8 optical table weighs around 2000 lbs so we're also trying to cut the weight down a little if possible. Because of this we're just curious if an aluminum sheet would be better (realizing it would not stand up to heat as well though). I also realize optical tables use shock absorbence materials and honeycomb construction to absorb impacts and keep a true flat surface. Just curious if we can in fact get away with a thick steel or aluminum sheet.

We went ahead and welded up a simple work table for now using just 1.5" x 1.5" x 1/8" tubing for a frame and 3/16" steel sheet welded to the top of the frame. We were going to put down 3/4" MDF on top of the sheet but unfortunately it bowed up in the middle after releasing the clamps so it's definitely no good for jigging.

I've been trying to explore different types of jigging technigues and I've found using upright jigs bolted to the table is one of our best options. We tried using just MDF sheet with 1" pieces of wood nailed to it to hold a flat plane but when it came to stacking the planes (such as fabbing the bulkheads and welding in the role hoops), there was no way to keep the frame from twisting/bending/warping.

So I'm just curious to get other ideas from anyone who wishes to offer any that has experience with these types of tables. I'm also wondering if we should stick with just mild steel sheet or up it to stainless. Sorry for the long post but I felt it's good to express my situation so you all get a good understanding what I'm after.

[AJS]

A few years ago we acquired a large amount of 3/4" aluminum plate from military surplus and we cut a roughly 4x8 piece and bolted it to an older wooden table. Having a clean plate allows us to drill and tap holes where we need them and this makes designing jigs and fixtures a bit easier. It does get confusing when holes are not labeled and there are many in a small area but this can be taken care of with a hammer and alphanumeric punches. We've never had any issues with the whole chassis warping with aluminum jigs and the aluminum table.

[Drew Price]

Do you have an oxy-acetylene torch that you can try to straighten your first attempt with? If you can set something heavy one it, or clamp it back into shape with big pipe clamps and anneal all the joints you should be able to straighten it pretty good.

Just remember that as any of your welds are formed, the joint will initially push apart the pieces you are joining, depending on your penetration, then as the bead cools it will shrink and try to pull the pieces together. Always try to tack your tubing joints in a minimum of 6 places, with the smallest angle formed between them being the most important. When you tack make sure the joint is held together tightly, and do it as quickly as feasible to avoid putting in too much heat that will warp the joint.

Your 3/16" sheet should be plenty, just be smart about where you put the framework underneath to support the fixtures when they start to tug (make sure the middle isn't unsupported, etc.).

I actually like a smooth heavy flat sheet, because you can tack your jig, or your tubes directly to the table and then grind is gently back to smooth when you're done, not as good as a bolt fixturing table, but much cheaper and quicker. Besides, if you're having trouble keeping your fixturing table from warping, you probably aren't going to be keeping 0.020" accuracy on your node locations anyways, not for a $500 budget.

Best,
Drew

[Wes Burk]

We always made sheetmetal jigs before and placed them on a flat welding table in our engineering machine shop. This year we had our laser cutting sponsor cut us three 2'x2' sheets of 0.250" thick steel with 3/8" coordinate holes in a 2"x2" pattern. We bolted these to two 8 ft. C-Channels and placed it ontop of a lab table we had in our shop. All the jigs are also 0.250" thick sheet pieces that were laser cut and then we jigged up to 90 degree blocks and welded together. Works like a dream, as long as you check your base table with a level to make sure it's reasonably flat then you could use a coffee table if you wanted. In the end I beleive everything is accurate to within 1/16th of an inch, and most people will agree that most teams have much more to worry about than 1/16th of an inch off on their frame. Total cost: $300 of material. For next year we will have to replace $40 worth of laser cut parts to jig up a new frame. Yes it's a little annoying to have to bolt everything down as opposed to having tapped holes but its a small price to pay. I would also suggest getting the CNC cut frame tubing option as it fits together like a puzzle and is almost a jig in itself (and isn't too expensive).

http://i609.photobucket.com/albums/tt171/Snipes540/th_frametable-1.jpg (http://s609.photobucket.com/albums/tt171/Snipes540/?action=view&current=frametable-1.jpg)

http://i609.photobucket.com/albums/tt171/Snipes540/th_035.jpg (http://s609.photobucket.com/albums/tt171/Snipes540/?action=view&current=035.jpg)

http://i609.photobucket.com/albums/tt171/Snipes540/th_034.jpg (http://s609.photobucket.com/albums/tt171/Snipes540/?action=view&current=034.jpg)

[Wes Burk]

Along those lines, it was SUCH a nice time working with CNC cut tubes this year. I would highly suggest it to any team seeing as it takes 100+ hours to cut and notch all the tubes for any formula frame, more if you bend your own (we have done all of this in the past). We worked with a company CARTESIAN TUBE in Ontario, CA http://www.cartesiantube.com/ProfilingProcess.html. They were close enough for us to pick up our kit but they ship anywhere. We got frame in a box ready to weld, all pieces individually labelled and everything fit well. They give formula/baja teams a discount and have worked with several before, cost us $1600 for the entire thing, material included. Would have been a chunk cheaper if we didn't have so many bends in our tubes. I think they had our entire kit finished 3-4 days after I sent them the CAD files and answered a few questions. They are great to work with and are looking for more teams who are interested in the future, or for those who haven't started their frame yet and think that they can make it themselves in the next 2 months...photos above.