Building a Jig

[zkoobs1978]

Can anyone give me advice on the best way and material to build a jig out of? I am going to start building mini sprints.

Zeb

[turboglenn]

depending on the jig it could be made from anything from plywood to thick 1018/A36/SS etc.... I usually will just get some plain old steel of the rack at the metal supply place, i just eyeball what kind of strength it needs and use the cheapest materials that will do the job for at least long enough to pay for it's self a few times over.

Are you making the bottom chassis JIG first? If so i would start by making a big rectangle out of 2x2'' 1/4 wall box section then add attachemts needed for the other parts from there.

On a sprint chassis like that, unless we have a set of plans we will usually lay out a grid of chalk lines on the floor, then start making the rectangle. The base rectangle of steel should touch the lower frame secion in at least 3 sides so that it can be properly clamped for welding it up flat and square from teh start. Use as many clamps as you can and use them to clamp in several directions as well... Getting the first floor pan section even 1/16th out can end upwith parts of the car being an inch out overall after the rest of the is is built off a crooked/warped chassis pan

We've had some of our best luck by taking and building the jig on a piece we'ce already built and reworked until it was perfect. that way the places for parts to fit in the kig are perfect to start off with..

best of luck and post some pics!

[zkoobs1978]

Thank you for the advice. I will post pics as soon as I start. I also have a question. I heard that when you start welding the chassis together that it will "walk" so to speak. What I mean is it will become out of square. Is there a way to prevent this and if so how? I am new to the welding and fabrication but learn quick and am always open to sugestions and advice. I am looking at the econotig series. Is this a good machine? I dont have alot of money to spend right now and this fits into my budget. Can I buy longer lead for this machine?


Zeb

[turboglenn]

Yea, the better you can clamp it, the less it will walk/warp, but there's still going to be tension to pull it out of square once it's unclamped, so you can either beat/bend it back to square, or while it's clamped square, start triangulating the frame (running bars diagonally and such) there's also a way to initially tack then weld a beggening square structure to minimize warpage. I will scan some pages for you if you PM me and remind me in the AM.

ALso, the less heat and the less mass of filler you put on in the beggining the less it will warp. A lot of it comes from teh cooling weld, and if you think about it a cubic CM of weld will he more mass and there fore contract more than a square MM of the same filler when it cools. Then once everything is tacked really good and made square you can run a few diagonals in and then finish your beads.. The biggest warpage issue i run into is not out of squar, but rather one leg of the assembly wanting to "lift" up off the floor as the welds cool... After a while you will learn to control the way it pull by where and when you put the filler and how much

[KC1]

I don`t know if this helps but I build all my chassis on a 3/4 thick 4x16 foot long surface plate supported buy 2x4x11 gauge frame. I make fixtures to hold the chassis and I keep it clamped thru the whole welding process. I have used the Ecocotig and have no complants with it. Some would probably disagree but Tig welding 4130 Chromoly price vesus function the Econotig is great. Hope this helps.

[FusionKing]

Now is the time to get a new Econo tig cheap...Miller is dumping them according to the new catalog. They are no longer in the line-up.

[pro70z28]

I made my Jig out of 2''x3'' tubing. A double rail deal with webbing between the rails to stiffen it more. I had wheels that slid in the jig to move it around. I also had adjusters on the bottom (2 in front, 2 in back, 2 in the center) that I used to level the jig before I started. Once I had it leveled I lag bolted the jig to the floor to keep it level and to stiffen it more. It worked great. I sold it when I was done with it, since I'm short on available floor space.

[turboglenn]

Here's the page on the tacking and welding sequence for trying to keep warpage to a minimum on square structures.

I cna't find the other diagram i had in one of my books because it's loaned out to a friend, but when i get it back i will post it if you still want it

[Geezer]

turboglenn: Could I please have the title and author of the book? Thanks

Geezer

[Geezer]

turboglenn: Could I please have the title and author of the book? Thanks

Geezer