A Racing Dog

I was going to do only one more post, but I haven’t painted it yet and now both Honey and I have the flu. On one of my trips to the hospital they gave me a flu shot so my symptoms aren’t too bad. Honey has been down for the count. It’s almost 1 am and I don’t want to run a flap sander this late. It’s still a bit loud and she needs to rest. Today at Lowes I looked for bulk Rustoleum in Sail Blue, my shop colors but they only had Royal. Sail Blue only in rattle cans and I got a case at Mc Fadden Dale last year so I still have some left. They make it in half pints and quarts, I just have to find it locally. I suppose I could go online as well. I’ve got a can of proper PPG Ditzler for Snap On red (code 73504, powder coat AR320), at $26 a rattle can special order from the truck. I’m going to repaint the box Snap On red, but the cart I’m going to do in my shop blue.

When it comes time to paint the car, It will go from Miata SU red to a non factory Reflex blue from TCP Global though I also like the Viper Blue metallic. I might even do a two tone with some gloss black. I’m a long way from body paint, though.

Next up for the car was cutting the shelves from 1/2″ 20 expanded. I’m using a Hypertherm Powermax 30 at 20 amps. A good thing about a quality plasma cutter as opposed to these offshore cutters is they emply more modern power supply designs, torch designs and long consumable life. They have a feature know as “pilot arc” which lets you cut things with gaps like expanded with ease. Many low cost units don’t offer that feature.

With the shelves cut to size, it’s time to tack them on. I was going to use TIG to show it as a demo but as I tacked the shelves it became clear that MIG would be faster and easier. They both use the same filler material, ER70S-6 The strength of any particular weld, regardless of process is dependent primarily on two things. Penetration or fusion and the tensile strength of the filler material. For more esoteric materials TIG is preferred because you can weld almost anything with it. You also have much great arc hence bead control using TIG. The downside is the deposition rate (and operator skill), that is how fast you can get the work done. For project like this MIG is a more appropriate process but we’ll show some TIG parts.

Here are the parts of the torch. TIG uses a tungsten electrode to generate the arc and a handheld (in this case) filler material. MIG, OTHO, uses that filler material as the electrode and is fed via a mechanism controlled by a gun. Here is what a WP9 TIG torch looks like. My tack settings were 75 amps, DC- or “normal” polarity, 1.5% lanthanated tungsten with 100% argon at 20 CFH.

Part of getting a good TIG weld is proper choice and prep of your tungsten. If it’s not right or contaminated, you’re screwed. MIG is much for forgiving but also has disadvanges. Tungsten needs to ground to a proper end for the app. Sometimes a ball, sometimes a sharp tip, sometimes a blunt tip. It depends on the base material and the type of machine. I use a TechSouth handheld tungsten grinder I got new in box from someone on eBay that wanted to learn to TIG, but never started. Many of the old school guys use a bench grinder with a dedicated wheel. A dedicated, purpose built grinder is much more consistent and offers a better grind, for me.

Here are the shelves after switching to MIG. I finished it in under 5 mins. TIG would have taken longer and offered no advantage in this app.

Now with the final fab complete, we need to install the casters and test the design prior to painting. WE don’t want to paint unless we are pleased with the design. I’ve already tweaked my back lifting the 325# of tools in the box. So I used the shop crane. Here’s the testing version, fully loaded.

In the morning, or rather, when I wake up tomorrow if I’m still not too sick I’ll rattle can the stand Sail Blue. Then get back to getting that car off the wheels. But not before finishing a stock car project that is reinforcing the bumpers with 2″ x .250 DOM front and rear. Legal for the class. It’s called a battering ram and installing a new tach in a car and relocating the shifter from the tree to the floor. So I may not even make the chick car build this weekend (my weekend is Sun/Mon). But I’ll get more than enough dough to support next weeks eBay tool deals of the week.

Been flat on my back most of the week. Literally. Readers will know I pulled a lower back muscle trying to move my top box about a week ago. Just starting to heal. I started training again, working in the walking pool, whirlpool and steam room.

As we last left our top box cart/workstation I was just starting the fitment and initial welding. To notch the tubing, or cope the tubing as some call it, I use a JD2 Notchmaster as show in this previous post. There are other notchers and methods as well. Some fabricators use chop saws and grinders to cope the tubing. Ant Fab did the 00 car using that method. I prefer a hole saw type notcher. I usually cut the pieces to length, going a shade over and then cope to fit the piece as I go. Bendtech software can provide cutting templates to use for the copes but I’ve not used them in production, only in testing. They seem to work well so I may use them as I finish the Miata cage later this year.

This is what you want a good cope to look like.

For MIG welding you can leave a bit of a gap, but not too much. Ultimately you want contact with the tubing wall all the way around. If you are TIG welding, it becomes much more critical because the GTAW, or TIG process as it is commonly known, does not handle gap filling as well as MIG. In the best of worlds you want no gaps no matter what process you are using. The edges of the cope get cleaned up with either a grinder or a disc or belt sander. I use an HF 6″ bench grinder, an HF 12″ bench disc sander, both great for the money. They’ve been champs for me. I use the sander most of the time to clean the copes. I use CGW grinding wheels and Norton sanding discs and stay away from the HF stock abrasives.

Here the welding has started. The frame is tacked together before any finish welding to minimize heat distortion and insure that everything fits. Sometimes getting the welder settings correct for a new material, joint or project take a couple of passes to set. Below, is one of the first finish welds. A bit too much wire speed (amps) and almost the right amount of “heat”, or volts. It’s ugly but it will hold. As you complete the finsih welds you “chase the heat”. That is, you weld on one end of the pice, then weld on an opposite end while the first joint cools. This is also a method to reduce heat distortion.

The end of the tube has been extended from almost the intersection of the cope. There was a measurement error and on a piece like this it’s OK to add some tube. I wouldn’t do that on something like a cage though I have seen others do it. In the race fab business it’s considered poor practice to extend cage tubing and some sanctions will not allow extended tubing. After the tack, each joint is hit with 120 grit flap wheel to knock off the mill scale and prep the joint. I then clean the joints with acetone. The method used to clean and prep the joints varies depending on the material and welding process. With mild steel and MIG this is acceptable. In fact, some won’t do the acetone wash. With TIG and aluminum or 4130 the prep process as well as the welding application will change. I’m using a Lincoln Pro MIG 180, 75/25 argon/CO2 gas at 30 cfm with ER70S-6 wire.

For the casters I wanted to use some 3/8″ studded casters I had left over from another project to save a bit of money. They are rated at 150 lbs each so they should be fine for the job. To mount the casters into the ends of the tube I fabricated bungs from 3/16″ plate. I looked for pre made bungs but didn’t find any locally with that thread size for 1″ tubing. Washers with nuts welded to the back weren’t going to cut it for this one.

First, I drilled the plate with a 1″ hole saw in a drill press. I’d been using the HF small press but after 6 years or so of light use, it burned up. It was replaced with a 10″ Craftsman bench top drill press. It’s held up well and is is a good size if you don’t have room for a floor mounted drill press.

And of course you’ll need some machinist’s Astroglide…

We end up with this…

Then weld them to the bottom of the tube, hand drill to the tapping size, tap the hole, add the caster. The reason I did it in that order instead of prefabbing the bungs was because I wasn’t sure of what sort of heat distortion and fitment I would get. If for some reason they weren’t exactly perpendicular to the tubing wall, I could fix that after the initial piece was welded in place.

Now that basic fab is almost complete, we’ve got expanded metal shelves, testing then finishing left for our final installment.