Had to make some equipment changes to move from steel to Ti, first and foremost is the required elements for the Tig torch. The water cooled tig handle does not change, but pictured below are the two different set ups dependant on material. In the lower right is the steel set up I use; a fairly tight cup for argon dispersal, a 3/32" collet body with gas outlets, and a 3/32" collet.
On the lower left is the Ti set up; a 3/4" ceramic cup to help cover a larger surface area for the shielding gas, a diffuser lens collet body really spread out the gas coverage, and a longer collet to hold the tungsten. The Ti equipment is larger as welding Ti requires an oxygen free environment to prevent contamination during welding and cooling.
A close look at the Ti tig setup, sans tungsten.
In addition to covering the exterior of the weld zone, you must also insure an oxygen free environment on the backside of the weld, so one must purge the tubing as well. I spun up this purge plug to be pressed into the end of the bar grip to flood the interior of the tubing during welding. The argon will flow from the tank through the black tubing and out the end of the purge plug into the bar.
The first step to welding up a bar is to clean, clean, clean everything. I use dedicated stainless steel brushes to break down the oxide layer, a degreasing solution wash, air blow dry, brush again, and then an acetone bath. The first actual welding is to fuse on the end cap and give it a quick spin on the vertical belt sander to smooth it out. After running a few of these through, I've decided that I'm going to have to make a dedicated purge fixture to help control the coverage of the gas on the exterior of the cap. I'm getting some contamination as the gas does not like to pool over the acute edge due to the stirring effect of the atmosphere where it breaks over the edge. Not a concern here, as this is not a structural piece, but something I do want to address to insure the best possible product.
Next up, I set up the bar for tacking. On one end of the bar goes the purge plug, the other gets some tape with a small hole in it to allow the air to be pushed out and replaced by the inert gas.
This is a good shot of the tacking process; one good and one bad. The Ti weld should be colorless or have a slight golden straw color to it. The tack on the left is what I am looking for. The tack on the right is contaminated, due to me moving the bar accidentally while making the tack. When this type of oxygen contamination occurs, you must stop immediately, grind the contaminated material away, clean again, and re-tack.
Here is a first pass weld, joining the grip to the center section.
The argon I purge with is heavier than air, so I purge from the bottom up. Here I'm allowing the bar to fill before moving on.
And finally, the finished product before any finishing...
Now brushed up and finished, my Luv Handle model Em is showing it off :)
Emmy is sporting her new shorter hair after donating 11 inches of hair to Locks of Love, an organization that uses donated hair for children who need wigs due to disease or medical treatments.
The recap...this is some of the most difficult Ti welding I've done, mostly due to the tight wrap around portions of the miters preventing sufficient gas purge flow to all areas of the tubing. I had to really work the bar in different positions with multiple gas flow rates to insure a clean uncontaminated weld. Unlike a frame that has fairly large easy transitions that allow the purge gas to flow easily, the bar is more of a challenge. If I choose to make these a standard item, I'm going to have to make a few extra purge pieces and get a set methodology for welding these to increase my efficiency. I also will need to find an increase cup size as the 3/4" I've used in the past just did not allow for longer bead runs, taking a long time to weld up the piece.
I'm going to have a few of these out on the trail in the next week to see how they do. I can tell you right now they will be MUCH more compliant than the steel bars, as during some stress testing (bar anchored in a vise and levered on with a 4' cheater bar) I can get them to bend quite a bit before they snap back into shape. Should address the needs of those riders doing the marathon rides.
On another note...I'm a few days behind in answering email. Having no Internet for a week put me about 90 emails behind, so please be patient, I'm getting to them :)
Tomorrow is Father's Day, I'm going to spend mine in the paint booth finishing Micheals Yo and Jeff's Bruiser.
cheers,
rody
1 comment:
That was pretty neat description of the process, and nice result. But the best part of all is the hair donation. Way to go! I know how hard it can be to cut off that much hair after growing it for so long, but definitely for a good cause.
IF52
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