Now there are 4 A-arms and two push rods ready to be welded and heat treated. The sphericals locations will be bored out to after to allow for any distortion during heat treatment. The rod ends will come last.
I still need to make the upper mounting brackets or plates to allow for double shear on the bolts. After that it's upright / knuckle work. At the very least, when these are done it'll go a long way towards making me feel like I've had some real progress after such a long time.
I had a friend and a friend of a friend come over to my place and get the A-arms and pushrods welded up. He has a lot of experience (training and job) and knowledge (degree) in materials / materials joining so really it was a no-brainer when he agreed to help with these. He has a new, water cooled Tig setup from Miller and was happy to have a project for it again.
Since the parts are 4140 and 4130 that I bought in the annealed state and I want to get them heat treated, he hunted down some 4130 filler rod instead of the typical ER70.. or ER80.. type filler. This would allow the weld area to be more uniform with the base metal and be able to be heat treated to the same levels instead of the ER series wire.
So... on to pictures.
I used my oven to get the parts preheated to 400F to help ensure the weld areas in the alloy steels wouldn't later crack. We then locally heated the weld areas with a MAP torch before welding began.
He welded all of the tube ends first. Notice the safe attire haha. He said it's the first time he's welded in sandals but not the first time in shorts. We experienced record breaking heat this weekend in Seattle so I couldn't blame him. Molten metal might have felt cooler with the humidity and heat we're not used to (typical 70s or 80s and it hit almost 110 at my place this weekend)
All the tubes were stuck in a bucket of sand to control the cool down rate after the ends were welded. When those were cooled we started the pre-heat cycle for the tubes to the machined lugs. Weld. Sand cool-down.
I'll drill the pushrod holes after heat treat and bore out the spherical bearing holes to their final diameter to account for any shift or deformation during heat treatment:
I just dropped off the parts to a local heat treat shop (ok, a business that does large castings, machining, and heat treatment) that agreed to put my personal project in their flow since I asked for a fairly typical heat treat level of 150-160ksi.
Now it's a waiting game for them to anneal, heat treat, and temper before I can chase the threads in the ends and finish machine everything. In the mean time I'm finally getting back to moving the Bridgeport base in place to re-assemble that.
First, the Bridgeport is finally getting assembled in position!
Then knee, turret, and ram. This accounts for a majority of the 'heavy' items. Once I replace the bearing in the knee that goes over the lifting screw, I'll be able to get the table put on. The head re-assembly will follow all of that.
Now for the front suspension update:
The arms and pushrods are back from heat treatment. At first I specified a minimum strength of 160ksi (160,000 lbs tension capability per square inch of material cross sectional area). I didn't specify a maximum because that was a fairly easy target to hit. I figured it'd come back around 180ksi. Turns out they figured they could skip tempering and that resulted in almost 240ksi. Way over the minimum so technically they met my requirements. Since stronger equals harder which equals less elongation and more brittle (in a relative sense, not like a ceramic brittle), I asked them to temper it lower. In the end it came out to 200-215ksi depending on the 4130 tubing and 4140 lug. Still has good elongation to prevent cracks due to bumps or road hazards but still strong enough to give me extra safety margin from what I calculated originally.
In this picture you can see where they removed the scale after quenching so they can do hardness testing (and calculate strength based on that). Look close and you'll see multiple, tiny dimples from the tester on the end and on the tube.
The dark arms are after heat treat, tempering, and quenching. The light is after a soft sand blasting to get the scale off. I don't think I'll polish or powder coat the arms but I will probably clear coat them after I solvent clean the outside to keep the metallic look but prevent rust on the alloy steel.
Next up is boring out the lug ends for the spherical bearings and grooving them for a snap ring. The lowers will also have the hole drilled for the pushrod rod end.
I'm also starting on the upright parts for the spindle, brakes, steering, etc.
I did a quick test fit of the A-arms on the chassis and I think they'll work pretty well once I get some proper spacers/parts made to take up the gap between the arm lugs on the chassis and the rod ends. This will also be one of the ways I can adjust the caster in the front even though I'd rather the lower arms stay relatively fixed due to the pushrods connecting there.
The upright has also made progress with the LH/driver's side one. I started with a billet of 14lbs of 7075 aluminum and started machining away.
Mid progress before flipping:
The end result is an upright that weighs 5lbs, 2oz. Not super duper light but considering I'm doing hand calcs and conservative estimates (I hope haha), I don't think it's too shabby. If anyone wants to weigh the front spindle Factory Five provides to compare, feel free to post the weight of that.
Finally, this is the configuration of the front suspension including the upright, hub, brakes caliper and rotor, steering bracket, etc. There's still a few 3d printed parts I need to fabricate out of metal but the progress was good for a couple weeks.
Still on the list is boring out the a-arm lug ends for the spherical bearings and grooving them for a snap ring.
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