You will be fine with those cutters. By the way you can get them at Fastenal among others fyi. The frame rail thing will require you to put on your thinking cap. It is definitely easier to do one at a time as you only have to block up the engine and trans  and hold up one side of the cab at a time but it is definitely your business. your circus and your monkeys. lol

I cried because I had no shoes till I met a man who had no class.

I tear the truck down if I'm replacing rails like your doing,when you get the new rails drilled and mounted on the axles you can blast and paint a rolling chassis and its done, then go on to the cab and other parts that need to be repaired, the only time I would pull one rail at a time would be just to replace like for like and not a restoration.
Keep us posted on what you do.


Driving the greenies nuts
http://www.killcarb.com/

So after all the advice that was offered, this it what happened. I started off marking the centers of the old rails. Then used a plasma to cut the flanges off the old rails. That was working really nice until I let the smoke out of the plasma cutter. Finished them off with the torch and ground the slag on the edges so the pattern would lay on the new rails nice and flat. The plan was to set the pattern on the new rail align the center marks, clamp and make metal shavings.  Mag drills don't like to stick to anything that isn't nice and clean so on the first hole the annular spun out and burnt up. The plan then evolved to making a very light center mark using 3/4" and 5/8" drill bits through the template, then removing the template and center punching the marks. This plan made the mag drill pay off.

Old rail used for template
I started drilling using Unibore bits. These bits are not for drilling this type of steel as it turns out. They ran smooth, but the shavings would be thinner and thinner until they just stop cutting making a nice work hardened hole.


Work hardened hole when bit stopped drilling.

Not knowing if it was operator error on cutting pressure / feed rate, my brother bought me a new set of Unibore bits. I proceeded to make the record 13 holes and burnt the new set up. This is getting expensive! Took a shot on some cheaper Evolution bits and that paid off big. They are a number or two harder on Brinell scale. They are hard to keep in a sweet spot but just keep cutting. On the holes that spun out we ended up just drilling them with twist bits, these proved to be too much for the Evolutions. I was told that it is possible to heat them to red then spin the annular back through the started hole, but didn't want to risk the base of the mag drill.

The moment of truth!!! Would any of the holes line up. First rail, no problem.


2nd rail, no problems either! So far so good.

The trick to bit longevity in tough and high tensile strength material if keeping the speed in surface feet per minute less that 100. For a 3/4" bit that is about 500 rpm. I usually shoot for 80 fpm. Also you need to keep a steady and even feed rate. If you relieve pressure on the bit so it is not cutting but just rubbing it quickly generates heat and case hardens the cutting surface which can make it next to impossible to start cutting again. This means don't stop to clear the chips; just keep going and relieve pressure just as the bit starts to break through. Coolant is also important weather it be from the machine's own system or a trigger squirt bottle like I use. I use Lenox Saw Master, a water base synthetic fluid for cooling and lubricating. 


Tony

Had a pretty successful weekend. It sure is nerve racking not knowing if there are things being overlooked. Hope she doesn't look like an old hound going down the road.


Rolled the front axle into place for fit up. This was a process. The axle is from a 90's Volvo, which is pretty close to what was in the old Acar. The trouble is there are a ton of variables. Its hard to float the whole axle level into place, I would say next to impossible. So there was a lot of compensation for the floor not level, tires not the same size, springs and bushings being worn.

It looks like progress.

When you polish the aluminum rad shell watch for pits in the aluminum. If they are result of the casting process as fast as you sand them out you'll likely have more pits appear, polish what you have and smile.

Double Mountain Manufacturing LLC
EddyLucast@hotmail.com 
203-228-1961

Here is a video of a 5/8" hole being drilled through 5/16" grade 100 steel. So much easier than jobber bits. I set the phone on the top of the rail looking down. Using a cutting compound on the bit.

It may be an optical illusion with the camera but it strikes me that the drill could stand to be slowed somewhat. just my thoughts. I still like the annular cutters better than twist drills.

I cried because I had no shoes till I met a man who had no class.