The value of 1-2-3 blocks

KeithB

Resident Half Fast Machinist
One of the pieces we make for our main buyer is tailwheel pivot socket. We needed to make a fixture to hold the weldment in alignment while cutting an arc in one side of the thin wall tubing. We cut off and bore/ream the tubing pieces to size and cut a fishmouth on one end of the smaller piece. Our buyer has a guy that does the welding, and then they press in the plastic bearing/bushings. We get them back and cut the arc, which fits the nose of a spring loaded cross pin that lets the tailwheel pivot but forces it back to the center.

One of the handy things to have if you have a milling machine is 1-2-3 blocks. They are typically sold in pairs and measure a nominal 1" x 2" x 3". I mostly use them as parallels or riser blocks to get work up off the table top. They ones I use have 23 holes drilled in them, with almost half of the holes tapped to 3/8-16 and the rest are big enough for a 5/16 through bolt. (Also have a set of 2-4-6 blocks, same idea, bigger holes)

I knew this job was coming so I had time to think about how to hold and align the piece while still permitting access by the milling cutter. I had made a sketch using the block as a base and had to make a couple of pieces to attach to the block but it didn't take long to get everything together and start cutting.

When we first ran this job (pre-CNC mill) we had to mount the rotary table on the manual mill and crank the handle while reading a degree wheel. A long setup and essentially hand making each piece. With the CNC mill I just mount the fixture in the Kurt vise, find the center of the pin and the height of the tubing top and run a very short program that takes 15s from start to finish.

pivotfixture1.jpgpivotfixture2.jpgpivotfixture3.jpgpivotfixture4.jpgpivotfixture5.jpgpivotfixture6.jpgpivotfixture7.jpg
 

Brad

Benevolent Overlord and site owner
Staff member
It is the setup that makes the work possible. The more I learn about machine work the more impressed I am with the ability of people to find a way to hold something just right to make a cut.
 
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KeithB

Resident Half Fast Machinist
I posted a thread a while back on using a sine table to make a part for a weld fixture. The weldment shown is held in that weld fixture. I knew when we made the component pieces and the weld fixture that we would need to make a fixture to do this job. Nice to have a little time to think about things, I kind of process thing in the back of my head while I'm doing routine work.
 

pokute

Active Member
Hmm... I used to watch a guy build custom bicycle frames that did that with a file, sandpaper, a wet towel and a torch.
 

Ian

Notorious member
Brad, my thoughts exactly. I think Keith has been in the teaching biz long enough to recognize when and where to introduce a little tidbit....... just before it will be really needed.

BTW, I've picked up a lot of set-up tips just watching Adam Booth's videos. He really has a natural knack for filming the interesting parts of a process, and I usually learn ten new things in a 30-minute video about something else entirely, just by paying attention to the little things he does out of habit.
 

KeithB

Resident Half Fast Machinist
Takes a lot of skill and manual ability to do that. I like to eliminate that wherever possible. That's the way my customer made the first ones. Then he talked to me. He doesn't make them that way anymore. A couple of simple fixtures and boom, they are easy to weld and all come out the same. His welder loves the fitup. And they get made quickly.
 

KeithB

Resident Half Fast Machinist
http://www.flyboyaccessories.com/RV-and-Homebuilt-Tailwheel-Products-s/1.htm

We make a lot of the component parts for these guys, including the Bell forks and pivots that get welded together. We're running a couple hundred of them right now. We just made the pivot sockets for a new aircraft model so they could use the Bell forks. These parts are for a homebuilt aircraft called a Rocket; not sure what the new model aircraft the re-angled sockets are for.
 

RBHarter

West Central AR
Took me a minute ......... I've been away from the airport too long . Small little world we roam around in .
 

Pistolero

Well-Known Member
Thanks for the education, Kieth. I have used a hole saw to do the fishmouths in some of the work
I have done, like a ladder/scaffold for our local art museum to work on giant shuttlecock sculptures.

Bill
 

smokeywolf

Well-Known Member
1-2-3 blocks are handy for all machinists, but a must have if you use a mill. There are also 2-4-6 blocks which are more often used for setups on the mill table or in a large vise on a shaper.

Keith, if I had a dollar for every time I've used a vise-grip as a "machinist clamp"...

Just a little piece of trivia... Cutting a radius on one piece of pipe or tubing to butt up to or fit against the side of another piece of tubing is usually refered to as "coping".