123 Blocks- What to buy?

[Maxx]

I have 4 pairs of 1-2-3 blocks and they are handy as heck doing set-ups.
I have even used them to cover the table slots for clamping where the step blocks would be ineffective.
I have also bolted things to them that my 1/2" studs were too big to go through.
I'd like to get some 2-4-6 blocks but alas poor Yorick....
I purchased my 1-2-3 blocks from Discount Machine and have had no issues with the threads so far.
I have ordered some interesting clamps which should be in tomorrow that look promising and may start a thread on them..

 

[Ulma Doctor]

1-2-3 blocks of sufficient quality are ground parallel on six sides to a specification. some very precise others not so but still acceptable unless your a machine builder.
some are tapped unc threads, some are metric be very careful!
by the way the metric 1-2-3 blocks are not really 1" X 2" x 3" they are 25mm x 50mm x 75mm.
they can serve in many set up as well as machining and grinding as hold down fixtures for odd shape work.
if kept in good condition they will serve for years.
they can also aid in the measurement of surface imperfections.
if a dial indicator is also employed in the correct plane and a known to be flat surface is used as a base, the imperfections or anomalies are quickly identified.
i have 2 different types expensive and cheap.
the cheap ones are the work horses where precision is not the prerequisite and they get beat up and tossed out as necessary.
the expensive ones weren't expensive to me but they can get very pricey.
i use them more for set up rather than work.
my 2 cents anyway
i hope the info helps someone!!:jester:

 

[brucer]

They also make 246 blocks... they measure 2"x4"x6" and are used in the same manner as 123 blocks, usually the 246 blocks are used on bigger machines.

You put these blocks under your workpiece, keeping the part parallel with the table.. When you put a 123 block under a workpiece, if at all possible you also want your clamp over the top of the 123 block.. I've never had the need to bolt 123 blocks together..

you can also use 123 blocks as a platform to measure from on a surface plate or while on the machine..


and to add, the import 123 blocks are usually within about .0003 which is pretty close, no need to spend a bunch of money on a pair or set for hobby work..