I have written to ask if there's a UNITED KINGDOM distributor and await a response.

MCB

Just put "dowel nuts" into google and you will find loads if you can't make your own. Also better choice of threads as the ones in the hardware kit are likley to be UNC.

Or contrary to what he says you don't need to spend a fortune to get blocks that will screw together, the ARC ones are correctly drilled and tapped

I've never felt the need to make or acquire a set yet, nice to have but a good selection of accurate parallels are far more useful to me…

M5 dowel nuts are 8mm diameter. Next time I'm in my favourite fastener supplier I'll see if they stock them.

I have two pairs of 123 blocks in my stock which I have never had much use for largely beacuse 1) they are not obviously 1-2-3 by design (metric or imperial), 2) they only have holes drilled through from the front face and not from the edge and 3) None of the through holes are threaded. Do they have any potential use as 1-2-3 blocks?

You missed the point that ARC's ones are correctly drilled clearance size and tapped not drilled tapping size so bolts screw in without the need for dowel nuts

Just buy dowel nuts to fit 8mm OD would be closest to the 5/16" American ones and fit the larger ARC blocks, 6mm OD for the smallest

I use mine as parallels and packing a lot as I only have sets of thin parallels. Also 20mm one gets used to set tool height on the CNC as I don't have gauge blocks either. The holes also make them easy to bolt to a faceplate or work when balancing things up for turning.

Edited By JasonB on 20/07/2022 12:14:12

With respect, I have NOT missed the point,

I understand what has been written about ARC's blocks being tapped but it seems to me that the HEADS of the bolts used would get in the way and that a fixing below the surface of the blocks would be preferable.

.

I bought 2 sets of the 124 blocks to sit the Tom Senior bed on while milling 1.5mm off the top, and got lucky with the sizes, in fact they are so perfectly matched that I have long since muddled up the pairs, better than 0.0001" the same in all axes. When I got out the older set of 123 blocks, they turned out to be also 124 size, but I have never measured them relative to the other 2 sets. I bought a pair of 246 blocks on ebay and it wasn't till much later when I was having trouble with setting something up that I realised they were parallograms. Sitting them back to back on the surface table, there was room for a 0.025" feeler gauge in the 4" side. Chris got them ground square in all axes.

Edited By old mart on 21/07/2022 20:11:56

Unfortunately, Bernard … the underlying design principle was rather lost when the threads were metricated: Metric standard cap-head screws have different proportions  to Imperial ones.

Not sure if I will be able to find it again [I will look this evening] but there was an old Starrett publication showing their use for metrology set-ups … it only worked with the  Imperial blocks !

MichaelG.

Mine are 123 blocks with 3/8 UNC Threads. Have been playing with them this afternoon and to be honest they are appalling, the long through holes have obviously been drilled from both ends and never the twain shall meet and the short plain holes are miles out of square with the 3ins face. It looks like they are a bin job. They were bought from a well known mod eng supplier.

I use mine a lot but seldom screw them together so would not want to bin any of mine even if the holes were wonky. This week I have.

Used two 20-40-80 block stood to give me 100mm and then used my usual 10-20-40 block to set the height of various cutters and drill bits on the CNC relative to the 98mm ctr height of the rotary table, just enter +22mm off the 100mm stack rather than the usual 20mm off the top of the work.

Used two 1-2-3 blocks to pack a chuck that had 3 studs sticking out the back up off the mill table so it could be clamped down.

Used two 10-20-40 blocks to pack up some work that had a spigot sticking out the bottom, again so it could be clamped down to the mill table

Use two as paperweights to support a background for a photo

Used another to prop my phone up to video a bit of filing in the lathe.

And there is still Sunday to go.

Game, Set and Match to Jason!!