A Question on Bench Blocks

A question for those who may know the answer...

About two years ago, ARC used to sell a product described as 'Precision Bench Block', as shown in the picture below:

It is an imperial size 3" in diameter, with nine oversized holes ranging from 1/8" to 5/8". The block is hardened and ground steel, ground vee groove to accommodate round stock.

If you have a look at the top view of the drawing below, two of the holes are located in the vee groove, but they are not center to the vee. One of the holes is 6.6mm in diameter, and the other is 3.7mm in diameter (yes I know I am stating metric measurements here.. because that is how they are made). Anyone know the exact reason why their positioning is the way it is?

There is no fault in the original drawing/specification for this product. This is exactly how it has been specified by an American importer, many moons ago.

Some people refer to this block as a jewellers block, others refer to it as a block for gunsmithing. For engineering, I would suggest that it is a great support when drifting out pins and drilling small parts, but I am unable to figure out why the positioning of the holes are the way they are in the vee groove.

I am unable to find an explanation.

Ketan at ARC.

The only bench block I ever came across was the ones we had in the Tech many moons ago.

These things were just big lumps of iron or steel, not sure which, and we used or abused them when centre punching our masterpieces.

"Do not centrepunch on the wooden bench!!!"

Yes Sir/No Sir, three bags full !

I now have on old 56lb weight which I use for the purpose

The offset 6.6 mm (1/4" clearance) might be derived from gunsmithing practice. Specifically removal of the link pin from 911 style barrels, as fitted to the Colt M1911 handgun and clones, which I believe is slightly off centre when the barrel is laid in the Vee groove.

Clive

The ones for sale on Amazon don't have the offset hole!

"Jewellers Tools Staking Anvil Bench Block Round Toolmakers Hammer riveting Tool Hardened Steel"

Ha Ha, got it, have a look at the site. It something to do with "gun smiths" ??

Gunsmiths block

Click on the image with the guy with the hammer.

Edited By Speedy Builder5 on 24/12/2019 13:09:52

How many did you get returned as 'crap Chinese shoddy drilling' ?

If not something for the gun nuts I was gong to suggest an original drawing made in imperial fractions that got converted by some kid on a holiday placement 'cos it wasn't important enough to waste a proper draughtsman on it.

I have an original Starett bench block in unused condition. Both holes in the vee are exactly central, no offset at all.

I would guess the drawing is wrong as I cant see any reason for having a hole offset as shown.

I will post an image if necessary

Mick

The original patent (US1442415A) was taken out Arthur Hermone Starrett in 1921. The patent drawing doesn't show the holes being offset, and no claim about them is made in the wording. It's all rather vague:

These holes may be spaced about the top of the block in any manner, but are preferably arranged in the symmetrical manner disclosed in Fig. 1. Intersecting certain of the holes is a diametrical centering groove 5, preferably V-shaped as indicated in Fig. 3.

and

The intersection of the groove 5 with the three sizes of holes makes it possible to set or remove a pin from a finished cylindrical object without danger of having its slip or dent, while the pre dominant flat top of the block will support any flat object.

My 50th Anniversary Starrett Catalogue of 1930 says: 'The V in the center is a feature needing no explanation.'

I usually suggest patent evasion for odd features like this - someone claiming their Block isn't a copy of the Starrett because of the differences. In this case, if I read it right, the Patent expired in 1940.

No mention gun-smithing or jewellery either, it's a general purpose engineering tool for driving pins in and out of round and flat work.

Mine doesn't get a lot of use, but it's handy when it does. Made by Soba, the holes are centred in the 'V'...

Very mysterious!

Dave

Edited By SillyOldDuffer on 24/12/2019 13:58:49

My money is on Clive Foster and SpeedyBuilder.

Brian

Harumph!

Humbug!

I obviously wasted my time centring the holes when I made mine...

Neil

Only if you're repairing 1911 Colt pistols Neil.

Brian

It also looks like the Starrett and Neil's have the holes on a single pcd. Having different circles is a small niggle.

Nah Neil you made it to suit your needs Merry Christmas

H

After reading Clive Fosters explanation and seeing the drawing on SpeedyBuilders link, it is making more sense as to why the maker we were buying from makes them the way he does.... especially considering that he predominantly makes for the American market.

Bazyl: I had 6 pieces returned from a batch of 300pcs. based on the comment you made. However, it would be wrong to presume that the product was made incorrectly. I raised the question via this thread to get some explanation, which I now have. The maker we purchased from has been making this block in this way for a specific U.S. dealer for a very long time. The only reason we stopped buying was because there was no certainty on delivery. Our demand is low, and we have to wait to fit in with a high volume purchase... which only the U.S. could give.

Plasma: Thank you for the photograph of the block you have from STARRETT. Looking at the photo, it gives an impression that the vee groove on the left is narrow (with larger hole), and wide on the right (with smaller hole)?...similar to SpeedyBuilders link?.

S.O.D.: Thank you for the original patent details. After reading the various comments, I would suggest that this product has been modified/ or developed futher perhaps? to meet the demands of the U.S. importers market.

Thank you all for your contribution.

Ketan at ARC.

Clive is right on the money. I have seen this type of block (with offset holes in the V) used to remove the link pin on Colt style 911 pistols. This I hasten to add was a gunsmith friend of mine, who operates in the USA.

I believe that Brownells sell the offset hole block in the US for this very purpose.

Andrew.

Yes I have one as well and the holes are central to the V.

I think the photo is distorted by perspective.

Neil

.

Interesting to see that the Gunsmiths version is plastic

MichaelG.

I suppose plastic is more than good enough for knocking out a few little pins, I thought they were 3D printed until I saw the ejector pin marks.

One thing puzzles me, how can anything with clearance holes be classed as 'precision'? And precisely what bit of the 'precision bench block' is the 'precise' bit? that'll be two things that puzzle me!

Ian

Probably more precise than a plastic one