A Question on Bench Blocks

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Jason is correct [many a true word is spoken in jest]

Precision is really about repeatability ... So if the clearance holes and the vees are well made, and correctly positioned, and the material is suitably robust; the Starrett item [for example] can be regarded as ’precision’ ... because it can be relied-upon to serve the same purpose every time it is used.

Arc’s version ... likewise, if the holes in the vee were deliberately placed off-centre.

But if their positioning is not understood by the user ... who then rotates the block, unwittingly, between jobs ... precision is lost.

MichaelG.

Gunsmiths use the plastic ones so they do not mar the finished surfaces on the gun parts. You can buy them (in America of course) with all kinds of specialised niches and slots and holes for specific tasks on certain common guns.

Precision is a subjective/relative term. My mate the builder regards anything within a quarter of an inch as precision. Within a couple of millimetres is spot-on in his book. Gunsmithing can be a bit like clock making in that a precision result is reached sometimes by careful hand fitting rather than high-precision measurement and machining. So, no the holes in the pictured block may not be sized or located to the nearest tenth of a micron. No focused beam microscopes required.

Edited By Hopper on 25/12/2019 09:39:50

Wow! 1/4" precision! My scrap bin is full of precision made stuff

Everything is relative, Hoppers mate's 1/4" may be over 50ft which is 5thou per foot which is not bad if all you have got is a 3ft spirit level.

Still not sure how conversion from imperial to metric would affect the angular positions of the holes as Bazyle mentions, drawing suggests that is how they have been dimensioned on the drawing.

Jason, I was thinking something dimensioned as 1/4" gets converted to 6mm, or 1 1/16 well that's 26mm as a nice round figure.

A new question. Why round? There is nothing that needs to be turned except perhaps the layout of the holes and square would be better to hold in a vice, even better for production. The plastic ones obviously had a rethink.

I suppose round would work nicely if a socket was provided in the workbench, and it can be held in a vice at any angle. Perhaps the Starrett 119 has the cleverest approach with a round top and hexagonal base, as it can be held six ways in a vice and the overhanging top will rest on the vice jaws?

Not so sure about 198 USD though! I wonder if Ketan could source a (much) cheaper alternative?

Brian G

Precision.....my Hillman Imp in the Sixties was accurate to about an inch (thickness of a ten packet of cigarettes. Garage couldn't understand my course of 'conversation ' and I was referring to building site accuracy at the time. .....Shuttering joiners.

Merry Christmas to all ,and all who are so free with their help and assistance.

Marischal

If the back (non-V) side was as flat and hard as the front, it would be easy to flip the block if the smaller holes were needed without the groove getting in the way. Just in case you are thinking of going round again, Ketan.

And a jolly yule with plenty of wassail - Tim

The discussion on this thread has been very educational. Some great ideas, explanation and links, for which I am very grateful.

I was, and still am uncertain if ARC will re-introduce this product. If we do, I will take on board what has been said when deciding what to do.

Thank you once again, and Merry Christmas to you all.

Ketan at ARC.

My Starrett 129 is hollow like this one. **LINK**

Well Starrett still list them under precision metrology tools. The only thing that I can see as precise is the top and bottom faces are ground, presumably flat and parallel. For non-precision, non-marking work I use a ice hockey puck. Thesse can be cut and drilled to accomodate odd shaped work pieces. They are made from filled hard rubber which is "dead", high friction and won't damage cutting edges. Pretty cheap if you are in North America and not bad prices from the usual online retaillers. Make good pads for trolly jacks too.

Robert G8RPi.

A solid bottom would be less likely to ding a wooden workbench as well

Brian G

Is it a casting? Alternatively is the hollow base useful to the user (there doesn't seem to be any precision to it but that might not exclude this)?

The answer to one of those ought to be 'yes' otherwise I don't see the advantage and it increases the manufacturing cost.

Yes, it does look like a casting judging by the rough surface inside.

According to Starrett, it is made from Steel

**LINK**

https://www.starrett.com/metrology/product-detail/129#Features

... so perhaps it is a forging.

MichaelG.

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Edit: ... Just found this, which is worth a look:

https://rick.sparber.org/beb.pdf

Edited By Michael Gilligan on 25/12/2019 19:49:40

I'm guessing the answer to the OP's question is "poorly made".

I've had a Starrett bench block on my bench(es) for longer than I can remember, a useful thing to have. if you don't then its a couple of productive hours to make one.

Not sure what makes the block precision, other than the parallelism of the top and bottom surfaces, thats been useful on the mill a good few times.

As for using it as a drill and tapping guide, the Sparber article, surely using it inverted would be better?

John

A quick search on Ebay shows them to be on sale for £16.85 inc post.

Brian

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The drawing is obviously done by hand, and there are no dimensions on the copy provided by Ketan; so we can only guess the angles, but it seems quite clear that the holes at [roughly] 9 o’clock and 12 o’clock are intentionally offset.

... and, although less clear, also the one at [roughly] 6 o’clock.

MichaelG.

Edited By Michael Gilligan on 26/12/2019 08:56:52

Hi, the one I have was given to me by a work mate at my last day job, it was given to him by an old boy who made clocks, along with some other tools, he had no use for this block.

The two holes in th V are in the centre of the crux, the V being 95 degrees inclusive with the side on the left being approx. 8mm deep and the side on the right being 7mm deep. The V is approx. 2mm offset to the right of the block by approx. 2mm and is approx 4mm deep and the large hole, for arguments sake, is in the centre of the block. I've found no manufacterers name on it but believe it to be a commrcially made item and there is a small number 5 stamped into the top face on the left hand side.

As can be seen in the above photo, the block is hollow.

Regards Nick.

Edited By Nicholas Farr on 26/12/2019 09:53:29

Thanks for sharing the photos, Nick

That looks entirely adequate for the general use that most of us would find for it.

The Starrett one, however, does appear to be in a different league; being hardened and ground.

MichaelG.