Drive Dogs etc

Hi Duncan, I have used one of those "bar square" items quite often, but a vastly better quality one than the one in your link.

As far as bell punches are concerned, I've only ever used one once, and that was in metalwork class at school, but can't remember what we were making for the need to use it.

Regards Nick.

They may not have had modern chucks like we do nowadays, but I expect they had face plates which could be ‘adjusted to grip/hold material for drilling the ends with their Slocombe centre drills.

Edited By not done it yet on 20/12/2022 21:37:02

The simple centre square **LINK**

https://www.toolbank.com/0/p/FAICSQUARE38

pre-dates the combination square with V stock like that linked to by Duncan. I imagine that would have been a common way for craftsmen to locate teh centre of a round bar for puching to make a drill starter hole. Back in the day a combination square set would have been seriously expensive. Few ordinary workers could have afforded their own.

I've had mine for 50 years and use it so rarely I've almost forgotten I have it. More likely to grab the Starrett combination set I scrimped & scraped up the price for second and 40 odd years back.

Clive

If you have nice clean round stock a carpentry marking gauge, which most old timers probably would have made for themselves, quickly scribes a square or triangle on the end to guide a centre punch.

Jenny leg calipers, centre punch, drill press.

Before Slocombe centre drills they just drilled a hole with a normal small diameter drill bit then opened the end of the hole out with a normal larger diameter drill bit ground to a . 60 degree angle. Still done that way today on some larger lathes (think 15foot+ beds) with large centres rather than use a giant centre drill bit. Less chance of breaking the tit off the end that way too.

I worked in a place that had a centre drilling machine. It had a spindle, and various V blocks with clamps. On the bottom plate was a centre pin. Then there was an adjustable plate that rose up , that was keyed to the column and could be reset from the one on the ground. This matched the centre of the spindle. The Vee block could be moved in or out and the centre of a part could be corrected for its position as well. We used it for drilling the centre of quite large bars, then they were put into the lathe for turning between centres. We often made custom dogs for parts, and others had drive pin holes placed into the main drive end of a part.

Some of those very entertaining "Safety Last" YouTube videos from Pakistani machine shops show them marking out the end of a bar with odd-legs and then giving it a really good whacking with a large (home made) centre punch, no centre drill required.