Problem making Universal Pillar Tool.

I am in the process of making the GHT Universal Pillar Tool with Sensitive Drill attachment and having run into a problem with the dimensions I hope a previous constructor may be able to help me. The castings came from Hemingway and as there are no separate drawings available I'm working from the book "Building the Universal Pillar Tool" by George Thomas. My query relates to the arm and drill-head clamping arrangements as there seems to be some ambiguity in the dimensions shown. For the column end of the arms and drill-head the bore is 7/8" and whilst for the arms the bore to clamp pad centre is shown as 19/32" that for the drill-head is 5/8", a difference of 1/32". In the text of the book George Thomas refers to the centre distance between bore and clamp as being "fairly important and should be held to within about 15 thou." Given a discrepancy of some 32 thou between the conflicting dimensions I'm in a dilemma as to which of them to go for to ensure correct clamping and releasing of arms and drill-head to column. It may be a misprint in the book or perhaps I'm missing the point but given the cost of the castings I don't want to risk any scrappers. I don't understand the geometric constraints for this type of clamping arrangement so am unable to work out the dimensions from first principles. Any help or advice would be most gratefully received.

Thanks in advance, Michael.

Hi,

I made the universal pillar tool and almost certainly slavishly followed the dimensions in the book so mine will be as drawn - works perfectly! Tomas was my (virtual) hero during my model engineering apprentiship and trained me well.

Ian

In the reprint "Workshop Techniqes" he shows then ALL as 5/8 I have not personally built this (on the ever lengthening to do list) I have used this type of locking device many tines and never really found the distance critica - not that I would ever question a master like GHT of course.If you have (or can scrounge) a bit of 1 1/2 sq. bar then why not try a mock up - bore the main hole for the column and try each length either side of the bore.

Phil

Many thanks to Ian and Phil for their comments. I drew the conclusion that maybe the dimensions were not that critical after all but out of interest I decided to follow Phil's suggestion of making a mock-up out of a piece of bar using the conflicting dimensions on opposite sides of the main bore. I've now completed this and in in fact found no discernible difference in the clamping abilities of either. I can now look forward to completing the Pillar Tool.

In the Seventies, as a strugglinng beginner, I came to admire the writings of George Thomas with his attention to detail and analytical approach. His was a counsel of perfection which we may not all be able to achieve but when at exhibitions in the past his work was on show I, and I'm sure many others, found it to be inspirational.

Michael

When I started out in model engineering I too was given a recommendation to get George H Thomas´s books. I can only agree with what has been said above.

 

I also made myself a universal pillar tool, but had to adjust the dimensions to suit my equipment and what material was possible to find. I live in Sweden and only have metric tooling so I had to re-calculate all dimensions. The result turned quite OK in the end as shown in the attached illustration.