Post by springcrocus on Aug 23, 2015 18:59:59 GMT
I'm about to start machining the side rods for Britannia so today I made a combination beam compass and drill jig to help keep things accurate. It's not the correct term but is sometimes called a trammel. It is similar to the one on the first page of Jims Boadicea thread.
The two arms are made from 25mm x 3mm flat bar one of which has had a 4mm slot milled into it and the other has three M4 x 0.8 holes tapped into it. I have set bushes into the adjustable arms with 1/8" reamed holes in them. The bushes are shouldered and on opposite sides so that the device always sits level on a surface. I have also made a pair of trammel points from 1/8" silver steel with a sixty degree inclusive angle to suit standard centre drills and have filed a notch on the centre-line at each end to aid alignment.
The first use will be to set across the leading and driving axles and transfer the holes to the front side rods. I take no credit for the design of this, these things have been around in one form or another for donkey's years
Steve
The two arms are made from 25mm x 3mm flat bar one of which has had a 4mm slot milled into it and the other has three M4 x 0.8 holes tapped into it. I have set bushes into the adjustable arms with 1/8" reamed holes in them. The bushes are shouldered and on opposite sides so that the device always sits level on a surface. I have also made a pair of trammel points from 1/8" silver steel with a sixty degree inclusive angle to suit standard centre drills and have filed a notch on the centre-line at each end to aid alignment.
The first use will be to set across the leading and driving axles and transfer the holes to the front side rods. I take no credit for the design of this, these things have been around in one form or another for donkey's years
Steve