wp55b0dd48.png
wpd530b04e.png
wp91074f43.jpg
wpa4923fff.jpg
wp0fe7637b.jpg
wp54b53ef2.jpg

Harold Hall

wpff6a4396.png
wpcbf9ee95.png
wpcbf9ee95.png

The second jig is for a common task in the home workshop involved in model engineering, that is drilling the end flanges and cylinder block of a typical steam engine. Photograph 13 shows the jig and a plug for locating it when drilling the end of the cylinder as seen in Photograph 14. The jig positions itself directly onto the end covers for drilling as these have a small boss for locating them when fitted to the cylinder block, Photograph 15.

 

If the jig is marked out using a rotary table or a dividing head then the jig is worth making if only for the accuracy of the results, Photograph 16. Incidentally, since the holes were drilled the jig, Photograph 13 shows a second set of holes has been drilled for some reason should you be confused.

 

The third jig is very special and is unlikely to be required in the home workshop,  unless the owner is going to make the boring head, described  here.  The task is to produce a partial hole on the edge of a round component and for this to be tapped M6,  a seemingly impossible task as only 1/3 of the hole’s diameter  is in the component with the other 2/3  in fresh air.

 

For this to be achieved a drilling jig was produced with a close fitting hole into which the component being made was fitted. This was then drilled as shown in Photograph 17 and the two, that is the part and the jig, tapped before the workpiece was removed. Photograph 18 shows the jig after being used together with the required component but this having been completed with other operations since being drilled and tapped. The partially tapped hole can though be clearly seen in the component, also in the jig itself. If required, the jig could have been used for more than one part by drilling more holes round the periphery of the large hole, though in this case only one part was needed. Even with there only being one part to be made the jig was all but essential as an alternative method would have been difficult to find.

Metalworking

Workshop Processes

Drilling Jig
Drilling Jig, using
Drilling Jig, using
Steam engine Tina, Cylinder and end cover
Drilling Jig, using
Mini Boring Head, Cylinder.

Not just a scriber and centre punch job

I do hope these pages have convinced you that positioning holes in a workpiece is not always a rule, scriber and centre punch task, but that there are other, and often better, methods for placing a hole in the required position.

wpe7285997.png

13

wpe7285997.png

14

wpe7285997.png

15

wpe7285997.png

16

wp5edc7c73.png

17

wp5edc7c73.png

18