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Harold Hall

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Next, using a 1/4" slot drill make the two slots required. Finally with this set up, turn the vertical slide to 7 degrees and machine the taper on the two parts requiring this, Photograph 6. The ability to swivel the vertical slide in the two planes is a definite bonus over the facilities available with a normal vertical mill, often worth making use of in the more fully equipped workshop.

 

Drilling and tapping the required holes is straight forward though in the case of the bush holder assembly it would be a good idea to drill tapping size holes first in the thinner part and use this to transfer the positions to the actual bush holder.

 

Mount the body with bush holder assembly onto the top slide and centre drill the bush holder followed by drilling and reaming 3/8" completely through holder and body. Finally, drill holder, Photograph 7 and ream 1/2" diameter. Note, the assembly is being fed by the tailstock and not the saddle mechanism, hence the bar between tailstock and the rear of the body.

 

If you do not have a 1/2" reamer you could set up the part on the faceplate and bore to size, use the tailstock with centre in the pre drilled hole for positioning. The last task for these parts is to slit the bush holder as shown in Photograph 8. This is an excellent example of a task more easily set up on the lathe even if a vertical milling machine is available.

 

The turned parts, see Photograph 9

These are very simple and need little comment except for three points. The cross drilled hole in in the part, front right of the photograph, can be done using this jig after it has been completed. The drawings call for silver steel (mild steel supplied) to be used for the drill bushes and eventually to be hardened, but unless you are to put the jig to considerable use normal mild steel should suffice. The drawing call for three bushes to be made and you may be concerned if wishing to cross drill another size. In this case first drill with a smaller size then remove the bush and open up to the size required.

Metalworking

Workshop Projects

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Cross Drilling Jig, parts
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 9

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 8

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 7

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 6