interesting technical web site

Got this site from else where, theres some interesting stuff on there


http://www.metalwebnews.com/ed.html

Paul

The drill and tap guide is really usfull, nice one

the chain drilling method they claim is interesting, especially since they consider using a milling maching necessary, i have a slightly simpler way of doing it.

take for example, the size of the hole you want to create, say 50mm, and you've got just one drill, a 6mm or for old money chaps, 1/4" (i know theres a small difference, but humour me)

to chain drill effectively, get a block of 1/2x1/2 square bar about 3" long.

then get your calculator out, take the size of your drill, half it, and take the resulting number away from half of the diameter of the bore you want to create, as per

drill size, 6mm 6/2=3

bore size 50mm 50/2=25

25-3 = 22mm


now, mark the 1/2" bar 10mm from one end, then, accurately as possible, mark off another mark, 22mm from this one. if you want the bore less than 50mm and you want to file it, go 21mm or 21.5mm in.

centre pop both marks in the centre of the bar like this

[You must be registered and logged in to see this image.]

now drill both holes with your 6mm drill, and also drill a hole in the centre of the proposed bore you want to create.

grip the plate you want to drill, in the machine vice, place the drilled bar with the hole 10mm from one end over the top of the hole drilled in the plate, and drop a 6mm bolt through, if you've got a 6mm bolt with a shoulder on it, thats even better.

now you can just leave the bolt loose, but if you have a 6mm locknut, use this to bring it upto a snug fit, this will improve accuracy.

now, in you drill press (or a hand drill if you dont have a small pedestal drill, you can use this to accurately drill a sucession of holes all around the proposed bore. the spacing between if down to how close you dare go to each hole, but the radial accuracy is assured by the jig you've just made

when the drilling is done, you can enlarge each hole a further 0.5-1mm, if that allows you to stay in tolderance, and this will bring the holes closer together still, and allow you to drive the centre slug out with a small chisel.




Disclaimer always wear eye protection when drilling, grinding, or chiselling. tie off all loose clothing and hair, wear protective cover clothing, such as overalls or dustcoats. if using cutting fluid, use an apropriate barrier cream on hands, and wash after work.

Paul