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Message: <blockquote data-quote="Tazza" data-source="post: 40274" data-attributes="member: 82">Well, i finally got some time to work on mine. The one i did previously was very crude and didn't use bearings, i made up cast iron bushes for the rod to run on that gauled up pretty fast, but got the job done, the bearing idea sure made it easy.I started off with a length of 1" bar, i drilled two holes for tool steel and two set screws. The distance between the two sections i needed to machine were too far apart for the machine i was using to do the work, i was even considering two cutters 180 drgrees apart and drill both ends at once, but i wasn' that motivated. Here are the goodies used. Two self aligning bearings with mounting plates so i could weld them to the bobtach to hold the boring bar. Two tapered sleves to align the bearings for welding. Without them, you will not be asured that the new hole is where the old one was. I simply slid the bar in one end of the bearing, through one side of the bobtach, installed the two guides facing outwards then slid the rod through and installed the last bearing. Holding the guides out into the holes, tack the bearings onto the bobtach. When both are done, slide the bar out and remove the guides. You will notice a 1 1/4" rod with a taper, this fits the machine i used to drill the holes. I cheated and tacked it to the 1" bar.<img src="http://users.tpg.com.au/tazza_/Bobtach/Image090.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />Here is a picture if the drilling machine all hooked up ready for work. The drive unit is an old rail drill. They use them for drilling holes in railway tracks. I removed the petrol engine and put an electric motor on, much quieter and smooth running. It rotates quite slowly, about 60-90 RPM and every rotation the lead screw turns a bout 1/8th of a turn giving a very slow in feed, but an excellent cut.<img src="http://users.tpg.com.au/tazza_/Bobtach/Image086.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />Here you can see the chips it was making, i may have been cutting more than i should, but it cut it with ease, didn't dull the cutter either. I made sure i kept at it with cutting fluid.<img src="http://users.tpg.com.au/tazza_/Bobtach/Image088.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /><img src="http://users.tpg.com.au/tazza_/Bobtach/Image087.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />Here is the end result, nice clean cut and it in perfect alignment with each other. As the holes were not the exact same size, i made bushings to fit and pressed them in. It brought it back to 1 1/4". The pin slides in with a slight tap, it doesn't bind so it shows its just right.<img src="http://users.tpg.com.au/tazza_/Bobtach/Image089.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />I had two to do, both worked very well, only took an hour or so, but the preperation took a lot longer. The rail drill needed repairs, the tapered drive shaft for the drill needed making, but its all worth it for the results. I'm planing on using it to bore out my lift arms to install bushings as they are worn and the only way to fix it is to bore them out and make a bushing.</blockquote>

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