looking at buying or building an economical line boring setup. any suggestions or warnings to stay away from. have a good mag drill looking at one of the bar set ups for it . probably only will use once or twice a year . boring 1.25" up to at least 120mm loaders,excavators,conveyors,highway trucks and crushers in the fleet . just another toy er tool in the box
I'm looking at building one myself. If you already have a mag drill, you're halfway there. Just get a large diameter piece of barstock, turn down one end to fit your mag drill chuck, drill a cross-hole at an appropriate height for a turning tool, get a large self-aligning flange mount bearing to fit the bar, and tack-weld it to your workpiece on the opposite side as you're going to mount the drill. basically like this: http://www.americanmachinetools.com/images/line_boring_photo-2.jpg
For the bar, look for "4140-ht P&G" That'll be heat treated to Rc 28-30, but still able to be drilled and tapped, and polished and ground so will fit your bearings with a nice slip fit. It's a very common material.
1.25 is getting down a bit. You would need a skinny bar to get in there. That bar wouldn't bore 120 mm so you may need to set up with a couple of different bars.
we are trying to figure out the best way to make it auto feed and was also talking about squaring up the holes for the tooling I think it's called broaching. we buy bearings all the time for conveyors so thats not a problem. does the mag drill set up work good and do have a problem with the turn down shaft breaking
Have a machine shop make your bar from the above posted material. Yes, they will drill your cross holes and broach them in a simple press set-up. You can also buy a square socket to put inside a drilled (round) hole, but your running out of material with the smaller bar to do it this way. On the necked down portion (to fit in the drill chuck) make the transition to the larger dia a large radius, and polish out any tooling marks. Power feed, I would look at the power feed motors sold for a Bridgeport, take off the quill handle, and make it fit there, re-apply the quill handle outside of it.
I am in process of building a 1 1/4" bar set up right now, but I'm just making it up as I go. Your tool holes need to be off center on the bar so the cutting is on center for positive cutting rake. With a 5/16 sq hole on an 1 1/4 bar, that was .157" (5/32, half the tool bit) offset from center. The hole for a 5/16 broach is 21/32, which also happens to be the tap drill for 3/8-24 NF, so I'm going to tap for back-up set screws for the bit, which will also have the added benefit of relieving some of the metal the broach would otherwise have to plow out. You need to make a fixture with a couple of 2 pc shaft collars to hold the bar while you broach because since you're pushing off-center, the broach is going to try and turn the bar, resulting in a broken $100 broach (don't ask how I know that ), also, a hand lever arbor press is way better for broaching than a hyd press where you have no feel and the ram continues after you let off a little. For the feed, I bought a worm gear screw jack off ebay ( http://www.ebay.com/sch/i.html?_odk...+gear.TRS0&_nkw=screw+jack+worm+gear&_sacat=0 ) and am rigging a variable speed electric motor to the input. I have two collet lock flange bearings to hook the feed to the bar wherever I want. I got looking around and think I might try a ratchet feed like this https://www.youtube.com/watch?v=RRS__yHZghw or https://www.youtube.com/watch?v=YzNKX3um3yA I don't care for the York style drive/feed because it hangs all the weight of the drive off you end bearing and has no provision for mis-alignment between the bar and the drive spindle. A bar that's held tweaked can give you some nasty chatter you can't get out of sometimes. The other draw back of the York style is you have to have all the head room at the end of the bar for the drive, which isn't available every time. I am either going with a right angle bevel gear drive or a parallel motor drive with a heavy timing belt positive drive. I'll build a hollow spool with bearing that slips over the bar so the drive can be positioned anywhere on the bar. I burned some bearing mounts out of 1/2 plate. They will bolt down like the Hofmann supports so they can be positioned easier. I tapped them 3/8 instead of 1/2 so there was some movement to fine tune the bearing position. Greyson
gtermini, I do like the way that your brain works. About forty years ago I got the job of line boring two bores on a press brake. A piece of ground rod w/#3 morse shank on one end, and two blind holes for round hss blanks, a set screw to advance the cutters, and set screws to lock the position. It was a one time deal with a big rush factor. The cutters were adjusted in a lathe using an indicator, and removed from the bar prior to sliding the bar through two four bolt flange bearings that had been spaced away from the mounting faces to allow clearance for bore through. The cutters were reinstalled, locked in position, and the Milwaukee drill was lugged up a step ladder and hung on the bar, magnet turned on and waited for the drill to knock me off the ladder. It did not. This was done by a much younger man, do not try this at home, check your insurance for exclusions........ The bores were within .005" of tnf arget. The cutters were 180 deg. from each other to balance the bar flex. The same drill was used to drill out and re-tap a series of stripped 1 1/2"nf holes for heli-coils. Good luck, and work safe
gtermini, I do like the way that your brain works. About forty years ago I got the job of line boring two bores on a press brake. A piece of ground rod w/#3 morse shank on one end, and two blind holes for round hss blanks, a set screw to advance the cutters, and set screws to lock the position. It was a one time deal with a big rush factor. The cutters were adjusted in a lathe using an indicator, and removed from the bar prior to sliding the bar through two four bolt flange bearings that had been spaced away from the mounting faces to allow clearance for bore through. The cutters were reinstalled, locked in position, and the Milwaukee drill was lugged up a step ladder and hung on the bar, magnet turned on and waited for the drill to knock me off the ladder. It did not. This was done by a much younger man, do not try this at home, check your insurance for exclusions........ The bores were within .005" of tnf arget. The cutters were 180 deg. from each other to balance the bar flex. The same drill was used to drill out and re-tap a series of stripped 1 1/2"nf holes for heli-coils. Good luck, and work safe. After a quick look at the ratchet feeder, I can see a place for a pipe die holder, and a modified insert. Would you have enough room to mount a salvaged quick change gear box from a small lathe to get adjustable feed rates.
anybody know any thing about JT Dixon line boring equipment or american machine tools