How might I get this done?

WesPete66

WesPete66

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I have a project in the works and could use some suggestions. I am making an adapter plate for a Gibson tractor rebuild. This adapter plate is .500 x 6.00 flat steel bar x 7.50" long. First step is making a pilot hole through the plate, 2.840 dia and offset from the center of the plate. Since the hole is offset the part is too big to swing in my Atlas 10" lathe, fastened to a face plate. What other options do I have to make this hole? (my shop is limited to the Atlas TH/QC54 lathe, drill press & hand tools..) Pics of possible solutions are appreciated!
Thanks in advance!
 
Others will give you better advice, because my idea will be a big pain in the butt. With no mill to run a boring head in, I think you're going to have to drill a bunch of holes around the inside of the 2.480" circle and knock out the center. Then mount a drum sander in your drill press to sand down the high spots between the drill holes.

Or maybe convince your significant other that you have to have a mill! This would be a simple job for a boring head.

Good luck!

Bruce
 
If you had a mill I'd say boring head.
For a drill press how about a bi-metal hole saw?
Much depends on the required acccuracy of the final hole.

-brino

...another thought...how about the boring head held in the lathe spindle with the plate mounted on the cross-slide. Is there enough clearance from one side of the plate to the top of the cross-slide?
I have even seen boring bars mounted "off centre" in the four-jaw chuck to bore large holes in stationary work pieces.
 
^x2 on Dlane's advice.

As an aside a mill (especially with a DRO) would make this a piece of cake but if you that's not in the near future consider getting a x/y vise for the drill press. It gives you a lot more control and precision than without. Still not as accurate as a mill but good enough for most common things.
Edit: I missed the part about the large-ish diameter but as other suggested, a hole-saw, drilling a bunch of holes, a jigsaw with an appropriate blade or oxy/plasma cutter are all workable options.
 
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If it were me I would, A) take it somewhere that has a plasma table if the hole has loose tolerances, B) take it somewhere that has a cnc mill if it needs to be exact.
At 1/2" it will be a lot of filing and grinding most any other way. Although those other ways can produce a mighty fine hole! :pickaxe:
 
Trepanning Tool on a drill press, ya gotta go as slow as possible, have the work very well secured and use cutting oil.
Here is a link to when I used one on my mill, in this case it was aluminum and the part was the disc, but I have done it successfully on a Drill Press in steel.
 
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How critical is this pilot hole? Is doing it with a hole saw good enough? And I would use your drill press, much safer. And with a slooow speed. Maybe cut from both ends. Don’t use your hands to hold the plate when drilling.
 
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Sorry I should have been clearer.. This hole is a pilot to mate the transmission to a frame crossmember using the input bearing's O.D. for alignment. The existing part's counterbores are about .007-.010 larger than the bearing (2.831), so a target of ~2.834-2.840 would be awesome if I can do it with what I have available.
I like the idea of mounting the plate on the cross slide, with a boring bar in the 4-jaw. Down side is building a workable fixture, but seems more likely to succeed (?).
The trepan in the drill press seems easiest to achieve. But can a common belt drive drill press like mine pull a tool like that without issues?
A hole saw would be so easy, but is limited to nominal sizes. Does an adjustable hole saw exist?
Thank you all!
 
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