1.25" Thru Hole On A Angle??

[Matt4wheels]

I'm needing to mill, drill and/or bore a 1.25" thru hole in .75" 1018 CRS on a 17 degree angle from vertical. Would the preferable method be to mill a flat then use a twist drill or could this be made with a boring bar which would start and end with an interrupted cut? Twist drills and EM options seem to be more limited and $$$ at this size. Please kindly advise how you would go about this using a manual mill to produce this feature.

 

[John Hasler]

Based on the tools I have I'd mill a flat, drill to 7/8", and bore.

 

[Tony Wells]

I'd calculate the largest size hole that could be put in straight, just to get the material out of the way, drill it, then incline the mill head or material and switch to a boring head to finish it.

 

[Matt4wheels]

Thanks for the responses. With regard to boring on an angle, it sounds like an interrupted boring cut isn't a forbidden approach as I would likely encounter this with either of your suggested scenarios. Is this correct?

 

[Tony Wells]

That is correct.

 

[Matt4wheels]

Thanks for the help.

 

[Tony Wells]

That's what we're here for. Any time.

 

[T Bredehoft]

Boring at an angle will produce a far better hole than drilling at an angle. Just be sure everything is solidly fastened down, the quill should have as little play as possible, (snug the clamp, but not tight.) My PM25 has about .0025 play in the quill when it's fully loose.

Edit: correct typo.

 

[hman]

I've had pretty good luck with hole saws. You could set up the work piece at the correct angle and use a 1" (or maybe 1 ⅛") hole saw to get the bulk of the material out, then switch to a boring bar. Use lots of lube if going with the hole saw!

 

[Wreck™Wreck]

If you want to make using hole saws much easier, drill some holes just inside the hole saw OD, the coolant or oil will wash the chips out of the groove through these holes and the work will go more than twice as fast, one of the problems with hole saws is that the chips can not exit the groove that they create so when the teeth fill it stops cutting and must be pulled out and cleared. If the chips have a place to go one may cut through in one pass.

Try it

As far as the OP's question is concerned it would depend upon the accuracy required by the customer or job., if meeting someone elses demands, (assuming that they have a way to measure it) the angle may require the use of a sine bar or other fixture thus produced. If just a clearance hole throw it in the mill vice, use a protractor to set the angle, plunge straight in with the largest center cutting end mill that is smaller then the finished bore and drill or bore away.