Drilling question

Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.

Moderators: GlennW, Harold_V

whateg0
Posts: 1114
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Drilling question

Post by whateg0 »

Glenn Brooks wrote: Fri Jul 27, 2018 10:19 pm John, it strikes me you could put helicoils in the bronze worm gear in lieu of drilling and tapping on top of the interface. Certainly if your attempts to tap the hole go awry, you could use the inserts and do just fine, I think.

Glenn
I'm not sure how that would solve the problem. Even the helicoil needs a threaded hole to screw into. I have managed to find ways around this type of situation so far, but is it possible that an over-sized round hole could be bored in the correct location and then a steel or bronze bushing could be pressed in and threaded?

I know it isn't always going to be acceptable, but in some situations like this, could a smooth bore be made in one material and a threaded hole made in the other, then excess material removed so that what is left is half of one hole and half of the other?

Dave
User avatar
SteveHGraham
Posts: 7788
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Drilling question

Post by SteveHGraham »

Bore it oversize, fill the hole with some kind of brazing, and then use a drill.

I'm bored, so I felt like posting another idea.
Every hard-fried egg began life sunny-side up.
Inspector
Posts: 721
Joined: Mon Feb 23, 2009 4:25 am
Location: Saskatoon, SK, Canada

Re: Drilling question

Post by Inspector »

Even if you can make perfectly positioned and sized holes you will likely have the same issues with the tapping. Rather than pressing in a solid bronze bushing and then tapping I would use press fit threaded inserts unless the holes were out of position in which case the solid bushing would let you correct.

https://www.grainger.com/category/threa ... alog/N-8nr

https://www.mscdirect.com/browse/tn/Fas ... mc=0778629

Pete
User avatar
GlennW
Posts: 7284
Joined: Sun Apr 15, 2007 9:23 am
Location: Florida

Re: Drilling question

Post by GlennW »

The only real solution is thread milling...
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Drilling question

Post by jscarmozza »

Attached is a photo of the culprit, it's a worm gear that I want to attach to one end of an engine rotisserie that I'm making so that I have control with a load on it. I basically used GlennW's approach, two holes are tapped, one hole was plunge cut to 3/8" diameter with a pin installed as it was too far off to do much else with. I have installed oversized threaded brass plugs that were drilled and tapped afterwards to the correct size, but I didn't think it was necessary in this case. Thanks for all of the suggestions and helpful hints, John
Attachments
image.jpeg
Post Reply