Question: Boring a larger hole on a piece too wide for a metal lathe

I once enlarged a hole using a fly cutter by the method discussed earlier, adjusting the cutting bit out incrementally until reaching the proper diameter. If no mill is available using an angle plate bolted securely to the cross slide. You may have to adjust the work several times to get it centered then bolt as rigidly as you can.
Good luck
Ray
 
waldenc1 said:
Here is the trunnion and hole that I need to enlarge. Where the shaft goes into the black cast iron trunnion I need to hog that hole from ~16mm to 25mm.
Click to expand...

That's scary; I'd think a bronze or even brass bushing, and 18 or 20mm, might be enough. Cast iron is generally not strong, just
easy to shape (or wear OUT of shape, as I suppose has happened here).
If you can use a lathe-trimmed bushing, almost any roughly-the-right-size drill will suffice for the job.
 
waldenc1 said:
I need to bore a larger hole in a table saw trunnion from about 16mm to 25mm to accept a bearing.
Click to expand...
Is this to convert it to ball bearing?
Thanks for the pics. Seems to me that I would not mess with that design unless it is worn or defective.
But if you have to do it on a lathe then mounting the trunnion on the carriage and using an adjustable boring head in the spindle would be simple enough.
 
Yes as has been sid above, mount the job on the lathe carriage and use a boring head, or if you don't have one, make up a shaft to run between chuck and tailstock live center set a cutter into a slot with a grub screw behind it for adjustment, like a line boring setup.would work well and be very accurate.
 
As others have said I would be cautious about opening the hole up that much. The end of the part may fracture then you're really in deep weeds
mark
 
Thanks for all the tips I really appreciate it! I thought about the surrounding casting 'possibly' being too thin after the mod I'll remeasure but I'm pretty sure there is enough meat on the cast iron. I'll also upload some pics on what I end up doing...
 
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Tozguy said:
Is this to convert it to ball bearing?
Thanks for the pics. Seems to me that I would not mess with that design unless it is worn or defective.
But if you have to do it on a lathe then mounting the trunnion on the carriage and using an adjustable boring head in the spindle would be simple enough.
Click to expand...
Yes it is to convert and it is defective the brass thrust washers have worn out twice it's a terrible design. I was looking at the parts lists of a newer model table saw and gone are the thrust washer and a sleeve and replaced with bearings and thrust bearings.
 
Take your part off, walk into any machine shop and and walk out. have a cup of coffee and go back in and take your finished part home.

You could already be done with this.
 
I agree, I'd take it to a machine shop. Before I had a mill I'd take stuff to the engine rebuilding machine shop I used. Much cheaper than taking stuff to a machine shop that did contract work who's prices were always higher & didn't always have the time to squeeze you in.

After seeing what needs to be done & what the part looks like, I wouldn't attempt this myself without a mill. Too easy to screw that up. If things were to go wrong, my thought is how much would it cost for that replacement part & is it even still available?
 
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