Making larger holes?

[swatson144]

V blocks would work. Or as mentioned off set in a 4 jaw chuck should do unless the chuck/lathe is 2 small. I've done 1/2 " plate for 6" sheaves that way.

Steve

 

[astjp2]

Chain drill and a file, no cost, just time and you can get a very accurate fit that way. Tim

Chain drilling requires you to drill a series of holes along the inside of the major hole you are trying to drill and then filing out the extra material until you have a smooth hole that is the right size.

 

[refinery Mike]

Just a word, to silver solder those large pieces of copper will take a lot of heat. I doubt you will be able to do that with a standard brazing tip in a torch. The copper steals the heat away so fast that you have to heat the whole piece at once. maybe try to braze it while the piece sets over a charcoal grill. or heating the whole piece with a rosebud then brazing with a tip. Also copper is a strange material. It cuts funny and not well at all, it can be grabby as well as much harder to drill than it's hardness would suggest. Also what kind of copper are you using, if it is electrical grade copper you will find that it becomes quite brittle when heated. The metal tends to absorb oxygen into the metal and oxidizes the grain of the metal. Plummers copper has alloys to prevent this so you can safely braze their copper pipe.

 

[DianneB]

It is plumbing copper and I plan to set the whole thing up over a 10,000 BTU propane burner and go at it with the oxy-acetylene torch. I will shroud as much as I can with firebricks, etc.

I am aware of copper's machining peculiarities - just makes machining fun LOL!

 

[george wilson]

I got used a set of boring tools and can't recall the name right off. Not something I use very often. It consists of a 3/4" drill,and a steel shaft you can put progressively larger flat cutters into,with pilots for the last size hole. With it,you can gradually drill large holes with a Bridgeport. I can't recall offhand how large they get. 2 1/2"? The set costs about $400.00. I wouldn't pay that,but got this used set off of Ebay a few years ago for much less. The type thing you never use unless you need to bore a BIG hole! I had bought one for the shop at work and used it. Except,I took a light grind along the 3/4" drill to reduce the diameter,to make it fit the 3/4" bar better,for a more accurate hole diameter with the inserted flat cutting tool.

For thinner stock,maybe up to 1/2" max.,a drag cutting trepanning tool is available. It costs money too. How thick is the material you are drilling? I hate turning copper.

 

[DianneB]

I guess I will set up the flat plates on a faceplate and bore the holes. For the smaller hole in the curved surface I think I will wait until my rotary table arrives
(next week?), set it up on V-blocks, and use the mill to make the hole. Seems like the safest way to get an accurate hole without screwing anything up.

Thanks for the ideas gang!

 

[george wilson]

Be careful to have the work securely clamped. Copper is grabby as anything,and I hate to machine it. Silver is a close second,and nickel (German silver) is another bad metal to machine. I've done them all,but they aren't my favorite!!

 

[DianneB]

I decided to bore the 1-5/8" holes in the flat plates and it worked out fine. Quite a bit of time in getting the plate centred on the hole but it did a nice job.


For the 1-1/8" hole in the boiler barrel I thought I would try a crude, huge, and OLD plumber's reamer that I had in the bottom cupboard.


That worked as well! So now I have all the large holes completed and all the pieces made for my boiler.


Thanks gang!

 

[xalky]

We want to see pics of the soldered assembly. )

 

[stevecmo]

This looks like a very cool project. You'll definitely have to post more pics as it comes together.

Thanks for sharing.