2014 POTD Thread Archive

[darkzero]

Finally finished the backplate to mount a 6.25" chuck on my 8" RT. Well, I still need to make some T-nuts & then I'm done.


Started with an 8" blank backplate from Grizzly (SouthBend branded "fine grain" CI).





Took sometime to rough it out as it was thick & 1/4" oversized (Ø)







I hate machining cast iron. Anytime I machine a lot of CI (or Ti) is when I really take the time to clean up after.





Bolt circles made easy, can't get any easier than with my ES-12's graphical display. Well I do have a SS.

 

[12bolts]

Nice work Will

Cheers Phil

 

[schor]

So this is the start of a new project. Getting my buddy's lathe up and running. It's missing the leadscrew and who knows what else. :bitingnails:

 

[KenS]

Finally finished the backplate to mount a 6.25" chuck on my 8" RT. Well, I still need to make some T-nuts & then I'm done.


Started with an 8" blank backplate from Grizzly (SouthBend branded "fine grain" CI).

How are you holding the backplate in the chuck? Double-faced tape? It looks like the rear register would not have enough depth for the chuck to grab. One of the problems I have turning disks is figuring out how to hold the work in the lathe. I guess a mandrel or expanding arbor would be one way to go, but they can get expensive real quickly.

 

[schor]

Part 2 is about removing the spindle (again) so I can put on a new belt.

 

[fixit]

Have the timber frame on my shed assembled, now for a roof.

View attachment 85130

Greg

BEAUTIFUL job, Just OUTSTANDING.

 

[darkzero]

How are you holding the backplate in the chuck? Double-faced tape? It looks like the rear register would not have enough depth for the chuck to grab. One of the problems I have turning disks is figuring out how to hold the work in the lathe. I guess a mandrel or expanding arbor would be one way to go, but they can get expensive real quickly.

The blank already had a short register on it. It wasn't that much of a register but plenty enough for me to hold the blank securely. I do use double sided tape for some small things, nothing this large, it was much too heavy for that. Holding with that register, I faced it flat, trued up the bore, & turned down the OD to size. Then I flipped it, machined to thickness & machined the register that I needed.

 

[f350ca]

Got the rafters and sheeting on. Maybe the steel tomorrow.

The tractor is going to like some shelter from the elements.

Greg

 

[schor]

Looking really good Greg.

 

[JimDawson]

Re: POTD - Repairing a Broken Carbide Burr

This was a brand new carbide burr that I damaged doing this project: http://www.hobby-machinist.com/show...our-Shop-Today?p=233001&viewfull=1#post233001




How to fix it.:thinking: I decided to try friction brazing first.


First I made a nipple that that I could ''bore'' with the burr. I needed a way to hold it on center, and keep it from turning for the next operation




A closeup of the burr



I chucked it up in a collet. I'm not worried about damaging a cheap Chinese collet, they are expendable in my book. But it didn't spin, so no collet damage.



Next bore into the nipple I made out of a HF air fitting I had laying around. ( I replaced all of my leaky HF air fittings with good ones)




Next I tried to friction braze the assembly back together. I spun the lathe up to 1200, and started working the tailstock in, but it just wasn't stable enough and I couldn't put enough pressure on it to get hot enough to stick. So that didn't work.
:think1:



On to plan B, brazing the two pieces back together. Since I still had the two pieces captured on center, this was pretty easy. I just extended the shaft out so I wouldn't heat the collet. Then I ''tinned'' both pieces with brass. I would have rather used nickle-bronze, but I didn't have any, and I didn't feel like making a trip to the welding supply.



Then I brought both pieces together, and applied pressure while heating. Once they joined, and bottomed out, I stopped heating. During the process the torch flame was in a more normal position, but I couldn't get a picture of that. I've always thought that machinists and mechanics should have been born with 3 or 4 arms.




Let it cool in place for a few minutes with the pressure on.



Hey, it didn't fall off.



Over to the disk sander to take off a couple of high spots of brass, then back to the lathe for a final polish.



And there it is, good as new. :biggrin: I must be a hobby machinist because I only spent about an hour of shop time saving a $24 expendable tool. :nuts: