Chuck Backplate

[Hawkeye]

Some months ago, my favourite tool store had a 6" 4-jaw chuck on sale for $65. I had been thinking about replacing the worn out one on my Hercus (SB9A) lathe, so it seemed like the ideal opportunity.

Turns out that not too many suppliers sell 6 1/4" backplates with 1 1/2" x 8 spindle threads. That's what the diameter of the chuck actually is. I tried to find one on-line, to no avail. Several trips to the scrappers didn't net me an appropriate piece of metal to make one. I even considered casting one from aluminum.

In the meantime, I wired a new shop for one of the owners of the scrap yard - a 3500 square foot addition to his garage. He (Kelly) was quite pleased with the result. During the construction, I went to the yard a few times to browse. On one trip, I noticed some broken pieces of cast iron that could come in handy. Kelly says, "Throw them on your bike." Last trip, I found another piece from the same parent chunk that was about 1 1/2" thick and very large. I was heading for the scale and Kelly says, "Throw it in your van. It's a tip for the good job." The two top pieces (and one thicker one that missed photo day) were from the first trip. The big one was from the last trip.
   

It takes a bit of cutting to get a 6 1/2" circle out of a piece that's too big for a 9 x 12 bandsaw.
   

With the blank bolted to the faceplate, the spindle side is faced and bored first.
   

Then the centre is threaded for the spindle.
   

After that, the piece is removed from the faceplate and the other side is faced and the register step cut.
   

Back to the rotary table on the Victoria for drilling and counterboring the bolt holes.
   

I'm quite pleased with the results. The rim of the backplate shows a TIR of less than 0.0005" and the body of the chuck shows a TIR of 0.002".
   
   

[Micktoon]

Nice , job Mike , it should serve you for many years to come

Cheers Mick

[TomG]

Excellent work Mike. It's always a plus when you can make something useful out of a piece of scrap.

Tom

[stevec]

Mike, lotta good work, nice results. I hope to do as well when I get around to doing one for my "soft jaw" project.

[DaveH]

Nice work Mike, - looks very good

DaveH

[aametalmaster]

Nice find and nice work. I am always looking in the scrap hopper for nice sized chunks of cast iron off broken parts...Bob

[oldgoaly]

Well got to admit I would not have thought a scrap chunk of cast that part of a broken part would have not turned so nicely. I was thinking there would be small stress fractures and would turn terrible. Just another nugget of knowledge!:
Do you think my wife will go again to the scrap yard? last time she loaded 600 lbs of truck axle stock, wish I have gotten more! (I was a couple days after major knee surgery walking with a cane)

[Hawkeye]

I don't know what the original piece was. None of my chunks nested with any of the others that I could see. It must have been huge. Good quality metal. No noticeable crust.

One interesting thing - When you get a piece of metal from the scrappers, it may have been handled by an electromagnet. When the piece was turning on the lathe, I could see some CI dust clinging to the carbide bit. As the polarity of the residual magnetism reversed, the dust would pulse in and out on the edge of the tool. I should have made up a sensing coil to see how much voltage it was generating. I'll bet I could see it on the oscilloscope.