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. That's a 12" scale on top.


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, screwed onto the spindle 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". Nice and smooth at 700 RPM.

 

[Ray C]

Nice! Fun project. So, how dirty are the hands and fingernails now?


Ray

 

[Hawkeye]

Ray, by the time I was finished, my hands were black. Needed scrubbing several times with Gojo, soap and shampoo to get close to clean.

 

[DMS]

Great work there Hawkeye.

Side note, I need to make friends with more people who run scrap yards...

 

[Hawkeye]

Shawn,

I used my 5 x 5 Portaband to cut out the blank, which is just over 1 1/2" thick. The long cuts were done in two stages - cut from each end. Once the piece was small enough, I moved out to the 9 x 12 in the garage. Square first, then nipped off the corners to make a rough octagon.

When I made the faceplate (years ago), I drilled and tapped a bunch of 3/8" holes for bolting. The plate wasn't thick enough to do T-slots. I used a wood-turners trick to pick the best centre point. Years ago, I made a plexiglass disk with a 3/16" hole in the centre and a whole bunch of concentric grooves out to the 8" total diameter. You place the disk on the work and move it to get all of the largest possible ring on solid material. Then you drop a centre punch into the hole and give it a tap.

Scribe a line across the work, running through the centre punch, then use a protractor to mark an accurate cross-line, also through centre. A scriber in a compass marks the bolt circle radius. The centre punch mark hardly moved. I did plan the blank to be suitably larger than the final diameter.

 

[Ray C]

Ughhh, I hate machining the stuff because it's so messy but, the finished work always looks great. Surface ground CI is positively sexy!


Ray

Ray, by the time I was finished, my hands were black. Needed scrubbing several times with Gojo, soap and shampoo to get close to clean.

 

[ARM]

Shawn,

I used my 5 x 5 Portaband to cut out the blank, which is just over 1 1/2" thick. The long cuts were done in two stages - cut from each end. Once the piece was small enough, I moved out to the 9 x 12 in the garage. Square first, then nipped off the corners to make a rough octagon.

When I made the faceplate (years ago), I drilled and tapped a bunch of 3/8" holes for bolting. The plate wasn't thick enough to do T-slots. I used a wood-turners trick to pick the best centre point. Years ago, I made a plexiglass disk with a 3/16" hole in the centre and a whole bunch of concentric grooves out to the 8" total diameter. You place the disk on the work and move it to get all of the largest possible ring on solid material. Then you drop a centre punch into the hole and give it a tap.

Scribe a line across the work, running through the centre punch, then use a protractor to mark an accurate cross-line, also through centre. A scriber in a compass marks the bolt circle radius. The centre punch mark hardly moved. I did plan the blank to be suitably larger than the final diameter.

Hello there HAWKEYE

Thanks for this post, most interesting to say the least.
Just a quick one, how did U bolt the RAW piece initially to the FACE PLATE ???
U could not have DRILLED AND TAPPED as U required those holes exact for the finished piece, did U ???
U will appreciate that as rookies, for us it's always ............."now how did he do that", 'cos there's so much we don't know !!!
And BTW, U used no coolant whilst turning this CI ???
Thanks a mill in advance and
LORD BLESS
aRM

 

[pdentrem]

Great job. I too am making two backing plates for my lathe. One for a small 5" 3J and a collet chuck. I am starting from raw 8" blanks so I can start turning right away. I have one done except for drilling the mounting holes. I will start the second one Saturday.
Pierre

BTW I use Tide powder laundry detergent for most of my hand cleaning requirements.

 

[Hawkeye]

Arm, the faceplate I made for the 9" lathe has quite a few holes drilled and tapped for mounting. The holes near the centre boss are drilled and counterbored to fit the faceplate. The holes that mount the chuck are around the outer rim and show up in later pictures.

 

[ARM]

Arm, the faceplate I made for the 9" lathe has quite a few holes drilled and tapped for mounting. The holes near the centre boss are drilled and counterbored to fit the faceplate. The holes that mount the chuck are around the outer rim and show up in later pictures.

Thanks a stack for the input.
It does make sense to go the way U did.
Will remember this permanently.
Take Care
aRM