Garrett Lambert
04-06-2003, 3:11 PM
I experimented with some of the 1 1/4 x 8 tpi nuts I purchased last week to make some faceplates. Here are 3: a "normal 5" plate, a 4" vaccuum chuck cup plate, and a 6" flat vaccuum chuck plate,, each showing a different method of attachment:
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The first one I made is on the right. I simply drilled 4 holes through the nut, and countersunk them for 4 #8 wood screws which fastened it to the piece of MDF. I'm not sure why I drilled 4, but it must have seemed like a good idea at the time. 3 would have done. After facing it to run true, I applied a piece of 1/8" closed cell foam with an impermeable backing - the foam shop guy called it a "skin" -with contact cement. I also sandwiched a small piece of the foam between the nut and the MDF to ensure a good air seal.
Having bought a few 3" washers as well, the next was the plain one on the left. This was actually an attempt to see if just a nut and washer could provide a 3" plate on their own. I turned a hardwood arbor to fit tightly inside the nut with a small shoulder that fit tightly inside the washer. With the parts clamped together in a vise, I drilled 3 holes through the washer and nut simultaneously, tapped the nut for 10-24 machine screws, and enlarged and counter-sunk the holes in the washer. When I assembled the nut and washer and put it on the lathe, the wobble wasn't bad, but it certainly wasn't acceptable. With nothing at risk, I took an angle grinder to it while it was spinning to see how closely I could get it to true. A small improvement, but basically futile, so I added a Baltic Birch disk. I mortised it slightly for the washer, epoxied the washer in the mortise, and then drilled and countersunk 3 holes through the washer and the disk. That done, I re-mounted it and faced the disk so that it runs true.
Finally, the cup chuck in the centre. This was made the same way as number 2 except that I simply screwed it together rather than mortising the washer with epoxy, since the vaccuum itself will help keep it all together. The cup is just a 4" ABS connector fitting cut almost in half on the bandsaw - almost, because I retained all of the internal ridge to provide a larger gluing surface for a ring of closed cell foam. A rabet in the MDF accepted the cup which was epoxied in place. Finally, I trued and gently rounded the edge of the ABS, and glued on a piece of foam for the seal.
This was all very satisfying, and not difficult to do. The cost was about $1.50 per nut/washer combo and %1.50 for the ABS.
Cheers, Garrett
<IMG SRC="http://www3.telus.net/GLI/Chucksup.jpg">
<BR>
<IMG SRC="http://www3.telus.net/GLI/chuckdown.jpg">
<BR>
The first one I made is on the right. I simply drilled 4 holes through the nut, and countersunk them for 4 #8 wood screws which fastened it to the piece of MDF. I'm not sure why I drilled 4, but it must have seemed like a good idea at the time. 3 would have done. After facing it to run true, I applied a piece of 1/8" closed cell foam with an impermeable backing - the foam shop guy called it a "skin" -with contact cement. I also sandwiched a small piece of the foam between the nut and the MDF to ensure a good air seal.
Having bought a few 3" washers as well, the next was the plain one on the left. This was actually an attempt to see if just a nut and washer could provide a 3" plate on their own. I turned a hardwood arbor to fit tightly inside the nut with a small shoulder that fit tightly inside the washer. With the parts clamped together in a vise, I drilled 3 holes through the washer and nut simultaneously, tapped the nut for 10-24 machine screws, and enlarged and counter-sunk the holes in the washer. When I assembled the nut and washer and put it on the lathe, the wobble wasn't bad, but it certainly wasn't acceptable. With nothing at risk, I took an angle grinder to it while it was spinning to see how closely I could get it to true. A small improvement, but basically futile, so I added a Baltic Birch disk. I mortised it slightly for the washer, epoxied the washer in the mortise, and then drilled and countersunk 3 holes through the washer and the disk. That done, I re-mounted it and faced the disk so that it runs true.
Finally, the cup chuck in the centre. This was made the same way as number 2 except that I simply screwed it together rather than mortising the washer with epoxy, since the vaccuum itself will help keep it all together. The cup is just a 4" ABS connector fitting cut almost in half on the bandsaw - almost, because I retained all of the internal ridge to provide a larger gluing surface for a ring of closed cell foam. A rabet in the MDF accepted the cup which was epoxied in place. Finally, I trued and gently rounded the edge of the ABS, and glued on a piece of foam for the seal.
This was all very satisfying, and not difficult to do. The cost was about $1.50 per nut/washer combo and %1.50 for the ABS.
Cheers, Garrett