06-28-2015, 01:59 PM
(This post was last modified: 06-28-2015, 02:00 PM by Roadracer_Al.)
Hey there gang...
I had a repeating job in the shop yesterday. I belong to the South End Rowing Club in San Francisco, and I am one of the volunteers who maintain our antique wooden boat fleet. The job which came up was to make "nut plates" out of SAE 954 Aluminum-Bronze. The parts are 5.75" long, .5" wide, .25" thick and have 5 tapped holes, and 3 countersunk mounting holes. Very straight forward. These are for a 6-person "Barge" (quite similar to a Cornish racing gig), with 3 required for every position, plus a couple of spares, for 21 pieces total.
Late last year, I did the same job with slightly different dimensions for 3 different boats.
The mill finish on 954 is very ripple-y and is oversized by roughly .08" so it can be cut down to it's nominal size. The smallest stick I could find is 1" x .375", so there's a LOT of roughing.
As a nerdy aside, while the blanks were cutting off in the bandsaw, I used my Rhodes shaper to square up one side. This worked out great!
Last time, I used a slitting saw quite successfully to split the piece lengthwise, if memory serves... taking the .375" DOC in a single pass.
This time, it wasn't working well at all. I set the RPM to 300, which was a somewhat slower than last time. I was using a modest feed - it's a manual mill, no power feed. I'd estimate about 2" per minute. The first cut was wildly crooked: it sloped up by almost .1" over 5" ! When I went back to try to trim it flush with a second pass, the slitting saw blade snapped.
On the second piece, I found another, similar saw, got the height of the cut set right, and tried to take roughly half the depth ~.18" in one pass. The first pass went OK, but the second pass showed some crookedness as a slope up toward the end of the cut, much like the first one, then promptly snapped when it touched the third workpiece.
Down to my last saw, I fell back and punted: taking 5 passes, using heavy sulfured cutting oil.
I'm at a loss as to why the first two blades broke - I've rarely had any trouble with slitting saws. They always seem to work great, and will take lots of feed. Any thoughts? The arbor is a nice made-in-USA quality piece.
Thanks!
I had a repeating job in the shop yesterday. I belong to the South End Rowing Club in San Francisco, and I am one of the volunteers who maintain our antique wooden boat fleet. The job which came up was to make "nut plates" out of SAE 954 Aluminum-Bronze. The parts are 5.75" long, .5" wide, .25" thick and have 5 tapped holes, and 3 countersunk mounting holes. Very straight forward. These are for a 6-person "Barge" (quite similar to a Cornish racing gig), with 3 required for every position, plus a couple of spares, for 21 pieces total.
Late last year, I did the same job with slightly different dimensions for 3 different boats.
The mill finish on 954 is very ripple-y and is oversized by roughly .08" so it can be cut down to it's nominal size. The smallest stick I could find is 1" x .375", so there's a LOT of roughing.
As a nerdy aside, while the blanks were cutting off in the bandsaw, I used my Rhodes shaper to square up one side. This worked out great!
Last time, I used a slitting saw quite successfully to split the piece lengthwise, if memory serves... taking the .375" DOC in a single pass.
This time, it wasn't working well at all. I set the RPM to 300, which was a somewhat slower than last time. I was using a modest feed - it's a manual mill, no power feed. I'd estimate about 2" per minute. The first cut was wildly crooked: it sloped up by almost .1" over 5" ! When I went back to try to trim it flush with a second pass, the slitting saw blade snapped.
On the second piece, I found another, similar saw, got the height of the cut set right, and tried to take roughly half the depth ~.18" in one pass. The first pass went OK, but the second pass showed some crookedness as a slope up toward the end of the cut, much like the first one, then promptly snapped when it touched the third workpiece.
Down to my last saw, I fell back and punted: taking 5 passes, using heavy sulfured cutting oil.
I'm at a loss as to why the first two blades broke - I've rarely had any trouble with slitting saws. They always seem to work great, and will take lots of feed. Any thoughts? The arbor is a nice made-in-USA quality piece.
Thanks!