Last Saturday, I got to put in some extra time on my Duif Workholding project, and my goal was to produce ten sets of the dovetail vice with baseplates. Unfortunately, I severely underestimated how long it would take and found myself five hours in with only a few of the baseplates complete.
I haven't really done this small scale of "production" work before, and so went about it in a slightly different method than one-off parts. Run time and consistent quality were something I had to take into account, so I had to program the piece so that it would only require me to come and swap the parts out when it finished.
I started by cutting many plates from a larger piece of bar-stock to use for the baseplates. I did this on the large bandsaw, which has a self-feeding mechanism so I could set it running and walk away. Because I wanted consistent stock sizes, I set up a quick and dirty hard stop using a chunk of aluminum to slide the large bar against. However, I didn't consider that since the diameter of the metal was so large, that as the bandsaw blade was cutting through it, the back slot where it just passed through would crimp together. Thus applying pressure on the blade prevented its movement and caused it to catch in the material. I didn't think this would be an issue as the stock was only resting gently against the hard stop, but even that gentle touch was enough to push the hot metal inward slightly. My boss gave me the solution: to have a finger spacer that you would put up against the hard stop and set the stock in place, then remove the spacer before clamping it down.
For the milling side of the project, I was able to take advantage of using soft jaws to hold the round stock in place, then milling the backside of the plate, flipping it over, and doing the final side. Starting with the backside gave me a stable workpiece to sit completely flat on when flipping it over versus doing the front first, which had angled sides making it difficult to get a good clamping grip on. I made the mistake of tightening my part in the jaws too much, which didn't manifest itself in a problem until I cut the dovetail in the center groove of the part. Because the plate was quite large, I could only grip it by a small portion on either side, so when you clamp it together, the center gets pushed up ever so slightly. When I cut the dovetails, it acted as a spot to release pressure and actually pushed the aluminum into the cutter itself, leaving a very odd surface finish. My solution was to take lighter cuts with the dovetail instead of re-cutting the soft jaws. Definitely, not a great solution as the material still pushed upward, but it worked for what I had.
I sadly only had the time to finish up seven of the baseplates. Still, the rest is ready to go for their final operation, and the programming for the final two parts is mostly finished, so I should, fingers crossed, get these completely done within a week or so.
Working on this and a self-centering vice project (new post to come about this) brings my hours to a total of 36:00:00 for this project so far. I'm getting close to finished with the products and should hopefully start selling them shortly.