Recently I posted a thread about a clamshell hinge system I use to open a mold for which a hinge is especially well suited. It turns out that I have a pattern for a 36” camelback casting that is, because of its length, pretty tricky to open without breaking a little sand along one edge or another. I believe that what often happens is that just at the moment the cope lifts off the drag there may be the slightest lateral movement. This is despite the fact that I use rather well-fitting pins to guide the opening and closure of the mold. Today I decided to try to use a pry bar to crack the mold from one end and wedge it open about 1/4.” Then I went to the other end and did the same. Next I used my hoist to complete the opening. I got a “perfect” split with no cracked sand along any edge! Sweet! I think the fact that one end of the cope stayed in contact with the drag while the other was wedged upward help prevent any lateral movement. Do others ever use this technique? It is new to me. Denis
I have seen some jobs that could be done that way but others failed because of lack of clearance...usually tall part with long draw. I have seen a split fork that slides in between the cope and drag flask and when rotated downward it lifts the cope...very similar to the rotolift type squeeze machine. They are only good for separation as they only travel about two inches. They would work well...once the separation is made you are clear to use the lifting hoist...one hand on fork and one on the lift controls.
Yes, horses for courses as they say. Draft angles limit which molds can be done. But for this pattern/mold this method improves accuracy of those critical first mm’s of opening. BTW, since my hoist is controlled with a radio-controlled foot pedal, both hands can help control opening motion. RC Control Foot Pedal Hoist Denis
BTW, I no longer use that hook on the mechanical trigger switch to reverse direction. I carefully split the motor case, routed wires, and brought the wires out to a DPDT switch. That is a better setup. The other worked OK. But I had to be careful to fully mechanically move that little rectangular switch. The DPDT is very binary—-for. or rev. with nothing in between. When I built the hoist I was unsure if it would work and I hated to “mess up” the drill motor as that made that drill motor useless for any other purpose. I think you’ll be pleased if you make one. Denis
I have been pricing the lifts from HF and they are not too high. Since they are building one right down the road from me I will most likely get one in a couple weeks.
