Last year while using a "top of the line" Harbor Freight arbor press, I wound up having a broach wind up shattering. The wobbliness of the press was the largest contributing factor. In the broaches defense it knocked out probably around 100 or so 12mm square holes in 1 3/4" couplers for boat racing.
Once I quit bleeding from some small pieces of schrapnel and mulling the loss of a $220 tool, I figured that I had to do some work to get everything rigid and guided on rails.
I poked around on e-bay from some linear bearings. Being known as very frugal I waited until something finally showed up for what I thought was a reasonable price. 1" diameter recirculating ball bearing units showed up and I was in business. I am simply using 1" stainless boat prop shaft for the rails since I had in my metal inventory already. It isn't hardened as it should be for the application, but in this setup, they shouldn't really see an appreciable side load so am not worried about it. I also welded all the junctions of the frame for better rigidity over the just the through bolts and added legs to have it mounted to the wall for even better stability.
I wound up making a new crossbar under the bottle jack. In hindsight, I realized that with the three bearings it was over-constrained. The left hand guide could have simply been a piece of plate running between two pieces of angle iron. I had already welded and painted the assembly though, so simply mounted the guide shaft on large shoulder bolts to allow for any runout between the vertical C columns. The linear bearings are a light slip fit into counterbores that I turned on the housings and held in by three 6-32 button heads. On the tops I made up simple chip and dirt shields of .062" aluminum with a piece of felt that drags the shaft sandwiched in between them.
The bottom of the press ram has a tapped 3/8-16 hole, so I can make up different press mandrels as needed and screw them in. This will make those parts sacrificial and help maintain the flat surface on the ram instead of it getting beat up.
It works out great now and is about as precision as something like this can get.
Steve
Once I quit bleeding from some small pieces of schrapnel and mulling the loss of a $220 tool, I figured that I had to do some work to get everything rigid and guided on rails.
I poked around on e-bay from some linear bearings. Being known as very frugal I waited until something finally showed up for what I thought was a reasonable price. 1" diameter recirculating ball bearing units showed up and I was in business. I am simply using 1" stainless boat prop shaft for the rails since I had in my metal inventory already. It isn't hardened as it should be for the application, but in this setup, they shouldn't really see an appreciable side load so am not worried about it. I also welded all the junctions of the frame for better rigidity over the just the through bolts and added legs to have it mounted to the wall for even better stability.
I wound up making a new crossbar under the bottle jack. In hindsight, I realized that with the three bearings it was over-constrained. The left hand guide could have simply been a piece of plate running between two pieces of angle iron. I had already welded and painted the assembly though, so simply mounted the guide shaft on large shoulder bolts to allow for any runout between the vertical C columns. The linear bearings are a light slip fit into counterbores that I turned on the housings and held in by three 6-32 button heads. On the tops I made up simple chip and dirt shields of .062" aluminum with a piece of felt that drags the shaft sandwiched in between them.
The bottom of the press ram has a tapped 3/8-16 hole, so I can make up different press mandrels as needed and screw them in. This will make those parts sacrificial and help maintain the flat surface on the ram instead of it getting beat up.
It works out great now and is about as precision as something like this can get.
Steve
