Thread: Cast aluminium spindle mounts

I have been lurking here a long time and have learned so much from the members of this forum.. thank you.
I have been slowly building .. nearly a year.. my own designed machine with a cutting area of 600x1200x150 and hope to add a fourth axis much later.
I am at the stage where I had to mount the spindle and looked at options. I could buy them from Ebay, get them made somewhere or have a go myself. The thought of cutting and shaping two plates of ally by hand, to get two identical mounts was for me daunting. However, I am a member of a group of enthusiastic volunteer engineer "wannabes" at the Petrie Markets in North Brisbane. We do aluminuim casting there so I had a go at casting the mounts. I made a pattern out of MDF, sealed it to make it smooth; it is obviously the red object in the pic. I then used the pattern and cast two mounts. They come out a bit rough but easy enough to clean up. Due to shrinkage and some distortion of the metal during cooling, I had to work out how to get them back into correct shape. I bolted the MDF pattern and one of the cast mounts ogether, then used a bench router table with a 9mm straight flute blade with a ball bearing to follow the pattern. Taking it carefully, the cutter easily reshaped the casting to match the MDF pattern. Happy with that, I then bolted the next casting to the already shaped casting and did the same process to make the second casting match the first.
As an experiment it seemed to work out very well although I had to shimm around the spindle to make it clamp up tight. The lesson learned if I was to do it again would be to shape the pattern to size but then add a few layers of masking tape to
make it oversize for the casting process, then remove the tape when using the pattern and router table to shape the casting. This gives a bit more metal to work with to allow for some distortion during cooling.
If anyone is inetersted in having mounts cast and supplied in the rough, let me know. We would ask for a donation and as an example the 80 mm mounts I made in the rough would be $5 each plus postage. You would have to supply the pattern in MDF or similar as long as it is smooth and non porous.
Some pics are in order...
cheers
peter