rusty wrote:Harold I need some advice, I've never worked with plastic before.
I purchased this a few years back, forgot what type of plastic it is, I can tell you when you try to pull the stringers away they're elastic and it machines reasonably well.
Looks like it could be polyethylene. Definitely not Delrin, Teflon or Nylon. Most likely has a bit of a waxy smell when being machined, eh?
On the small end facing the tail stock, when the bowel is completed this is the end that will mount onto the motor shaft. Something in my head is telling me that I should bore this hole larger then install an insert with the hole reamed out to fit the motor shaft. What is your take on this idea.
If you have means to install the insert so it is reliable, I agree.
The inset would be held in place with roll pins, or flanged on the bottom then secured with screws , drill a slightly larger hole to access the set screw located on the insert which also would have a key way broached in, the maximum RPM is 1500 or slower.
Ok, now I'm thinking that the flange on that metal insert should come from the inside of the bowel with a washer on the bottom side with countersunk bolts topside going straight through
I was thinking something on the order of flanges as well. I'd consider a large nut, with enough inside diameter to permit the extension portion to be large enough to accept the required bore and keyway for the motor shaft. Sort of like a flange assembly for mounting grinding wheels.
Keeping things concentric is going to be a bit of an issue unless you hold sizes quite close. You may have to balance the entire assembly when it's completed. Castings are notorious for not being homogenous, so it could have a heavy side, even if it's machined on all surfaces, and is concentric.
I most likely would have recommended the bowl be made from 7075-T6 instead of a casting. Much more uniform, and of greater tensile strength. The strength may not be an issue, depending on the velocity of the bowl in operation.
Like to hear how it turns out. I rarely get on the board these days, so please send me an email when you post, directing me to your comments.
Wish you were near my location. I'm keen on learning more about foundry work. I intend to pour ductile iron in the future. While I never had enough interest to make the foundry my way of making a living, it has held my attention since I was a young lad---used to hang out at a couple foundries. I enjoyed all aspects, from watching cores being made to ramming and pouring molds.