Posts: 4,779
My VIN: Banged your VIN'S mom
I am definitely going to be in the market for a printer this year. I remember just a few years ago when this was fairly new technology a printer cost about the same as a decent DeLorean.
Any suggestions for a good budget priced unit designed for idiots?
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
Well as I suspected the pouring of the white epoxy on the inside will not work because I can't clean all the uncured print "ink" prior to pouring. Now my next problem is if I print the part to pour from the outside then that "decal" has to printed last (away from the base plate) because of the little inside part of the "R" and "4" since you can't put a support on those parts.
So it looks like I need a way to machine both sides of the ball. I'm thinking of a way to print an area that will support one side in my lathe 4 jaw chuck. The other side is supported by the threaded insert for machining.
Another option is to print the ball in two halfs and glue them together. Or print the lettered area as a disk that is then glued into the printed ball.
Last edited by Bitsyncmaster; 01-13-2020 at 05:30 AM.
Location: Austin MN
Posts: 583
My VIN: 03500
I've seen some videos on youtube of people sticking UV LEDs in hollow prints to cure them on the inside.Originally Posted by Bitsyncmaster
Is that something that would work for your project?
Dave B.
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
That may be a good idea on some designs but my problem was I could not wash the uncured resin out of the fine lettering outline.
Posts: 448
I think you're on to something with the two halves. But perhaps split it bottom third, top two/thirds. Or even larger ratio. Just enough to give you access for cleaning thru the bottom. It might also be an advantage to have the bottom open for incorporating the required mounting thread. Finally, when top and bottom get assembled, the mating crease is fairly hidden on the lower side of the ball.
Ron
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
Well I printed a ball with the lettering pointing down (this is the last thing printed and is away from the base, my printer the base is on top and it moves down to start and then moves up with each slice printed). I printed a "box" around the numbers and letters. So I was able to fully clean out any liquid resin and pour the white epoxy into that box. After it hardened I could then use that box to clamp it into my 4 jaw chuck on my lathe. So I machined the bottom of the gear ball.
The hex insert was a little tight but I got it installed so now I can use that threaded insert to hold it in my lathe and machine the top half (machine that box off to expose the numbers). It's funny that hex insert printed about 0.006" smaller just because it is now printed at 15 degrees offset from the base. Probably would have been same size if I printed thinner slices but that adds a lot of print time. I'm printing 100 mm slices and could select 50 mm or 25 mm.
I also find machining the ball if your take off 0.010" cuts you get a little chipping of the ball but 0.005" cut seems to stop that. So final cuts I do at 0.0025".
Last edited by Bitsyncmaster; 01-14-2020 at 08:50 PM.
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
Well I'm keeping the 15 degree offset on the "decal" so all I'm doing now is making changes to make machining changes to my 3D model. I put two rings on the ball so I can center it with my dial indicator for each the halfs that get machined. It turns out those hex inserts are not made well enough to depend on the threaded part to be exactly centered and parallel. Not that it matters when finished it's just to get the ball machined. I would have to machine my own inserts to get perfection but that would take to much time if I decide to sell these.
It looks like 600 grit sand paper wet sanding the ball it pretty good to eliminate any scratching before I polish the ball. The "decal" comes out perfect in that you can not even feel it with your finger nail. I guess if you don't like glossy you just don't do the final polish.
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
I had a great idea while machining the last gear ball I just printed. I am having trouble getting the second half of the ball machined because of the accuracy of the threaded insert pressed and glued into the ball. I thought of making a holder for the head-stock of my lathe that will center from the first machined ball end. My lathe head-stock has a #1 Morse taper so I ordered a Morse blank that I can machine a ring into and an 8 mm threaded rod. So if this works it should not need any centering, just screw the part onto the holder.
Location: Burnsville MN-Moving to Kalispell MT. in June 20111
Posts: 886
My VIN: 2691
curious what type of lathe you have...
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
I have the Sherline lathe and mill along with a lot of their accessories. Maybe someday I will update them the CNC.
https://www.sherline.com/
Posting Permissions
Reply With Quote
Dave M vin 03572