1 Topic by blarz

  • blarz
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  • From: Hazleton, PA
  • Registered: 2013-06-26
  • Posts: 72

Topic: Size problems with functioning parts

Ok I know this is probably buried here someplace, and I have searched. I just cannot find it. I am having a problem with getting correct sizes when attempting to make functioning parts, ie bolt/screw holes, mounts for buts or bolt heads, etc. I don't have issues with actual size of the objects being created, but problems with making them functionally fit and work together. Should I be using a multiplier when making the parts for shrinkage?  I am using autocad, sketch up and am currently trying to figure out openscad. So any and all suggestions are greatly appreciated.

SD3/SD4 Mods completed: glass bed, changed zrod to 5mm, slop nut, aluminum arm-originally wood, plexi-glass case, Z Wobble Preventer,  Lawsy Carriages, X\Y motor fans, control board fans, extruder cartridge heater, MK5, Esd Lite
Mods working on:Direct Y Drive
Remember.......All you touch and all you see is all your life will ever be....Pink Floyd...Dark Side of the Moon.

2 Reply by machinistjoe

  • machinistjoe
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  • Registered: 2013-01-26
  • Posts: 64

Re: Size problems with functioning parts

Well, it's more a matter of how your parts need to fit as well as the printer settings. inside diameters tend to print under size. The amount that the print is off will depend on your printer and filament settings. I would say it's trial and error, mixed with designing for your intended material. I have had to rework entire assemblies for the sake of printing the objects rather than machining them.Also, toss in a fair amount of calibration as well. SD machines tend to make oblong holes and bosses out of the box, so dialing in your belt tension and stepper motors will help.

3 Reply by IronMan

  • IronMan
  • IronMan
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  • From: SC
  • Registered: 2012-09-14
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Re: Size problems with functioning parts

machinistjoe wrote:

Well, it's more a matter of how your parts need to fit as well as the printer settings. inside diameters tend to print under size. The amount that the print is off will depend on your printer and filament settings. I would say it's trial and error, mixed with designing for your intended material. I have had to rework entire assemblies for the sake of printing the objects rather than machining them.Also, toss in a fair amount of calibration as well. SD machines tend to make oblong holes and bosses out of the box, so dialing in your belt tension and stepper motors will help.

+1
Since I.D.s will generally be more prone to being undersized than mating studs, I will usually upsize the I.D. of the hole by about 0.5%.  Seems to work pretty well for me...

SD2 - Stock - Enclosure - Heated Bed - Glass Plate - Auto Fire Extinguisher
Ord Bot Hadron - RAMPS 1.4 - Bulldog XL - E3D v6 - 10" x 10" PCB Heated Build w/SSR - Glass Plate
Thanks for All of Your Help!