Sunday, April 05, 2009
A gripping read
I have done some work comparing the amount of grip that different extruder drive methods achieve. I measured the amount of force the following devices gave before the filament slipped: -
The results where as follows: -
The red figures are lower or marginal compared to the force required to extrude 0.5mm filament at 16mm/s.
More details in my blog hydraraptor.blogspot.com/2009/03/pulling-power and hydraraptor.blogspot.com/2009/04/all-torque-and-no-traction.
| A 4mm splined shaft. |   |
| A 13mm timing pulley |  |
| The original M5 thread drive |  |
| A 13mm knurled wheel |  |
| A 13mm threaded "worm" pulley |  |
The results where as follows: -
| PCL | HDPE | ABS | PLA | |
| 4mm splined shaft | 2.5 Kg | 3.0 Kg | 5.0 Kg | 7.5 Kg |
| 13mm timing pulley | 4.0 Kg | 10.0 Kg | 8.5 Kg | >8 Kg |
| 13mm knurled wheel | 5.0 Kg | 10.0 Kg | 12.0 Kg | >12.5 Kg |
| 13mm M4 worm pulley | 6.0 Kg | >12.5 Kg | >12.5 Kg | >12.5 Kg |
| 13mm M3 worm pulley | 8.0 Kg | >12.5 Kg | >12.5 Kg | >12.5 Kg |
| M5 thread | 9.0 Kg | >12.5 Kg | >12.5 Kg | >12.5 Kg |
The red figures are lower or marginal compared to the force required to extrude 0.5mm filament at 16mm/s.
More details in my blog hydraraptor.blogspot.com/2009/03/pulling-power and hydraraptor.blogspot.com/2009/04/all-torque-and-no-traction.
Labels: extruder design
Monday, March 17, 2008
A high temperature extruder?
I made a quick lash up which shows that it is feasible to replace the PTFE heat barrier with a short stainless steel pipe and a heat sink. That will allow the extruder to operate easily over the full temperature range for thermoplastics and make it far more mechanically stable.
More details here: hydraraptor.blogspot.com/2008/03/high-temperature-extruder.html
More details here: hydraraptor.blogspot.com/2008/03/high-temperature-extruder.html
Labels: extruder design
Friday, September 14, 2007
More on the granule extruder
The main problem with the extruder was the conduction of heat up the brass and copper screw auger. I decided to make one from a less conductive material - JB-Weld. Here are the initial results. I cast an ordinary 13 mm drill bit in silicone, took it out, then injected mixed JB Weld from the bottom of the cavity with a syringe (to exclude bubbles):
And here it is (with the original drill) after being cut out of the mould:
I probably won't use a drill as the master finally (it's pitch is too coarse, and you have to turn it anti-clockwise, which tends to loosen things), but this shows that you can cast from virtually any helical shape to get what you want.
And here it is (with the original drill) after being cut out of the mould:
I probably won't use a drill as the master finally (it's pitch is too coarse, and you have to turn it anti-clockwise, which tends to loosen things), but this shows that you can cast from virtually any helical shape to get what you want.
Labels: extruder design
