User:OliReadingUK
Just starting out the world of RepRap, currently pulling together bits for a Prusa Mendel.
Parts
My parts collection so far consists of:
- Printed Parts including parts for Wade's Geared Extruder from User:ParCan on http://www.emakershop.com for £75
- Fasteners, Bar and Studding from User:Bob_balthazar on http://www.emakershop.com for £34
- Bearing from User:rsoarer on ebay for £4
- Thick sheet set from genesismachines on ebay for £20 (if I were buying again I'd shop around ebay for this)
- Belts from alex-par64 on ebay for £16
- Set of 5 NEMA 17 stepper motors (torque not enough for extruder though) from astrosyn_excess on ebay for £36
- RAMPS and Arduino and mechanical end stops from Ultimachine for £137
- High torque stepper motor from Ultimachine for £12
- 2.3Kg black PLA from Ultimachine for £58
- Hot End from ParCan on http://www.emakershop.com for £60
- Hobbled bolt for extruder, from Arcol.HU for £7
- VAT bill and clearance fee for £50 for the Ultimachine order
All prices include postage to UK. FYI Shipping from Ultimachine (using cheapest shipping option) took 18 days from ordering to receiving the letter saying ParcelForce were holding the package (in UK) until VAT bill paid (which was quick to do online).
Currently totalling £510 (including PLA and spare motor) - sourcing PLA from Europe (more expensive list price) might avoid the VAT bill which made the US sourced PLA appear cheap.
Plus assorted bits from EBay:
- Extruder bolts (M4x50mm)
- Extruder mounting bolts (M4x40mm)
- Box of springs
- Grub screws for pulleys (M3x5mm)
- Crimping sleeves
I have the following extras from the Prusa parts list:
- 2 x belt-clamp
- 2 x bar-clamp
- 2 x rod-clamp
- 4 x pla-bushing
Software
- OpenSCAD for design
- Repsnapper for ad-hoc testing of the printer
- Skeinforge for generating G-code to send to printer
- Sprinter as the firmware for RAMPS
Power Supply
I had an old PC with a 300W power supply so pulled it out for powering the RepRap.
I cut the connectors with blank and yellow cables and one red. I checked with a voltmeter and found black-red was 5.6v, black-yellow 10.8v. I put an LED and 1k resistor between the red and one black, as a power light. I bundled all the yellows and all the blacks together for connection to other cables for connection to RAMPS. After bundling I found black-yellow had gone up to about 11.5v.
This PSU delivers 8A on yellow lines, and RAMPS needs 5A ('minimum'). If I were to get a heated bed I'd step up to a 'proper' PSU but hope this will do for starting out.
Questions
Stuff I have to find out about...
- I have a board for the print surface, should I cover it?
Answers I got were:
- I thought belts were continuous loop but they're not
- Need to clean up bushings so 8mm rod runs smoothly through
- 1m of 3mm filament makes 10cc so 100m makes a cubic decimeter
- Bar should run smoothly through bushings, consider mild heat to bar until it runs smooth
- Mechanical end-stops better than opto
- The seller of the hot end advises "My thermostors read slightly lower than default settings. For PLA run them at about 215 C - that will give you around 200 C real temp"
- Recommendations for a power supply? I took the PSU from an old PC, at 200W which is plenty. I cut the connectors off and bundled all the black and yellow (0v and 12v) together to feed the RAMPS module
- ABS = tougher, but stinky and hardly enviro-friendly, also takes much higher temps to melt it and almost requires a heated bed.
- PLA = Compostable, lower temp to work with, but more brittle by comparison and harder to glue.
- G code looks fun
Handy page http://www.onlineconversion.com/torque.htm
Another handy page for calculating firmware values http://calculator.josefprusa.cz/
Should I upgrade RAMPS to latest firmware? https://github.com/kliment/Sprinter
Websites
UK
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Filament | |
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Assorted bits | |
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Assorted bits, including extruder hot end | |
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Printed parts | |
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Filament (expensive) |
Elsewhere
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Assorted including electronics | |
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Stuff from assorted countries | |
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Lots, mostly kits | |
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Everything! | |
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Assorted parts | |
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Hot ends |
http://www.beltingonline.com has lots of pulleys & gears, though not specific to RepRap - one I bought had rims which made it inappropriate for what I wanted.
Experiences
- Some difficulty getting the bearings into the extruder, had a lot of filing down to do to make them fit
- Considered Sanguinololu but went with RAMPS as it's more available and suspect better supported
- The stepper motors don't have the screw holes they should have on the face with the shaft coming out, but where they should be are holes filled by the bolts holding the motor together, the heads of whom are on the other side. I had to unscrew these, ensuring not to let the motor fall apart, then put a nut on the top of the bolt and screw them back in, which left just enough thread in the holes on the shaft face to allow the motor to be screwed into mountings etc
- The stepper motors I got don't have the square face which the printed parts expect, but have some extra mounting bits on them. I've had to mount some of them in odd ways to make them work - for instance, the Z motors don't sit in the cut-outs designed for them, but hover above them
- I had to buy some grub screws to fix the X and Y pulleys onto the motors, as a standard screw was too long and got in the way of the pulley turning
- I had some trouble drilling through the PEEK block to mount the hot end - until I realised the electric drill was spinning the wrong way around!
- The Y stepper mount has 3 holes but one is obscured by the mudguard washer so that's only screwed in by 2 screws - fixed with cable ties
- The motors I got were 0.9degree whereas the firmware defaults to expecting 1.8degree. This means they only move half as much so make half sized prints. Fixed by doubling the values of "*_steps_per_unit" (for x,y,z) in the firmware
- The motors get hot and distort the pulleys. The motors don't have a flat face on the drive shaft, so any slight distortion of the pulley means the grub screw no longer makes good contact with the drive shaft - the shaft spins and the pulley doesn't move. Solution was to buy metal pulleys, which makes the X and Y movements much more reliable
- The metal pulley sometimes failed to push the extruder big cog because the motor would slip a little out of alignment - only takes a few mm to cause the pulley and cog not to mesh. Cured with a cable tie to pull the motor in to the extruder assembly, and also differing numbers of washers on the screws mounting the motor, to change its alignment
Tricky crimping... this helped... http://www.robotshop.com/gorobotics/articles/miscellaneous/how-to-crimp-connectors
