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Re: New light extruder concept out of bolt - 11 years ago

I finished fabricating the nuts and assembled everything today. Test printing will commence tomorrow if everything works. There are more photos of the assembly here: Extruder cover assembly Extruder side view Extruder assembled The small gears, tubes, drive nuts, and bearings all come off the unit by removing the four cover screws, without taking the extruder off the printer mounting plate.

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

While waiting for some parts to arrive I decided to address some of the less desirable features of the extruder. - using smaller gears to turn the nuts to reduce overall size and speed up extrusion (let's hope the motor has sufficient torque for the extra load) - using smaller bearings to shrink the size (went from 5x16x5mm to 5x8x2.5mm) The previous iteration size, excluding motor, was 100mm

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

Check out DesignSpark Mechanical- free CAD, similar to Solidworks. http://www.designspark.com/eng/page/mechanical You don't have to make the gears. If you make/print them you have to worry about strength as well as some means to affix them to the tubes/shaft. The gears I used, which can press fit onto a 5mm shaft/tube, are available on ebay or from American Science and Surplus very cheaply.

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

New controller board has arrived. Testing will resume this week.

by the_digital_dentist - Mechanics

Re: assist bowden with second small stepper - 11 years ago

QuoteOhmarinus I would just do 2x Nema 17 just like with the Z-axis. You can hook up two stepper motors to one driver and have them push and pull the filament working together. In my fantasy it would be that you replace the idler with the 2nd stepper motor, so instead of the filament having a filament driver on one side and a bearing on the other side, the filament is sandwiched inbetween two ste

by the_digital_dentist - Mechanics

Re: J head clone issues - 11 years ago

I feel your pain. Hot-end reliability is the #1 problem with FDM printing. I don't think that anyone designing them really knows what they are doing. I don't think anyone really understands why they jam so often- is it poor filament quality, foreign objects, poor temperature regulation, retractions pulling molten filament up into cold part of hot-end, or ? I have found that most of the time w

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

I am dead in the water. My ATMega2560 controller board is toast and can't be seen by my laptop or desktop machines. I think the 16U2 chip is blown. I will continue testing after I get a new controller board.

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

In case anyone is interested, here are the parts I used: Gears: 625ZZ bearings: Brass tubing 5mm OD, 0.45mm wall: 6-32 left hand tap: I had the NEMA-17 motor from a QU-BD extruder (ugh!) and the rest was 3D printed.

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

QuoteChri Hmm, interressting concept, but i can`t see the real benefits of this type compared to a "normal" geared extruder ? a Printer with a geared extruder can also make 500m/s (movement), and most ABS/PLA isn`t even good enough to print with this speed. pro: alot of force, but is so much really necessary? con`s: -slow acceleration -> slow retract -large design (bulky) , even with built

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

QuoteA2 Congrats I love the looks of it. I would like to see a line drawn on the filament with a fine permanent marker, zoom up close and post a vid. It will be interesting to see if it can feed 100's of feet of filament without twisting. Have you thought about how to swap out the inverted-worm to switch to a different filament diameter? Print herringbone bevel gears, might help with the backl

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

You can't have one side twisting without the other side twisting the same amount or the filament will twist apart. It doesn't. I mounted the extruder over a scale, limited to about 5kgs, and ran the filament down onto it. It overloaded the scale so I backed off a bit to capture the force at about the limit of what the scale can measure- 5.2 kg or about 51 N. There was no evidence of torque sli

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

Update: video here: vimeo First test complete. TLDR: IT WORKS! The NEMA-17 motor has adequate torque! The filament moves through the extruder without twisting! Video will be available via Vimeo in about 45 minutes. Next I will need to change the settings in the firmware and pull the jumpers off the controller board to eliminate microstepping and calibrate the steps/mm, then mount it on th

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

I didn't buy left hand nuts because I anticipate having to make a few runs at this to get it right. A tap allows me to make nuts of any thickness and to vary the cutting depth (into the filament) by tapping different sized holes. The nuts can be put arbitrarily close together simply by moving the tubing through the bearings and gear. There is no reason they can't be 1mm or less apart. Since f

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

Progress! The bearings arrived, I did a slight redesign of the base and cover to eliminate some impingement on the bearing races, printed new base and cover and assembled it. The gears mesh perfectly and turn smoothly with no bad behavior and minimal backlash. I ran a piece of filament through it manually and found there is a small and variable residual torque that tries to twist the filament

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

Progress: I fabricated the left-hand threaded nut today and soldered the nuts to two pieces of 5mm brass tubing. When the bearings arrive I'll mount them and test the whole thing. The left nut (no jokes, please) is a normal, right hand threaded 6-32 nut. The right nut (oh come on!) is a left hand threaded 6-32 nut. The gears mesh well and alignment seems to be OK for testing purposes. I'll

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

Yeah, it's a little hard to wrap one's brain around it. My thinking is that the torques applied to the filament by each nut gets applied to the whole filament, including beyond the other nut, therefore the two equal and opposite torques should result in a net zero torque on the filament. If the torques aren't balanced- say one nut is tighter on the filament than the other, there will be a nonze

by the_digital_dentist - Mechanics

Re: Z axis with 1 stepper motor over belt - 11 years ago

My printer (MegaMax) has two acme screws to lift the X-axis that are turned by a single belt/motor and it works perfectly. The only reason I can think of to use two motors instead of a belt with one motor is cost. Two motors are often cheaper (especially if one has access to surplus motors) than a closed loop belt and all the required pulleys (unless you can get those surplus). A big advantage

by the_digital_dentist - Mechanics

Re: New light extruder concept out of bolt - 11 years ago

I am prototyping a nut drive extruder and should be able to test later this week if the bearings arrive. My design uses counter-rotating nuts to cancel the torque that tries to twist the filament when a single nut turns on the filament. See attached images. A 6-32 nut will twist onto a piece of 3mm filament with finger torque but will not allow the filament to slip. With 6-32 threads, the m

by the_digital_dentist - Mechanics

Re: Calculate required filament per extruder - 12 years ago

gcode viewer (gcode.ws) will show how much filament is used and let you check your gcode before printing. Not sure how it handles multiple extruders, but worth a try.

by the_digital_dentist - Slic3r

Re: Slicing multiple objects and moves between objects - 12 years ago

I have seen the same thing and it drove me nuts and resulted in a lot of extruder jams. What you want to do is check the little box in the settings that says "avoid crossing perimeters". It is in the print settings tab, layers and perimeters page, all the way at the bottom. When you check that it will force slicer to complete each object layer before moving to the next object on the same layer

by the_digital_dentist - Slic3r

Re: Slic3r creating bad layers when slicing with support - 12 years ago

I slice an object that has an indentation in the bottom. First I made the depth of the indentation 5mm, then sliced with 0.25mm first layer thickness and 0,2mm layers after. Slicer creates the support material for the indentation and throws in a layer that is 0.05mm thick and consists only of support material just before it covers the indentation. So I figured that 5mm doesn't work with 0.25mm

by the_digital_dentist - Slic3r

Re: New machine, trying to get it moving - 12 years ago

How do people program/debug/apply this stuff without any documentation? When I learned programming about 40 years ago (silent 700 terminals on a PDP-11, Fortran IV), we were taught to make diagrams before we ever started writing code. When I do PIC projects in assembly, I still make diagrams and review them frequently to optimize things before I write any code, and then physically order the cod

by the_digital_dentist - RAMPS Electronics

Re: New machine, trying to get it moving - 12 years ago

mitchese: You have triggered the built in safety switch, since marlin can't detect the temperature of your hotend it refuses to do anything (prevents fires and hot end failures) How do you know this and how would someone who doesn't find it out? Is there some documentation that tells how Marlin works, including safety switches, etc., or do people just have to dig through notes in the source c

by the_digital_dentist - RAMPS Electronics

Re: MegaMax 3D printer at Milwaukee Makerspace - 12 years ago

Got sidelined by my wife moving out from Ca., then buying a house, then moving into that house, then car shopping for the wifey, then entertaining family at the house for Xmas. Started back to work on the printer this week though and have made a schedule to have it printing by the end of this month. I bolted 20, 0.5 Ohm, 1%, 25W resistors to the aluminum plate I will be using for a print-bed a

by the_digital_dentist - General New Machines Topics

Re: New machine, trying to get it moving - 13 years ago

I found the problem- first the controller was flashed with firmware for some Chinese printer that for some reason makes the axes hunt back and forth. I DL'd the latest Marlin, edited the config file for my machine, then tried to compile the firmware so I could flash it to my controller. That's when the real trouble started. The Arduino IDE refused to compile. After trying several versions of

by the_digital_dentist - RAMPS Electronics

Another problem - 13 years ago

nevermind...

by the_digital_dentist - RAMPS Electronics

Re: New machine, trying to get it moving - 13 years ago

I'm wiring the endstops with the switch normally open and the signal line connects to ground when the switch closes. According to a few sources on the web, the Mega 2560 has on-board pull-up resistors that are enabled by default in Marlin. Than means the ports are looking for a transition from hi to lo to signal an event such as an endstop. I also find info that says that the default endstop c

by the_digital_dentist - RAMPS Electronics

Re: New machine, trying to get it moving - 13 years ago

I tweaked the current pots on the drivers before I ever connected power. They are not an issue. When I use no endstops, I can communicate with the controller via pronterface. I can see the G-code that is moving the axes back and forth and can inject commands to move an axis. Here is a sample of the G-code that is driving the axes back and forth: Marlin: 1.0.0 RC2 - SUMPOD echo: Last Updated

by the_digital_dentist - RAMPS Electronics

MegaMax 3D printer at Milwaukee Makerspace - 13 years ago

This is my 3D printer project that I'm building at the Milwaukee Makerspace. http://wiki.milwaukeemakerspace.org/projects/megamax_3d_printer Most of the parts came from recycled industrial machines and a local scrap dealer. Build envelope will be about 1 cuft when finished. My goal is to process dicom files from CT scans into STL files and use them to print life-size human skulls (among many

by the_digital_dentist - General New Machines Topics

OK Pronterface runs and talks to the printer, - 13 years ago

but the machine still keeps moving a little back and forth in each axis. I can reset it from pronterface, and I can jog the axes in between the firmware's own x, y, and z movements, but nothing seems to stop it from taking off into the x, y, and z motion routine that is coming from the controller board. Any suggestions? Thanks!

by the_digital_dentist - RAMPS Electronics