Hello, It's been quite a while since I've messed with my SCARA arm. I hope I can provide some insight. I had great trouble creating a repeatable accurate automatic homing. Initially I tried using limit switches, which where cumbersome and I could never get them out of the way. Second, I created optical limit switches, but they where too inaccurate. Thirdly I tried using hall effect sensors bby vitaminrad - Polar Machines, SCARA, Robot Arms
Also, I've discovered that while manual moves are typically clamped, your initial homing offset may be out of bounds so to speak. Make sure after you've homed that you request a G0 move to a valid point.by vitaminrad - Polar Machines, SCARA, Robot Arms
I've worked out a bit of the kinematics for Marlin using Single Arm Scara. Bed 0,0 is from Top Right of bed if looking forward and down. Tower is offset from bed 0,0 - If bed is 200mm x 200mm and tower is centered to bed in X coordinate and back about 120mm (safety), the offset would be 100mm in X and -120mm in Y Homeing expects arm to be extended directly forward (given the manual homing coorby vitaminrad - Polar Machines, SCARA, Robot Arms
Your math looks good, however you mention "max X distance is the distance between the two parallel linear axis." where this should (I believe after testing) to be the distance between the effector and the linear rail (or rather, half the distance between the linear rails).by vitaminrad - Developers
Awesome - I'll take a look at Marlin and see if I can come up with something... In the Arduino Preferences there's an option to select "Show verbose output during: [ ] compilation [ ] upload" and you can select those to get verbose output. Don't mind half the warnings you see - if there's an error you'll see it at the end. What side of the world are you on? Mind if I ask?by vitaminrad - Developers
How far have you gotten? Are you reworking the CoreXY implementation? Have you posted any source publicly? Github? I'd love to take a look... maybe I can help? Have you sorted out the math for the kinematics? I created an application to double check my math and coordinates and such. Re-flashing a Printrboard is a real pain in the ass. Disabling thermistor should be as simple as setting aby vitaminrad - Developers
You're probably going to have to modify the homing so that each carriage initially travels simultaneously and then backs off each axis (similar to a delta). While building my single arm scara I was able to modify the Morgan firmware fairly easily. I'd look to whatever they're using in the Morgan camp for the end effector. I have some rather large IGUS plastic bearings and even a few heavy dutyby vitaminrad - Developers
Hey Craig, Any progress? Excited to see more! I came across this post earlier - TandemB. Looks like they're searching for firmware. - Nathanby vitaminrad - Developers
Very cool! Excited to see the wireframe. Have you seen this build - tuga? Similar in certain regards, however I'm very interested to see your machine work. Does Freecad do kinematic simulation? I'm always looking for a program that does this and right now I'm experimenting with Gazebo, but it's less than friendly. Thanks for posting, brother!by vitaminrad - Developers
Hey Mike, Thanks for the kind words and your interest. I'm re-designing the arm to be much more flexible in terms of calibration and reach. I'll post an update if you are interested. Not complaining, but I've been in a really dark space lately and haven't felt like communicating much. I'll try and post some new shots soon. I tried printing something the other day and it worked pretty darn aby vitaminrad - Polar Machines, SCARA, Robot Arms
In my experience, Marlin is fairly easy to modify. Marlin_main.cpp is where most of the kinematics takes place. The most recent builds of Marlin have SCARA support for a Morgan type machine - I would look to modifying those routines as they are very similar to the Delta's and there are still a few development breadcrumbs in there.by vitaminrad - Developers
Thank you. (Marlin for SCARA Arm)by vitaminrad - Polar Machines, SCARA, Robot Arms
I'd also like to say I've gotten a lot of feedback from Nicholas Seward. I haven't implemented much of what he's suggested yet, but will soon.by vitaminrad - Polar Machines, SCARA, Robot Arms
Greetings, I've been working on a SCARA arm prototype and reworking the kinematics in Marlin firmware to support it. At the moment I've got a working build of Marlin and most of the forward / inverse kinematics solved - there are issues with my design that necessitate a re-design in respect to using physical end-stops. I'm looking to use Hall Effect sensors in place of mechanical switches. Caby vitaminrad - Polar Machines, SCARA, Robot Arms
Dear Evil Monkey, Have you decided on a linkage? Are you going with the Morgan type arrangement or something more like the latest renderings? I'm interested in making a SCARA type machine and have gone through a few design iterations, mainly looking at firmware at the moment. Have you sorted out the firmware? The ancient TTSALO Marlin branch is pretty stale and although the main trunk of Marby vitaminrad - Polar Machines, SCARA, Robot Arms
They're quite common in laptops as they have a short profile. I have one that came with my Bulldog Lite extruder setup and it's woefully underpowered.by vitaminrad - General
I'm interested to know what your Acceleration and Jerk settings are. Would you be able to perform a M503 and copy the response?by vitaminrad - Printing
I went last year and saw a lot of cool things, but was disappointed to find that a lot of the folks couldn't answer technical questions and were hired hands. The best part was seeing and meeting a few artists.by vitaminrad - General
If you motors are vibrating and roaring it might be a loose connection to one of the steppers motors. Do NOT connect or disconnect a motor while the board is energized. This kills the stepper drivers and or board. Do investigate the connections though. Sometimes the pins can be pushed out of the connector and cause a lot of grief.by vitaminrad - General
Sounds like a short. Are you using an external power supply and relay to heat the bed or is the current coming from Ramps?by vitaminrad - General
I've ordered a few E3D hot ends from Filastruder.com and they were delivered the very next day with a complimentary pack of gummy bears. Had a few questions regarding the E3D and they were very helpful. I wouldn't hesitate recommending them to anyone that needs a quality product and expects quality service.by vitaminrad - Plastic Extruder Working Group
Does anyone have any clue as to why this happens? It's almost a weekly occurrence for me. I've tried creating backups of the plist and such ... Repetier Host doesn't seem to reload the plist once it's been loaded into memory. You can start and stop Repetier host, open the plist file in a plist editor, make some changes - like the Max Dimension (which is never set properly through Repetier Hostby vitaminrad - Repetier
Not bad at all! I'd imagine your retraction settings are trying to pull too much too quickly. I'd recommend setting your retractions to 1mm at 12mm / sec with an acceleration of around 400mm/s and possibly setting your E-jerk to a conservative 1 or even less to get things sorted out. I wish there was a way of setting the amount of retraction based on the amount of travel, but some day man!by vitaminrad - Reprappers
I was getting a lot of communication errors using Slic3r after having updated it a few times and corrupting my settings. During my testing I discovered Cura and haven't gone back to Slic3r (even though I did sort out the comm errors by doing a clean install). I believe the root of my problem was Slic3r trying to generate GCode for the initial layer at a certain percentage of reduced speed. Givby vitaminrad - Reprappers
I'd imagine your X and Y axis are not perpendicular. If you have a way of adjusting for one or the other, you can use a protractor to adjust and then take a piece of paper and place it on the bed while holding a pencil perpendicular to the hotend and manually making a square with the pencil to see how true things are. I had a similar issue and was able to compensate and adjust accordingly althoby vitaminrad - Reprappers
I think it looks really sharp!by vitaminrad - Extruded Aluminum Frames
Thanks for the follow up! I was able to fix a similar problem thanks to your thread!by vitaminrad - Reprappers
Makerfarm.comby vitaminrad - Delta Machines
This is one of my favorite programs for generating gears, there's an online version and also a Windows binary https://woodgears.ca/gear_cutting/template.html ... whoops - sorry I didn't see you already knew about this.by vitaminrad - General
Please forgive my naive optimism, however, is it possible to append the BabySteps within the prepare_move() function within Marlin_main.cpp, similar to this: void prepare_move() { clamp_to_software_endstops(destination); previous_millis_cmd = millis(); #ifdef DELTA float difference; for (int8_t i=0; i < NUM_AXIS; i++) { difference = destination - current_position; } float caby vitaminrad - Firmware - mainstream and related support