my xnaron magarms
Posted: Mon Jun 03, 2013 1:06 pm
For people considering this mod, here's how it went for me. In short, it's as cool as I'd hoped, I'm happy so far but I haven't tested much since I only installed it yesterday. More pictures at the end.
disclaimer
My experience level is very low. This is my first printer and I'm learning as I go. Before doing this, I was completely stock rmax except for polygonhell's extruder cap, my led light ring and belt tensioner brackets. I also added the 1" peek fan suggested by mhackney.
materials
First, I ordered the magnets, bearings and carbon fiber rods all sourced from links in xnaron's post. I bought jb weld & screws at my local hardware store & I already had some superglue. You might want to make sure you get screws that will be attracted to the magnet. My kit came with extra tiny washers that I used for the screws.
print parts
I printed the xnaron's carriage mounts no problem. But when I tried the boom ends, they came out too small for the magnets & rods. Maybe a calibration issue with my printer? My favorite thing about the 3d printing project is that my kids are already thinking "just make your own!" So based on a suggestion from my 8 yr old son, I made my own in openscad, just like xnaron's only they came out fitting my rods.
I wanted to be able mount a camera & cooling fans on the effector later and I thought xnaron's effector wouldn't have all the mounting holes for me so I also made my own effector in openscad. I planned to use the standoffs to create a space for my peek fan, so I made a rudimentary heat shield for the center hole of the effector with aluminum foil & kapton tape. Not sure what happened to the top surface but I can always print another.
prep bearings
You need 12 of these, but I suggest preparing a few extras (a) so you can reject a few if they don't come out as well and (b) so you have extras in case they ever come detached from the screws. I taped off the bearings leaving about a 5mm diameter exposed circle. Holding the bearing in my hand, I used a coarse sanding drum on a dremel to abraid the exposed area. Then I removed the tape and soaked the bearings and screws in acetone.
epoxy screws to bearings
Using a fork, I fished the bearings & screws from the acetone, dried them in a paper towel and put each bearing in a boom end w/magnet, abraded side up. If you do this, I suggest keeping the boom arms at least 6 inches apart from each other to prevent them from jumping together. I mixed the jb weld on a piece of cardboard using a wooden kabob skewer. Then one at a time, I added a blob of epoxy to the abraded area, placed the screw on the epoxy and then used the skewer to shmear a bit more epoxy around the sides of the screw cap. I tried to avoid getting epoxy on the base of the cap since that may affect how far I can screw it in to the effector or carriage mount and thus how far it sticks out - a distance we want to control. Following xnaron's instructions, I let them cure under a hot light for at least an hour and then didn't touch them until the next morning.
make arms
My carbon fiber rods came as one 48" and one 24". I cut six 240mm segments using the dremel cutting tool, measuring with a pencil and ruler. I did file a couple ends do they matched more closely, but I did not do the jig. I had already cut them before I learned of the jig idea and holding them next to each other with the boom ends on, I could not detect difference. So I glued the boom ends (w/magnets) to the rods with superglue. Not sure it matters, but I aligned the polarity of the magnets the same on each rod.
attach bearings to effector & carriage mounts
To avoid twisting the epoxied bearings, I pre-threaded each hole where the bearings screw in using an extra screw. One of the holes in a carriage mount was too loose, so I shoved some epoxy in there with my kabob skewer. The other bearings are currently just screwed in (through washers).
install
I removed my hot end, fan & LEDs from the stock effector and then removed the arms. Then I removed the old carriage mounts and replaced with new ones. Fit was perfect, although the holes for the end stop screws are a bit looser than I would like. I attached the hot end, LEDs and fan to the new effector and then finally came the fun part. Attach the arms & effector using magnetic arms.
calibrate
First I set the z height at X0 Y0. Then I leveled using the end stop screws. I edited the adjustment to delta radius until the edges were no longer lower than the center. Then I printed a hollow square where the inside was supposed to be 145mm per side. It came out 148.4mm, so I upped DELTA_DIAGONAL_ROD to from 267.5 to 271.0 because that fixed the size (trial & error). This edit required further modification to the DELTA_RADIUS value. My final adjustment value there is +3.2.
results
No more delta arm blues and motion is a bit smoother. On my machine, it wasn't that bad initially, but then I tried greasing the ujoints and I think I made it worse. So that's better now. I just think it's cooler and it's trivially easy to pop off the effector now.
trouble
I noticed when the effector is close to the Z tower, the magnets in the boom ends come close enough to my peek fan to slow it down. It returns to normal when it moves away.
Also, this is a problem I was having even before this mod, but when I print a big 245mm diameter circle, The nozzle is too close to the bed when it's opposite each tower. When it's at the towers, it's either too high or just right, depending on how I set my overall z height. But it's always lower opposite the towers. No issue on smaller prints, but if my print goes to the edges there, it will suffer this effect. I don't know if it's bed flatness or delta geometry … any ideas?
disclaimer
My experience level is very low. This is my first printer and I'm learning as I go. Before doing this, I was completely stock rmax except for polygonhell's extruder cap, my led light ring and belt tensioner brackets. I also added the 1" peek fan suggested by mhackney.
materials
First, I ordered the magnets, bearings and carbon fiber rods all sourced from links in xnaron's post. I bought jb weld & screws at my local hardware store & I already had some superglue. You might want to make sure you get screws that will be attracted to the magnet. My kit came with extra tiny washers that I used for the screws.
print parts
I printed the xnaron's carriage mounts no problem. But when I tried the boom ends, they came out too small for the magnets & rods. Maybe a calibration issue with my printer? My favorite thing about the 3d printing project is that my kids are already thinking "just make your own!" So based on a suggestion from my 8 yr old son, I made my own in openscad, just like xnaron's only they came out fitting my rods.
I wanted to be able mount a camera & cooling fans on the effector later and I thought xnaron's effector wouldn't have all the mounting holes for me so I also made my own effector in openscad. I planned to use the standoffs to create a space for my peek fan, so I made a rudimentary heat shield for the center hole of the effector with aluminum foil & kapton tape. Not sure what happened to the top surface but I can always print another.
- effector
You need 12 of these, but I suggest preparing a few extras (a) so you can reject a few if they don't come out as well and (b) so you have extras in case they ever come detached from the screws. I taped off the bearings leaving about a 5mm diameter exposed circle. Holding the bearing in my hand, I used a coarse sanding drum on a dremel to abraid the exposed area. Then I removed the tape and soaked the bearings and screws in acetone.
epoxy screws to bearings
Using a fork, I fished the bearings & screws from the acetone, dried them in a paper towel and put each bearing in a boom end w/magnet, abraded side up. If you do this, I suggest keeping the boom arms at least 6 inches apart from each other to prevent them from jumping together. I mixed the jb weld on a piece of cardboard using a wooden kabob skewer. Then one at a time, I added a blob of epoxy to the abraded area, placed the screw on the epoxy and then used the skewer to shmear a bit more epoxy around the sides of the screw cap. I tried to avoid getting epoxy on the base of the cap since that may affect how far I can screw it in to the effector or carriage mount and thus how far it sticks out - a distance we want to control. Following xnaron's instructions, I let them cure under a hot light for at least an hour and then didn't touch them until the next morning.
make arms
My carbon fiber rods came as one 48" and one 24". I cut six 240mm segments using the dremel cutting tool, measuring with a pencil and ruler. I did file a couple ends do they matched more closely, but I did not do the jig. I had already cut them before I learned of the jig idea and holding them next to each other with the boom ends on, I could not detect difference. So I glued the boom ends (w/magnets) to the rods with superglue. Not sure it matters, but I aligned the polarity of the magnets the same on each rod.
attach bearings to effector & carriage mounts
To avoid twisting the epoxied bearings, I pre-threaded each hole where the bearings screw in using an extra screw. One of the holes in a carriage mount was too loose, so I shoved some epoxy in there with my kabob skewer. The other bearings are currently just screwed in (through washers).
install
I removed my hot end, fan & LEDs from the stock effector and then removed the arms. Then I removed the old carriage mounts and replaced with new ones. Fit was perfect, although the holes for the end stop screws are a bit looser than I would like. I attached the hot end, LEDs and fan to the new effector and then finally came the fun part. Attach the arms & effector using magnetic arms.
calibrate
First I set the z height at X0 Y0. Then I leveled using the end stop screws. I edited the adjustment to delta radius until the edges were no longer lower than the center. Then I printed a hollow square where the inside was supposed to be 145mm per side. It came out 148.4mm, so I upped DELTA_DIAGONAL_ROD to from 267.5 to 271.0 because that fixed the size (trial & error). This edit required further modification to the DELTA_RADIUS value. My final adjustment value there is +3.2.
results
No more delta arm blues and motion is a bit smoother. On my machine, it wasn't that bad initially, but then I tried greasing the ujoints and I think I made it worse. So that's better now. I just think it's cooler and it's trivially easy to pop off the effector now.
trouble
I noticed when the effector is close to the Z tower, the magnets in the boom ends come close enough to my peek fan to slow it down. It returns to normal when it moves away.
Also, this is a problem I was having even before this mod, but when I print a big 245mm diameter circle, The nozzle is too close to the bed when it's opposite each tower. When it's at the towers, it's either too high or just right, depending on how I set my overall z height. But it's always lower opposite the towers. No issue on smaller prints, but if my print goes to the edges there, it will suffer this effect. I don't know if it's bed flatness or delta geometry … any ideas?
- installed 1
- installed 2