Since I last wrote a blog post, I have carried out several changes to my current setup. The aim of this post is to try and consolidate all of the changes I have made to try and put a stick in the ground for the readers.
Summary of changes so far
The controller board has been changed to a duet 2 Ethernet. This has been detailed here and here. As well as this, I have changed the effector to a smart effector. This change also meant changing the hot end from the standard v5 clone to an authentic E3D v6. These changes were detailed here.
My setup summarised above was using the original arms that came with the machine. If you follow the Facebook group for the predator, or any other social media channels, you may have heard about the issue of the rapidly wearing rod/arm connectors. This is where the ball in the middle of the connector becomes loose and introduces play into the system. I was suffering from this issue, and it meant that the calibration deviation on my machine was getting worse and worse. One fix for this issue suggested by the community is to replace the rod connectors with ones made by IGUS. These would be great for a normal unmodified machine, but as we’ve already fitted a smart effector, these aren’t really the way to go. It would also be very difficult to make sure that the rods are the same length. This is critical to ensure that the printed parts are accurate, especially as resolution decreases the larger the part.
I ordered a set of arms from Haydn Huntley. He has been known for supplying high quality, high precision arms to the delta community for several years now. I decided to stick to a length of 440mm for the arms, although it has been suggested that arms as short as 405mm will still work. The reduction in length to 405mm will counter the loss in height when fitting a smart effector (which is around 30mm due to the different position of the hot end). I’m not going to tell you which length to order as I have not read anywhere of anyone ordering 405mm and getting them to work over the whole print area. If you feel you will need that extra z height, maybe go for 415 or 420mm. If you are planning to use any sort of multi material changer at some point in the future and will be planning to purge the material outside of the build platform, then I would stick to 440mm arms. The order came within about 2 weeks or so. Just keep in mind that when getting them delivered to the UK that you would be paying somewhere in the region of £30 import duty. They come well packaged, in a cardboard tube and have the length of each arm written on a label. All the ones I received were 440.38mm.
To enable the arms to be mounted to the carriages of the predator, some custom mounts are required. It would be great if the adaptors included with the smart effector fit, but unfortunately, they don’t. I used the adaptors designed by Nealz Engeland but I found that some modification was required to get the holes to line up with the carriage. Don’t forget to swap the little ‘flag’ over required to activate the optical end stops.
I carried out this change while also carrying out some maintenance on my machine. One of the good design factors of the predator is the ability to remove an upright from the machine without much hassle. The predator even stays in place without requiring any other support. I removed each upright in turn and stripped it down to parts. This way, I was able to check that all the rollers of the carriage were correctly in contact with the extrusions and that no play was present. Fortunately for me, there was no play present, but I have read on Facebook, about a number of other predator owners that have had to adjust their rollers to make sure they are all in contact. I also swapped the original 1.8 degree motors with 0.9 degree motors and re-tensioned the belts, but more on that later.
As mentioned earlier, I have previously upgraded the effector from the original to a smart effector. I had modelled up a mount to allow use of the original arms and to mount three radial fans for cooling. The design can be found here.
I have since updated this design to allow the fans to be mounted to the smart effector while using magball arms instead. The design can be found here.
When mounting the arms to the printer, make sure you alternate the polarisation of the magnets. With mine, Haydn fixed the labels on each on at the same polarisation, which made it easier to alternate the arms. Basically, mount one arm label in to the effector, then one arm label to the carriage and then alternate. This helps reduce magnetic interference of the fans etc. Also make sure that you apply lubricant to each of the ball cups. I used bike chain lubricant as per Haydn’s advice.
The motors are very easy to change from one type to another. I had a bunch of motors left over from then I had to send a 3D printer to 3D printer heaven. The main thing to check is that the toothed gear is fitted with the same offset as the gear at the bottom of the printer. Wiring is the same as a 1.8 degree motor. If you’re lucky, you’ll get 0.9 degree motors with removeable cables, in which case, you just plug the old cable into the new motor. Don’t forget that the steps per mm need to be changed from 80 (for 1/16 microstepping) to 160. I’m still assessing whether changing the motors has been a good change or not.
Only a small note to say I’ve added a PanelDue 7 inch. I have mounted it to the top of the frame as shown below.
Duet firmware updates
Along with the above hardware changes, I have been trying to tweak my duet config to improve my settings. I have uploaded my current config to a separate branch on my github for your use. You will notice that the acceleration and jerk are quite high. Below are a couple of pictures of an example part. Ignore the bottom of the part, I am currently working to improve the quality. I will endeavour to keep github up to date.
I have moved a couple of items out of config and into my start gcode. I now do the following.
G32 ;This carries out a delta calibration at the start of the print
G29 S2 ;This reloads the mesh height map which is cleared when carrying out the delta calibration.
That pretty much brings you up to speed.