Introduction: FlexionHT Retrofit to Leapfrog CREATR

I've had a Leapfrog CREATR Dual for a few years now and it's been fabulous. Unfortunately the non-standard nozzles are expensive and rare as rocking-horse poo, so it's time to do something about it.

If I am going to fiddle with the machine I might as well go the whole hog and do an upgrade to enable printing with some of the new and interesting filaments turning up, so that's how I ended up at Flexion.

Flexion is a replacement extruder, available as a dual kit, made to be compatible with Reprap style 3d-printers in general, and the HT version should be able to handle filaments like NinjaFlex (well it really should because these are the people who developed NinjaFlex in the first place) and other flexible and high temp filaments. Of course not all Reprap style printers are totally identical so there will be some fiddling about to fit them to various different machines.

Which brings us to here. How to get the Flexion HT to play nicely with the Leapfrog CREATR Dual.

Step 1: Preparing Your Leapfrog

The Flexion HT uses Heater Cartridges and Thermisters which are smaller than the Leapfrog originals so we will need to replace those as well. The Leapfrog is a 24v system so make sure you get 24v Heater Cartridges, Flexion needs 6mm cartridges.

The extruders on a Leapfrog are easily accessible and mounted on a simple, solid, aluminium carriage. We will need to get into the electronic guts so heat up the extruders and remove any loaded filament. Move the bed to about 3/4 height as you need to work under the carriage and access the electronics.

You can now turn the machine off and unplug it, hopefully we don't need power any more.

I also took the sides off as I was expecting to need to get into the electronics bay to replace the heaters and thermistors. In the end I hooked into the existing wiring up near the extruder, but the job was much easier with the sides off, so I still recommend doing that.

Step 2: Dissassemble the Extruder Carriage

Pretty much everything above the carriage deck needs to come off, except the front fan plate. This plate also mounts the carriage belt and if we can avoid fiddling with that our job will be much easier.

First undo the wiring train and move it out of the way.

To remove the extruder/stepper motor assemblies undo the four bolts through the mounting block. To access them you will need to remove the fans. The back plate with the wiring mount won't come off until you remove the mounting block as the bolts are too long to take out in-situ.

The top plate simply lifts off with a bit of leverage.

Once that's done you have a nice flat deck to work with. In the photo you will notice two bolts protruding from the fan plate below the deck. The Flexion heater blocks are larger than the original Leapfrog blocks and hit these bolts so cut off the protruding threads.

Step 3: The Mounting Block

The Flexion setup comes with a nice looking Mounting Block with integrated heat sinks. It won't fit the Leapfrog carriage. I've included a photo of the carriage with both the original (left) and Flexion (right) mounting blocks with the original screw holes visible. The Flexion mounting block can't use the original mounting holes and the Leapfrog carriage is put together in just such a way that there are joints right where the Flexion mounting block would require holes. So we will use the original mounting block.

The Flexion hotends, however, have a slightly larger diameter than the holes in the Leapfrog mounting block, sothese holes will need to be enlarged. Not by much, I ran an 8mm drill bit through them on a mate's drill press.

Step 4: Preparing the Steppers

The next step is to remove the old extruders from the stepper motors and install the Flexion replacements. The nearby image shows all the relevant bits. The extruder on the left has the Flexion fitted and all the Leapfrog bits laid out in front. The extruder on the right has the Leapfrog extruder fitted and the Flexion bits laid out in front.

The thing to note is the large spacer which is fitted between the stepper and the extruder on the Leapfrog setup. This causes a bit of an issue because the screws on the Flexion won't go through all that and they are machined to fit the extruder. It may well be possible to get similar screws a bit longer, I got around the problem by removing that spacer.

Removing the spacer is great for fitting the extruder to the stepper motor but it moves everything forward and out of alignment. To solve that issue I cut a spacer from a length of 3mm x10mm aluminium bar I picked up at my local big box hardware outlet. I have included an image of my custom spacer, you need to grind it to fit the profile of the steppers.

The other issue with spacing is that the shafts on the steppers had obviously been rubbing on the front plate and had worn nice little craters. The new setup was even further forward so I cut holes in the front plate to let them turn freely. Try to do a neater job than I did.

Once all that is put together the filament path should go straight down through the extruder and continue straight into the hotend.

At this point the carriage is ready to be rebuilt. It's a good idea to put the wiring for the fans back in place while you are putting it all together. If you are having trouble getting the screws to align try turning the mounting block over, it looks symmetrical but isn't.

Step 5: The Filament Guide

At this stage everything is back together except for the filament guide, which won't go back on as the Flexion extruders stand a little high.

I made a little bracket from some brass that was lying around and mounted it on the post that holds the cable chain. There will be some longer machine screws left over from the previous steps that fit in the existing threaded holes.

I'm not entirely happy with this fix, but it works and that will do.

Step 6: Wash Up

When I first got the extruders the retrofit job looked painful, but in the end while it was a little fiddly, everything went together nicely and fairly easily and I'm quite pleased with the result.

The image shows the first print off the new rig, in PLA. The print on the left is the old setup, on the right is the Flexion setup (this is Thingiverse thing 590532, "Handy Coat Hook).

Seeing as I had done no tuning of the Flexion setup at this point I'm quite pleased at the result and looking forward to nice prints once it's properly set up.