The Frog - Assembly Guide

Step 1

Disassemble the stock extruder body as PRUSA's guide for extruder B6 to B7 upgradings says. Disassemble also the x-Carriage

Step 2

x-CarriageMK7 (Part #2)

Printing: No support needed to print this part.

Assembly: It uses the same five square M3 nuts as the PRUSA MK3 part, and it must be assembled identically

Step 3

ExtruderBody (Part #3)

Printing: No support needed to print this part.

Preparation: Clean well the filament passage with a 2 mm drill bit.

Assembly: Identical assembly as the stock prusa part, with the same hardware: bolts, nuts, hotend, fans, stepper, PINDA probe, etc. all the same.

Aditionally place three square nuts in the slots in the upper part of the body to secure the sensor cover (two at the right, one at the left). (Part #B)

IMPORTANT

When assembling the ExtruderBody in place against the X-Carriage, make sure that the guides for the SliderCart on top both parts are well aligned, both horizontally and vertically. A small edge might be present in both parts where they were in contact with the printing bed. Remove it so that the SliderCart can move well along the guides.

Step 4

CutterAssembly

Printing: Print the BladeHolder (Part #10) in vertical position. Open end of the blade slot upwards. Better if you use raft. No support needed.

Preparation: Once printed, prepare meticulously the printed plastic part: First use the Blade (Part #K) to clean very well the blade slot. Run dry tests to check that the Blade sits well along all along the bottom. Do not glue the Blade yet.

Assembly: Set the three small Magnets (Part #J) in the slots with the same polarity facing the Blade. The easy way to check if all three Magnets in the BladeHolder have the same polarity is putting another magnet against the back of the part. It will seat straight and centered if the assembly is correct.

Now you can glue the Blade (Part #K) with a drop of CA glue in each side. Make sure it sits well in the bottom. If it doesn´t, just clean the slot of the dried glue and redo again. It is very important that the Blade sits well all along the bottom of the grove. It cannot be angled or tilted.

Note that the Blade slot is not centered in the BladeHolder, and when assembled the Magnets (Part #J) must be placed facing upwards.

The CutterAssembly is ready

Step 5

CutterLever. (Part #11)

Printing: I printed this part with raft and support.

Preparation: The M3 bolt must not screw in the holes, it should be a tight fit but the part must be able to rotate freely with an M3 bolt as a shaft.

Step 6

FrontTrap (Part #5)

Printing: Print this part with the MK7 embossment facing down. No support needed.

Preparation: IMPORTANT Clean well all cavities. Clean specially well the blade slot. It is very important that you clean throughly specially the bottom part of the slot where the BladeHolder moves. Use a magnifying glass to check if necessary. You might have to sand a bit one end of the BladeHolder (Part #10), the one you printed in contact with the bed. The CutterAssembly must move really smooth inside the part. If your print oozed inside the cavity too much you might need to sand the BladeHolder.

There is only one M3 screw to be cut in the part. This bolt will be the CutterLever hinge shaft. I reccomend using a tap male because I do not like fighting, but I guess forcing a bolt through it (PRUSA's way) should also do. The one vertical blind hole does not need a screw.

FrontTrap is ready

Step 7

FrontTrapAssembly

Assembly: Slide the CutterAssembly in the front slot of the FrontTrap with the Magnets facing upwards. Place the CutterLever (Part #11) from the top and fit the M3 x 18 bolt.(Part #D) The bolt must be loose enough so the lever moves easily. Slide the back Magnet ((Part #I) in its slot. Polarity of the magnet must be set so that the magnets are atracted.

Start checking that the Blade is centered vertically in its slot. It means that you assembled it right and not angled.

Now check that the movement of the CutterAssembly is really smooth, and that when you pull the lever the blade shows about 2 mm. When retracted, the blade should not show AT ALL in the filament's path. The retraction of the blade must be smooth and perfect. ALWAYS. If it isn´t then disassemble and clean the blade holder slot again. When retracted, the blade should not show at all in the filament's path. If it does, it means that the blade does not sit in the bottom of its slot in the blade holder (but at least the blade holder slot seems to be clean, because the blade holder went all the way to the bottom.

FrontTrapAssembly is ready

Step 8

BearingFix A/B (Part #8 and Part #9)

Printing: I usually employ rafts when printing very small parts like these.

Preparation: One of the parts holds the bolt head, and must not be thread. Use the tap male or a bolt to enlarge the hole if necessary.

The other part holds the tip of the bolt and must be screwed. Use a tap male or a bolt to cut the screw in the plastic part before proceeding with the assembly.

Step 9

Roller.(Part #1)

Printing: Print it in TPU. The softer the better. The blade will fight against the rugosity of this part (layer upon layer), so make it a good print. No support necessary. There's one good way to print this part and another wrong one. Make sure you position it properly or the bearing won`t sit right centered.

Step 10

SliderCart. (Part #7)

Printing: A small but difficult part to print. Print it with the magnet side against the printing bed. My best prints have been using no raft, but supports and a support blocker in the magnet cavity.

Preparation: Clean meticulously this part. Inspect well looking for support traces in all surfaces of both guides at the sides Once printed and clean, make a screw for the filament sensor bolt (Part #G) in the hole. Again I reccomend using a tap male but you can force the screw with an M3 bolt.

Step 11

SliderCartAssembly.

Assembly: Place the Bearing (Part #H) in the TPU roller (Part #1). Use a slotted 16 mm bolt (Part #C) as the shaft for the bearing. Drive the Bearing's fixes A and B (Parts #8 and #9) to the bottom of their cases tightening the shaft bolt. Once they are in place, loose the bolt (Part #C). Make sure you do not tighten the bolt too much. The roller must rotate with barely any friction. Place the magnet (Part #I) in the slot. Polarity must be set so when in position (the roller in contact with the blade), the BladeHolder magnets and the SliderCartAssembly magnet should repel each other (though they are pretty far away)

Polarity of all the magnets of the device, starting from the front and going to the back of the extruder must be set like this:

(+/-)(+/-)(-/+)(+/-)

(+FrontTrap 10 x 2 magnet- )(+BladeHolder 3 units x 3 x 2 magnets-) (-SliderCart 10 x 2 magnet+) (+BackTrap 10 x 2 magnet-)

Now you should test that you can assemble easily the filament sensor. Use the M3 x 4 Nylon6 bolt (Part #G). Remember that the mirror must be facing the roller, but do not assemble it just yet.

The SliderCartAssembly is ready.

Step 12

TopCover (Part #4)

Printing: Print it upside down with support.

Preparation: Make sure you clean well the filament passage and the four holes for the bolts. One of the holes (the flat one) must have a screw. It is best to use a Tap male for it because this hole is going to be the FrontTrapLock (Parts #F and #12) thet keeps the FrontTrap shut , so you want it to run really smoothly. The other three holes must let the M3 x 30 bolts (Part #A) through and cannot be threaded.

Use a hot soldering Iron tip to place the M5 nut (Part #E) for the Festo connector in place.Make sure it sits straight.

TopCover is ready

Step 13

BackTrap (Part #6).

Printing: Print this part with no support.

Assembly: Place the 10x2 mm magnet (Part #I). Polarity of the magnet must be so that the slider cart pulls away from the back trap and pushes towards the filament.

BackTrapAssembly is ready.

Step 14

FrontTrapLock

For the FrontTrapLock, the best is to use a bolt (Part #F) and a Plug (Part #12) for easy inspection with no need of tools. Fit the bolt (Part #F) into the Plug's hole (Part #12) with a nut and a washer from the other side until the bolt's head gets to the bottom. It will stay there. Remove nut and washer.

Step 15

Top Assembly

Follow these steps in order:

1- Install the FrontTrapAssembly on the TopCover. Use both bolts (Part # A and #F) to set it correctly in place, but do not tighten them. The bolt on the left (M3x30) (Part #A) is the shaft fot the hinge of the FrontTrapAssembly. The one on the right is the FrontTrapLock

2- Slide the SliderCartAssembly FROM THE BACK into the TopCover.

3- Place the nylon bolt (Part # G) in the filament sensor hole.

4- Put the filament sensor with the bolt (Part #G) through the side window of the TopCover (Part #4)

5- TILTING the SliderCartAssembly you will easily be able to screw the filament sensor bolt into its hole in the SliderCart. Remember that the mirror must be facing the roller. The filament sensor could be bolted also into the SliderCartAssembly with the TopCover in place in the extruder, but I find that it is more difficult, uncomfortable and the procedure is finally much slower.

5- Slide the BackTrapAssembly into the TopCover FROM DE TOP, until it is flush.

TopAssembly is ready

Step 16

In the assembled ExtruderBody, put in place with care the TopAssembly . First the BackTrap guides, then the bolts. Do not do it hastily. Take care that the filament sensor does not move while assembling.

Step 17

Set the three M3 x 30 bolts (Part #A) but do not tighten them. Tolerances are tight, and the sensor cover has not been designed too strong so it would be light. If you tighten these bolts too much, plastic parts will bend ever so slightly, and the SliderCart might not move.

Step 18

First check that the TopAssembly is correctly in place and everything looks nice and neat. Now open the FrontTrap and check with your finger that the Slider cart can move with ease. Check that it comes back to the front right away. Tighten the three bolts slowly and jumping from one bolt to the other. Stop and ease the moment you detect that the slider cart does not move as easily as before. There are no big forces there, those three bolts don´t need to be that tight. Just check that nothing moves loose and that the FrontTrapAssembly can be opened when you free the FrontTrapLock.

Step 19

Last pre-flight check: Loose the FrontTrapLock and open the FrontTrapAssembly

• Does the Roller rolls easily?
• Does the SliderCartAssembly moves backward easily when pressed with a finger?
• Does it come to the front right away once it is left alone?
• And in the FrontTrapAssembly:
• Does the blade gets out easily when the lever is actioned?
• Does the blade retract swiftly when the lever is no more actioned?
• Is the blade completely hidden from the filament's path when retracted?
• Close the FrontTrapAssembly again and secure the FrontTrapLock. If you didn´t close it well, the TopCover would raise and bend, and a creek would appear between the parts.

Step 20

Place the electrical connector in the filament sensor's pins. Red cable at the front, white cable to the back of the machine. If the sensor cable is just a bit too short I reccomend redoing the textil seath work on the cables again. Ten minutes job but it's worth it. There's enough filament sensor cable (the one that is red, blue,white & black) in the MK3 to do a nice and neat job.

Step 21

Connect the Festo, and here we are ready to go.

The frog is assembled. Happy printing.