Designing a Front-Mounted Toolhead + A Pro/Plus Hybrid Refit

[formal knoll]

Background:
Turtlecrawler released X joints for front-mounted belts in January. I started work on a front-mounted toolhead in late February. This is a build log until (and if) there's a mod release.

The Toolhead Plan:

• Front-mounted belts
• Minimalist: light and rigid
• Simple assembly and disassembly
• Cutter and/or hotend runout sensor option
• Part Cooling: Dual 4010 fans (potentially dual 5015)
• ABL: Beacon (all form factors), Carto, and probably Klicky support

The Refit Plan:

For this project, I will refit Gonzo, a build with a Plus bed on a Pro-height Z axis. It's good for big PLA prints and toolhead prototyping.

Gonzo's Todo List:

• New belts
• New idlers
• New X Joints: https://discord.com/channels/747612067951018075/1459741403776159881
• Deep clean the printer

[formal knoll]

hmm, not liking how the fan fits together with the hotend mount. May restart.

ideally the cooling fan and hotend mount are one piece, but the ductwork in there makes that tough. Maybe as a shim between fan and hotend?

[formal knoll]

Got some ideas about the hotend mount; gonna let it simmer. Going back to the Core mount for now.

looks like this at present. Four front mounts for the toolhead proper, side attachments with shoulder bolts for the belts.

I should scooch the bolts in a little. there's room.
Also:

• Add bottom lip with two anchors for ABL
• Add wire management stuff

Scooted the bolts, added wire anchors

fixed up the fastener positions, added m3x6 screws.

[formal knoll]

ABL, part cooling, and MCU next

[formal knoll]

internal part cooling debates, going on right now in the Premium Channel.

[forest forge]

following this for sure

looks long forward

how much?

[formal knoll]

68.5 to the carriage

[formal knoll]

I shortened it to 55mm

[formal knoll]

took a moment to make the front not look silly

not there yet, but enough to start with

I'd like the duct to be one thing that comes off with the hotend cooling fan, to give immediate access with 2 screws

[forest forge]

looks better

[forest forge]

BTW can't you make these 2 a single piece?

[formal knoll]

Prolly, but it would mean removing belts to change the extruder mount

gonna take a look at thinning walls and slimming down the screw head holes

[forest forge]

going modular?

[formal knoll]

less modular than considering maintenance in the design. I consider the core plate unremovable aside from belt maintenance. design should never change, it should never be touched.

consider that top plate to be more like E34M1's extruder mount in that it's meant to be extruder-specific

[forest forge]

got it

I really need to publish mine, it has been good so far no maintenance really needed, it was also stopped for a few months and no issues

[formal knoll]

doo eeet

just throw the files on printables with some vague instructions 🙂

"Steps: 1. download the files. 2. you know the rest lol 3. profit"

[forest forge]

I even have an assembly ready to export all parts with the correct printing orientations

[formal knoll]

ooh okay do it then!

working on mass reduction today

[forest forge]

nahh more like:

• Download files
• Print files
• CNC plates
• BOM
• Screws etc
• Assembly, check assembled STEP for instructions if needed

[formal knoll]

that's better than 90% of other toolheads. even mentioning assembly is a win, lol.

this is better.

[forest forge]

how big are those fillets on the belt area

might be worth making them bigger if there's space

[formal knoll]

there's a lot of fillets there. which do you mean?

[formal knoll]

ahh okay. lemme see

nah, not much room

just enough for the belt

i drafted the front face to add some mass, though

huh

what if the bolt bolted to the carriage. all stress would be on screws

or if the bolt slide back to trap the belt

ohhhh okay yeah this is cooking

[forest forge]

the strongest way I have found so far is the method on mine, kinda tricky to get in place but uses the belt tension itself to tighten

[formal knoll]

link to some pics?

oh sh**

idea

oh more ideas

hotend needs to screw into the extruder mount, for sure. it'll help prevent cantilever effects, and allow removing the hotend and extrduer as one

gonna replace that shoulder bolt with something else as a compromise

[forest forge]

was going through my log none there hold a sec

very very old proof of concept picture with my kid lego

I thinks I never made it in cad

can get actual toolhead pictures

[formal knoll]

interesting!

the long bolt is in the wrong place then

i dunno, i kinda like the setup as is, assuming it works

oooh butttt

[forest forge]

my setup needs 2 screws

[formal knoll]

what if there's a left and right "core" piece

and the belts and sandwiched between them

[forest forge]

why not just 2

[formal knoll]

so that you can attach one belt, stop, and then attach another

I think I figured it out now

[formal knoll]

well, got it right but also messed up. i'll try again in a sec.

[formal knoll]

hrrrrm seeing something in my mind's eye

Yeah I think I can design this.

[formal knoll]

ABL inserts need adjustment now, but good progress. it's printable, too.

[formal knoll]

Getting big bird warmed up for this, gonna print a little to see what happens

[formal knoll]

oof it smol

gotta make it taller by a few mm, prolly 2mm wider, which is def okay

here's an extruder mount in the mean time

[formal knoll]

got a more refined version printing. 2mm thicker, 2mm wider

[formal knoll]

i guess i'll print the rest of it and mount it

[formal knoll]

this, uh, appears to work

maybe need to make one tweak, but it works

[formal knoll]

dropping the bolt for the belt grabber. gonna use it as a shim that screws in with the two MGN12H mounting holes

ooh maybe not

[formal knoll]

two grabbers, two inserts. attach belts to them individually. should make installing belts super easy, too.

[formal knoll]

a couple iterations later and i'm making more progress

[formal knoll]

apologies for the zits.

[formal knoll]

LFG

[formal knoll]

Printing a finished extruder mount now

[formal knoll]

I need a second point to attach the hotend to the extruder, so that they stay attached and in position when removed together

[formal knoll]

was fiddling with mounting hotend and extruder together and may have cooling inlet idea

what if the fan bolts to the cooling duct and the hotend mount is just part of that connection

so the hotend mount will have a 30mm fan intake in the front, but no duct for it between the fan and hotend

the duct will have the heat set inserts. screws for the fan go through mount (the intake), the fan, then connect them to the duct

[formal knoll]

like this

not great looking, but on the right track

gonna tweak the core module, make the pillars for the toolhead and hotend mount taller

[formal knoll]

Better. Coming to life a bit.

[formal knoll]

plenty of work I can do on fillets later, so I'm going to stop twiddling so much and get the basics done

[formal knoll]

ooh, i can stick zip tie anchors inside the hotend mount, so no wires are visible

also figured out the gap between hotend and extruder is perfect for a cutter mount

currently considering how to use that space to anchor top (extruder) to bottom (hotend)

[formal knoll]

i doubt the hotend cooling duct design will change, so will print that today

oooh

[formal knoll]

@forest forge q: how much space do I need to leave between the hotend and extruder for a cutter? is 7mm enough?

[forest forge]

I need to check mine, but I think maximum 10mm

rough measurements 6 or 7, I'll check in cad

8mm measured in cad, you may be able to fit in less space

[formal knoll]

version 4 looks much better. i'll see how it prints tomorrow. tired.

[formal knoll]

progress. making this entirely parameter driven

the standoffs between extruder and hotend are temporary. that'll be filled by a cutting tool

[formal knoll]

i need to play with the extruder mount thickness, but the overall design is right

core v4, the one i did this morning, needs some zip tie anchors added, for sure

once this hotend mount reprint is done, i will have a nearly complete assembly and can make some more decisions about mounting the hotend fan.

Designing a Front-Mounted Toolhead + A Pro/Plus Hybrid Refit

Changing the title. Nobody knows wtf Gonzo or TBD Toolhead means.

[formal knoll]

made it so the carriage can't run off this rail I'm using as a test rig. anxiety is down, lol.

i am printing a third revision of a simple tool mount that does nothing but act as a spacer. hopefully there is enough space to design a cutter in.

28mm in there. hopefully the screw standoffs don't interfere too much. I can move them out, perhaps?

[formal knoll]

Mostly tuning and fixing bugs discovered during assembly rn. I'll have more pics up once I have a complete extruder/hotend/toolbox together

toolbox is what i'm calling the tool compartment for cutter/runout sensor

[formal knoll]

Looks more toolhead-ish. Had to extend to 62mm and elongate the hotend cooling fan duct

the little hole in the side is for wiring passthru

[formal knoll]

Beacon support added. Docs say it should be 30mm from the nozzle, so it is.

[formal knoll]

building up context in the assembly model

[formal knoll]

ducts

stopping for the night

[formal knoll]

Lowest point is 2mm above the nozzle

[formal knoll]

toolhead

[formal knoll]

gonna take a break on the ducts and work on the limit switch and MCU

all that's left is mounting them with magnets, but that's a lot of backwards integration I don't feel up to rn

[formal knoll]

had some duct ideas, gave up on some duct ideas. struggling with mounting it, preferably with magnets.

meanwhile the limit switch idea seems pretty simple

[formal knoll]

now to figure out the mcu bit...

[reef turtle]

I'd highly recommend adapting the speed clips that Zruncho's used on madmax and vampire bat (mostly just because they're real nice and if you're iterating on a toolhead design zruncho's said it's quite useful to not have to deal with the tensioning over and over). The only thing that's a smidge irritating about them is prepping the dowels, but 🤷 it's nice because if you do need to take off the gantry it's quite painless.

[formal knoll]

I should probably print this last duct iteration and see if it's the right direction

overall, though, I think it's time to start v5

i like the overall direction atm, but it needs work, especially the toolbox and exterior look

the hotend mount needs to extend lower so the ducts have something to attach to

the toolbox needs to be leaner, easier to install and remove

i am thinking I should design a cutter in for the toolbox

a 5mm spring on each side would fit, I think?

wondering if I need a microswitch involved

this is doable

now with springs

I see this as a 3 piece part

toolbox body, microswitch/PTFE tube component, and the cutting blade holder

Microswitch + ball bearing will act as a load sensor and sit after/below the cutter

I guess we're doing MMU now

15mm springs 20mm springs, 5mm of travel, seems right

think i got a design in mind, too. sick. gotta work this morning, but i'll be back.

[formal knoll]

gonna use 3mm dowels to ensure the springs compress evenly and the travel is smooth

i had to order the parts from amazon, so this can pause until sunday

[formal knoll]

gonna find out how well the X limit switch mounts before fussing with the cutter one more.

ideally, pins will fit through holes. we'll see.

what if i make the hotend mount taller and integrate the cutter to that, and make the switch part of the extruder plate?

cutter with hotend = short purge

switch with extruder = load sensing close to the extrduer gear

[formal knoll]

huh

i should consider using M2.5 more

it'd be handy if the fans and cutter attached to the toolhead with M2.5 socket head

that raises the question of M2.5 inserts. dang.

[formal knoll]

i've been mulling the cutter/switch layout (and working, etc)

thinking i will not use a lever. instead use springs on the bumper to push back against the cutter springs

two springs in the cutter, two in the bumper

it'll keep the toolhead more compact, to boot, since levers are bulky

[formal knoll]

oh snap kids

figured out how to hold the toolbox AND extruder together

m3x 25 to the rescue, again

orrr shoulder bolts

probably a better idea

[formal knoll]

shoulder bolts should arrive today. reworking the extruder so that the microswith is built into the extruder mount.

[formal knoll]

so i am in love with these shoulder bolts and will use them for something else

but the ext. diameter is the same as the spring's internal diameter and it will not slide over.

back to screws it is

[formal knoll]

sick cat yesterday, had to hit pause.

cat is better.

[reef turtle]

This one likes the heated bed I got her 😂

[formal knoll]

cats love enclosed printers. they love unenclosed ones TOO much!

hopefully the cat (and some work) drama is done. will pick up this weekend, see what's next.

[formal knoll]

Still kinda recovering from cat situation. She's doing way better, but I'm still stressed. >.<