So the preferred way to print soft TPU (we’re using 85A here at work) is to suspend the spool overhead and lead the filament straight down into the printhead. I’ve got a bridge (printed end supports and strip of plywood) on which sits an HT. But that got me to thinking…
A static overhead spool support has a stationary output. The HT sitting on its bridge has a stationary output. Both options require removal of the top cover. why not just drill a hole in the cover, line with a little piece of PTFE, then TPU could be printed with the cover in place. The entry point into the printer won’t really be more static than it is anyway…
Just a thought, looking for good reasons why not to… thanks.
Probably not a bad idea as long as you can keep the hole sealed for other things.
I’m dabbling a bit into TPU, not running AMS or anything crazy (obviously), but definitely not taking it out of the PTFE tubing or building some contraption to put it on top.
I use a spool holder I designed for pallet racks / wall that uses skate board bearings (i put 3kg spools on them mainly for other materials) and find it’s perfect for TPU as I think the biggest hurdle is the friction from pulling on the spool.
Let me tell you, you have a spool that can rotate on needle bearings / freewheel for 20 seconds at a time, there ain’t much friction
So I have no issues using the left nozzle, running it through the TPU port (ptfe tubing) all the way to the spool holder I designed that has a PTFE quick disconnect as well. No open air printing. No removing the PTFE. No taking the top lid off. No TPU assist thing etc.
Thanks, @Tool_Maker . I know what you mean about the bearings. I designed a dual holder for my Neptune 4 Pro at home with 608’s, and the spools turn too freely.
At work we have AMS2’s on both nozzles. Primary filament on right, mostly support on left (but also sometimes embedded text). I don’t mind unplugging the RH PTFE, just thinking it would be nice to just set the HT on the top cover (I’ve needed to Gorilla Tape it onto my plywood bridge to keep it from walking around…)
It’s a nice idea for BL, but the last thing I want to do is drill into glass. Just seems too easy to have a hairline crack and have the whole thing shatter.
Well, if you do end up drilling a hole successfully, make sure to set up at least a grommet; and probably should be sized 4mm ID so that it could also hold PTFE at a future date [this same setup would be useful for ultra brittle CF filled engineering jank]
The print head moves in both the x and y axis, if you drill a hole in the top, then the TPU would be dragged (or worse, snagged) against the edges of the hoke you created for most of its motion.
This is counter to the reason it is meant to be direct feed to reduce friction.
Instead of the hole, it certainly is better to just feed from the rear input.
If you want to keep the TPU in the AMS HT, I would go with the assist module.
Thanks for all the feedbacks, I did say “looking for good reasons why not to” and you all have not let me down.
Drilling tempered glass is no problem, and I’ve worked in the scientific instrumentation field all my career, and machining a custom grommet out of pure PTFE rod would be no problem at all. But all your reasons not to are good ones.
The HT is sitting on its bridge, with its output (I heat-formed an upside-down-U PTFE tube for the lid hole) above the center of the printing area. But the outlet of the PTFE is a good 150mm (6 inches in Freedom Units ) above the plane of the lid and that is the main consideration for me.
So “lid on, lid off” it will continue to be. At least my printed bridge supports are relieved on the bottom so I can slide the lid off without disturbing the bridge.
Well, just think about it this way. You are simply removing (in my case because I want to use the left nozzle) the PTFE from the inside buffer for left side and poking it out the TPU hole, then the PTFE from the external spool lines up to that.
It’s literally a 20 second operation that requires virtually no setup or worrying about crossing over compared to messing around with the lid, and placing holders on top etc.
That’s why I did it was for convenience. I don’t want to have to set up some sort of jig and change the machine all around every single time to print a certain type of material.
Understandable if you are in some sort of wet environment, but I keep the shop frosty, naturally getting rid of humidity.
@Tool_Maker , I’m in north Texas which is not renowned for its low humidity… I don’t run 85A through any more PTFE than I can help (from expeience–90A and 95A were OK going through PTFE from the TPU input), and the 85A spool lives in the HT at an elevated temperature. I still need to go through an actual drying cycle every few days even so.
If you don’t want to fiddle around, get the TPU assist module, and run a new PTFE through the dedicated TPU tube inlet. You can put the filament in an AMS-HT, just feed it through the bypass hole.
I run 85A in the same exact setup and no issues whatsover. I’m from corn country, millions of acres of green crops in every direction. We have lots of humidity lol.
But the shop is a different story. I insulated the crap out of the machine shed when I built it, (spray foam, blown in, insulation board, and pole barn batts). So the AMS units read 6% without doing anything inside here. As long as I leave the main equipment doors closed, I never have to dry anything. The AC is constantly taking any humidity out of the air.
@CarbonForge , if we get a TPU assist module and run the TPU in through the extra rear inlet from the HT (I already have an internal 4-into-1 installed in the right-hand nozzle PTFE path from earlier experiments with the extra rear inlet), it would be treated as any other AMS filament with no special workflow required? Load and unload as with PLA, PETG etc? That would be sweet.
Well, its a bit more fiddly, to unload you need to stop the assist module, disconnect the PTFE at the printhead, then do the unload on the machine to cut it, and then use the TPU assist model to retract it. (it sounds alot, but its more intuitive when you actually do it)
The ting works great, and beside the disconnecting PTFE at the printhead the rest is no issue.
) above the plane of the lid and that is the main consideration for me.